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Video tags
Subtitles
Russian
00:00:03
Living Today again a lecture from00:00:07
Rosenheim namely Gaia by Professor Dr00:00:11
Stefan Jordan from the Center for Astronomy00:00:14
in Heidelberg Gaia is one of those00:00:17
cool spaceships that takes a closer look at the Milky Way00:00:21
and namely Gaia00:00:23
measures the Milky Way in the most precise00:00:26
positions and from these00:00:32
At the beginning, colleague Jordan will first00:00:35
introduce the mission and00:00:37
then go to the latest00:00:39
findings from the latest data release00:00:41
and those who already know the beginning00:00:43
can simply jump behind it with a jump mark00:00:45
and then go00:00:47
straight to it look at the results have00:00:49
fun there is the second star catalog00:00:52
sounds boring at first00:00:53
actually the first year00:00:55
is perhaps the most exciting part or00:00:57
the very last part there will be00:00:59
more catalogs coming they are getting better and00:01:01
better the first catalog was00:01:03
a certain way are small00:01:04
appetizers for the astronomers where we00:01:06
will therefore also say a little about how00:01:08
the comparison with the current00:01:09
star catalog compares. I will of course also00:01:11
pay particular attention to the current one, so the00:01:13
big step from Gaia was this00:01:15
second star catalog, the others are00:01:17
essential improvements that need00:01:19
We also definitely do, but this is a00:01:21
really, really big step within this00:01:23
project and that's why the00:01:26
publication on April 25, 2018, when00:01:30
this Gaia catalog was00:01:33
accessible to all astronomers at 12 noon, was00:01:35
a challenge for00:01:38
many who then immediately went to their computers00:01:40
Those who00:01:41
downloaded the data made00:01:42
the first publications within a few days,00:01:44
so that was really a00:01:46
big step in astronomy, not00:01:49
perhaps a big step like00:01:51
Neil Armstrong's step, but00:01:53
also a very, very00:01:55
huge step for astronomy00:01:58
I'm going to say a little bit about improving the Milky Way00:02:00
and what we see here is an00:02:01
animation, that's what it's a satellite.00:02:04
In reality, this parasol00:02:07
that you see here is 1000:02:08
and a half meters in diameter, so it00:02:10
's00:02:12
currently about a million and a half00:02:13
kilometers away00:02:19
The actual instruments00:02:21
are here in the shadow of this00:02:23
parasol, which is always aligned 45 degrees relative00:02:26
to the sun, which00:02:28
means that the00:02:29
temperature of Gaia remains constant. We have to00:02:32
ensure that somehow The00:02:33
measurements that are supposed to be so precise can00:02:35
then also be made in an environment00:02:37
that is very calm and00:02:40
predictable and Gaia actually rotates on its00:02:46
own axis as shown here,00:02:47
so that sounds a little more exciting.00:02:49
I have another one00:02:50
In reality, it was made a little faster,00:02:51
but that was six hours, that00:02:53
was once it rotates around the axis, but00:02:54
then you would hardly see anything,00:02:56
that's why we just sped it up a little bit00:02:57
here as we00:02:59
speak, Gaia is making more measurements,00:03:01
new stars are constantly being measured and00:03:04
every minute On average, the number of stars we are here will be00:03:07
measured at more than 110,000, and00:03:12
this data will00:03:13
be constantly collected and transmitted to the ground every day.00:03:16
Typically, we have six00:03:19
to eight hours of ground contact with one of00:03:21
the 35 meter antennas that ESA has there There are00:03:23
three of them, one in Spain, one in00:03:26
Australia and one in Argentina and00:03:29
sometimes we need all three00:03:31
then if you know me, yes, the one along the00:03:33
Milky Way then there is a00:03:34
particularly large amount of data in the Rhine, the00:03:36
memory would overflow pretty quickly and00:03:38
then sometimes three antennas and00:03:39
then downloading the data.00:03:41
Sometimes we also compete with00:03:43
other projects,00:03:45
especially when we land on Mars, then00:03:47
they also want a bit of something,00:03:49
but we are actually the main users of00:03:51
the antennas at the moment with00:03:53
the Goya project and on April 25th00:03:57
We have published our second Gaia catalog00:04:00
and that is a00:04:01
huge amount of numbers that00:04:04
you can do something with, namely00:04:06
1.7 billion star00:04:10
positions that we have measured and00:04:12
the brightness of the star00:04:15
is 1.7 billion billion How00:04:17
can you spend a large sum when it comes to00:04:18
money? It's quickly spent00:04:21
1.7 billion if you00:04:23
want to count for each team that needs 1.7 billion for00:04:25
every paying second. Looked at00:04:27
that 51 years so that's a00:04:30
big number for 1,00:04:33
We also measured the brightness of 4 billion stars,00:04:35
not only in the overall brightness00:04:37
but also the brightness in the red00:04:38
range and in the blue range I would certainly have00:04:40
range so that we also know the colors of the00:04:42
stars, that is, the colors of the00:04:45
stars tell us something00:04:46
about them, for example Temperature of the star A red00:04:48
star is cooler than a blue star00:04:50
and there is no point in00:04:53
us knowing exactly the positions of the stars and00:04:54
a lot about the stars but, for00:04:56
example, not knowing certain parameters00:05:00
Special is00:05:02
hidden in this sphere here or00:05:04
hidden on this circle here that is 1.300:05:07
billion positions, to which is added00:05:11
the movement of the stars,00:05:13
how they move in the sky and their00:05:16
distance measurement and that is00:05:18
really the great progress that is00:05:21
in here And it00:05:22
's really incomparable if I00:05:24
compare it with the first star catalog from00:05:25
Gaia that we published in September 2016. There00:05:28
were two million00:05:30
stars now 1.3 billion and the two00:05:34
million were 20 times more than we00:05:36
had before, that is Not only do you00:05:38
have a small appetite, it was already00:05:39
quite a good appetite, with which00:05:41
many astronomical00:05:42
discoveries have already been made.00:05:44
Here, another00:05:46
parameter such as the00:05:48
surface temperatures, radii, luminous00:05:50
forces, amount of dust in the direction of the stars00:05:53
was also measured for seven million stars00:05:55
The speed will be measured by the stars00:05:58
moving towards us or away from us. There will be00:06:01
many more to come. At the00:06:03
moment these are only the brightest stars. That00:06:05
will be significantly more in the next catalogs. There will00:06:08
be significantly more stars that measure with Gaia Just how00:06:10
does the star in the00:06:12
sky move tangentially to the00:06:14
direction of view, so to speak, but if we00:06:16
want to know the real movement in space00:06:18
we still have to know how fast00:06:20
the star is moving towards us and away from us.00:06:23
We only know that for 7 stars at the moment00:06:25
In the end we will00:06:27
have maybe something like 100 million stars00:06:28
that is a little more difficult to measure00:06:30
that came because we don't get quite as deep00:06:32
from the brightnesses so that's why00:06:35
it will be less than00:06:37
this but the crucial thing00:06:39
is and the distance measurement of the00:06:41
stars, which I00:06:43
will say a little more about,00:06:45
then the catalog contains a00:06:47
little appetizer for people who00:06:50
deal with variable stars, i.e. star conductor00:06:52
brightness changes, so we have00:06:54
half a million at the moment00:06:55
Objects in there will be a lot more00:06:58
and 14,000 objects in our00:07:00
solar system mainly asteroids00:07:02
that will be around 250,000 300,00000:07:04
that we will measure with Gaia where we can00:07:07
not only measure urban measurements00:07:09
but also objects in our00:07:10
solar system and thus their orbits00:07:12
The future00:07:14
is, so to speak, the00:07:17
rough result of what many00:07:19
places have in the catalogue, but I would00:07:20
n't stop there, but of00:07:22
course I'll first tell you a little00:07:24
about how this came about00:07:25
and what you've done with this data00:07:28
It definitely had00:07:30
this influence on the00:07:32
astronomers and in jargon the 600:07:34
stand catalog is not called the Aryan catalog00:07:36
but Gaia data release to also since the00:07:40
second data release of Gaia00:07:43
Gaia DDR2 is, so to speak, the key word00:07:46
when you look at the position that we00:07:48
measured in the sky applied to00:07:50
a sky map and00:07:52
we have such a sky map here both its00:07:54
electrical representation you have a00:07:56
hammer projection where the entire sky00:07:58
is shown here we see the00:08:00
stars of the plane of the Milky Way here where there are a00:08:03
particularly large number of stars and00:08:05
here we also see them Accompanying00:08:06
galaxies of the Milky Way, the Large and00:08:09
Small Magellanic Clouds and such00:08:12
a map, you may have already00:08:13
seen it yourself and thought, well,00:08:15
what's special about it? What's00:08:17
special is that this00:08:19
isn't a photograph of the sky where you00:08:20
simply00:08:21
put together different images In order to have a large picture00:08:23
of the Milky Way or the00:08:25
entire sky, these are all00:08:28
just stars,00:08:29
which means that all the gas nebulae and00:08:32
everything that drives me to a point are missing,00:08:33
which means that here every point there is in00:08:37
reality the star, this is the00:08:38
distribution of the stars00:08:39
Of course, you can see indirectly that there00:08:42
are also gas clouds in meters of space00:08:44
because there are such dark00:08:46
structures that come00:08:47
about because the light00:08:49
is swallowed up by the stars that lie behind them, that00:08:51
is, indirectly you can see that there are00:08:53
fewer stars in certain00:08:54
places In reality,00:08:56
this is a map that really shows a00:08:57
star map of 1.7 billion stars,00:09:01
so of course this is00:09:02
just the density distribution. You can't00:09:03
see every stone individually,00:09:04
but there is a version where you00:09:06
can also zoom in so that you can see up to The00:09:08
individual star comes later, but what I00:09:11
want to show now is we have00:09:12
a small program with which,00:09:13
by the way, this initial animation00:09:15
and most of the animations that I'm00:09:17
now showing here were made, that00:09:19
's called Gaia Sky, with which we00:09:21
animated how The stars then00:09:23
move so let's think about00:09:27
this sky program that is00:09:29
colored a little differently here00:09:30
and if we look now00:09:32
we see that the stars are moving00:09:34
and the stars are all almost00:09:37
moving and that is a movement00:09:40
which is now about a million times00:09:43
faster than the movement in00:09:44
reality, which means a00:09:46
big time lapse, so to speak, if you00:09:48
could look that quickly then you can00:09:50
see the individual stars moving00:09:52
and that is something that Altwasser also00:09:55
says about the stars from the movement00:09:57
The stars can be00:09:58
explained a little later about how our00:10:00
Milky Way is structured and how it00:10:02
came into being.00:10:04
I will00:10:05
go into certain things in a little more detail later if00:10:07
you simply record the movement of the00:10:09
individual stars, i.e. a line trace,00:10:11
on the computer Then it looks like00:10:14
this at first it looks pretty00:10:16
chaotic or so that's the00:10:18
movement within 800,000 years00:10:21
how the place changes because sometimes there are a00:10:22
lot of stars are like star clusters that00:10:24
then move parallel across the00:10:25
sky and that's so to speak the00:10:28
lines recording the We have just00:10:29
produced00:10:31
for the seven million stars for which00:10:34
we also have the movement of the stars towards us and00:10:35
away from us. There is this00:10:38
representation of the stars that are00:10:41
moving away from us, which are colored reddish here00:10:43
because the Doppler effect00:10:45
is measured I don't want to00:10:46
go into it in more detail now, for the experts00:10:48
know that of course they are shifted in red00:10:50
and the others that are00:10:52
approaching us are shifted blue00:10:54
and you can see that is spread over the sky00:10:57
if you then subtract00:11:00
the movement The sun is00:11:02
much easier because now00:11:04
the stars come towards us on one side00:11:06
and away on the other side00:11:07
because we observe with00:11:09
Gaia of course because also with00:11:11
the sun through the universe duty00:11:13
through those around them00:11:15
We observe the Milky Way from a carousel, so to speak,00:11:16
and you actually have to00:11:18
take this carousel off, so to speak, if00:11:20
you want to do that exactly in order to get the00:11:22
actual movement of the stars00:11:25
and the goal is00:11:27
of course to say something overall about the00:11:29
Milky Way and the star system00:11:31
as well We belong and these 1.700:11:34
billion stars sounds like a lot but the00:11:37
Milky Way contains, we don't00:11:39
even know, between 100 and 30000:11:41
billion stars,00:11:42
which means that it's always just a00:11:44
sample, but from this sample00:11:46
we want from this relatively00:11:48
large sample Because something00:11:49
close and about the Milky Way00:11:52
itself with other galaxies it is00:11:54
much easier to say what does00:11:56
this galaxy look like because you take a00:11:58
photo from above that most of00:12:01
you who are00:12:02
involved with astronomy with me know, of course00:12:03
here in the 51st century This whirlpool nebula00:12:07
or this this galaxy00:12:09
you can clearly see these spiral arms spiral arm00:12:13
are always the areas where young stars00:12:15
are formed,00:12:16
these are not necessarily more stars00:12:19
than in the other areas but these00:12:21
are particularly young, bright00:12:22
stars and in between there are almost00:12:25
exactly the same Many stars, perhaps ten00:12:27
percent more in the spiral arms than00:12:29
outside the spiral, this is something that00:12:31
you may not even notice,00:12:32
but essentially it will give you the location in the00:12:35
spiral arms where00:12:38
star formation takes place. You can see00:12:40
exactly on these routes areas that are00:12:41
the clouds in where00:12:43
star formation takes place in order to00:12:46
create our Milky Way.00:12:49
You have to go there and do00:12:52
n't know the distance because we have the00:12:54
advantage of being very close to00:12:56
the stars, but on the other hand we do00:12:58
n't have the good perspective that we do So we00:13:00
can look out from above and that's why00:13:02
it's much00:13:04
more difficult for us and we don't know00:13:06
exactly what our Milky Way00:13:07
looks like and it's not even very inaccurate,00:13:08
so this picture, which00:13:10
many of you may also know,00:13:11
gives the actual impression00:13:13
that it's all in white and that's00:13:15
not the case at all, so the sun is00:13:17
about here and here are the00:13:19
different spiral arms here in the00:13:21
middle you have this this production00:13:23
this ball stars a bar in it which,00:13:27
in contrast to this spiral galaxies, it's00:13:30
round in the middle this production00:13:32
that is So a bar spiral our00:13:35
Milky Way you know that pretty well00:13:36
but how true how these arms00:13:40
position themselves exactly you only know that00:13:42
if you also know the distance of the00:13:43
stars because as we00:13:45
saw before in the projection we00:13:47
only see how they are Distribute stars in the sky00:13:48
but in order to then create a00:13:51
distribution in the sky00:13:53
we need to know the distance of the00:13:55
stars and that is of course one of the00:13:56
reasons why you want to measure very precise distances with da00:13:59
if you00:14:02
want to briefly say what should you do00:14:04
Then it's a very simple and00:14:06
classic task. We want the00:14:08
position, the movements, the distance00:14:10
of a billion or more.00:14:12
We have already measured more stars00:14:14
and we simply take00:14:16
all the stars up to a certain00:14:18
brightness, i.e. up to a certain00:14:21
size limit what you call it and the00:14:23
specialists of them know what the00:14:26
twentieth magnitude is. In reality,00:14:28
it goes up to the 20.6 magnitude, which00:14:31
is a candle about 20,000 kilometers00:14:33
away.00:14:34
These magnitudes. Well, the astronomers00:14:37
are the most conservative00:14:40
scientists ever when you think about it00:14:42
A unit of measurement was invented in 15000:14:45
BC by a Greek00:14:48
astronomer who entered the brightness into00:14:50
his star catalogue. The00:14:52
brightest stars have the first size and the00:14:53
weakest point has six greetings.00:14:55
Then we still use that today,00:14:57
so of course the system has00:15:00
been expanded up and down The00:15:01
twentieth magnitude class talks larger00:15:04
this number is the weaker are the00:15:05
stars and five magnitude classes are in00:15:07
my factor 100 weaker, i.e. in the00:15:10
star 15 the largest e.g. the one hundred times00:15:13
brighter and stars up to the sixth magnitude you00:15:16
can probably not get them in Rosenheim00:15:18
But like the00:15:20
fourth magnitude or something like that you can00:15:22
see it here and if you have the opportunity to see something beautiful in the arch of the00:15:24
Alps00:15:27
or in the desert00:15:29
then you can greet from there to the sixth00:15:30
that you can see that only up00:15:32
to one certain brightness and00:15:34
one thing that is a bit negative with Galia,00:15:39
we can't get the really bright stars because they are00:15:40
overlooked. Our00:15:41
instrument is so sensitive that00:15:45
we can't measure the bright stars.00:15:46
We then have to00:15:47
resort to the data Of the predecessor00:15:50
satellites that made measurements between 1987 and 1993, they00:15:53
only00:15:56
measured 100,000 stars,00:15:57
but in the end they also00:15:59
led to around 3,000 publications00:16:08
The person who00:16:11
invented the size classes made a catalog of stars under this star catalog, which was00:16:13
later used by Chromeos00:16:15
and published.00:16:18
There were about 100,000 stars measured,00:16:21
about 120 thousand stars, and with Gaia00:16:24
we want to have the billion so00:16:27
probably even more with a factor of 10 A thousand times00:16:29
more than in the parking garage catalog and the00:16:33
accuracy is increased by a factor of around 5000:16:35
and as I said with the00:16:37
Bright Star, we are unfortunately still00:16:39
appropriately dependent on the data from00:16:41
Demi Partners satellites, yes, but why do00:16:45
we even want to know how far00:16:47
away a star is I mean, I don't need to explain it to people who are00:16:50
always interested in astronomy,00:16:53
but you can00:16:55
easily imagine how we00:16:56
actually know that our sun is a star00:16:58
or that the stars are something00:17:00
like our sun is00:17:01
a clue would be that they have approximately the00:17:04
same luminosity if they00:17:05
were at the same distance00:17:07
shine equally brightly00:17:08
certain year a star that is twice as00:17:10
far has only a quarter of the00:17:12
brightness, which means it decreases with the00:17:14
square of the distance,00:17:17
which means we can If we00:17:18
know the distance, of course we can calculate00:17:21
how bright the stars actually are00:17:24
and we can then compare that with00:17:26
the sun and so we can see00:17:28
that the sun is a very typical star in terms00:17:30
of brightness and that was00:17:31
at least an indication that stars00:17:34
and these Our sun are similar objects00:17:36
or are the same objects. Today00:17:39
we are of course dealing with much more00:17:41
detailed questions. It is00:17:43
precisely about understanding stars and00:17:45
of course you have to know how much00:17:46
energy is really given off by such a star00:17:48
and of course we only know that00:17:50
if We know its distance00:17:52
because from the earth we measure how00:17:53
much radiation reaches us and so that00:17:56
we can calculate how much has gone away00:17:57
we have to know the distance and00:17:59
that is one of the main reasons for how to00:18:02
measure if you are measuring the distance of00:18:05
a star and this star Up there00:18:08
if you open a book in astronomy00:18:10
you can00:18:12
find dozens of methods for measuring the distance of stars,00:18:14
but there is only one00:18:15
method that is relatively independent of00:18:18
what assumptions we make about the stars00:18:21
themselves and that is the metric00:18:23
method that perhaps many You00:18:25
also know that the parallax method00:18:26
uses the fact that we walk around the sun with the earth00:18:28
and thus divide a star00:18:32
from different directions and00:18:34
the maximum deflection here is called the00:18:37
parallax angle, which comes about00:18:39
because we are at a distance from the00:18:41
sun of 150 million kilometers00:18:43
and twice the parallax angle are00:18:45
covered in half a year,00:18:47
i.e. 300,000 kilometers and this means that00:18:49
we see that the star shifts its direction a00:18:52
little and this00:18:54
shift is of course greater00:18:56
the closer the star is and the smaller00:18:58
the further away it is star is and this00:19:00
measurement is of course in reality00:19:03
completely exaggerated here00:19:05
in reality the angles are00:19:07
much smaller the data plays the role00:19:08
and the first who measured such a parallax00:19:11
he took advantage of that00:19:13
and star when I look at it when I00:19:15
and If you go in another direction when you walk around the sun,00:19:19
that's Friedrich Wilhelm Bessel who00:19:24
measured the first significant parallax of a star in 1838 and he00:19:30
made these measurements with this instrument in Königsberg in East Prussia and then00:19:33
found out that this parallax00:19:34
angle is 0 .31 arc seconds is an00:19:38
arc second is the 3600 part of an00:19:41
angle degree, which is already very small00:19:43
and so that the defense is not00:19:45
left completely alone, I will00:19:46
explain to him a little bit the00:19:48
small angles that are what this00:19:49
whole thing is about thing you can00:19:52
calculate that the distance is eleven00:19:54
light years that was a very precise00:19:56
measurement and by the way this is the star00:19:58
in the constellation here Spanish Albiol deneb00:20:01
and here the wings of the swan is a00:20:03
relatively inconspicuous star you00:20:05
can imagine maybe00:20:07
the experts know that Here's why00:20:09
Bessel took this star of all things for00:20:12
his parallax vests. He00:20:13
also took other stars, but this was the00:20:15
first time he made a measurement00:20:17
that was credible.00:20:19
How did he come to the conclusion that it might be00:20:21
a star that was a little closer00:20:23
than that Others that it wasn't moving particularly brightly,00:20:25
that was exactly00:20:27
the star because it had the greatest proper motion known at the time. You00:20:31
saw an00:20:33
animation of this Gaia data from me that the00:20:36
stars were moving in the sky and at that time00:20:38
that was the star where you could see them The00:20:39
largest movement per year was measured in the00:20:42
sky and that's why he thought it could be00:20:44
particularly close and that's what it turned00:20:46
out to be. The next00:20:48
star is 43 light years away, that00:20:50
their light is the next star but one of00:20:52
the next stars in there00:20:54
is and that's why Friedrich00:20:56
Wilhelm Bessel took these measurements there00:20:57
in order to make it clear to himself that the00:21:00
small ones are actually the angles that have to00:21:01
do with it. I want to00:21:04
illustrate this a little bit, let's take00:21:05
these people here, let's put00:21:09
them 200 meters away typical00:21:11
size 1 meter 75 and we measure00:21:14
the angle between foot and head, so to speak,00:21:16
then that is half a degree at a00:21:20
distance of 200 meters that is or00:21:23
angle diameter that the moon00:21:24
or the sun also has in the sky if we00:21:27
now this person now in 38000:21:31
kilometer distance places because00:21:33
that's what00:21:34
the seconds are per second so the00:21:36
3600 part of the angle is straight so it's00:21:39
something that is very very small and00:21:41
amateur astronomers who00:21:42
work with telescopes for this arc00:21:44
second something that corresponds to the00:21:46
resolution of the telescope00:21:47
and sees But then you see00:21:50
the third of a second that corresponds to a00:21:52
distance of 1000 kilometers and00:21:54
this person is a small spelled that00:21:55
Friedrich Wilhelm Bessel then00:21:57
measured of course from several00:21:59
many measurements that00:22:01
he took for 3000 individual observations in order to00:22:02
then create this parallax To00:22:05
determine this, you have to make a lot of00:22:06
measurements so that you end up with it.00:22:08
Now let's go further by a factor of00:22:10
1000. 380 x 1000 are 380,000. That's where00:22:15
the moon is. That's one00:22:19
millisecond, or thousandths of an arc00:22:21
second, and that's about the00:22:22
accuracy with the David Akers00:22:24
satellites between 89 and 9300:22:27
made his measurements so the00:22:28
final positions the individual00:22:30
measurements are always worse than those00:22:32
in the catalog with an elbow second00:22:35
so that is the typical accuracy00:22:37
we had before Ghana and with Gaia00:22:40
the target for stars is 15 of size00:22:43
that are a bit brighter than00:22:44
these very faintest stars to achieve an accuracy of 2500:22:47
or 20 or 25 micro arcseconds00:22:50
and that00:22:52
corresponds to these people 15 million00:22:55
kilometers away.00:22:56
You can imagine that this00:22:58
is an ambitious goal and we can00:23:00
also see how far He00:23:01
has already come up with this with this second00:23:03
star catalog if we can do that then00:23:07
that means that we can also00:23:09
measure the distance of the stars very, very precisely00:23:12
and have converted that00:23:14
into light years00:23:15
then we can00:23:18
have an accuracy of 25 micro arcseconds00:23:20
The distance of a star that is00:23:22
130 light years away is measured with an00:23:25
accuracy of one tenth of a percent00:23:27
1 percent corresponding factor00:23:30
10 further to 1300 light years 10 to 1300:23:33
thousand light years our Milky Way00:23:35
belongs to so that you still00:23:36
have my ideas there has its typical00:23:38
diameter of 100 thousand light years00:23:40
So at greater distances00:23:43
the data becomes more precise again,00:23:44
of course you have to know that but it's00:23:47
a huge advance of course that you can00:23:48
make it with such precision so00:23:51
now we want to make it clear what00:23:52
this looks like with the parallax and00:23:54
with the movements of the Stars,00:23:56
we now want to00:23:57
imagine that the parallaxes would00:23:58
actually be a hundred thousand times larger00:24:00
than they actually are. To do00:24:01
this, I once again took our00:24:03
computer program Gaia Sky, which is called by the way,00:24:05
and moved a camera00:24:09
around the computer, so to speak,00:24:11
on the orbit around the sun ran which00:24:13
is not 150 million kilometers but00:24:15
is simply a hundred thousand times larger.00:24:17
If you remove the stars or leave them the same00:24:19
then you see the following. By the00:24:22
way, if you look closely you will see the big dipper. There is the00:24:24
polar star and00:24:28
that is the movement that the stars00:24:30
make Our movement around the00:24:32
sun, these stars run back00:24:35
and forth on these parallaxes, that is, the00:24:36
big dipper, you can see that they are00:24:38
about the same distance away and you will00:24:41
also see the00:24:43
constellations faded in here the little one00:24:46
was the big bear here the Andromeda00:24:50
and the perseus and so on and so00:24:53
forth you see how the stars in the contract00:24:55
then something else happens immediately00:24:56
then we stop it for a moment and then00:24:58
we let the stars run across the sky so00:24:59
again00:25:00
we show our own movement in an extremely distorted way00:25:06
and you see The constellations00:25:08
very quickly no longer have anything to do with00:25:10
how they look today, so00:25:11
constellations are something that only works for00:25:14
a certain time in the sky.00:25:16
Now I've cheated on them a00:25:19
bit. I00:25:20
said the stars make a00:25:22
movement like that At the same time, I told him that00:25:24
Friedrich had00:25:25
chosen the star that00:25:27
moves the fastest in the sky. So he00:25:28
can't just make an ellipse00:25:30
in the sky, but he has to00:25:32
move across the sky at the same time, which means that he00:25:33
removes such a loop00:25:35
In reality that means a star that00:25:37
runs from down here upwards and at00:25:40
the same time it does this parallax00:25:41
and the path together, that's how00:25:43
the movement looks so composed.00:25:46
In reality that's what it looks like such00:25:48
movements that gala measures in the sky and00:25:50
from which we then Both the00:25:52
proper motion and the parallax00:25:53
then came out and for the experts00:25:56
what we need is in the catalog there are00:25:59
five numbers for most stars plus00:26:01
of course errors and00:26:04
correlations and everything else you00:26:05
need but for the star position00:26:07
five data are important there is one The00:26:10
position at the time of a certain00:26:12
reference imports at a certain00:26:14
time for the gala catalog 2 is00:26:16
that the means of 2015 that is the00:26:19
means of the measurement time because the00:26:22
Gaia catalog second was created from00:26:23
the first 22 months of the Gaia mission00:26:27
so that is This position there, that's00:26:32
true to us, is that there are angles in the sky,00:26:34
that there's something similar to00:26:35
geographical latitude and longitude on00:26:37
earth. There's a coordinate system in the00:26:39
sky that you take Recker's censoring and00:26:41
declination and then I have a00:26:43
movement in the sky So that means we00:26:44
indicate how the coordinates of00:26:47
recession and deflation change per year,00:26:51
that gives us something in milly00:26:53
arcseconds per year00:26:54
and that's up here, that means we00:26:57
have two angles there two angle00:26:59
velocities and then the00:27:00
parallax this one The effect here is that there00:27:03
are five numbers that we distill for stars00:27:05
at the end, so to speak, from all the00:27:07
individual measurements,00:27:09
which then go into this star catalog00:27:12
at the end 15 so 5 billion numbers or00:27:17
if we then have 2 billion stars00:27:19
ten billion numbers,00:27:20
that's so to speak But there are many,00:27:23
many numbers added so that you can00:27:24
interpret them correctly and so on00:27:27
and so forth and so that you can do this measurement and now very00:27:29
precisely, you have00:27:31
n't put satellites into00:27:33
an orbit directly around the earth like the savings course00:27:35
but stores it, so to speak,00:27:38
has the observation location in the bag, rank00:27:41
point l2 here is the sun here is the00:27:44
earth these00:27:45
are the well-known 150 million00:27:47
meters distance between earth and sun and00:27:50
Trieste the moon's orbit is of course00:27:52
not to scale and here is00:27:54
the l second is a percent further away00:27:56
than the distance to the sun and that is00:27:59
an equilibrium point in the00:28:00
rotating reference system of this L2 on it00:28:03
I also want to go around the sun once a year so it00:28:07
has the same angular velocity, so to speak, but00:28:09
on an orbit that is 1 percent larger00:28:11
and This is an equilibrium point where00:28:14
you can imagine that the00:28:16
attractive force of the sun and the earth00:28:17
together, both pulling on the00:28:19
other, is balanced out at this point.00:28:23
I have that you have a slightly00:28:24
larger centrifugal force and that has the00:28:26
greatest force is greater if If you00:28:27
are at a greater distance and that is,00:28:30
so to speak, this L2 is the more unstable00:28:33
if you put something in then00:28:35
don't get it out again at some point, which00:28:37
means we have to do maneuvers every month and every00:28:39
two months at the moment so00:28:41
that we stay there00:28:42
otherwise we won't stay For a long time00:28:45
now it's not quite right if we00:28:48
were exactly L2 then the00:28:50
earth would still almost completely00:28:52
shade the sun. We don't want that.00:28:53
We also want to have an energy supply00:28:55
and we want to have the same00:28:57
temperature. That's why it's00:28:59
actually moving in Such an orbit00:29:03
in all three spatial directions around the00:29:05
sun00:29:06
takes yes, yes, you can see it very small00:29:08
here, of course, ultimately00:29:09
enlarged here and it always takes00:29:11
half a year to go from one direction to the00:29:13
other00:29:14
in all three spatial directions and that is00:29:15
definitely a size of about 200,00000:29:18
kilometers and that's scary, that00:29:20
's realistic for the experts in00:29:23
this field00:29:37
Mission and that within the00:29:42
first two weeks flew to00:29:43
this L2 and then00:29:46
moved into this orbit and by the00:29:48
way started near Caen00:29:51
in South America where these Russian00:29:54
Soyuz rockets launch together with the in00:29:56
collaboration with the ESA00:29:58
and Here you can see above Gaia on top of that00:30:03
of course the Gaia mission didn't start00:30:05
with the start00:30:07
there is a lot of work that has to be00:30:09
done beforehand and the people who have been00:30:11
in the project the longest sat down00:30:13
right after the end of the hit00:30:15
parking garage mission and have We00:30:16
said we need something new, something00:30:18
better, the next project and that's why00:30:22
the first proposal for something00:30:24
like this was back in May 1993 and at that time we were00:30:32
thinking about a certain optical system that we would use an interferometer with which we00:30:35
could measure angles particularly well in the sky00:30:37
I wouldn't go into detail about the00:30:38
measuring principle, but then it was00:30:41
discovered that that's why it's called00:30:43
Ghana, by the way, yes, that stands00:30:44
for global entry metric interferometer00:30:47
festival six global astro metric00:30:50
center ferro meters for astrophysics00:30:52
but then they thought about it The00:30:56
actual limitation is not00:30:58
this angular accuracy like the00:31:00
amount of photons we get there,00:31:02
but if we want to get to the L2 and it00:31:05
was already clear back then that we had to go there00:31:06
in order to have a stable stable00:31:09
environment, which was also far away00:31:11
from the earth the earth has a00:31:12
modern gravitational field and the00:31:15
infrared radiation from the earth is also00:31:17
in homogeneous, that is, far away from the00:31:19
earth it is good to make such measurements first00:31:20
and then of course00:31:22
you need to transfer the data to the earth00:31:24
and that It doesn't work arbitrarily because00:31:27
with Geiger, for example, you are not allowed to use a parabolic antenna.00:31:30
You would always align it towards the earth00:31:33
and as soon as you do that,00:31:35
the moment of inertia of the satellite is completely00:31:36
different, which means the measurement00:31:38
is completely disturbed, which means it00:31:40
only works with those phase-controlled00:31:42
antennas that, so to speak, direct the directions00:31:45
in a certain direction00:31:47
electronically and you can00:31:51
achieve the data transfer rates that we00:31:53
achieve of around 8 megabits per00:31:55
second, better than perhaps some00:31:57
internet providers here in the country, but00:32:00
at least they are 1.5 million kilometers00:32:03
away That's a really good00:32:04
thing with data compression and everything00:32:06
we do there, but then we00:32:08
realized that a conventional00:32:09
telescope is actually the better00:32:11
solution. We've00:32:13
already gotten used to the name and that's why we've00:32:15
kept the name00:32:17
no acronym no more abbreviation gaal00:32:19
just means cool, maybe it's00:32:21
not that good after all because00:32:23
we don't observe the earth with gaal00:32:25
that the species belongs there and but now00:32:28
the name was born at some point00:32:29
and the thing is also called gaia00:32:32
in In 2000, the project was00:32:34
accepted by the ESA as the so-called00:32:36
cornerstone of the mission.00:32:38
Then, of course, the industrial phase began,00:32:40
the exact construction, various00:32:42
assessments up to the launch00:32:45
and then there was a00:32:48
phase where the00:32:50
satellites appeared for half a year We checked thoroughly, we00:32:52
looked carefully, we calibrated, we00:32:55
checked whether everything was in order. We00:32:57
also discovered a few problems00:32:58
that were then solved quite well00:33:01
and it was during this phase that00:33:04
we were very heavily00:33:06
involved in quality control in Heidelberg00:33:07
because Namely, we have a program that00:33:10
analyzes the data from Gaia every day00:33:12
and checks whether it is OK. We00:33:14
even do a small00:33:15
astrometric solution every day with which you00:33:18
can determine how good this00:33:19
data is and the program runs. It's00:33:24
a huge program with lots of them A00:33:25
hundred thousand parts00:33:27
that runs every day00:33:30
in Spain and there they are00:33:34
checked to see whether everything is in order00:33:36
and when the fixed phase, as I said,00:33:38
this data was of course particularly important00:33:39
in order to understand the satellite and how it00:33:41
behaves in reality00:33:43
It's a matter of constructing the thing00:33:45
and seeing how it00:33:46
behaves in reality. Then00:33:49
the regular measurements began in August 2014 and00:33:52
then from the first eleven to thirteen00:33:54
months there were a few gaps in it,00:33:56
that's why I say eleven to 13 months00:33:58
You then publish the first catalog that00:34:01
Data Wiesmann published in September 2016,00:34:05
which still has some00:34:09
data from how the parking garage used for00:34:11
its catalog and the parking garage00:34:14
not only bit through these 100,000 stars00:34:16
but was also00:34:18
able to measure positions for00:34:19
one and a half million stars using an auxiliary instrument00:34:21
And because we have such a long00:34:22
time base, we can get the00:34:24
proper motion of these stars quite well00:34:26
because from the eleven to00:34:27
thirteen months we would00:34:29
n't have been able to separate parallax and proper motion00:34:31
and that's why we were able to create this00:34:32
first catalog for 2 million00:34:34
stars decision and self-movement00:34:38
that means that was our appetite00:34:40
and then we had it00:34:42
but in a certain way the00:34:45
catalog that we published this year in 201800:34:47
last year in00:34:49
April is the first real gala catalog00:34:51
no longer includes old data from00:34:53
others devices will be used next00:34:57
year. The00:34:58
nominal western phase of five years will end in the middle of next year,00:35:02
but we have found out that00:35:05
from what we consume,00:35:09
so to speak, from the00:35:10
consumables that we have on board, we00:35:15
can in principle measure it for another five years This is essentially00:35:16
cold gas, cold gas nozzles with which the00:35:19
satellite is aligned and that is00:35:21
what is consumed first and00:35:23
that would last for about another five years00:35:25
and that would bring huge progress00:35:27
in the accuracy, especially of its00:35:29
own movement00:35:32
So we hope that maybe at the00:35:33
end we'll get ten years instead of five years, so00:35:36
far we've got00:35:39
another year and a half approved for another year and a half,00:35:41
that means we'll00:35:43
definitely00:35:45
measure until the end of 2020 because everything is technically in order with Gaia and00:35:49
then There will be another two years00:35:50
and then another year and a half00:35:53
until at some point the00:35:55
cold gas is all gone and then, so to speak,00:35:58
we would have the longest mission you00:36:01
can have with it00:36:02
in the first half of 2021, by the way, we00:36:06
also want the next one The next00:36:08
date is our next star catalogue,00:36:11
there will be more strength00:36:13
coming in again, there will be more radial00:36:16
speeds in there,00:36:18
above all, more precise systematic00:36:20
errors will become smaller, which are00:36:23
still in this catalogue, and then00:36:26
the fourth catalog will be published at some point in 202300:36:32
Due to the nominal missions,00:36:33
so to speak, we will publish all the objects that we00:36:37
want to publish00:36:39
and then at some point there will be another update for the00:36:40
extended mission.00:36:42
That is, so to speak,00:36:43
the planning for the future. You see,00:36:46
it is a certain period of time and I00:36:48
have only been there since 2004 In the Gaia project, but00:36:50
some people have been00:36:52
working on this project with us since 1993.00:36:55
For the experts, what is00:36:59
actually how it is set up up00:37:01
there in this part above00:37:04
the parasol,00:37:05
this goalless is00:37:08
actually located there Isn't that a gate but00:37:10
a bit in the square and this00:37:12
one that is made of silicon chapter00:37:15
material which is solid is very light00:37:18
and is very stable and then there are00:37:22
a lot of mirrors in here which are00:37:23
the two reflecting telescopes on00:37:26
board at gala By the way, they are also00:37:27
made of silicon carbide, they are00:37:29
naturally mirrored on the surface00:37:31
and down here is the local level that00:37:34
the actual camera consists of 106 ccd00:37:36
detectors and if you00:37:38
add up the pixels we have almost all of the00:37:40
gigapixel cameras at the moment00:37:42
The space camera with the largest00:37:44
number of pixels and the various mirrors00:37:46
are there to create a telescope with a00:37:48
focal length of around 35 meters00:37:51
and both telescopes that look in two00:37:53
different directions00:37:55
combine their light in a00:37:57
common plane, which means we00:38:00
measure two directions at the00:38:01
same time, so to speak once you look in this direction00:38:03
that one discourse is this00:38:04
main mirror 1 you look there and the00:38:07
other looks in a direction that is 10600:38:09
one and a half degrees different in the sky, that00:38:12
means I look that way once about that00:38:14
way and with that I can00:38:18
not only take measurements in a field of view00:38:20
that a telescope has but is also00:38:22
large-scale measurements that is the00:38:24
advantage of the two telescopes00:38:26
that has another advantage that is00:38:27
a little more difficult to understand00:38:29
that if this angle00:38:31
is really exactly stable you can also find the zero point of00:38:32
the parallax determine from the data00:38:34
but I only want to do that now00:38:36
if you ask me about it try to00:38:39
explain it's not that easy00:38:41
35 meters break more and each of00:38:43
these mirrors has a meter 45 x00:38:45
50 centimeter opening here is a00:38:47
rectangular mirror not like your00:38:49
telescope Mirrors at home or here in00:38:51
the observatory have the round mirror,00:38:53
it's not because the main00:38:55
resolution is in the scan direction when00:38:58
the Gaia thing is rotating around its own00:39:00
axis, the stars run over the over the00:39:02
over the over the over the detectors and we00:39:05
mainly have measurement in the00:39:07
direction of rotation and that's why we make the00:39:09
mirroring of the direction larger than in the00:39:11
other, this is simply an optimization00:39:12
so that my weight saves, so now00:39:15
let's look at each other in an animation from the esa,00:39:16
this is exceptionally not done with the00:39:18
Kayak Sky program, we have00:39:20
the two directions are 106.5 degrees00:39:22
apart and look at stars here00:39:24
from the field of vision, they are00:39:26
colored turquoise here and then magenta here,00:39:29
the others have stars from the other00:39:32
field of vision and the00:39:34
ccds are set up down here and then you can see00:39:37
them straight away Stars are now wandering over them, they00:39:38
come from one field of vision, these are00:39:40
these turquoise ones and here they are00:39:43
together in a local plane and in00:39:46
these two stripes you can00:39:47
see them, by the way, you only see the ones00:39:48
from the field of vision and from the other00:39:50
so that you can see them here too You can construct00:39:51
from which direction the star00:39:53
was then measured.00:39:54
By the way, these two are00:39:57
here these photometers where the blue one00:39:59
threatens00:40:00
brightness is measured. To be more precise,00:40:01
a small spectrum is measured00:40:03
with which you can measure the energy distribution of the00:40:05
stars and this is where00:40:07
the world is located The Doppler00:40:08
measurements were made with the display to00:40:10
find out whether the star is coming towards us00:40:12
or away from us and what00:40:14
is the actual measurement quantity. You00:40:17
can see that the images of the stars00:40:19
move over the local plane and depending on00:40:23
where a star is located, this runs over the00:40:26
local level at another00:40:27
different point in time that means what00:40:29
we actually do is that we determine the00:40:30
center of these images of the stars00:40:33
centro idea is what this is called and00:40:35
next to the atomic clock to say exactly when00:40:37
is the star where in the local level00:40:39
and we have to get out of that Where00:40:42
the star is in the sky is the00:40:45
transit instrument. Do you00:40:46
know a bit about astronomy? There are00:40:48
these median circles.00:40:52
Look when does death run through00:40:53
the meridians in a southerly direction.00:40:55
But they have a fixed direction. If they were00:40:57
the direction here It's constantly changing and00:41:00
that's one of the problems, by the way,00:41:01
how can it be done that you can00:41:05
somehow00:41:07
figure out the star position from such measurements? Damn,00:41:08
if I00:41:11
want to use it to measure the star position very precisely then00:41:12
I have to know where it comes from actually00:41:13
a telescope at any time and00:41:20
you have to know the geometry of such a measuring instrument exactly because00:41:22
otherwise it is completely pointless. Now00:41:26
you can make any effort on the00:41:29
ground to determine how the geometry00:41:30
of my telescope of my00:41:32
measuring instrument helps Nothing happens after00:41:33
the start, everything is different anyway and00:41:36
the ccds, of course they were00:41:38
put on there by people, they are00:41:39
perhaps a bit offset from00:41:40
the position where they are supposed to00:41:42
be, a bit twisted or00:41:43
distorted. How do I find00:41:46
out what the damn thing is? The instrument is00:41:49
kuka at any time,00:41:51
the very smart ones from your car,00:41:52
maybe I don't know about00:41:55
satellites, they all have00:41:57
tractors on board that compare00:41:59
star positions, so to speak, and tell me00:42:01
where I'm going,00:42:02
but they do that with an00:42:03
accuracy of maybe six seven00:42:05
eight arc seconds00:42:07
but we want to get a micro arc seconds00:42:09
yes how do you do that00:42:12
that's in the end I'm home00:42:14
is the one who was also known for00:42:17
pulling himself out of the swamp with his own head so that's00:42:20
a bit of the picture you I have to00:42:21
use the Gaia data myself to not00:42:25
only measure the position of the stars00:42:27
but also to answer the question of where am00:42:29
I looking at every moment and00:42:31
what is my telescope like? This is the00:42:32
geometry of my telescope. By the way, this can00:42:34
change a little every day Geometry It does that00:42:36
too, which00:42:38
means we also have to get five00:42:40
sizes per star out of our data00:42:42
and a few tools,00:42:44
which are much less00:42:46
than we need for the stars.00:42:47
In the end, the stars connect, so to speak,00:42:50
everything from the whole but the whole00:42:52
calibration Is this effect, it's00:42:56
also an art that makes Gaia exciting,00:42:58
you really have to say there's a00:43:00
lot of math involved in00:43:02
getting it out and it's00:43:05
not finished yet. Our star catalog contains00:43:07
even more systematic errors that00:43:09
are larger than they should be in the final catalog00:43:10
And so there's still a lot of00:43:12
brainpower to get more00:43:15
calibration out of the data, so to speak,00:43:17
and that's been00:43:20
quite successful because if we00:43:24
look at the second star catalog and its accuracy then00:43:27
we're actually pretty good00:43:29
plotted here on the00:43:31
y-axis is the accuracy of the parallaxes00:43:34
in billy arc seconds, which by the way is the00:43:38
logarithmic size here, so here is00:43:40
a millisecond,00:43:42
which is a tenth because it is a hundredth, which00:43:43
means this is a logarithmic00:43:45
size where nothing is not linear00:43:47
but always jumps from factor 10 from00:43:50
there to there and this is the00:43:52
brightness of the stars, that means the very00:43:55
bright stars are here and the00:43:57
weaker stars are there and now00:43:59
let's look at where the data from00:44:01
the parking garage satellites are, these are00:44:02
the green ones here lie up there you00:44:05
can see that it typically takes a00:44:06
millisecond, some are a00:44:08
little better but above all I can00:44:11
measure the parking garage a little brighter stars that they are the ones on the left, you ca00:44:14
n't get behind them00:44:17
As soon as the third00:44:19
magnitude is approximately at there, yes,00:44:22
we don't have the weaker and star,00:44:23
unfortunately, then here we have the00:44:25
status catalog 1, the two million00:44:27
stars that we published in September 201600:44:30
and they were already around00:44:32
0.37 seconds00:44:36
a factor of 3 better than the parking garage00:44:38
and for 20 times more stars00:44:40
that's what's special and then here is00:44:43
the data for the ndr 2 do00:44:47
n't be surprised that there are a lot of stars here too,00:44:49
well four inaccurate ones are the yellow ones that00:44:51
they now have quite a few Stars the majority00:44:53
of the stars are there it was00:44:54
represented here in this purple color and then let's00:44:58
see what the best stars00:45:00
are, i.e. the ones that are particularly far down00:45:02
and here we are at 13 the size00:45:05
of about 30 microbes seconds00:45:09
225 we want to go there00:45:11
However, we still have systematic00:45:13
errors that are about the same size,00:45:15
so that's what you have to00:45:16
put together.00:45:17
We want to get them down by a factor of ten,00:45:18
hopefully by the00:45:20
time we get to the final catalog. There's something00:45:22
special there and that's00:45:24
the prediction for five years of measurement time00:45:27
and that took 14 years of measurement time for00:45:29
the parallax we will only gain a factor00:45:32
at twice the best time of00:45:34
root two 1.4 gain in the00:45:37
self-motion we will gain the accuracy00:45:39
by facts fast factor 8 because00:45:41
there is with the one and a half power for00:45:43
that Experts so that we have00:45:46
a big, big advantage,00:45:47
that means we already have very, very00:45:49
good data and these extremely precise00:45:52
data that ensure that00:45:54
astronomers have00:45:55
been able to do some really great science with this data.00:45:57
Now let's take a look at where we stand00:45:59
Today we00:46:00
have collected the data,00:46:03
of course not all of it has been00:46:04
included in the catalog.00:46:05
Today we are in day 1629 of the00:46:08
nominal mission. Today we are so far00:46:11
more than 1.5 million kilometers00:46:14
away from Earth and we00:46:18
have more than 1, 1 million00:46:24
measurement astro metric measurement made00:46:27
that in real billionaire 1.100:46:29
million us then here for example00:46:32
measurement from the radial velocity00:46:35
instrument that is seven billion00:46:36
here for example that can be so00:46:38
every day you can00:46:39
look up these00:46:41
updated numbers on the esa website And with this00:46:44
star catalog, publications have been made since April 25,00:46:49
2018 and I00:46:52
counted it again yesterday, so00:46:54
this time was actually from yesterday.00:46:56
There are 887 publications that have used the things00:46:58
catalog,00:47:00
that's 3.4 publications every00:47:04
day and that's what it has as far as I know00:47:07
never done before in a project, so with the00:47:10
Hubble Space Telescope you have certainly had00:47:11
the most publications. This is00:47:13
one of the instruments that is of course00:47:14
special, but he loves this00:47:16
short period of time, not sure that00:47:18
Hubble Space Telescope didn't do this00:47:20
and these are the00:47:22
subject areas of the work and that is00:47:25
certainly not completely what has been00:47:28
contributed and just pick00:47:31
out an area you will00:47:32
probably find in this list00:47:34
and as you see the special thing about00:47:38
the mission is that it is the basis00:47:40
for practically all areas of choice00:47:43
astrophysics and not so much an00:47:45
instrument that gives us an answer00:47:47
or wants to observe a certain type of00:47:49
stars or wants to00:47:50
look at a certain wavelength range00:47:53
and you can of course get the individual papers00:47:56
if you click on this link,00:47:57
but yes, that's00:47:59
how it is Before we get to the00:48:01
science, let's do00:48:03
a little bit between entertainment, a00:48:06
little flight through the Ghana catalog00:48:09
again with Gaia Sky, of course, we're00:48:15
starting in Europe, it's a00:48:17
European satellite, an00:48:18
excellent European00:48:21
collaboration. Everyone you00:48:23
see here dies, the very bright ones There are parks from here00:48:25
that are weaker, Gaia stars,00:48:27
it wobbles a bit, that's not because00:48:29
my notebook is about 5600:48:32
years old, that I have a new one, then00:48:34
it doesn't wobble anymore, that there's00:48:36
a little video that we produced with it00:48:37
and now we're flying for a00:48:39
moment Access first of all, that00:48:41
means our trip begins with00:48:43
us just one and a half million kilometers00:48:44
from the earth looking at the satellite00:48:47
and that is again that we00:48:48
look something like what we00:48:49
had at the beginning, we look from behind at00:48:52
our ten meter diameter parasol00:48:54
We have now turned on the time00:48:55
a little bit00:48:58
so that we can see something at all and now00:48:59
we will00:49:01
fly around a bit. By the way, in the background we can00:49:03
now see the stars of the00:49:04
Milky Way. As usual, you can see 1000:49:05
o'clock and here the thread and 14 700:49:09
billion and Now you look at00:49:11
it, his team has an00:49:12
acceleration again, let's look at a year00:49:13
of measurements of the ghost satellites of00:49:17
the NASA satellite of course not00:49:18
only have to go in one direction but also does00:49:21
a scanning position with which it00:49:22
scans the sky but always 45 degrees to the00:49:25
sun remains that that's the sun,00:49:28
by the way, it passed next to Angela,00:49:30
which means we walk around00:49:32
and look but at least one00:49:33
direction so that you can see it, so to speak,00:49:35
such a movement makes there over the00:49:37
course of a year,00:49:38
by the way, mom is just passing by there00:49:40
Above, yes and now let's swing00:49:45
in the direction of the higher ones and we00:49:48
want the hurdles are a00:49:49
star cluster and here we have00:49:50
drawn all the star clusters that we00:49:51
know so far. The star clusters are00:49:53
groups of stars that were00:49:55
born together. Now the straight ones also get00:49:56
to and The old baran, which wasn't even part00:49:58
of it, didn't just fly past us in front of the listeners00:50:02
and here comes the star cluster of the00:50:04
Pleiades that you can see, you're also00:50:07
theirs, it looks a bit strange, it does00:50:08
n't look the same as it did00:50:10
before You still have the Pleiades00:50:11
a little further away and now00:50:13
let's spin this star cluster so00:50:16
you can see a bit of the00:50:17
three-dimensionality of the whole thing and00:50:20
a star cluster like that means these stars00:50:23
in a star cluster00:50:24
emerged together from a molecule cloud and00:50:27
have many things in common00:50:29
Many have properties that are similar in chemical00:50:30
composition,00:50:32
they have similar things, age because they were00:50:34
born together and they00:50:36
also move in the same00:50:38
direction, unlike the other stars,00:50:39
they move together in the00:50:40
direction that had these molecular clouds00:50:42
and we'll show that Here I used00:50:44
a file to clean up the stars that00:50:46
belong to it, they all run in this00:50:47
direction and others00:50:48
in a different direction. Now I have a00:50:49
million time lapses again,00:50:52
so you can now see how the stars all00:50:54
run in one direction and other00:50:57
stars that run otherwise do that00:50:58
can you identify which stars00:51:00
and actually star clusters belong to it00:51:01
then we have to look which ones00:51:03
are running in the same direction00:51:04
first against Mettmann and dedication on the00:51:06
computer the time goes back again then00:51:08
we are back to today and now00:51:10
we are backwards from the star00:51:11
catalog like this Now we let the00:51:16
old monitor lizard pass by again00:51:19
then the sun comes by and we00:51:21
now fly backwards out of the star00:51:23
catalog out of the many hundreds of00:51:26
millions of stars and now we have00:51:29
only faded once a picture of our00:51:31
Milky Way. Now that's a bit00:51:33
fake because we I don't00:51:34
know exactly yet,00:51:35
but that should roughly say00:51:37
where Gaal is in there, by the way,00:51:39
if you're interested in this program,00:51:40
even Sky, it's available for00:51:43
Windows, it's available for Max, it's available for Linux, you can00:51:46
download it here00:51:48
and do it yourself00:51:50
Make a little virtual flight through our00:51:52
Milky Way and for people who00:51:55
have windows and have VR glasses, you00:51:57
can even have a VR like that.00:52:00
We can look at you in every direction00:52:01
in the sky and make virtual flights00:52:04
through the galaxy00:52:06
Colleague of this00:52:08
Christa who works in my team is00:52:11
that he is really a master of his00:52:12
field when it comes to visualization. He00:52:14
developed this program with00:52:17
my support but the whole00:52:18
program is his work and the knowledge that00:52:20
how to do it comes from him00:52:23
and that can I would really00:52:25
recommend it to anyone who has a little bit of interest00:52:27
in something like this, so that if you do00:52:28
n't see any advertising,00:52:30
the data has been scientifically00:52:32
analyzed in between, then you also have to check00:52:34
that we also have the colors of the stars.00:52:37
Here we only have them 50,000 Gaia00:52:39
stars that have had00:52:40
different colors for ten years. By the way, these are00:52:42
colors that were also measured by Gaia00:52:44
and we will now sort them from blue00:52:46
to red. On the left there will be the blue00:52:49
stars, on the right the red ones and then00:52:52
we will sort in another00:52:53
direction the luminosity00:52:54
the luminosity is not just the00:52:56
brightness dj am is00:52:58
distance is of course00:52:59
taken into account so that we know the00:53:01
star is really bright so the00:53:02
distance is included for information purposes and00:53:05
then a diagram is formed that00:53:07
my heart of russell calls a diagram and00:53:10
here you can see that there are many stars00:53:12
on this so-called main sequence,00:53:13
these are stars like our sun that00:53:17
burn hydrogen into helium in the middle, here are the ones that00:53:19
become red giants, up there are the ones that00:53:21
burn helium in the center and here00:53:23
and are white ones dwarves that00:53:25
look like stars in the star and those00:53:26
in between are in bloom and that is, by the way,00:53:29
we heard it from the00:53:31
Junkers that this is something that00:53:33
I have been dealing with for a long time00:53:35
with white dwarves and that's why00:53:37
Not even to tell00:53:38
a little something about it with white dwarfs, but00:53:42
paint the diagram a little differently then it looks like this,00:53:44
here we have the00:53:47
color on the left is blue, on the right is red. By the00:53:50
way, up there are the00:53:51
surface temperatures that go with it00:53:52
and the spectral types for the experts00:53:55
and here is the absolute brightness i.e.00:53:57
what the brightness of the stars really00:54:00
is taking the00:54:01
distance into account i.e. bright stars are00:54:03
up here weak stars are00:54:05
down here blue stars so hot stars00:54:08
are the smaller stars on the left and right00:54:12
have surface temperature and00:54:14
here are, as I said, the stars that00:54:15
are like our sun,00:54:17
here are stars that are no longer00:54:20
burning in the center of the hydrogen00:54:22
and here are these clumps of it up there, these00:54:24
are stars that are00:54:26
burning helium in the center that there is00:54:28
such a thing the later phases in the00:54:30
development of a star and these00:54:32
are the white dwarfs if we00:54:34
now travel over them into the white00:54:36
dwarfs because if you look closely you will see00:54:39
that there are actually two00:54:40
sequences here and there and this00:54:44
splitting has something This has to do00:54:46
with the surface composition up00:54:49
there, there are those that have hydrogen from the00:54:50
surface and those that00:54:52
have helium, but if you look at the models that you00:54:54
have before, then according to00:54:57
the models this split is much00:54:58
smaller than we observe, by the way00:55:00
You've never observed this00:55:01
split before, you can only observe it00:55:03
because of the range finder and00:55:05
that we now have with Gaia,00:55:07
otherwise we would never have been able to see this,00:55:08
this detail and this00:55:11
split is larger than it00:55:13
was in the models and you also have it00:55:15
a good idea why this is the00:55:18
objects that are in there00:55:20
probably have even heavier elements00:55:21
in them which then00:55:24
lead to this shift00:55:25
I don't want to discuss this in detail now,00:55:27
in any case you can00:55:29
indirectly tell00:55:31
something about them through this size of the split You00:55:33
can see chemical composition on the surface00:55:35
that you could never have seen spectroscopically alone,00:55:38
so spectrum00:55:40
you don't see any lines from these elements.00:55:42
Nevertheless, through this splitting you can00:55:44
indirectly say something about the00:55:45
amount of heavier elements in these00:55:48
objects. The00:55:50
nice thing is that we can do a lot with Gaia00:55:52
have discovered white dwarves,00:55:54
so far we knew 30,000 white dwarfs00:55:57
and now we know 260,000 with white with00:56:00
Gaia. By the way, I am involved in the00:56:01
helper who identified these white dwarfs00:56:03
and that is in the sky,00:56:06
which now only consists of white dwarfs.00:56:07
I have it now Everything00:56:09
else, all the other stars are blinded away,00:56:10
by the way, Sirius but Sirius B, the00:56:13
companion who is so bright here and now00:56:16
you can also see the stars00:56:17
and the white dwarfs are moving.00:56:19
Now I have once again00:56:20
done exactly what I did with the normal00:56:21
stars the movement00:56:22
is switched on, which means00:56:25
you can also see their movements. By00:56:26
the way, here is a little bit here you00:56:27
can see small shadows in the center of the00:56:29
galaxy, we can't in the00:56:30
area we have them star densities so00:56:32
high that you're missing objects that00:56:34
are actually there and then If you have00:56:38
looked at some of these white dwarfs and measured their speed, you00:56:40
have found that some00:56:41
of them are extremely fast. Our sun00:56:44
moves around the galactic00:56:46
center at around 220,240 kilometers per00:56:50
second and there are these and three white dwarfs00:56:53
that move with it move more than 100000:56:55
kilometers per second and one00:56:58
of them moves at almost 2000 kilometers per00:57:00
second00:57:01
and you have an idea that this has00:57:04
become so fast and that is the00:57:05
following: it is assumed that these00:57:09
white dwarfs, these three originally00:57:11
formed a pair with each other00:57:13
So in reality there were00:57:15
six white dwarfs that formed twice and00:57:17
were so close00:57:19
together that they00:57:20
orbited each other very quickly and now one00:57:25
of the masses passed on to00:57:27
this star because they were so close and00:57:30
it was one has had its day a bit00:57:32
and it has become even closer for us00:57:34
and then one of them exploded in a00:57:36
supernova. Now the path is00:57:39
the partners who previously00:57:41
circled each other through their gravity and each other,00:57:43
what happens the same thing happens when00:57:45
you have them on one00:57:47
Throw the string around or and the rope breaks00:57:49
because the force is gone, so to speak,00:57:51
the ball goes tangentially away and00:57:54
that happens to the white dwarf, which00:57:55
then also has the speed of00:57:57
1000 or 2000 kilometers per second that00:57:59
it previously had as an orbital00:58:00
speed and the beautiful thing is00:58:03
on one of these objects because you can00:58:06
calculate that it is00:58:08
currently standing here in this place00:58:10
and that is the movement in the future00:58:13
and that is the movement 90,000 years into00:58:17
the past and there is the supernova remnant, i.e.00:58:20
an explosion cloud Such a00:58:22
supernova, that means it really comes00:58:24
from his area and it shows that00:58:26
this picture is probably consistent.00:58:28
This is one of the results that has00:58:30
a bit to do with white dwarfs.00:58:31
Not only can you look at our own galaxy,00:58:35
but also our00:58:37
neighboring galaxies00:58:38
Maybe you saw in his picture00:58:39
that our neighbors had the large and00:58:41
small Magellanic clouds in there,00:58:43
they are so far away that we00:58:46
can no longer measure the parallax, they are00:58:48
simply because the parallax is no longer00:58:50
significant,00:58:51
but the movement is still there Significantly,00:58:53
that means we know how00:58:55
the stars move and in the Gaia data00:58:57
release 1 2016, one day after00:59:02
the data archives were opened, this paper00:59:04
was published where they are with 28 stars00:59:07
that are in the 28 of these two00:59:09
million places for which we see the00:59:10
movement and the practices have measured,00:59:13
as I said, these in00:59:14
significant you can see that you are00:59:17
obviously moving in this direction00:59:21
28 stars00:59:23
now we have the 2 there we have00:59:26
eight million stars in the00:59:29
Marian people whose movements we00:59:31
can study in detail and00:59:33
we simulated that too,00:59:35
they just let it run straight ahead00:59:36
and for two million00:59:41
years and then you see how00:59:43
this diesel road slowly turns a little bit00:59:54
Now you00:59:56
can study in detail how the00:59:58
stars move in the Marian cloud.01:00:00
After01:00:01
closing it, you can see how many stars are there,01:00:02
how much dark matter is in there, these01:00:05
are all things that you01:00:06
can conclude at some point, there are01:00:07
no definitive ones yet Results01:00:08
but they indicate what kind of01:00:11
perspective the whole thing has and you can01:00:13
even measure the movements, for example of01:00:16
the Andromeda Nebula or M33 of01:00:19
our two large my neighbor01:00:20
galaxies. You can see the rotation01:00:23
here but you can also see at01:00:26
what tangential speed that01:00:28
move in the sky and that is01:00:30
very crucial for the Andromeda Galaxy01:00:32
because it will come towards us in about three01:00:33
billion years and01:00:36
collide with our Milky Way.01:00:38
Now we know that01:00:41
from measurements of the Doppler effect.01:00:43
You can also do that Make the apartment quite good,01:00:44
but you want to know how far01:00:47
it runs past Mühlstrasse.01:00:49
To do this, we need to know what the01:00:50
tangential speed is, not01:00:51
just the one coming towards you, but how fast01:00:53
it will pass us and that's what01:00:56
you have now with Gaia Values in the catalog01:00:59
are not yet that precise 5701:01:01
kilometers per second but the error01:01:02
is still 30 kilometers per01:01:04
second so 50% error but once01:01:07
we have sat for ten years01:01:09
then only 1 2 kilometers per01:01:11
second will remain of it So it will be possible to make01:01:13
a highly accurate statement about01:01:16
how the Andromeda Nebula will approach01:01:18
our Milky Way at some point01:01:20
and be thrown around again into the stars01:01:23
in the Milky Way. By01:01:25
the way, what we01:01:26
have now measured with Gaia is no longer true,01:01:27
but that is only in a few billion times01:01:30
years, important when things get really big,01:01:34
the expansion speed01:01:37
of our universe is determined01:01:38
by this so-called Hubble constant.01:01:40
You have probably heard of it before.01:01:43
This indicates how quickly stars01:01:46
move away from us when they are at a01:01:47
certain distance.01:01:49
You have to do this You can't measure the distance from other01:01:51
galaxies01:01:52
with anything, but with Gaia01:01:56
you can calibrate the objects you use for this01:01:58
measurement. You01:02:01
use a certain type01:02:03
of variable star, so-called01:02:04
satisfied,01:02:05
that have a change in light, that01:02:07
get bigger over time01:02:09
They become smaller again and then01:02:11
larger again and very regularly and the01:02:15
light curve the values are is the cdu01:02:16
from they become brighter like the dark the01:02:18
brighter darker again and this is a very01:02:20
periodic process that for some01:02:22
stars dies it lasts a few days01:02:25
and some for one a few hundred01:02:27
days and the longer this period is,01:02:30
the brighter these stars are, which01:02:32
gives a period of brightness01:02:35
bz, by the way, by this lady Henrietta01:02:38
Horn limit, which was determined on the stars in the01:02:41
Large Magellanic Cloud at the beginning of the01:02:44
twentieth century01:02:47
and this method works But01:02:52
only if we can, so to speak, convert this period into01:02:54
a luminosity01:02:57
and this in turn can be converted into a distance01:02:59
and to do this we need to01:03:02
know as many C4s as possible in our Milky Way in order to01:03:04
precisely calibrate this relationship with which we can get01:03:06
this hubble constant again this01:03:08
design speed of the01:03:09
The universe certainly can01:03:11
do that and has now come01:03:14
to a value of 73.5 2 km per second01:03:18
per megaparsec plus minus 1.62 is01:03:21
a relatively small error there01:03:23
is still in it and that is from a paper here by01:03:25
Adam Ries and others Reese is a01:03:28
Nobel Prize winner who01:03:33
received the Nobel Prize alongside two others for01:03:35
finding out that the universe is01:03:37
expanding at an accelerated rate and he has01:03:40
the Gal measurements in addition to the measurements01:03:42
from the HP space telescope, but01:03:44
the accuracy here is01:03:46
really the Gaia measurements01:03:47
Having made the error so small it comes01:03:50
to this value and then now01:03:52
the three take the small01:03:54
problem with other methods you come01:03:57
to a different value the Planck satellite01:04:04
measured this background radiation this microwave background radiation01:04:05
and if you have the models for what If01:04:08
you take the extent of the universe01:04:10
into account then you can calculate what01:04:13
today's Hubble constant is and01:04:15
you get 67.4 kilometers per second. There01:04:18
would be an even smaller error of 0.501:04:20
kilometers per second and these two01:04:23
values were significantly different from each other01:04:26
is to do01:04:29
it may be that one of these01:04:32
two methods still has a methodological error01:04:34
kind of that is that it is perhaps the01:04:37
most likely explanation which one01:04:39
we don't know yet,01:04:41
we really don't know or maybe01:04:43
the new physics behind it that one01:04:45
can conclude from this discrepancy because01:04:46
that what we are observing here because he is in01:04:49
the microwave the reason we see01:04:51
the universe as it was 380,000 years after01:04:53
the Big Bang and with with with Gaia and01:04:56
what we see today we only see01:04:58
the present so to speak or just a01:05:00
little bit into the past and that01:05:03
They are so close to each other01:05:04
is a good01:05:06
confirmation, but this discrepancy is01:05:08
taken seriously and that's why there was01:05:10
a conference in Berlin ten November last year.01:05:17
Incidentally, here is also Adams, who01:05:19
also gave a lecture at a01:05:21
conference via Bild of the meeting it01:05:24
's about this discrepancy where it01:05:26
is discussed why it could be there01:05:28
was no real result. They took01:05:30
stock, so to speak,01:05:32
and I gave a lecture about01:05:34
Gaia and01:05:37
then others had something about these01:05:38
cosmological models and this trade fair01:05:40
held and this is a very current01:05:43
topic,01:05:44
this discrepancy and I'm excited to see what01:05:49
will come out of it in the end. At some point we will01:05:50
certainly understand this. With Gaia01:05:54
we want to measure not only the01:05:56
distance but also the movements of01:05:57
the stars.01:05:59
In reality, we have for01:06:01
stars if we All together01:06:03
we also have the radial speed, we have01:06:04
three coordinates, so to speak, that01:06:07
determine01:06:08
a position in the sky if you really01:06:10
have the spatial position and three01:06:11
speed coordinates with which01:06:15
we have the speeds, that's what01:06:16
physicists call in phases space 601:06:19
dimensional space, you make it out of it and01:06:21
if If you take a closer look, there01:06:23
may be structures in it01:06:24
that you didn't know before and one of the01:06:27
structures that you can find if you01:06:29
draw a diagram if you take the stars in01:06:31
our sun's surroundings and01:06:33
one of the coordinates is01:06:35
the positions Above or01:06:37
below the galactic plane,01:06:39
our Milky Way is essentially01:06:41
a galactic disk and, by the way, the sun01:06:43
is relatively exactly in the01:06:46
middle of this disk and this01:06:48
coordinate tells us how high a star is01:06:51
above the disk in the cinema01:06:53
so 1000 pair said a01:06:55
few 63 light 3.26 light years so that01:06:58
corresponds to 3000 light years closer and that01:07:01
's 3000 light years below the01:07:03
disk and that's the speed at01:07:05
which the star will like to01:07:07
move up or down01:07:09
and then there's color coded to01:07:12
make it even more complicated how fast01:07:13
they move around the galaxy, so to speak,01:07:15
you basically entered three01:07:17
different two speeds and01:07:19
a coordinate and01:07:22
you see a spiral and01:07:25
no one has predicted this spiral in the models01:07:27
so far, this spiral is really one01:07:30
Surprise, there was data in it01:07:32
and afterwards you can now01:07:35
find out what could have been the cause01:07:36
and one of the01:07:38
most likely causes is that this01:07:41
is a disturbance caused by the01:07:43
impact of a dwarf galaxy on our01:07:46
street and we know01:07:47
pretty well which one galaxy that01:07:49
was01:07:50
it is the Sagittarius galaxy01:07:52
that did that01:07:54
I want to say very briefly when a01:07:56
star goes up and down so how01:07:58
do you see stars in our01:08:00
Milky Way, that's how you imagine01:08:02
a star moving around01:08:03
the galactic center in our Milky Way01:08:05
important but always a bit up and01:08:07
down so but if it01:08:10
is completely uncoordinated that one star01:08:12
runs like this or others like that then it looks like a01:08:14
mishmash01:08:16
that there is no structure in it and01:08:19
not like the spiral In there and01:08:22
this spiral it must be01:08:23
created somehow so that the stars make some sort of01:08:24
common oscillation that they01:08:27
do this together.01:08:28
The most likely cause is that01:08:30
this Sagittarius galaxy01:08:33
collapsed into our Milky Way01:08:35
and then created such oscillations01:08:38
and this is the case here model that then01:08:40
this speed distribution01:08:42
has changed over time, so it takes01:08:44
a few hundred million01:08:46
years until such a spiral structure01:08:48
appears and here we know that01:08:50
the Guitarreros Galaxy here probably01:08:54
approached the galactic01:08:55
disk about 500 million years ago has done and caused such a disturbance,01:08:56
which means that we can,01:08:58
so to speak,01:09:02
say something about what happened in the01:09:03
past by measuring this speed structure.01:09:04
There is an alternative theory01:09:06
that is not the only hypothesis,01:09:08
it is perhaps this one of these bars01:09:11
in the The middle of the Milky Way is01:09:13
that it may have some structures that can lead to something like that,01:09:15
so it is not yet01:09:17
clear in this case how this01:09:19
comes about, so a wave like this runs through01:09:23
it and that ensures that we01:09:24
still have this wave today ga01:09:27
can see data01:09:28
but over time our Milky Way has01:09:30
not only this incursion of01:09:33
small galaxies we have but that01:09:35
it happens again and again and these01:09:37
are then torn apart over01:09:39
time by the potential of our01:09:40
Milky Way and a very special01:09:42
event has to do with it As we01:09:45
have now found out by studying01:09:47
the Gaia data, that this disk that01:09:49
we have has become thicker.01:09:51
People have always wondered how01:09:52
this thick disk came about in01:09:54
the Milky Way01:09:56
and that probably01:09:58
came about through the arrival of a large one01:10:00
Dwarf galaxies we first of all01:10:08
had a tenth of the mass of the Milky Way around 10 billion years ago, a01:10:10
quarter of the mass of the Milky Way at that time,01:10:12
our Milky Way was still01:10:13
growing when that happened and Helmi01:10:17
and others found out in a major paper01:10:21
that If you analyze the seven01:10:24
million stars for which we01:10:26
have this common motion01:10:30
then there are 30 thousand stars that01:10:32
have different motions than the times the01:10:35
majority of the stars and they also have01:10:36
a different chemical composition01:10:38
and that actually suggests01:10:40
that this is times that These are the debris01:10:42
of a galaxy that missed each other in the earlier01:10:43
phase of formation with the Milky Way01:10:45
and which led to01:10:48
our Milky Way01:10:49
disk becoming thicker and the01:10:51
countries Scala in the basement but this this01:10:54
this event that is the01:10:56
term they coined And I01:10:58
think it's really funny what justification01:10:59
Amina Helmi gave for this.01:11:03
I translated it into German.01:11:05
According to legend, it was buried in the basement01:11:07
under Mount Etna in Sicily and01:11:10
was responsible for local earthquakes,01:11:12
and the stars of Gaia became01:11:14
killers Buried deep in the Gaia data, it01:11:16
first has to be distilled out here, so to speak,01:11:17
and they01:11:19
shook the Milky Way, which led to the formation01:11:21
of its thick disk, so that's01:11:23
a bit of the mythological explanation01:11:26
for this term01:11:28
and here again thick disk is what this is called01:11:31
disk but the01:11:33
Milky Way viewed from the side01:11:34
that it is thicker and that a01:11:36
sun and a mixture of stars01:11:38
have formed, some of which also01:11:40
have a different chemical composition and in01:11:44
general it is the case that when01:11:45
dwarf galaxies fall into our Milky Way01:11:47
they are torn apart like01:11:49
we are This is what we see in this animation01:11:51
and we also observe something like this when we01:11:54
see foreign galaxies, then we see01:11:55
such structures, such as a01:11:57
case of such dwarf galaxies, which means that01:12:01
stars do not move with the01:12:03
other stars but on different01:12:05
orbits.01:12:06
This is called star streams and These01:12:08
star streams were partly01:12:11
planned, but with Gaia,01:12:13
additional star streams have now been found which01:12:18
can now of course be analyzed much more precisely in detail because01:12:20
with Gaia you can see speeds and distances and three-dimensional structure01:12:23
much more precisely and these star01:12:26
streams will Of course, they trace01:12:29
their orbits over the large area of our galaxy01:12:31
and these orbits tell you01:12:34
something, of course, about how much mass is in01:12:36
our galaxy. Thirdly,01:12:37
you conclude from this, for example, that our Milky Way01:12:39
is probably heavier than you01:12:41
previously thought, probably something01:12:42
like 10 to the power of 12 solar masses or something like that01:12:45
And of course the dark matter is also01:12:47
partly responsible and other01:12:50
things and this dark matter01:12:52
may have worked out, that is, it01:12:54
is not only distributed equally spatially01:12:56
around the Milky Way, but it is01:12:58
assumed that there are01:13:00
structures underneath because these01:13:02
structures are partly responsible for it01:13:04
Responsible for the fact that these two01:13:05
galaxies were formed there, but some01:13:08
of them contain no stars at all and01:13:10
others contain stars, so you01:13:12
have this dark matter and the structures01:13:13
and there is a stream of stars that01:13:18
came from a torn star cluster called a globular star cluster01:13:20
that now there are none Dwarf galaxies01:13:21
that had now been observed very closely with Gaia01:13:24
and a picture01:13:26
of what it looks like is this01:13:28
star stream looks like this and there is01:13:31
a gap in it01:13:32
around this gap, the01:13:35
authors interpret this to mean that some dark01:13:38
matter has passed through there who01:13:40
caused this gap is very speculative, I01:13:42
admit, but anyone who finds things like this01:13:44
could be evidence01:13:46
that this actually happened,01:13:48
so here you can see these01:13:51
arms shown and here are clumps of dark01:13:54
matter that could lead to01:13:55
such gaps being created because you You wo01:13:57
n't be able to get a gap like this, let's01:13:59
stay with this01:14:00
dwarf galaxy. You know the01:14:03
large Magellanic cloud and now01:14:05
you've found a galaxy in the data,01:14:07
a dwarf galaxy that's practically as big01:14:10
as the Marian cloud but does01:14:13
n't fan out 4000 times is and holds a lot01:14:14
fewer stars01:14:15
and you found them by01:14:18
seeing that there were a few stars01:14:21
of a certain type of variable01:14:22
stars in there that all had01:14:24
the same movement at the same distance01:14:25
and let's have which stones do01:14:28
we still have this movement and then01:14:29
The stars were found in the Gar01:14:31
data, so very indirectly, they were01:14:34
found about 420,000 light-years01:14:37
away from us and were the size of the01:14:39
Magellanic cloud but are much, much01:14:41
weaker in light, so such objects have01:14:43
now been discovered with Gaia due to01:14:47
these highly precise ones data So now01:14:51
I want to finish by asking the question again, what does our01:14:53
Milky Way look like? We do01:14:54
n't know exactly yet, it's not enough yet,01:14:56
but you can speculate a little bit.01:14:59
This is what it could look like. That's right, they01:15:02
are data The ones on01:15:04
the Spitzer missions that are essential to return a woman Roth01:15:06
telescope where01:15:08
the distance wasn't exactly01:15:09
known and they also sat down01:15:12
and the vultures took data01:15:13
from the young stars01:15:15
that are currently there where young01:15:17
stars are star formation regions and01:15:20
By the way, the errors are soon01:15:22
drawn in here and here is ours here01:15:24
is the galactic center there we are01:15:26
and there are the stars that you have even01:15:29
measured you can see that there01:15:32
are already happy ones in between and01:15:34
maybe spiral arms are allowed throughout so01:15:36
but it is so convincing01:15:39
I would say that we haven't yet, but01:15:41
that there are players who are willing to believe, but01:15:44
in between there are also a lot of stars in01:15:46
our sun's surroundings and maybe01:15:49
our galaxy looks a little01:15:51
different. There are galaxies that do01:15:53
n't have the clear spiral arms01:15:55
that they do at 51 but this more01:15:58
fuzzy galaxy ngc 4414 where we clearly01:16:02
have spiral arms where we also have a lot of01:16:04
structure in between and maybe01:16:07
there are first indications from the gaia01:16:09
data that our galaxy01:16:11
looks more like that but we01:16:13
just have to wait and see01:16:15
what they do Gaia data and other data01:16:17
in order to say something about the galaxy at the end01:16:21
and finally I would like to say01:16:22
that it is a project that is only possible01:16:26
if many people work together in a good way,01:16:28
if you01:16:31
work together in Europe to make such a project01:16:32
progress In01:16:34
some cases, people have been working on it for 24 years.01:16:37
450 scientists are still01:16:39
working on this project,01:16:41
not all of them full-time, but at least01:16:44
some of them are 160 institutes from 24 countries01:16:47
and of course the European01:16:49
space agency esa.01:16:50
Then we have six01:16:52
data processing centers and the whole thing01:16:53
runs under the under the consortium01:16:57
called data processing in the nla01:16:59
is this consortium of gaia and here01:17:02
you can see half of the people who01:17:04
worked on the approximately who met a01:17:06
few months ago01:17:07
to exchange the results01:17:09
and also prepare the next catalog01:17:11
and that's just how it works Such an01:17:14
interesting project and that's how you make01:17:16
progress when you work together and01:17:18
while I was speaking here, around01:17:21
another three million01:17:23
stars have probably already been measured,01:17:25
around 30 million astrometric01:17:27
measurements have been carried out, around 600,00001:17:29
star spectrum of 200,000 stars have01:17:32
been recorded and now I believe01:17:34
I should slowly come to the end01:17:36
and thank you for your attentionDescription:
Seit 2014 vermisst der Gaia-Satellit der ESA die Sterne der Milchstrasse genauer als je zuvor. Das Hauptziel der Mission ist es, eine riesige Zahl von Sternen der Milchstrasse hochpräzise zu vermessen. In diesem Vortrag geht Stefan Jordan nach einer kurzen Einführung auf den 2. Sternkatalog von Gaia ein und nennt Beispiele. Direkt zum Thema DR2: 45:00 WEITERFÜHRENDE LINKS: Live-Vorträge ► https://josef-gassner.de/index.html Unser Team ► https://www.urknall-weltall-leben.de/team Newsletter ► https://www.urknall-weltall-leben.de/Newsletter Instagram ► https://www.facebook.com/unsupportedbrowser Spende ► https://www.urknall-weltall-leben.de/spenden Vielen Dank an alle, die unser Projekt unterstützen!
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