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Gaia DR2— The first ”real” Gaia catalogue —
Michael Biermannon behalf of the Gaia Data Processing and Analysis Consortium DPAC
June 18, 2018
Michael Biermann Gaia DR2 June 18, 2018 1 / 50
The second Gaia Data Release (Gaia DR2) contains:
Gaia DR2 Gaia DR1 Hipparcostotal 1690 1140 0,12positions, parallaxes, proper motions 1330 2 0,12positions only 360 1140 —G magnitudes 1690 1140 0,12colours (GBP, GRP) 1380 — 0,12radial velocitites 7,2 — —stellar parameters 77 – 161 — — ︸
︷︷︸
millions
quasars 560.000 135.000 3variable stars 550.000 3.200 12.000asteroids 14.000 — 48
22 months of data; reference epoch = 2015.5
Michael Biermann Gaia DR2 June 18, 2018 2 / 50
Magnitude distribution of Gaia DR2 sources
Michael Biermann Gaia DR2 June 18, 2018 3 / 50
Magnitude distribution of Gaia DR2 sources
Michael Biermann Gaia DR2 June 18, 2018 4 / 50
Magnitude distribution of Gaia DR2 sources
Michael Biermann Gaia DR2 June 18, 2018 5 / 50
Magnitude distribution of Gaia DR2 sources
Michael Biermann Gaia DR2 June 18, 2018 6 / 50
Magnitude distribution of Gaia DR2 sources
Michael Biermann Gaia DR2 June 18, 2018 7 / 50
Magnitude distribution of Gaia DR2 sources
Michael Biermann Gaia DR2 June 18, 2018 8 / 50
Magnitude distribution of Gaia DR2 sources
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Magnitude distribution of Gaia DR2 sources
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Magnitude distribution of Gaia DR2 sources: 5p- and 2p-solutions
Michael Biermann Gaia DR2 June 18, 2018 11 / 50
Gaia DR2 precisions: parallaxes
typical precisions:
G magnitude precisions15 mag 0.03 mas17 mag 0.1 mas20 mag 0.7 mas21 mag 2.0 mas
Systematics below 0.1 mas.
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Gaia DR2 precisions: parallaxes
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Gaia DR2 precisions: proper motions
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Gaia DR2 precisions: photometry
calibration floors:
G 2 mmagBP 5 mmagRP 3 mmag
orange DR2magenta DR1
G band 330 – 1050 nmBP 330 – 680 nmRB 630 – 1050 nm
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Gaia DR2 precisions: radial velocities
RVS: 845 – 872 nm; only stars in the temperature range [3550,6900] KMichael Biermann Gaia DR2 June 18, 2018 16 / 50
Source IDs and cross-match: duplicates removed
Cycle-01 sources
−→ improved accuracy
Cycle-02 sources
Michael Biermann Gaia DR2 June 18, 2018 17 / 50
Significantly improved angular resolution
— dense sky areas —
0 1 2 3 4 5 6Separation [arcsec]
0
1e4
2e4
3e4Pai
rsin
0:1
arcs
ecbin
sDR2
DR2 w: GBP & GRP
DR1Constant ¯eld density
Gaia DR1: 2 arcsecondsGaia DR2: 0.4 arcseconds
}factor 5 !
Michael Biermann Gaia DR2 June 18, 2018 18 / 50
Significantly improved angular resolution
— sparse sky areas —
0 1 2 3 4 5 6 7 8 9 10Separation [arcsec]
0
100
200
Pai
rsin
0:1
arcs
ecbin
s
DR2
DR2 w: GBP & GRP
DR1Constant ¯eld density
Gaia “sees” real double stars with 0.4 – 3 arcseconds separation
Michael Biermann Gaia DR2 June 18, 2018 19 / 50
Room for improvements
1◦ checkered parallax pattern(0.03 mas, in the LMC, but present over all the sky)
6065707580859095100
¡73
¡72
¡71
¡70
¡69
¡68
¡67
¡66
¡65
¡64
¡63
¡0:10
¡0:08
¡0:06
¡0:04
¡0:02
0
0:02
0:04
0:06
0:08
0:10
Med
ian
par
alla
x[m
as]
Dec
linat
ion
[deg
]
Right Ascension [deg]
Med
ian
para
llax
[mas
]
... 20◦ spatial patterns of typically 0.02 mas
... and a -0.03 mas parallax zero point errorMichael Biermann Gaia DR2 June 18, 2018 20 / 50
Gaia DR2 is an independent catalogue!
stand alone this time
Michael Biermann Gaia DR2 June 18, 2018 21 / 50
Gaia DR2 is an independent catalogue!
stand alone this time
different photometric system (∆G ≈ −0.1 mag, colour dependent)
Michael Biermann Gaia DR2 June 18, 2018 21 / 50
Gaia DR2 is an independent catalogue!
stand alone this time
different photometric system (∆G ≈ −0.1 mag, colour dependent)
different source listI merged / split / new sourcesI Gaia DR2 ↔ Gaia DR1
F G < 16: 80-90% of the sources changed sourceIDF G < 18: 20% of the sources changed sourceIDF tracking table is delivered as part of Gaia DR2
I DR3 outlook:F roughly 10% changes to be expected overall
Michael Biermann Gaia DR2 June 18, 2018 21 / 50
Gaia-Archive
• ARI: http://gaia.ari.uni-heidelberg.de/
• ESA: http://archives.esac.esa.int/gaia
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Gaia Documentation & Videos
we highly recommend to read the Gaia DR2 A&A release papers(≈ 10 papers)
you should also consult the Gaia DR2 on-line documentationhttp://gaia.esac.esa.int/documentation
there are in addition science verification papers with valuableinformation(A&A, ≈ 10 papers)
we have videos for scientistsexplaining important aspects of Gaia DR2https://www.cosmos.esa.int/web/gaia/guide-to-scientists
Gaia User Forumhttps://www.cosmos.esa.int/web/gaia/forum
Michael Biermann Gaia DR2 June 18, 2018 23 / 50
A glimpse of science with Gaia DR2...
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LMC rotational field
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LMC rotational field
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Hertzsprung-Russell diagram
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Hertzsprung-Russell diagram
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Hertzsprung-Russell diagram
white dwarfs with H envelope
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Hertzsprung-Russell diagram
white dwarfs with He envelope
Michael Biermann Gaia DR2 June 18, 2018 30 / 50
Hertzsprung-Russell diagram
white dwarfs with C-O core that lost their envelope
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Hertzsprung-Russell diagram
binaries with two white dwarfs of equal mass
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Hertzsprung-Russell diagram
binaries with a white dwarf and a main-sequence star
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Hertzsprung-Russell diagram
unknown population of white dwarfs?
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Hertzsprung-Russell diagram
yet unknown population of white dwarfs?
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Hertzsprung-Russell diagram
giant branch
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Hertzsprung-Russell diagram
HRD of 32 open cluster
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Hertzsprung-Russell diagram
HRD of 14 globular cluster
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Hertzsprung-Russell diagram
Praesepe and Hyades cluster HRD
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“Clean” HR diagram of nearby (< 100 pc) stars
¡1 0 1 2 3 4 5 6
GBP¡ GRP [mag]
¡5
0
5
10
15
20
25
G+
5lo
g 10($=1
00m
as)
$ > 10 mas, $/σ$ > 10, phot xp mean flux over error > 10:338,833
Michael Biermann Gaia DR2 June 18, 2018 40 / 50
“Clean” HR diagram of nearby (< 100 pc) stars
¡1 0 1 2 3 4 5 6
GBP¡ GRP [mag]
¡5
0
5
10
15
20
25
G+
5lo
g 10($=1
00m
as)
Sources additionally filtered by (magnitude-dependent) chi-square: 249,793
Michael Biermann Gaia DR2 June 18, 2018 41 / 50
“Clean” HR diagram of nearby (< 100 pc) stars
¡1 0 1 2 3 4 5 6
GBP¡ GRP [mag]
¡5
0
5
10
15
20
25
G+
5lo
g 10($=10
0m
as)
Sources additionally filtered by chi-square and flux excess ratio: 242,583
Michael Biermann Gaia DR2 June 18, 2018 42 / 50
Stars within 50 pc from the Sun
73,246
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Stars within 50 pc from the Sun) stars
Sources additionally filtered by (magnitude-dependent) chi-square: 39,478
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Stars within 50 pc from the Sun
Sources additionally filtered by chi-square and flux excess ratio: 34,001(but at least 700 real stars lost)
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On the road to Gaia DR3 ...
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Forthcoming Gaia DR3 — planned for end 2020
photometric epoch data for variable stars
double stars
100,000 solar system objects with orbits
asteroid spectra
more than 1 million quasars and extended objects
35 million radial velocities
astrometry, photometry, spectroscopy, variable stars, ...:increased numbers, better accuracies/systematics
variable stars: more types of variability
Michael Biermann Gaia DR2 June 18, 2018 50 / 50