Gaia DR2 The first 'real' Gaia catalogue€¦ · Gaia DR2 | The rst "real" Gaia catalogue | Michael Biermann on behalf of the Gaia Data Processing and Analysis Consortium DPAC June

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


Magnitude distribution of Gaia DR2 sources
















Magnitude distribution of Gaia DR2 sources: 5p- and 2p-solutions


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.


Gaia DR2 precisions: parallaxes


Gaia DR2 precisions: proper motions


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


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


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 !


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


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




different photometric system (∆G ≈ −0.1 mag, colour dependent)




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


Gaia-Archive

• ARI: http://gaia.ari.uni-heidelberg.de/

• ESA: http://archives.esac.esa.int/gaia


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


http://gaia.esac.esa.int/documentation

https://www.cosmos.esa.int/web/gaia/guide-to-scientists

https://www.cosmos.esa.int/web/gaia/forum

A glimpse of science with Gaia DR2...


LMC rotational field


LMC rotational field


Hertzsprung-Russell diagram





white dwarfs with H envelope



white dwarfs with He envelope



white dwarfs with C-O core that lost their envelope



binaries with two white dwarfs of equal mass



binaries with a white dwarf and a main-sequence star



unknown population of white dwarfs?



yet unknown population of white dwarfs?



giant branch



HRD of 32 open cluster



HRD of 14 globular cluster



Praesepe and Hyades cluster HRD


“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



¡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



¡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


Stars within 50 pc from the Sun

73,246


Stars within 50 pc from the Sun) stars

Sources additionally filtered by (magnitude-dependent) chi-square: 39,478


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)





On the road to Gaia DR3 ...


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


Documents

Gaia DR2 The first 'real' Gaia catalogue€¦ · Gaia DR2 | The rst "real" Gaia catalogue | Michael Biermann on behalf of the Gaia Data Processing and Analysis Consortium DPAC June