Milky Way star clusters

Using Γα ια for studying Milky Way star clusters Eugene Vasiliev Institute of Astronomy, Cambridge MODEST-, 26 June

Overview of Gaia mission Scanning the entire sky every couple of weeks Astrometry for sources down to 21 mag Broad-band photometry/low-res spectra G BP RP RVS Radial velocity down to 1 mag (end-of-mission) [Source: ESA]

Overview of Data Release 2 astrometry Based on 22 months of data collection Total number of sources: 1.69 9 Sources with full astrometry (parallax ϖ, proper motions µ α, µ δ ): 1.33 9 Colours (G BP, G RP ): 1.38 9 Radial velocities: 7.2 6 RV colours Effective temperature: 6 Stellar parameters (R, L ): 77 6 Extinction and reddening: 88 6 Variable sources: 6 Number per.1 mag bin 8 7 6 4 3 2 Teff vrad Variable Gaia-CRF2 ICRF3 prototype SSO Gaia DR1 Gaia DR2 1 1 2 Mean [Brown+ ]

Photometry G-band uncertainty [mag] G magnitude at D= Kpc 13 1 17 Age= Gyr, [Fe/H]=-2 Age=1 Gyr, [Fe/H]= 7 8 9 11 13 G magnitude at D=1 Kpc R-band uncertainty [mag] 19 1 21.2.4.6.8 1.2 1.4 1.6 GBP GRP [Evans+ ]

Astrometry parallax uncertainty [mas] G magnitude at D= Kpc 13 1 Age= Gyr, [Fe/H]=-2 17 19 21.2.4.6.8 1.2 1.4 1.6 GBP GRP Age=1 Gyr, [Fe/H]= 7 8 9 11 13 1 G magnitude at D=1 Kpc Standard uncertainty in parallax (¾$) [mas] Semi major axis of error ellipse in p:m: (¾pm;max) [mas yr 1 ] 2 1 : :2 :1 : :2 :1 : 6 7 8 9 11 13 1 17 19 21 G magnitude 2 1 : :2 :1 : :2 :1 systematic error proper motion uncertainty [mas/yr] systematic error 1 mas/yr = 4.7 km/s (D/1 Kpc) : 6 7 8 9 11 13 1 17 19 21 G magnitude [Lindegren+ ]

Spectroscopy G magnitude at D= Kpc 13 1 17 Age= Gyr, [Fe/H]=-2 Age=1 Gyr, [Fe/H]= 7 8 9 11 13 G magnitude at D=1 Kpc RV measurements only for stars with T eff [3 69] K and G RVS radial velocity uncertainty [km/s] 19 1 21.2.4.6.8 1.2 1.4 1.6 GBP GRP systematic error [Katz+ ]

Correlations and systematic errors µ α correlations between parallax and PM (ω Cen region) µ δ µ α µ δ mean parallax and PM (Large Magellanic Cloud region).8.6.4.2.2.4.6.8.. 8 6 4 2 2 4 6 8 8 6 4 2 2 4 6 8 1.4 1. 1.6 1.7 1.8 1.9 2. 2.1 2.2 2.3 8 µα 6 4 2 2 4 6 8 8 6 4 2 2 4 6 8.1.1.2.3.4.6.7.8 8 µδ 6 4 2 2 4 6 8 8 6 4 2 2 4 6 8

Limitations No special processing for binary stars (but a poor astrometric solution is marked clearly) Colour photometry has lower spatial resolution (a quality control flag is provided) Poor completeness at faint magnitudes in crowded regions Need to apply various filters to clean up sample (but do it wisely, e.g., don t just cut off negative parallaxes [see Luri+ for a discussion]) [Arenou+ ]

Dynamics of Milky Way globular clusters Internal: rotation, velocity dispersion and anisotropy profiles: Rotation signatures from radial velocities [e.g., Fabricius+, Kamann+ 17] now complemented by proper motion (PM) data [HST: Bellini+, Watkins+ 1; Gaia: Bianchini+ ] Velocity anisotropy determined directly from PM Velocity dispersion profile in the outskirts, potential escapers [e.g., Claydon+ 17] External: 3d center-of-mass velocity data: galactic orbits [e.g., Helmi+ ], tidal effects possible correlations in phase-space distribution (cluster pairs) dynamical tracers of Milky Way potential

Example: NGC 139 (ω Cen) All stars Sky map PM map µδ [mas/yr] N=33469 1 2 3 Color - magnitude diagram Magnitude vs. distance from center 1 1 µα [mas/yr] Magnitude vs. PM error 1. 2. BP-RP [mag].2.4.6.8 R [deg].1.2 1 2 4 δµα [mas/yr]

Example: NGC 139 (ω Cen) Stars with full astrometry (ϖ, µ α, µ δ ) Sky map PM map µδ [mas/yr] N=22774 1 2 3 Color - magnitude diagram Magnitude vs. distance from center 1 1 µα [mas/yr] Magnitude vs. PM error 1. 2. BP-RP [mag].2.4.6.8 R [deg].1.2 1 2 4 δµα [mas/yr]

Example: NGC 139 (ω Cen) Parallax cut: ϖ ϖ < 3 δϖ, ϖ =.1 mas Sky map µδ [mas/yr] PM map N=798 1 2 3 Color - magnitude diagram Magnitude vs. distance from center 1 1 µα [mas/yr] Magnitude vs. PM error 1. 2. BP-RP [mag].2.4.6.8 R [deg].1.2 1 2 4 δµα [mas/yr]

Example: NGC 139 (ω Cen) Cut on astrometric quality: astrometric excess noise < 1 mas Sky map PM map µδ [mas/yr] N=7376 1 2 3 Color - magnitude diagram Magnitude vs. distance from center 1 1 µα [mas/yr] Magnitude vs. PM error 1. 2. BP-RP [mag].2.4.6.8 R [deg].1.2 1 2 4 δµα [mas/yr]

Example: NGC 139 (ω Cen) Cut on photometric quality: phot bp rp excess factor < 1.3 + 6 (G BP G RP ) 2 Sky map µδ [mas/yr] PM map N=89686 1 2 3 Color - magnitude diagram Magnitude vs. distance from center 1 1 µα [mas/yr] Magnitude vs. PM error 1. 2. BP-RP [mag].2.4.6.8 R [deg].1.2 1 2 4 δµα [mas/yr]

Example: NGC 139 (ω Cen) CMD cut Sky map PM map µδ [mas/yr] N=3989 1 2 3 Color - magnitude diagram Magnitude vs. distance from center 1 1 µα [mas/yr] Magnitude vs. PM error 1. 2. BP-RP [mag].2.4.6.8 R [deg].1.2 1 2 4 δµα [mas/yr]

Example: NGC 139 (ω Cen) Cut on proper motions: (µ α µ α, ) 2 + (µ δ µ δ, ) 2 < µ 2, µ α, = 3.2 mas/yr, µ δ, = 6.7 mas/yr, µ = 2 mas/yr Sky map µδ [mas/yr] PM map N=22342 1 2 3 Color - magnitude diagram Magnitude vs. distance from center 1 1 µα [mas/yr] Magnitude vs. PM error 1. 2. BP-RP [mag].2.4.6.8 R [deg].1.2 1 2 4 δµα [mas/yr]

Inferring the internal velocity dispersion Gaussian mixture modelling of PM distribution without applying hard cuts and taking into account individual errors (Extreme Deconvolution, Bovy+ 11) 4 2 2 G< G< 3 G<: data with errors G<: deconvolved G<: bootstrapped G<: data with errors G<: deconvolved G<: bootstrapped µδ [mas/yr] 4 6 # of stars 2 8 1 8 6 4 2 2 4 6 8 µα [mas/yr] 8 6 4 2 2 4 6 8 µα [mas/yr] NGC 672,.3 < R <

Results: radial profile of velocity dispersion and rotation ω Cen (D=.2 Kpc).8 R [pc] 3 4 µt.7.6 σr σt σmodel [Zocchi+ ] vlos [Baumgardt&Hilker ] 1 µ [mas/yr].4.3 v [km/s].2.1.1.2.3.4 R [deg]

Effects of various quality cuts.4.3 σµ [mas/yr].2.1 All filters All filters + G< No phot_bp_rp_excess_factor cut No error deconvolution No error deconvolution, G<.1.2.3.4 R [deg]

Proper motions for [almost all] Milky Way globular clusters 4 NGC_4_47Tuc NGC_139_oCen NGC_666_M_22 6 NGC_61_M_4 NGC_6397 NGC_672 NGC_94_M_ NGC_6_M_13 NGC_288 NGC_272_M_3 NGC_778_M_1 NGC_689_M_ NGC_641 NGC_6266_M_62 NGC_6341_M_92 NGC_362 NGC_789_M_2 NGC_624_M_ NGC_62_M_ NGC_31 NGC_6273_M_19 NGC_6388 NGC_6626_M_28 NGC_4833 NGC_6723 NGC_6441 NGC_1 NGC_4372 NGC_799_M_3 NGC_693_M_8 NGC_286 HST (Sohn+ ) Gaia (Helmi+ ) Gaia (new) 8 NGC_644 NGC_6838_M_71 NGC_986 NGC_6637_M_69 NGC_642_M_ NGC_24_M_3 NGC_6362 NGC_6333_M_9 NGC_194_M_79 NGC_6624 NGC_6681_M_7 NGC_49_M_68 NGC_632 NGC_6171_M7 NGC_63 NGC_927 NGC_67 NGC_288 NGC_634 NGC_622 NGC_6779_M_6 NGC_6293 NGC_684 NGC_636 NGC_61 NGC_63 NGC_669 NGC_6496 NGC_897 NGC_6864_M_7 NGC_662 NGC_671_M_4 Total magnitude NGC_6366 NGC_676 NGC_64 NGC_6638 NGC_6139 NGC_6642 NGC_63 NGC_644 NGC_64_Djorg NGC_6717_Pal9 NGC_68 NGC_639 NGC_2298 NGC_6287 NGC_641 NGC_628 NGC_6342 NGC_946 Pal_11 Djorg_2_ESO46- NGC_623 NGC_643 Lynga_7_BH4 NGC_617 IC_76_Pal_7 NGC_632 NGC_63 BH_261_AL_3 Pal_8 NGC_6284 NGC_6934 NGC_466 NGC_61 NGC_6981_M_72 NGC_3 IC_4499 NGC_47 Rup_6 NGC_6426 NGC_634 NGC_6229 NGC_824 NGC_694 NGC_76 NGC_2419 E_3 NGC_626 NGC_638_Ton1 NGC_7492 Pal_6 HP_1_BH_229 Terzan_3 36-283_ESO42 Ton2_Pismis26 NGC_6749 Pal_ Pal_ ESO-SC6_ESO28 Terzan_7 Arp_2 Terzan_8 Pal_ Pal_1 IC_7 Pal_2 Pyxis Djorg_1 Pal_13 Terzan_6_HP_ Terzan 11 Terzan_2_HP_3 BH_176 Pal_1 Pal_3 Pal_4 Pal_ Eridanus Terzan_ Whiting_1 Terzan_ Terzan_1_HP_2 Terzan_9 Terzan_4_HP_4 AM_1 1 2 Distance, Kpc

Phase-space distribution of Milky Way globular clusters Lz/Lcirc 3. 2. 2. 1. E/ (km/s)^2 NGC_4_47Tuc NGC_288 NGC_362 Whiting_1 NGC_61 Pal_1 AM_1 Eridanus Pal_2 NGC_1 NGC_194_M_79 NGC_2298 NGC_2419 Pyxis NGC_288 Pal_3 NGC_31 Pal_4 NGC_47 NGC_4372 Rup_6 NGC_49_M_68 NGC_4833 NGC_24_M_3 NGC_3 NGC_139_oCen NGC_272_M_3 NGC_286 NGC_466 NGC_634 NGC_694 IC_4499 NGC_824 Pal_ NGC_897 NGC_94_M_ NGC_927 NGC_946 NGC_986 Lynga_7_BH4 Pal_ NGC_693_M_8 NGC_61_M_4 NGC_61 NGC_64 NGC_6139 Terzan_3 NGC_6171_M7 NGC_6_M_13 NGC_6229 NGC_62_M_ NGC_623 NGC_624_M_ NGC_626 Pal_1 NGC_6266_M_62 NGC_6273_M_19 NGC_6284 NGC_6287 NGC_6293 NGC_634 NGC_63 NGC_6341_M_92 NGC_632 NGC_6333_M_9 NGC_6342 NGC_636 NGC_63 NGC_632 IC_7 Terzan_2_HP_3 NGC_6366 Terzan_4_HP_4 HP_1_BH_229 NGC_6362 NGC_638_Ton1 Terzan_1_HP_2 Ton2_Pismis26 NGC_6388 NGC_642_M_ NGC_641 NGC_6397 Pal_6 NGC_6426 Terzan 11 NGC_644 NGC_6441 Terzan_6_HP_ NGC_643 NGC_6496 Terzan_9 NGC_617 NGC_622 NGC_63 NGC_628 NGC_639 NGC_64_Djorg NGC_644 NGC_641 NGC_63 NGC_68 IC_76_Pal_7 Terzan_ NGC_669 NGC_684 NGC_6624 NGC_6626_M_28 NGC_6638 NGC_6637_M_69 NGC_6642 NGC_662 NGC_666_M_22 Pal_8 NGC_6681_M_7 NGC_67 NGC_671_M_4 NGC_6717_Pal9 NGC_6723 NGC_6749 NGC_672 NGC_676 NGC_6779_M_6 Terzan_7 Pal_ Arp_2 NGC_689_M_ Terzan_8 Pal_11 NGC_6838_M_71 NGC_6864_M_7 NGC_6934 NGC_6981_M_72 NGC_76 NGC_778_M_1 NGC_789_M_2 NGC_799_M_3 Pal_ Pal_13 NGC_7492 HST (Sohn+ ) Gaia (Helmi+ ) Gaia (new).2.4.6.8 (L/Lcirc)^2 1 2 4 6 8 1 3 Rcirc (Kpc) NGC_4_47Tuc NGC_288 NGC_362 Whiting_1 NGC_61 Pal_1 AM_1 Eridanus Pal_2 NGC_1 NGC_194_M_79 NGC_2298 NGC_2419 Pyxis NGC_288 Pal_3 NGC_31 Pal_4 NGC_47 NGC_4372 Rup_6 NGC_49_M_68 NGC_4833 NGC_24_M_3 NGC_3 NGC_139_oCen NGC_272_M_3 NGC_286 NGC_466 NGC_634 NGC_694 IC_4499 NGC_824 Pal_ NGC_897 NGC_94_M_ NGC_927 NGC_946 NGC_986 Lynga_7_BH4 Pal_ NGC_693_M_8 NGC_61_M_4 NGC_61 NGC_64 NGC_6139 Terzan_3 NGC_6171_M7 NGC_6_M_13 NGC_6229 NGC_62_M_ NGC_623 NGC_624_M_ NGC_626 Pal_1 NGC_6266_M_62 NGC_6273_M_19 NGC_6284 NGC_6287 NGC_6293 NGC_634 NGC_63 NGC_6341_M_92 NGC_632 NGC_6333_M_9 NGC_6342 NGC_636 NGC_63 NGC_632 IC_7 Terzan_2_HP_3 NGC_6366 Terzan_4_HP_4 HP_1_BH_229 NGC_6362 NGC_638_Ton1 Terzan_1_HP_2 Ton2_Pismis26 NGC_6388 NGC_642_M_ NGC_641 NGC_6397 Pal_6 NGC_6426 Terzan 11 NGC_644 NGC_6441 Terzan_6_HP_ NGC_643 NGC_6496 Terzan_9 NGC_617 NGC_622 NGC_63 NGC_628 NGC_639 NGC_64_Djorg NGC_644 NGC_641 NGC_63 NGC_68 IC_76_Pal_7 Terzan_ NGC_669 NGC_684 NGC_6624 NGC_6626_M_28 NGC_6638 NGC_6637_M_69 NGC_6642 NGC_662 NGC_666_M_22 Pal_8 NGC_6681_M_7 NGC_67 NGC_671_M_4 NGC_6717_Pal9 NGC_6723 NGC_6749 NGC_672 NGC_676 NGC_6779_M_6 Terzan_7 Pal_ Arp_2 NGC_689_M_ Terzan_8 Pal_11 NGC_6838_M_71 NGC_6864_M_7 NGC_6934 NGC_6981_M_72 NGC_76 NGC_778_M_1 NGC_789_M_2 NGC_799_M_3 Pal_ Pal_13 NGC_7492

Complementary instruments and surveys Astrometry (mainly proper motions): Gaia: down to G = 21, but only in the outer parts; central regions severely limited by crowding. + Provides absolute proper motions in the global reference frame (subject to systematic uncertainty of mas/yr). Hubble (HSTPROMO: Bellini+, Watkins+ 1, Sohn+ ): + performs well even in crowded regions; + precision comparable or better than Gaia (baseline 1 yr); + goes down to 26 mag in outer regions; much smaller FoV (3 ); PMs are relative (don t provide mean motion and rotation), unless enough background galaxies are used to anchor them. Ground-based: superseded by Gaia for all practical purposes.

Complementary instruments and surveys Radial velocities: Gaia: down to G 13 (improved by 3 mag towards the end of mission), but for the entire sky (8 9% compleness except dense regions). Ground-based: several magnitudes deeper, but more limited spatial coverage. Chemistry, stellar parameters: Gaia: T eff, R, L, log g down to G 17 in DR2 based on parallax and broad-band photometry only (G, BP, RP); will be improved in future data releases with low-res spectroscopy from BP/RP. Ground-based spectroscopy: produces much more information. Photometry: Gaia cross-matches with several other surveys (2MASS, SDSS, PanSTARRS, RAVE) is provided in DR2.

Future data releases DR3 (late ), DR4 (end 22): binary stars; BP/RP and RVS spectra; improved calibration, PSF modelling, etc.; better treatment of crowded regions; extended spectroscopic templates for hotter/cooler stars; variable star classification and lightcurves; epoch astrometry ( 3 observations for each star). Mission extension from nominal years up to years: parallax error T 1/2, PM error T 3/2!

Summary Gaia is awesome by itself, and complementary to other surveys Internal dynamics of globular clusters (velocity dispersion profiles, anisotropy, rotation, tidal boundary) Motion of globular clusters in the Galaxy