1. Open Cluster Stars for RAVE Observations in the Galactic Plane Ralf Scholz 1, Nina Kharchenko 1,2, Anatoly Piskunov 1,3, Elena Schilbach 4 & Siegfried Röser 4 1 AIP 2 MAO, Kiev 3 INASAN, Moscow 4 ARI Heidelberg

2. Motivation : • Out of ~1700 open clusters (OCL) there are only 326 (19%) with available radial velocity (RV) measurements: 229 OCL data taken from Dias et al. 2004 (http://www.astro.iag.usp.br/~wilton/) plus first RV determinations of 97 further OCL (Kharchenko et al. 2004c, in prep.) • RV data quality for OCL very heterogeneous: ~70% of available OCL RVs are determined from <4 stars. Cluster membership of corresponding stars not well defined. For ~30 OCL, the mean cluster RV errors are 10-30 km/s. • Uniform OCL memberships and reliable OCL RVs are needed for improving membership statistics and physical parameter determination of OCL, determining accurate space velocities of OCL of various ages, investigating OCL vs. Galactic disk (spiral structure) kinematics. • OCL stars with accurate RV measurements can serve as RV standards, because a number of physical properties of the cluster are known.

3. Our previous work on open clusters : • Proper motion and photometric studies of open clusters and associations (Pleiades, NGC6611, IC348, PerOB2) (e.g. Belikov et al. 1999a,b, 2000; Scholz et al. 1999; Belikov et al. 2002a,b) • ASCC-2.5 = All-Sky Compiled Catalogue of 2.5 million stars (Kharchenko 2001, Kinematics & Physics of Celestial Bodies 17, 409 (CDS: Cat. I/280A) • Astrophysical supplements to the ASCC-2.5: (0) Structural and kinematical parameters of 401 open clusters (Kharchenko, Pakulyak & Piskunov 2003, Astron.Reports 47, 263) (1) CRVAD = Catalogue of Radial Velocities with accurate Astrometric Data (Kharchenko, Piskunov & Scholz 2004a, Astron.Nachr. 325, 439) - including ASRV sub-sample of proposed Astrometric Standards with Radial Velocities (2) Cluster memberships in 520 open cluster areas (Kharchenko, Piskunov, Röser, Schilbach & Scholz 2004b, Astron.Nachr., submitted) (3) Physical parameters of 520 open clusters (Kharchenko et al. 2004c, in prep)

4. All-Sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5) Hipparcos family: Tycho 1/2, ACTRC, TRC, Mult.system annex PPM, CMC11 Systems: Hipparcos coords and pm Johnson V,B-V ASCC-2.5 Accurate positions and proper motions B-V,V for 2,501,304 stars + parallaxes, Sp, ids for many of them, + variability and multiplicity flags

5. X-Id. of ASCC-2.5 with GCRV (Barbier-Brossat & Figon 2000) Basic constraint : Spatial proximity Identification radii (r i ) 1 arcmin 95 % objects 3 3 % 10 2 % Other constraints: Hipparcos, DM, HD, CCDM designations Doubtful cases (checked manually): 17% Additional constraints (if several objects found within r i ): apparent magnitude color B-V Spectral Class Results: ~93% of the 36145 GCRV entries could be identified ASCC-2.5 GCRV Multiples unresolved in GCRV 34553 33509 1044

6. CRVAD completeness V compl ~ 5 mag ASCC-2,5 CRVAD ASRV ~4000 possible standards

7. CRVAD: distribution over the sky Galactic Equatorial

8. Astrometric Standards with Radial Velocities (ASRV sample) 3967 stars from CVRAD with: no var/mult flags;  RV < 2 km/s N RV > 3  coo < 0.04 mas  PM < 4 mas/yr  B,V < 0.05 mag  B-V < 0.07 mag But only 446 stars with V>9 (RAVE) Equatorial coordinates

9. ASCC-2.5 (I/280A) 2,500,000 stars positions, PM, B,V  Sp CRVAD RV of 34,500 ASCC-2.5 stars Galactic Open Cluster Lists Lynga (1987) - 1150 Dias et al. (2002) - 1630 Ruprecht et al. (1981) - 87ass Catalogue of166,000 stars in 520 sky areas supplied with membership probabilities Catalogue of data on 520 clusters (sizes, distances, ages, kinematics) Atlas of cluster diagrams (map,CMD,VPD,density profile for 520 clusters) & & NGP SGP 0°360°

10. Member selection scheme 1  -member: P >61% 2  -member: P =14-61% 3  -member: P >=1-14% Coordinate selection Photometric selection Proper motion selection 1  -member list changed ? Final member listNo Yes

11. Proper motion membership Vector Point Diagram

12. Photometric membership To filter out co-moving field stars influencing PM-selection Used: • sequences of Unresolved Binaries • Post-MS isochrones • Pre-MS isochrones Stars 1,3  P=100 % Stars 2,4,5  P>0 % Stars 6,7  P=0 % Post-MS Pre-MS q=0.8 q=1  bars

13. Blanco-1: an example of the member-selection procedure

14. Quality check using SSS I-band finding charts and magnitudes too bright (I<9) neighbouring star with I<16 within 8 arcsec bright star within 10 arcsec Out of 4592 candidates: Rejected - 1871 stars OK - 2721 stars target I>9 neighbours with I>16 next bright star outside of 10 arcsec 24 arcsec

15. RAVE targets in Galactic plane: open cluster stars/standards 1

16. RAVE targets in Galactic plane: open cluster stars/standards 2

17. RAVE targets in Galactic plane: open cluster stars/standards 3

18. RAVE targets in Galactic plane: open cluster stars/standards 4 01 02 03 06 05 07 04 08 09 10 11

19. Proposed RAVE field 01 (high priority) Many stars, but fibre allocation problem due to clustering (observe twice?)

20. Proposed RAVE field 02 (high priority) Better distribution with respect to fibre allocation Small overlap with field 03

21. Proposed RAVE field 04 (high priority) Good distribution for fibre allocation Overlap with field 05

22. Proposed RAVE field 05 (high priority) Many stars incl. 5 standards Good distribution Overlap with field 04

23. Proposed RAVE field 07 (high priority) Field centre shifted in order to get maximum number of standards (8) Total number of targets: 92

24. Proposed RAVE field 08 (lower priority) 8 clusters, but too few stars in field

25. Proposed RAVE field 11 (lower priority) Only 75 cluster stars but good distribution and 4 standards Additional stars could be selected from UCAC2 Overlap with fields 02 and 03

26. Number of selected RAVE target stars per open cluster

27. Distribution of ages and distances of selected RAVE target OCL

28. Magnitudes of OCL stars selected from ASCC-2.5 Only <10 of these stars have previous RV measurements. Even fainter cluster members could be added from the study of UCAC2 and/or SSS proper motions, in order to fill the RAVE fields with an optimum number of targets (~150/field).

29. Proper motions versus stellar magnitudes in selected areas ASCC-2.5 UCAC2 USNO-B1.0 & SSS (black)

30. Summary of proposed RAVE observations : • 7 high priority fields with 761 cluster stars + 20 RV standards • Only fields with >100 targets were considered to make effective use of RAVE observations • Field 01 proposed to be observed twice (~200 targets) • Total of 85 OCL = representative sub-sample with respect to age and distance distribution - some OCL and ass. are represented by >20 stars, RV can be used in membership study - but many OCL are currently represented by <3 stars selected as RAVE targets • Possible extension of target lists: - special efforts to increase minimum number of stars per OCL to >2, e.g. add fainter cluster stars (V>12) from UCAC2/SSS proper motion study - get more (non OCL) RV standards with less stringent criteria