Open Cluster Stars for RAVE Open Cluster Stars for RAVE Observations in the Observations in the Galactic Plane Galactic Plane Scholz 1 , Nina Kharchenko 1,2 , Anatoly Piskuno Elena Schilbach 4 & Siegfried Röser 4 1 AIP 2 MAO, Kiev 3 INASAN, Moscow 4 ARI Heidelberg
30
Embed
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.
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)
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Open Cluster Stars for RAVE Open Cluster Stars for RAVE Observations in the Galactic PlaneObservations in the Galactic Plane
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 forimproving 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.
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)
All-Sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5)
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°
Member selection scheme
1-member: P >61%2-member: P =14-61%3-member: P >=1-14%
Coordinateselection
Photometricselection
Proper motionselection
1-member list changed ?
Final member list
NoNo
YesYes
Proper motion membership
Vector Point Diagram
Photometric membership
To filter out co-moving field starsinfluencing PM-selection
Used: sequences of Unresolved BinariesPost-MS isochronesPre-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
Blanco-1: an example of the member-selection procedure
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
RAVE targets in Galactic plane: open cluster stars/standards 1
RAVE targets in Galactic plane: open cluster stars/standards 2
RAVE targets in Galactic plane: open cluster stars/standards 3
RAVE targets in Galactic plane: open cluster stars/standards 4
01
020203
06
05
07
04
0809
10
11
Proposed RAVE field 01 (high priority)
Many stars, but fibre allocation problem due to clustering (observe twice?)
Proposed RAVE field 02 (high priority)
Better distribution with respect to fibre allocation
Small overlap with field 03
Proposed RAVE field 04 (high priority)
Good distribution for fibre allocation
Overlap with field 05
Proposed RAVE field 05 (high priority)
Many stars incl. 5 standards
Good distribution
Overlap with field 04
Proposed RAVE field 07 (high priority)
Field centre shifted in order to get maximum number of standards (8)
Total number of targets: 92
Proposed RAVE field 08 (lower priority)
8 clusters, but too few stars in field
Proposed RAVE field 11 (lower priority)
Only 75 cluster stars but good distribution and 4 standards
Additional stars could be selectedfrom UCAC2
Overlap with fields 02 and 03
Number of selected RAVE target stars per open cluster
Distribution of ages and distances of selected RAVE target OCL
Magnitudes of OCL stars selected from ASCC-2.5Only <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).
Proper motions versus stellar magnitudes in selected areas
ASCC-2.5
UCAC2
USNO-B1.0 & SSS (black)
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