J/A+A/419/533 Pal 13 UBV, proper motions and radial velocities (Blecha+, 2004)
Palomar 13: a velocity dispersion inflated by binaries ? Blecha A., Meylan G., North P., Royer F. <Astron. Astrophys. 419, 533 (2004)> =2004A&A...419..533B
ADC_Keywords: Clusters, globular ; Photometry, UBV ; Proper motions ; Radial velocities Keywords: globular clusters: individual: Palomar 13 - mass-to-light ratio - techniques: radial velocities - stars: kinematics, population II Abstract: Recently, combining radial velocities from Keck/HIRES echelle spectra with published proper motion membership probabilities, Cote et al. (2002ApJ...574..783C) observed a sample of 21 stars, probable members of Palomar 13, a globular cluster in the Galactic halo. Their projected velocity dispersion sigmap=2.2±0.4km/s gives a mass-to-light ratio M/LV=40+24-17, about one order of magnitude larger than the usual estimate for globular clusters. We present here radial velocities measured from three different CCD frames of commissioning observations obtained with the new ESO/VLT instrument FLAMES (Fibre Large Array Multi Element Spectrograph). From these data, now publicly available, we measure the homogeneous radial velocities of eight probable members of this globular cluster. A new projected velocity dispersion sigmap=0.6-0.9±0.3km/s implies Palomar 13 mass-to-light ratio M/LV=3-7, similar to the usual value for globular clusters. We discuss briefly the two most obvious reasons for the previous unusual mass-to-light ratio finding: binaries, now clearly detected, and more homogeneous data from the multi-fibre FLAMES spectrograph. Description: All the new data presented in this paper were acquired between August 28 and September 3 2002, during the commissioning of the ESO/VLT instrument FLAMES (Fibre Large Array Multi Element Spectrograph), at Paranal, Chile. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 97 46 Barycentric radial velocities table3.dat 105 11 Membership probabilities
See also: J/A+AS/121/499 : BV and rg photometry of Pal 13 (Borissova+ 1997) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq Identification number (this study) 5- 7 I3 --- CDM ? Identification number (1) 9 I1 --- PMemb [0/1] Membership probability (this study) 11 I1 --- PMembCDM [0/1]? Membership probability (1) 13- 21 F9.5 deg RAdeg Right ascension (J2000.0) 23- 30 F8.5 deg DEdeg Declination (J2000.0) 32- 34 I3 arcsec R Distance to the cluster center 36- 40 F5.2 mag Vmag V magnitude (2) 42- 48 F7.2 km/s RV1 ? Radial velocity for FLAMES epoch 1, 2002/09/01 50- 56 F7.2 km/s RV2 ? Radial velocity for FLAMES epoch 2, 2002/09/01 58- 64 F7.2 km/s RV3 ? Radial velocity for FLAMES epoch 3, 2002/09/03 66 I1 --- o_RV1 Number of valid FLAMES measurements 68- 69 A2 --- q_RV1 Cross-correlation-peak quality (3) 71- 75 F5.2 km/s Sigma ? Standard deviation associated to FLAMES RV 77- 83 F7.2 km/s RV Mean radial velocity from FLAMES data 85- 89 F5.2 km/s e_RV Estimated error on mean RV 91- 97 F7.2 km/s RVCDM ? Mean radial velocity (1)
Note (1): Data from Cote et al. (2002ApJ...574..783C), Nb 1 to 118: Cl* Palomar 13 ORS NN in Simbad Nb 910: Cl* Palomar 13 CDM NNN in Simbad Note (2): Data from Siegel et al. (2001AJ....121..935S) Note (3): Quality flag: 1 for best and 9 for worst.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq Identification number (this study) 5- 6 I2 h RAh Right ascension hours (J2000.0) 8- 9 I2 min RAm Right ascension minutes (J2000.0) 11- 15 F5.2 s RAs Right ascension seconds (J2000.0) 17- 18 I2 deg DEd Declination degrees (J2000.0) 20- 21 I2 arcmin DEm Declination minutes (J2000.0) 23- 26 F4.1 arcsec DEs Declination seconds (J2000.0) 28- 32 F5.2 mas/yr pmRA Proper motion mu_alpha (1) 34- 37 F4.2 mas/yr e_pmRA Error on mu_alpha (1) 39- 43 F5.2 mas/yr pmDE Proper motion mu_delta (1) 45- 48 F4.2 mas/yr e_pmDE Error on mu_delta (1) 50- 51 I2 % PMemb Membership probability from proper motion (1) 53- 59 F7.2 km/s RV Mean radial velocity from FLAMES data 61- 66 F6.3 mag Umag U magnitude (1) 68- 72 F5.3 mag e_Umag Error on U magnitude (1) 74- 79 F6.3 mag Bmag B magnitude (1) 81- 85 F5.3 mag e_Bmag Error on B magnitude (1) 87- 92 F6.3 mag Vmag V magnitude (1) 94- 98 F5.3 mag e_Vmag Error on V magnitude (1) 100-105 A6 --- CMD Position in the CMD (2)
Note (1): Data from Siegel et al. (2001AJ....121..935S) Note (2): Position in the color-magnitude diagram: RRL: RR-Lyrae pulsating star, RGB: Red-Giant Branch, SGB: Sub-Giant Branch, BS: Blue Straggler, off-r: off to the right of the cluster sequences.
Acknowledgements: Frederic Royer
(End) Andre Blecha [Geneva Obs., Switzerland], Patricia Bauer [CDS] 04-Mar-2004
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