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 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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 97 46 Barycentric radial velocities
table3.dat 105 11 Membership probabilities
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See also:
J/A+AS/121/499 : BV and rg photometry of Pal 13 (Borissova+ 1997)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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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)
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Note (1): Data from Cote et al. (2002ApJ...574..783C 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 2001AJ....121..935S)
Note (3): Quality flag: 1 for best and 9 for worst.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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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)
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Note (1): Data from Siegel et al. (2001AJ....121..935S 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.
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Acknowledgements: Frederic Royer
(End) Andre Blecha [Geneva Obs., Switzerland], Patricia Bauer [CDS] 04-Mar-2004