J/A+A/555/A91 Kinematics of bulge red clump stars (Vasquez+, 2013)
3D kinematics through the X-shaped Milky Way bulge.
Vasquez S., Zoccali M., Hill V., Renzini A., Gonzalez O.A., Gardner E.,
Debattista Victor P., Robin A.C., Rejkuba M., Baffico M., Monelli M.,
Motta V., , Minniti D.
<Astron. Astrophys. 555, A91 (2013)>
=2013A&A...555A..91V 2013A&A...555A..91V
ADC_Keywords: Milky Way ; Radial velocities ; Photometry, VRI ;
Photometry, infrared ; Stars, giant
Keywords: Galaxy: bulge - Galaxy: kinematics and dynamics - Galaxy: structure -
Galaxies: kinematics and dynamics -
globular clusters: individual: NGC 6558
Abstract:
The Galactic bulge is X-shaped, caused by the two southern arms of the
X both crossing the lines of sight, producing a double red clump (one
bright and one faint) in the color magnitude diagram. In this paper
the authors measure the radial velocities and proper motions for a
sample of 454 individual bulge giant stars, roughly equally
distributed between the two red clumps to determine how such a
structure could be formed from bar instabilities. The radial velocity
distribution of stars in the bright red clump, which traces the closer
overdensity of bulge stars, shows an excess of stars moving towards
the Sun. Similarly, an excess of stars receding from the Sun is seen
in the more distant overdensity, which is traced by faint red clump
stars. This can be explained by the presence of stars on elongated
orbits, which are most likely streaming along the arms of the X-shaped
bulge. Proper motions for these stars are consistent with qualitative
predictions of dynamical models of peanut-shaped bulges. Surprisingly,
stars on elongated orbits have preferentially metal-poor (subsolar)
metallicities, while the metal rich ones, in both overdensities, are
preferentially found in more axisymmetric orbits.
Description:
The Kinematics and photometry for spectroscopic targets are presented.
For each star with proper motions determination, the coordinates in
each single epoch is provided.
The spectroscopic targets were selected based on the optical V, I
photometry of a bulge field centered at (l, b) = (0, -6), obtained
with the WFI camera at the 2.2m telescope at ESO La Silla, on
1999-04-15 as part of the ESO imaging Survey ESO programme (EIS,
ESO programme ID 163.O-0741(A)). A second epoch image was taken on
2010-05-06, with the same instrument and filters.
The resulting CMD has been already presented in Zoccali et al.
(2003A&A...399..931Z 2003A&A...399..931Z) and McWilliam & Zoccali (2010ApJ...724.1491M 2010ApJ...724.1491M).
Based on this CMD the red clump targets were selected among the bright
(red dots) and faint red clump stars (blue dots) for spectroscopic
follow-up with Magellan IMACS spectrograph at the Las Campanas
Observatory on 2010-07-10 (R∼5000) and VLT FLAMES-GIRAFFE
spectrograph within the ESO programme ID 385.B-0735(B) (R∼6500).
In order to derive space velocities for our targets, second epoch
images of the same field were obtained on May 6th, 2010 with the same
instrument and filters as in the first epoch (ESO program 085.D-0143(A)).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
bulge_rc.dat 122 454 Kinematics for bulge red clump stars
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See also:
I/317 : The PPMXL Catalog (Roeser+ 2010)
II/270 : TCS-CAIN: NIR Survey of the Galactic plane (Cabrera-Lavers+, 2006)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/MNRAS/421/3362 : Kinematics of galactic red clump stars (Bilir+, 2012)
J/AJ/143/57 : New RVs from the spectroscopic survey BRAVA II (Kunder+, 2012)
J/A+A/546/A57 : Spectroscopy of red giants in the Bulge (Uttenthaler+, 2012)
J/A+A/534/A91 : Galactic Bulge Valinhos Observatory Catalog (Teixeira+, 2011)
J/A+A/534/A80 : Metallicity of clump giants in Baade's window (Hill+, 2011)
J/A+A/530/A54 : Abundances of 650 bulge red giants (Gonzalez+, 2011)
J/A+A/527/A40 : Faint Galactic red clump stars (Saguner+, 2011)
J/ApJ/732/108 : Abundances of 92 giants in Plaut's window (Johnson+, 2011)
J/AcA/61/83 : OGLE-III photometric maps of Galactic Bulge (Szymanski+, 2011)
J/A+A/522/A79 : High-Galactic-latitude red clump stars (Valentini+, 2010)
J/ApJ/721/L28 : Red clump stars in Galactic Bulge from OGLE-III (Nataf+, 2010)
J/ApJ/691/1387 : Spectroscopy of the Galactic bar. I. (Rangwala+, 2009)
J/A+A/486/177 : Bulge field stars from FLAMES-GIRAFFE spectra (Zoccali+, 2008)
J/AJ/134/1432 : Proper motions in Plaut's window (Vieira+, 2007)
J/MNRAS/348/1439 : OGLE II Galactic center proper motions (Sumi+, 2004)
J/MNRAS/340/1346 : Bulge SC1 proper motions (Sumi+, 2003)
J/A+A/385/67 : HST VI photometry & PMs in NGC 6528 (Feltzing+, 2002)
J/AJ/112/171 : K Giants in Baade's Window. II (Sadler+ 1996)
J/AJ/110/1774 : K giants in Baade's window (Terndrup+ 1995)
Byte-by-byte Description of file: bulge_rc.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Pointing hour of right ascension (J2000)
4- 5 I2 min RAm Pointing minute of R.A. (J2000)
7- 11 F5.2 s RAs Pointing second of right ascension (J2000)
13 A1 --- DE- Pointing sign of declination (J2000)
14- 15 I2 deg DEd Pointing degree of declination (J2000)
17- 18 I2 arcmin DEm Pointing arcminute of declination (J2000)
20- 24 F5.2 arcsec DEs Pointing arcsecond of declination (J2000)
26- 37 F12.8 deg RA1deg ?=99.999 Right ascension for epoch 1 (J2000) (1)
39- 50 F12.7 deg DE1deg ?=99.999 Declination for epoch 1 (J2000) (1)
52- 63 F12.8 deg RA2deg ?=99.999 Right ascension for epoch 2 (J2000) (1)
65- 76 F12.7 deg DE2deg ?=99.999 Declination for epoch 2 (J2000) (1)
78- 83 F6.3 mag Vmag [16.1/17.3] ESO WFI V-band magnitude
85- 90 F6.3 mag Imag [14.7/15.5] ESO WFI Ic-band magnitude
92- 97 F6.3 mag Hmag ?=99.999 H-band magnitude
99- 104 F6.3 mag Jmag ?=99.999 J-band magnitude
106- 111 F6.3 mag Kmag ?=99.999 K-band magnitude
113- 118 F6.1 km/s HRV [-347.4/267.7] Heliocentric radial velocity
120- 122 F3.1 km/s e_HRV [0.4/3.3] Heliocentric radial velocity error
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Note (1): The time difference is 11.066 years between the 2 epochs
Epoch 1 = 1999-04-15 (B1999.28), as part of ESO Imaging Survey
(EIS, ESO program 163.O-0741(A)).
Eppch 2 = 2010-05-06 (B2010.34), with the same instrument and filters
(ESO program 085.D-0143(A)).
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Acknowledgements:
Sergio Vasquez, svasquez(at)astro.puc.cl
(End) Sergio Vasquez [PUC], Emmanuelle Perret [CDS] 04-Jun-2013