J/MNRAS/442/1663 Velocities of red giants in the SMC (Dobbie+, 2014)
Red giants in the Small Magellanic Cloud. I. Disc and tidal stream kinematics.
Dobbie P.D., Cole A.A., Subramaniam A., Keller S.
<Mon. Not. R. Astron. Soc., 442, 1663-1679 (2014)>
=2014MNRAS.442.1663D 2014MNRAS.442.1663D
ADC_Keywords: Magellanic Clouds ; Stars, giant ; Radial velocities
Keywords: stars: kinematics and dynamics - galaxies: evolution -
galaxies: individual: SMC - galaxies: kinematics and dynamics
Abstract:
We present results from an extensive spectroscopic survey of field
stars in the Small Magellanic Cloud (SMC). 3037 sources, predominantly
first-ascent red giants, spread across roughly 37.5deg2, are
analysed. The line-of-sight velocity field is dominated by the
projection of the orbital motion of the SMC around the Large
Magellanic Cloud/Milky Way. The residuals are inconsistent with both a
non-rotating spheroid and a nearly face on disc system. The current
sample and previous stellar and Hi kinematics can be reconciled by
rotating disc models with line-of-nodes position angle Θ
∼120°-130°, moderate inclination (25°-70°),
and rotation curves rising at 20-40km/s/kpc. The metal-poor stars
exhibit a lower velocity gradient and higher velocity dispersion than
the metal-rich stars. If our interpretation of the velocity patterns
as bulk rotation is appropriate, then some revision to simulations of
the SMC orbit is required since these are generally tuned to the SMC
disc line of nodes lying in a north-east-south-west (SW) direction.
Residuals show strong spatial structure indicative of non-circular
motions that increase in importance with increasing distance from the
SMC centre. Kinematic substructure in the north-west part of our
survey area is associated with the tidal tail or Counter-Bridge
predicted by simulations. Lower line-of-sight velocities towards the
Wing and the larger velocities just beyond the SW end of the SMC Bar
are probably associated with stellar components of the
Magellanic-Bridge and Counter-Bridge, respectively. Our results
reinforce the notion that the intermediate-age stellar population of
the SMC is subject to substantial stripping by external forces.
Description:
Follow-up optical spectroscopy for a subsample of these stars was
acquired during the period 2011 October 18-21, with the 2dF/AAOmega
instrument and the 3.9m Anglo-Australian Telescope (AAT) located at
Siding Spring Observatory, Australia. AAOmega is a two arm fibre-fed
multi-object optical spectrograph capable of the simultaneous
observation of 400 objects distributed over a two degree diameter
circular field of view.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 87 4172 Details of the 4172 red giants identified in our
spectroscopic follow-up of sources towards the SMC
table5.dat 87 351 *Details of the 352 carbon rich giants that were
included in our spectroscopic survey of the SMC
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Note on table5.dat: one star, 2MASS J00523546-7341421, was removed from
table5 at CDS: this star is in table4 with a velocity of 180.4±2.4km/s,
and was in table5 with a velocity of -248.7±2637.4km/s
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See also:
J/A+A/304/347 : 40 field red supergiants in the SMC (Meliani+, 1995)
J/AJ/131/2514 : Radial velocities of red giants in the SMC (Harris+, 2006)
J/AJ/136/1039 : CaII index of SMC red giant branch stars (Carrera+, 2008)
J/AJ/138/517 : CaII spectroscopy of SMC red giants (Parisi+, 2009)
J/ApJ/754/35 : Red supergiant stars in the SMC. II. (Yang+, 2012)
J/MNRAS/442/1680 : Red giants in SMC. Abundnances (Dobbie+, 2014)
Byte-by-byte Description of file: table4.dat table5.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 40 A16 --- 2MASS 2MASS star name (HHMMSSss+DDMMSSs)
42- 46 F5.2 mag Jmag [12/15.2] 2MASS J magnitude
48- 51 F4.2 mag e_Jmag [0.02/0.08] rms uncertainty on Jmag
53- 57 F5.2 mag Ksmag [10/14.6] 2MASS Ks magnitude
59- 62 F4.2 mag e_Ksmag [0.02/0.11] rms uncertainty on Ksmag
64- 67 F4.1 km/s Hcorr [10.6/13.9] Heliocentric correction on velocity
69- 73 F5.1 km/s vmod [17/316] Model velocity
75- 80 F6.1 km/s HV [56/249] Heliocentric velocity of star
82- 87 F6.1 km/s e_HV [1.7/9] rms uncertainty on HV
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History:
From electronic version of the journal
References:
Dobbie et al., Paper II, 2014MNRAS.442.1680D 2014MNRAS.442.1680D, Cat. J/MNRAS/442/1680
(End) Patricia Vannier [CDS] 02-Mar-2015