J/ApJ/887/267 OB stars embedded in the HI gas of SMC (Murray+, 2019)
The 3D kinematics of gas in the Small Magellanic Cloud.
Murray C.E., Peek J.E.G., Di Teodoro E.M., McClure-Griffiths N.M.,
Dickey J.M., Denes H.
<Astrophys. J., 887, 267 (2019)>
=2019ApJ...887..267M 2019ApJ...887..267M
ADC_Keywords: Stars, OB; Radial velocities; H I data; Proper motions;
Magellanic Clouds; Spectral types
Keywords: Galaxy kinematics ; Interstellar medium ; Radio astronomy ;
Neutral hydrogen clouds ; Magellanic irregular galaxies ;
Magellanic Clouds
Abstract:
We investigate the kinematics of neutral gas in the Small Magellanic
Cloud (SMC) and test the hypothesis that it is rotating in a disk. To
trace the 3D motions of the neutral gas distribution, we identify a
sample of young, massive stars embedded within it. These are stars
with radial velocity measurements from spectroscopic surveys and
proper motion measurements from Gaia, whose radial velocities match
with dominant HI components. We compare the observed radial and
tangential velocities of these stars with predictions from the
state-of-the-art rotating disk model based on high-resolution 21cm
observations of the SMC from the Australian Square Kilometer Array
Pathfinder telescope. We find that the observed kinematics of
gas-tracing stars are inconsistent with disk rotation. We conclude
that the kinematics of gas in the SMC are more complex than can be
inferred from the integrated radial velocity field. As a result of
violent tidal interactions with the Large Magellanic Cloud,
nonrotational motions are prevalent throughout the SMC, and it is
likely composed of distinct substructures overlapping along the line
of sight.
Description:
New observations of the SMC at 21cm were recently obtained by the
Australian Square Kilometer Array Pathfinder (ASKAP) during
Commissioning and Early Science observations in 2017 November. These
data were combined with single-dish observations of the SMC from the
Parkes Telescope as part of the HI4PI survey (2016, J/A+A/594/A116).
For details concerning the observations and data reduction for the
ASKAP+Parkes cube, we refer the reader to
McClure-Griffiths+ (2018NatAs...2..901M 2018NatAs...2..901M).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 143 Parameters for the 143 stars used in the
kinematic comparison
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See also:
II/236 : UBVR CCD survey of the Magellanic clouds (Massey+, 2002)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/MNRAS/289/225 : SMC HI shells velocities (Staveley-Smith+ 1997)
J/AJ/131/2514 : Radial velocities of red giants in the SMC (Harris+, 2006)
J/MNRAS/386/826 : Radial velocities of SMC massive stars (Evans+, 2008)
J/ApJ/745/173 : UV absorption sight lines of LMC and SMC (Welty+, 2012)
J/MNRAS/442/1663 : Velocities of red giants in the SMC (Dobbie+, 2014)
J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)
J/ApJ/817/113 : RIOTS4: spec. survey of SMC field OB stars (Lamb+, 2016)
J/ApJ/816/49 : Spitzer/IRAC observations of SMC Cepheids (Scowcroft+, 2016)
J/MNRAS/472/808 : YJKs light curves of SMC Classical Cepheids (Ripepi+, 2017)
J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)
J/ApJ/867/L8 : Gaia kinematic data of SMC OB stars (Oey+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 F6.3 deg RAdeg [7.79/24.4] Right Ascension (J2000)
8- 14 F7.3 deg DEdeg [-74.3/-72.1] Declination (J2000)
16- 20 F5.1 km/s RVel [105/198] Stellar radial velocity
22- 25 F4.1 km/s e_RVel [4/16] Uncertainty in RVel
27- 42 A16 --- SpType Spectral type
44 I1 --- r_RVel [1/2] Reference code for RVel (1)
46- 51 F6.3 mas/yr pmW [-1.5/-0.4] Proper motion in the
West direction (2)
53- 58 F6.3 mas/yr pmN [-2.2/-0.7] Proper motion in the
North direction (2)
60- 64 F5.3 mas/yr e_pmW [0.047/0.2] Uncertainty in pmW
66- 70 F5.3 mas/yr e_pmN [0.039/0.2] Uncertainty in pmN
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Note (1): Reference code as follows:
1 = Lamb et al. (2016, J/ApJ/817/113 ; <[M2002] SMC NNNNN> in Simbad);
2 = Evans & Howarth (2008, J/MNRAS/386/826 ; <2dFS NNNN> in Simbad).
Note (2): From Gaia Collaboration et al. (2018, J/A+A/616/A12).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 31-May-2021