J/ApJ/764/74 GASS HVCs in the Magellanic Leading Arm region (For+, 2013)
Galactic All-Sky Survey high-velocity clouds in the region of the
Magellanic Leading Arm.
For B.-Q., Staveley-Smith L., McClure-Griffiths N.M.
<Astrophys. J., 764, 74 (2013)>
=2013ApJ...764...74F 2013ApJ...764...74F
ADC_Keywords: H I data ; Magellanic Clouds ; Diffuse clouds ; Surveys
Keywords: galaxies: interactions; Galaxy: halo; intergalactic medium;
Magellanic Clouds
Abstract:
We present a catalog of high-velocity clouds in the region of the
Magellanic Leading Arm. The catalog is based on neutral hydrogen (H I)
observations from the Parkes Galactic All-Sky Survey. Excellent
spectral resolution allows clouds with narrow-line components to be
resolved. The total number of detected clouds is 419. We describe the
method of cataloging and present the basic parameters of the clouds.
We discuss the general distribution of the high-velocity clouds and
classify the clouds based on their morphological type. The presence of
a significant number of head-tail clouds and their distribution in the
region is discussed in the context of Magellanic System simulations.
We suggest that ram-pressure stripping is a more important factor than
tidal forces for the morphology and formation of the Magellanic
Leading Arm and that different environmental conditions might explain
the morphological difference between the Magellanic Leading Arm and
Magellanic Stream. We also discuss a newly identified population of
clouds that forms the LA IV and a new diffuse bridge-like feature
connecting the LA II and III complexes.
Description:
The neutral hydrogen data employed here are from GASS (Galactic
All-Sky Survey; McClure-Griffiths+ 2009ApJS..181..398M 2009ApJS..181..398M, Kalberla+
2010A&A...521A..17K 2010A&A...521A..17K) DR2 (http://www.astro.uni-bonn.de/hisurvey/gass/).
This survey covers the entire southern sky to declination +1° and
VLSR from -400 to +500km/s. The data have been corrected for stray
radiation, have an angular resolution of ∼16', a brightness
temperature (TB) sensitivity of 57mK, a channel width of 0.82km/s and
a spectral resolution of 1km/s.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 431 Galactic All-Sky Survey (GASS) catalog of detected
sources in the region of the Magellanic Leading Arm
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See also:
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
J/ApJS/209/12 : High-velocity clouds from GASS. I. (Moss+, 2013)
J/A+A/547/A12 : Leading arm Magellanic Cloud Catalog (Venzmer+, 2012)
J/ApJ/702/940 : Radio and UV spectra of HVC toward the MC (Lehner+, 2009)
J/ApJ/688/290 : GASS HI survey of the lower halo (Ford+, 2008)
J/MNRAS/339/105 : Western Magellanic Bridge HI observations (Muller+, 2003)
J/A+A/391/159 : A search for Compact High-Velocity Clouds (De Heij+, 2002)
J/AJ/123/873 : HIPASS high-velocity clouds (Putman+, 2002)
http://www.astro.uni-bonn.de/hisurvey/gass/ : Galactic All Sky Survey data
server
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/431] Identification number
5- 22 A18 --- Name Source designation (1)
24- 28 F5.1 km/s Vlsr [158.7/421.1]? Local Standard of Rest velocity
30- 34 F5.1 km/s Vgsr ? Galactic Standard of Rest velocity
(Vgsr=220cos(b)sin(l)+Vlsr)
36- 40 F5.1 km/s Vlgsr ? Local Group Standard of Rest velocity (2)
42- 46 F5.1 km/s FWHM [2/134]? Velocity Full-Width at Half-Maximum
measured at 50% of peak flux
48- 53 F6.1 Jy.km/s Fint [0.8/8575]? Corrected HI integrated flux
55- 58 F4.2 K Tb [0.1/9.4]? Peak brightness temperature
60- 64 F5.2 10+19/cm2 NHI [0.08/30]? Peak HI column density
66- 68 F3.1 deg amaj [0.2/1.6]? Semi-major axis
70- 72 F3.1 deg bmin [0.1/0.8]? Semi-minor axis
74- 76 I3 deg PA [-90/89]? Position angle
78- 80 A3 --- Flag Warning flag (3)
82- 93 A12 --- Class Classification or other name (4)
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Note (1): With a prefix of HVC for high-velocity clouds and GLX for galaxies
followed by the Galactic longitude, Galactic latitude and the
velocity in the Local Standard of Rest reference frame
({HVC|GLX}+LLL.l+BB.b+NNN).
Note (2): Defined by:
Vlgsr=Vgsr-62cos(l)cos(b)+40sin(l)cos(b)-35sin(b)
(Braun & Burton 1999A&A...341..437B 1999A&A...341..437B).
Note (3): Flag as follows:
SR = the detection lies at the edge of the spectral region;
M = the detection extends over to the masked Milky Way emission region;
E = the detection is next to the spatial edge of the image.
Note (4): Classification as follows:
HT = head-tail cloud with velocity gradient;
:HT = head-tail cloud without velocity gradient;
S = symmetric cloud;
B = bow-shock cloud;
IC = irregular/complex cloud.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Oct-2014