J/ApJ/722/367 HI clouds in Quadrant I of the Milky Way (Ford+, 2010)
Milky Way disk-halo transition in H I: properties of the cloud population.
Ford H.A., Lockman F.J., McClure-Griffiths N.M.
<Astrophys. J., 722, 367-379 (2010)>
=2010ApJ...722..367F 2010ApJ...722..367F
ADC_Keywords: H I data ; Milky Way ; Interstellar medium ; Radio lines ;
Surveys ; Molecular clouds
Keywords: galaxies: structure - Galaxy: halo - ISM: clouds - ISM: structure -
radio lines: ISM
Abstract:
Using 21cm HI observations from the Parkes Radio Telescope's Galactic
All-Sky Survey, we measure 255 HI clouds in the lower Galactic halo
that are located near the tangent points at 16.9≤l≤35.3° and
|b|≲20°. The clouds have a median mass of 700M☉ and a
median distance from the Galactic plane of 660pc.
Description:
The data used in this paper are from the Galactic All-Sky Survey
(GASS), an HI survey of the entire southern sky to declination
δ≤1° made with the Parkes Radio Telescope
(McClure-Griffiths et al. 2009ApJS..181..398M 2009ApJS..181..398M). GASS is fully sampled
at an angular resolution of 16', covers -400km/s≤VLSR≤+500km/s at
a channel spacing of 0.8km/s, and has an rms noise per channel of
ΔTb∼60mK. The data analyzed here are from the first release of
the survey which has not been corrected for stray radiation. A total
of 255 disk-halo HI clouds, some >2kpc from the plane, were detected
at the tangent points in the first quadrant region of GASS data, a
region in longitude, latitude, and velocity that is symmetric to the
fourth quadrant region studied in Paper I (Cat. J/ApJ/688/290).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 61 255 Observed properties of tangent point HI clouds
in the Quadrant I region
table2.dat 76 255 Derived properties of tangent point HI clouds
in the Quadrant I region
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See also:
VIII/73 : HI Parkes All Sky Survey Catalogue (HIPASS) (Meyer+, 2004)
J/ApJ/702/1472 : Column densities for HI, AlIII, SiIV, CIV, OVI (Savage+, 2009)
J/ApJ/688/290 : GASS HI survey of the lower halo (Ford+, 2008)
J/ApJ/626/887 : HI clouds in Southern Galactic Plane Survey (Kavars+, 2005)
J/AJ/122/3155 : Peculiar HI cloud near galactic plane (Higgs+, 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 deg GLON Galactic longitude
7- 12 F6.2 deg GLAT Galactic latitude
14- 18 F5.1 km/s VLSR Local Standard of Rest velocity
20- 23 F4.1 km/s e_VLSR Uncertainty in VLSR
25- 28 F4.2 K Tpk Peak brightness temperature (uncertainties
are 0.07K)
30- 33 F4.1 km/s DelV FWHM of velocity profile ΔV
35- 38 F4.1 km/s e_DelV Uncertainty in DelV
40- 44 F5.2 10+19cm-2 NHI HI column density peak
46- 49 F4.2 10+19cm-2 e_NHI Uncertainty in NHI
51- 52 I2 arcmin bmin Angular extent minor axis (1)
54- 55 I2 arcmin bmaj Angular extent major axis (1)
57- 61 F5.1 Msun/kpc2 MHI/D2 HI surface density (mass divided by
squared distance) (2)
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Note (1): Uncertainties in the maximum angular extents are dominated by
background levels surrounding the cloud and are assumed to be 25% of
the estimated values.
Note (2): Mass uncertainties are dominated by the interactive process used in
mass determination and are assumed to be 40% of the estimated values.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.2 deg GLON Galactic longitude
7- 12 F6.2 deg GLAT Galactic latitude
14- 18 F5.1 km/s VLSR Local Standard of Rest velocity
20- 23 F4.1 km/s e_VLSR Uncertainty in VLSR
25- 28 F4.1 km/s Vdev Deviation velocity
30- 33 F4.1 km/s e_Vdev Uncertainty in Vdev
35- 37 F3.1 kpc Dist Heliocentric distance
39- 41 F3.1 kpc e_Dist Uncertainy in Dist
43- 45 F3.1 kpc R Galactocentric radius
47- 49 F3.1 kpc E_R Upper limit uncertainty in R (1)
51- 55 F5.2 kpc Z Height from the Galactic plane
57- 60 F4.2 kpc e_Z Uncertainty in Z
62- 63 I2 pc Rad Radius of HI cloud
65- 66 I2 pc e_Rad Uncertainty in Rad
68- 71 I4 Msun MHI Physical HI mass
73- 76 I4 Msun e_MHI Uncertainty in MHI
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Note (1): Along a given line of sight, the smallest Galactocentric radius
possible is at the tangent point. If the cloud is not located at the
tangent point it must be farther away from the center and the error
on R must be positive.
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History:
From electronic version of the journal
References:
Ford et al. Paper I. 2008ApJ...688..290F 2008ApJ...688..290F Cat. J/ApJ/688/290
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Jul-2012