J/A+A/324/877 HI properties of spiral and irregular galaxies (Broeils+, 1997)
Short 21-cm WSRT observations of spiral and irregular galaxies. HI properties.
Broeils A.H., Rhee M.-H.
<Astron. Astrophys., 324, 877-887 (1997)>
=1997A&A...324..877B 1997A&A...324..877B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; H I data ; Morphology
Keywords: galaxies: fundamental parameters - galaxies: structure -
galaxies: kinematics and dynamics - galaxies: spiral -
radio lines: galaxies
Abstract:
We present the analysis of neutral hydrogen properties of 108
galaxies, based on short 21-cm observations with the Westerbork
Synthesis Radio Telescope (WSRT). The results of two HI surveys are
analysed to investigate the existence of relations between optical and
HI properties, like diameters, hydrogen masses and average surface
densities. For all galaxies in our sample we find that the HI
diameter, defined at a surface density level of 1M☉/pc2, is
larger than the optical diameter, defined at the 25thmag/arcsec2
isophotal level. The Hi-to-optical-diameter ratio does not depend on
morphological type or luminosity. The strongest, physically
meaningful, correlation for the sample of 108 galaxies is the one
between logMHI and logDHI, with a slope of 2. This implies that
the HI surface density averaged over the whole HI disc is constant
from galaxy to galaxy, independent of luminosity or type. The radial
HI surface density profiles are studied using the technique of
principal component analysis. We find that about 81% of the variation
in the density profiles of galaxies can be explained by two
dimensions. The most dominant component can be related to "scale" and
the second principal component accounts for the variance in the
behaviour of the radial profile in the central parts of galaxies (i.e.
"peak or depression") . The third component accounts for 7% of the
variation and is most likely responsible for bumps and wiggles in the
observed density profiles.
Description:
The type of HI data analysed in this paper contains more spatial
information than provided by single-dish observations, but less than
provided by usual synthesis observations. Also the sample size (108
galaxies) lies between those of single-dish and synthesis studies. In
this paper we therefore concentrate on properties that are special to
these two surveys: radial HI surface density profiles, average surface
densities and sizes of hydrogen discs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 108 Properties of the sample galaxies
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Galaxy name
8 A1 --- n_Name [a] Note on Name (1)
10- 13 A4 --- MType Morphological type
15- 17 I3 kpc DHI HI diameter defined by a surface density
of 1M☉/pc2
19- 20 I2 kpc D25 Optical diameter defined at the
25th mag/arcsec2 isophote and corrected for
Galactic and internal extinctions following
Tully & Fouque (1985ApJS...58...67T 1985ApJS...58...67T)
22- 23 I2 kpc Reff HI effective radius, enclosing 50% of the
HI mass
25- 28 F4.2 10+10Msun MHI Total HI mass
30- 34 F5.2 10+10Msun Mtot Total mass enclosed inside the HI diameter
DHI (see text)
36- 39 F4.2 Msun/Lsun MHI/LB HI-mass-to-blue-luminosity ratio (2)
41- 44 F4.2 Msun/Lsun MHI/LH ?=- HI-mass-to-near-infrared-luminosity
ratio (3)
46- 49 F4.2 --- MHI/Mtot HI-mass-to-total-mass ratio
51- 54 F4.2 Msun/pc+2 <sigHI> Mean value of the HI surface density, averaged
over the whole HI disc (see text)
56- 58 I3 km/s Vmax Maximum rotation velocity
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Note (1): a: The heliocentric velocity of DDO 185 in paper I (Broeils &
van Woerden, 1994A&AS..107..129B 1994A&AS..107..129B) was mistakenly listed as 373km/s
. It should be 140km/s. The adopted distance (and all the distance-dependent
parameters) will remain the same, since they are based on membership in the
M 101 group.
Note (2): The total blue luminosity has been corrected for Galactic and internal
extinctions following Tully & Fouque (1985ApJS...58...67T 1985ApJS...58...67T).
Note (3): The near-infrared luminosity has been taken from Tormen & Burstein
(1995, Cat. J/ApJS/96/123), which has been corrected for Galactic extinction.
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History:
From electronic version of the journal
References:
Broeils & van Woerden, Paper I 1994A&AS..107..129B 1994A&AS..107..129B
(End) Patricia Vannier [CDS] 27-Oct-2017