J/A+A/489/533 M83 volume densities of giant molecular clouds (Heiner+, 2008)
The volume densities of giant molecular clouds in M83.
Heiner J.S., Allen R.J., Ivy Wong O., van der Kruit P.C.
<Astron. Astrophys. 489, 533 (2008)>
=2008A&A...489..533H 2008A&A...489..533H
ADC_Keywords: Galaxies, nearby ; Molecular clouds ; Ultraviolet ; Radio lines
Keywords: galaxies: individual: M83 - galaxies: ISM - ISM: clouds -
ISM: molecules - Ultraviolet: galaxies - Radio lines: galaxies
Abstract:
Using observed GALEX far-ultraviolet (FUV) fluxes and VLA images of
the 21-cm HIcolumn densities, along with estimates of the local dust
abundances, we measure the volume densities of a sample of actively
star-forming giant molecular clouds (GMCs) in the nearby spiral galaxy
M83 on a typical resolution scale of 170 pc. Our approach is based on
an equilibrium model for the cycle of molecular hydrogen formation on
dust grains and photodissociation under the influence of the FUV
radiation on the cloud surfaces of GMCs. We find a range of total
volume densities on the surface of GMCs in M83, namely 0.1-400cm-3
inside R25, 0.5-50cm-3 outside R25. Our data include a number of
GMCs in the HI-ring surrounding this galaxy. Finally, we discuss the
effects of observational selection, which may bias our results.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 49 76 Locations and FUV fluxes of
candidate photodissociation regions (PDRs)
table3.dat 38 638 HI measurements, incident fluxes and volume densities
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See also:
J/ApJS/149/343 : Giant molecular clouds in M33 (Engargiola+, 2003)
J/A+A/426/119 : RCW 106 Giant Molecular Cloud 1.2mm maps (Mookerjea+, 2004)
J/MNRAS/353/1025 : JHK photometry of 4 W51 star clusters (Nanda+, 2004)
J/MNRAS/367/1609 : RCW 106 Giant Molecular Cloud 13CO mapping (Bains+, 2006)
J/MNRAS/379/663 : W3 giant molecular cloud 850um observations (Moore+, 2007)
J/A+A/471/103 : SIMBA observations of SMC (Bot+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/76] Source number
4- 5 I2 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 15 F6.3 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 28 F5.2 arcsec DEs Declination (J2000)
30- 33 F4.1 kpc Rgal Galactocentric radius
35- 39 F5.2 10-17W/m2/nm FFUV FUV Flux (in 10-15erg/cm2/s/Å)
41- 42 I2 arcsec Ap Aperture
44 I1 10+19cm-2 GrS Grayscale start
46- 49 F4.2 --- Inc Grayscale level increment (1)
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Note (1): (next contour) = (previous contour) * (grayscale level increment)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/76] Source number
3 A1 --- Patch [a-o] Patch number (letter)
5- 7 I3 pc rho Separation UV-HI patch
9- 13 F5.2 10+20cm-2 NHI HI column density
15- 19 F5.2 --- G0 Incident flux G0
21- 26 F6.2 --- GGbg G/Gbg source contrast
28- 34 F7.2 cm-3 n Total H volume density
36- 38 F3.1 --- Err Fractional error
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Acknowledgements:
J.S. Heiner, heiner(at)astro.rug.nl
(End) J.S. Heiner [Kapteyn Astron. Inst.], Patricia Vannier [CDS] 09-Aug-2008