J/ApJ/723/1019 Galactic SFR and gas surface densities (Heiderman+, 2010)
The star formation rate and gas surface density relation in the Milky Way:
implications for extragalactic studies.
Heiderman A., Evans II N.J., Allen L.E., Huard T., Heyer M.
<Astrophys. J., 723, 1019-1037 (2010)>
=2010ApJ...723.1019H 2010ApJ...723.1019H
ADC_Keywords: Molecular clouds ; Extinction ; Interstellar medium ; Milky Way ;
YSOs
Keywords: dust, extinction - galaxies: ISM - galaxies: star formation -
infrared: stars - ISM: clouds - stars: formation
Abstract:
We investigate the relation between star formation rate (SFR) and gas
surface densities in Galactic star-forming regions using a sample of
young stellar objects (YSOs) and massive dense clumps. Our YSO sample
consists of objects located in 20 large molecular clouds from the
Spitzer cores to disks (c2d; Evans, 2009, Cat. J/ApJS/181/321) and
Gould's Belt (GB) survey (L. Allen et al. 2010, in preparation). These
data allow us to probe the regime of low-mass star formation,
essentially invisible to tracers of high-mass star formation used to
establish extragalactic SFR-gas relations. We estimate the gas surface
density (Σgas) from extinction (AV) maps and YSO SFR surface
densities (ΣSFR) from the number of YSOs, assuming a mean mass
and lifetime. We also divide the clouds into evenly spaced contour
levels of AV, counting only Class I and Flat spectral energy
distribution YSOs, which have not yet migrated from their birthplace.
For a sample of massive star-forming clumps, we derive SFRs from the
total infrared luminosity and use HCN gas maps to estimate gas surface
densities. We find that c2d and GB clouds lie above the extragalactic
SFR-gas relations (e.g., Kennicutt-Schmidt law) by factors of up to
17. We use 12CO and 13CO gas maps of the Perseus and Ophiuchus
clouds from the COMPLETE survey (Ridge et al. 2006AJ....131.2921R 2006AJ....131.2921R) to
estimate gas surface densities and compare to measurements from AV
maps.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 96 21 Measured quantities for clouds
table3.dat 103 100 Properties of suspicious YSOs and MISFITS
(misidentified YSOs from SED FITS) for 13 clouds
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See also:
J/A+A/515/A42 : Catalog of high extinction clouds (Rygl+, 2010)
J/ApJ/715/310 : Early stages of star formation in IRDCs (Rathborne+, 2010)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009)
J/ApJS/185/198 : The Cepheus flare observed with IRAC and MIPS (Kirk+, 2009)
J/ApJ/698/324 : Spitzer IRDCs (Ragan+, 2009)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/ApJ/680/1295 : Optical spectroscopy of Cha-II PMS stars (Spezzi+, 2008)
J/ApJ/680/495 : Interstellar clouds in the Gould belt (Harvey+, 2008)
J/ApJ/683/822 : Star formation in Ophiuchus and Perseus II. (Jorgensen+, 2008)
J/ApJS/177/551 : Spitzer c2d survey of Lupus dark clouds (Merin+, 2008)
J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007)
J/A+A/468/1009 : Star formation in Perseus. II. (Hatchell+, 2007)
J/ApJ/551/852 : FCRAO CO survey of the outer Galaxy (Heyer+, 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Cloud Cloud name
10 A1 --- n_Cloud [*] *: data from litterature
12- 15 I4 --- Ntot Total number of YSOs above AV=2 (1)
17- 19 I3 --- NI ? Number of Class I objects above AV=2 (1)
21- 22 I2 --- NF ? Number of Flat SED objects >AV=2 (1)
24- 26 I3 pc Dist Distance to cloud
28- 29 I2 pc e_Dist ? Dist uncertainty
31- 36 F6.3 deg2 Omega Solid angle (angular area Ω) of cloud
38- 43 F6.2 pc2 Area Cloud area
45- 49 F5.2 pc2 e_Area ? Area uncertainty
51- 55 I5 Msun Mass Mass of cloud (gas)
57- 60 I4 Msun e_Mass ? Mass uncertainty
62- 66 F5.1 Msun/pc2 Sigma Surface gas density Σgas
68- 69 I2 Msun/pc2 e_Sigma ? Sigma uncertainty
71- 76 F6.2 Msun/Myr SFR Star formation rate
78- 83 F6.2 Msun/Myr e_SFR ? SFR uncertainty
85- 90 F6.4 Msun/yr/kpc2 SigSFR SFR density ΣSFR
92- 96 F5.3 Msun/yr/kpc2 e_SigSFR ? SigSFR uncertainty
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Note (1): Total AV mass from Pineda et al. (2010ApJ...721..686P 2010ApJ...721..686P)
and YSO data from Rebull et al. (2010ApJS..186..259R 2010ApJS..186..259R).
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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- 8 A8 --- Cloud Cloud name
10- 11 I2 h RAh Hour of right ascension (J2000)
13- 14 I2 min RAm Minute of right ascension (J2000)
16- 20 F5.2 s RAs Second of right ascension (J2000)
22 A1 --- DE- Sign of declination (J2000)
23- 24 I2 deg DEd Degree of declination (J2000)
26- 27 I2 arcmin DEm Arcminute of declination (J2000)
29- 33 F5.2 arcsec DEs Arcsecond of declination (J2000)
35- 53 A19 --- Class Spitzer classification (see Evans et al. 2009;
Cat. J/ApJS/181/321)
55- 59 F5.2 --- alpha Spectral Index, extinction corrected values
for c2d clouds only
61- 64 F4.2 K.km/s MBdV ? Integrated main beam HCO+line intensity
66- 69 F4.2 K.km/s e_MBdV ? MBdV uncertainty
71 A1 --- l_TMB Limit flag on TMB, upper limits are computed
as 2σrms
72- 75 F4.2 K TMB Main beam HCO+ line temperature
77- 80 F4.2 K e_TMB ? TMB uncertainty
82- 85 A4 --- SED SED class based on Greene et al.
(1994ApJ...434..614G 1994ApJ...434..614G)
87 A1 --- l_AV Limit flag on AV (1)
88- 89 I2 mag AV AV at source position
91-103 A13 --- Comm Line profile comments
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Note (1): Values that are found outside the AV map completeness limit are
given as < limit.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 24-Jul-2012