J/A+A/570/A51 Molecular lines in 4 IRCS clumps (Shipman+, 2014)
The physical conditions in IRDC clumps from Herschel/HIFI observations of H2O.
Shipman R., van der Tak F.F.S, Wyrowski F., Herpin F., Frieswijk W.
<Astron. Astrophys. 570, A51 (2014)>
=2014A&A...570A..51S 2014A&A...570A..51S
ADC_Keywords: Molecular clouds ; Millimetric/submm sources ; Line Profiles
Keywords: stars: formation - stars: massive - ISM: clouds; evolution
Abstract:
The earliest phases of high-mass star formation are poorly understood.
Aims. Our goal is to determine the physical conditions and kinematic
structure of massive starforming cloud clumps.
We analyse H2O 557GHz line profiles observed with HIFI toward four
positions in two infrared-dark cloud clumps. By comparison with
ground-based C17O, N2H+, CH3OH, and NH3 line observations,
we constrain the volume density and kinetic temperature of the gas and
estimate the column density and abundance of H2O and N2H+.
The observed water lines are complex with emission and absorption
components. The absorption is redshifted and consistent with a cold
envelope, while the emission is interpreted as resulting from
proto-stellar outflows. The gas density in the clumps is ∼107cm-3.
The o-H2O outflow column density is 0.3-3.0x1014cm-2. The
o-H2O absorption column density is between 1.5x1014 and
2.6x1015cm-2 with cold o-H2O abundances between 1.5x10-9 and
3.1x10-8.
All clumps have high gas densities (∼107cm-3) and display
infalling gas. Three of the four clumps have outflows. The clumps form
an evolutionary sequence as probed by H2O N2H+, NH3, and
CH3OH. We find that G28-MM is the most evolved, followed by G11-MM
and then G28-NH3. The least evolved clump is G11-NH3 which shows no
signposts of starformation; G11-NH3 is a high-mass pre-stellar core.
Description:
Spectra used to determine line parameters for 4 IRDC clumps. Spectra
from Herschel HIFI for H2O, H218O, and N2H+ 6-5 and APEX
data for C17O and N2H+ 3-2.
Objects:
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RA (ICRS) DE Designation(s)
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18 42 47.39 -04 01 58.0 G28.34+0.06 = [CCE98b] 028.34+0.06
18 01 26.15 -19 22 41.5 G11.11-0.12 = GAL 011.11-00.12
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 122 20 List of FITS spectra
fits/* . 20 Individual FITS spectra
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Source name as in Pillai et al. 2006
(2006A&A...450..569P 2006A&A...450..569P)
16- 23 F8.4 deg RAdeg Right ascension of the image center (J2000)
24- 31 F8.4 deg DEdeg Declination of the image center (J2000)
33- 36 I4 --- Np Number of velocity points
38- 44 F7.3 km/s bVel [-33/49] Lower value of velocity interval
46- 52 F7.3 km/s BVel [17/224] Upper value of velocity interval
54- 56 I3 m/s dVel [65/868] Velocity resolution
58- 60 I3 Kibyte size [17/124] Size of FITS file
62- 73 A12 --- FileName Name of FITS file in subdirectory fits
75-122 A48 --- Title Title of the file
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Acknowledgements:
Russell Shipman, russ(at)sron.nl
(End) Russell Shipman [SRON, Netherlands], Patricia Vannier [CDS] 26-Sep-2014