J/A+A/556/A57 Transitions in OMC-2 FIR 4 in the far-IR (Kama+, 2013)
The Herschel/HIFI spectral survey of OMC-2 FIR 4 (CHESS).
An overview of the 480 to 1902 GHz range.
Kama M., Lopez-Sepulcre A., Dominik C., Ceccarelli C., Fuente A., Caux E.,
Higgins R., Tielens A.G.G.M., Alonso-Albi T.
<Astron. Astrophys., 556, A57-57 (2013)>
=2013A&A...556A..57K 2013A&A...556A..57K
ADC_Keywords: YSOs ; Spectra, millimetric/submm ; Line Profiles
Keywords: astrochemistry - stars: formation - stars: protostars
Abstract:
Broadband spectral surveys of protostars offer a rich view of the
physical, chemical and dynamical structure and evolution of
star-forming regions. The Herschel Space Observatory opened up the
terahertz regime to such surveys, giving access to the fundamental
transitions of many hydrides and to the high-energy transitions of
many other species. A comparative analysis of the chemical inventories
and physical processes and properties of protostars of various masses
and evolutionary states is the goal of the Herschel CHEmical Surveys
of Star forming regions (CHESS) key program. This paper focusses on
the intermediate-mass protostar, OMC-2 FIR 4. We obtained a spectrum
of OMC-2 FIR 4 in the 480 to 1902GHz range with the HIFI spectrometer
onboard Herschel and carried out the reduction, line identification,
and a broad analysis of the line profile components, excitation, and
cooling. We detect 719 spectral lines from 40 species and isotopologs.
The line flux is dominated by CO, H2O, and CH3OH. The line
profiles are complex and vary with species and upper level energy, but
clearly contain signatures from quiescent gas, a broad component
likely due to an outflow, and a foreground cloud. We find abundant
evidence for warm, dense gas, as well as for an outflow in the field
of view. Line flux represents 2% of the 7L☉ luminosity detected
with HIFI in the 480 to 1250GHz range. Of the total line flux, 60% is
from CO, 13% from H2O and 9% from CH3OH. A comparison with similar
HIFI spectra of other sources is set to provide much new insight into
star formation regions, a case in point being a difference of two
orders of magnitude in the relative contribution of sulphur oxides to
the line cooling of Orion KL and OMC-2 FIR 4.
Objects:
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RA (ICRS) DE Designation(s)
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05 35 26.97 -05 09 54.5 [MWZ90] OMC-2 FIR 4 = V2457 Ori
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 162 719 Transitions detected in the HIFI spectral survey
of OMC-2 FIR 4
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 GHz Freq [480/1902] Frequency
10- 19 A10 --- Species Species (molecule)
21- 52 A32 --- Trans Transition
53- 60 F8.3 GHz Freq0 Rest frequency
62- 67 F6.2 K Eu Upper state energy
69- 76 E8.3 rad/s Aul A-coefficient (transition rate)
78- 82 F5.2 km/s Vlsr ? Gaussian fit LSR velocity
84- 87 F4.2 km/s e_Vlsr ? rms uncertainty on Vlsr
89- 93 F5.2 km/s FWHM ? Gaussian fit FWHM
95- 98 F4.2 km/s e_FWHM ? rms uncertainty on FWHM
100-104 F5.2 K Tmb ? Peak intensity
106-108 I3 mK rms rms intensity
110-115 F6.2 K.km/s Flux ? Integrated intensity
117-120 F4.2 K.km/s e_Flux ? rms uncertainty on Flux
122-162 A41 --- Blend Blends(B)/Notes (1)
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Note (1): Blending is indicated by a B: followed by an identification of the
blended line (only one B: line is given also for multiple overlapping blends).
Line profile parameters (Vlsr, FWHM, Tmb) are not given for the lines which
are blended. For some species, such as OH and SH+, the line parameters were
determined by fitting models of the hyperfine line profile to the data, these
results are plotted with red dashed lines in figures showing examples of the
data.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 07-Apr-2014