J/A+A/651/A9 HIFI molecular line survey of SgrB2 (M) (Moeller+, 2021)
Herschel observations of extraordinary sources:
Full Herschel/HIFI molecular line survey of Sagittarius B2(M).
Moeller T., Schilke P., Schmiedeke A., Bergin E.A., Lis D.C.,
Sanchez-Monge A., Schwoerer A., Comito C.
<Astron. Astrophys. 651, A9 (2021)>
=2021A&A...651A...9M 2021A&A...651A...9M (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Supernova remnants ;
Spectroscopy
Keywords: astrochemistry - ISM: clouds -
ISM: individual objects: Sagittarius B2(M) - ISM: molecules
Abstract:
We present a full analysis of a broadband spectral line survey of
Sagittarius B2 (Main), one of the most chemically rich regions in the
Galaxy located within the giant molecular cloud complex Sgr B2 in the
Central Molecular Zone. Our goal is to derive the molecular abundances
and temperatures of the high-mass star-forming region Sgr B2(M) and
thus its physical and astrochemical conditions. Sgr B2(M) was observed
using the Heterodyne Instrument for the Far-Infrared (HIFI) on board
the Herschel Space Observatory in a spectral line survey from 480 to
1907GHz at a spectral resolution of 1.1MHz, which provides one of
the largest spectral coverages ever obtained toward this high-mass
star-forming region in the submillimeter with high spectral resolution
and includes frequencies >1THz that are unobservable from the ground.
We modeled the molecular emission from the submillimeter to the
far-infrared using the XCLASS program, which assumes local
thermodynamic equilibrium (LTE). For each molecule, a quantitative
description was determined taking all emission and absorption features
of that species across the entire spectral range into account. Because
of the wide frequency coverage, our models are constrained by
transitions over an unprecedented range in excitation energy.
Additionally, we derived velocity resolved ortho/para ratios for those
molecules for which ortho and para resolved molecular parameters are
available. Finally, the temperature and velocity distributions are
analyzed and the derived abundances are compared with those obtained
for Sgr B2(N) from a similar HIFI survey. A total of 92 isotopologues
were identified, arising from 49 different molecules, ranging from
free ions to complex organic compounds and originating from a variety
of environments from the cold envelope to hot and dense gas within the
cores. Sulfur dioxide, methanol, and water are the dominant
contributors. Vibrationally excited HCN (v2=1) and HNC (v2=1) are
detected as well. For the ortho/para ratios, we find deviations from
the high temperature values between 37 and 180%. In total 14% of all
lines remain unidentified. Compared to Sgr B2(N), we found less
complex molecules such as CH3OCH3, CH3NH2, or NH2CHO, but
more simple molecules such as CN, CCH, SO, and SO2. However some
sulfur bearing molecules such as H2CS, CS, NS, and OCS are more
abundant in N than in M. The derived molecular abundances can be used
for comparison to other sources and for providing further constraints
for astrochemical models.
Description:
The synthetic spectra of Sgr B2(M) between 480 and 1907 GHz. The
synthetic spectra were resampled to the same frequency channels as the
observed spectra. There is one ASCII file per band, where the HIFI
bands are divided into a and b bands as well.
The intensities are in main-beam temperature scale in K. Each file is
ordered by increasing frequency.
Objects:
--------------------------------------------------------
RA (2000) DE Designation(s)
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17 47 20.5 -28 23 06 SgrB2(M) = NAME Sgr B2 Main
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
sgrb2m1a.dat 74 15005 Observed and synthetic spectra of band 1a
sgrb2m1b.dat 74 13024 Observed and synthetic spectra of band 1b
sgrb2m2a.dat 74 15434 Observed and synthetic spectra of band 2a
sgrb2m2b.dat 74 14640 Observed and synthetic spectra of band 2b
sgrb2m3a.dat 74 11244 Observed and synthetic spectra of band 3a
sgrb2m3b.dat 74 17846 Observed and synthetic spectra of band 3b
sgrb2m4a.dat 74 18358 Observed and synthetic spectra of band 4a
sgrb2m4b.dat 74 9460 Observed and synthetic spectra of band 4b
sgrb2m5a.dat 74 21060 Observed and synthetic spectra of band 5a
sgrb2m5b.dat 74 10569 Observed and synthetic spectra of band 5b
sgrb2m6a.dat 74 16999 Observed and synthetic spectra of band 6a
sgrb2m6b.dat 74 24320 Observed and synthetic spectra of band 6b
sgrb2m7a.dat 74 17334 Observed and synthetic spectra of band 7a
sgrb2m7b.dat 74 22223 Observed and synthetic spectra of band 7b
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See also:
J/A+A/559/A47 : Sgr B2(N) and Sgr B2(M) IRAM 30m line survey (Belloche+, 2013)
J/A+A/604/A6 : Sgr B2 ALMA continuum and spectral index (Sanchez-Monge+, 2017)
Byte-by-byte Description of file: sgrb2*.dat
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Bytes Format Units Label Explanations
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1- 24 E24.18 MHz RFreq Rest frequency
26- 50 E25.18 K T(MB) Observed intensity in main-beam temperature scale
51- 74 E24.18 K T(MB)M Modeled intensity in main-beam temperature scale
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Acknowledgements:
Thomas Moeller, moeller(at)ph1.uni-koeln.de
References:
Neill et al., 2014ApJ...789....8N 2014ApJ...789....8N
(End) Patricia Vannier [CDS] 17-May-2021