J/AZh/93/409 L379IRS3 radio lines (Kalenskii+, 2016)
A study of the region of massive star formation L379IRS1 in radio lines of
methanol and other molecules.
Kalenskii S.V., Shchurov M.A.
<Astron. Zh. 93, 409 (2016)>
=2016AZh....93..409K 2016AZh....93..409K (SIMBAD/NED BibCode)
=2016ARep...60..438K 2016ARep...60..438K
ADC_Keywords: Infrared sources ; Spectroscopy
Abstract:
The results of spectral observations of the region of massive star
formation L379IRS3 (IRAS 18265-1517) are presented. The observations
were carried out with the 30-m Pico Veleta radio telescope (Spain) at
seven frequencies in the 1-mm, 2-mm, and 3-mm wavelength bands. Lines
of 24 molecules were detected, from simple diatomic or triatomic
species to complex eight- or nine-atom compounds such as CH3OCHO or
CH3OCH3. Rotation diagrams constructed from methanol and methyl
cyanide lines were used to determine the temperature of the quiescent
gas in this region, which is about 40-50K. In addition to this warm
gas, there is a hot component that is revealed through high-energy
lines of methanol and methyl cyanide, molecular lines arising in hot
regions, and the presence of H2O masers and Class II methanol masers
at 6.7GHz, which are also related to hot gas. One of the hot regions
is probably a compact hot core, which is located near the southern
submillimeter peak and is related to a group of methanol masers at
6.7GHz. High-excitation lines at other positions may be associated
with other hot cores or hot post-shock gas in the lobes of bipolar
outflows. The rotation diagrams can be use to determine the column
densities and abundances of methanol (10-9) and methyl cyanide
(about 10-11) in the quiescent gas. The column densities of A- and
E-methanol in L379IRS3 are essentially the same. The column densities
of other observed molecules were calculated assuming that the ratios
of the molecular level abundances correspond to a temperature of 40 K.
The molecular composition of the quiescent gas is close to that in
another region of massive star formation, DR21(OH). The only
appreciable difference is that the column density of SO2 in L379IRS3
is at least a factor of 20 lower than the value in DR21(OH). The
SO2/CS and SO2/OCS abundance ratios, which can be used as chemical
clocks, are lower in L379IRS3 than in DR21(OH), suggesting that
L379IRS3 is probably younger than DR21(OH).
Description:
The observations were carried out in 2003 and 2007 using the 30-m
radio telescope of the Institut de Radioastronomie Millimetrique
(IRAM) at Pico Veleta in Spain.
Objects:
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RA (2000) DE Designation(s)
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18 29 24.80 -15 15 49.0 L379IRS3 = IRAS 18265-1517
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 143 449 Gaussian parameters of the lines and column
densities of the molecules detected in L379
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 arcsec oRA Offset in right ascension from L379IRS3
(18 29 24.80, -15 15 49.0, J2000)
5- 7 I3 arcsec oDE Offset in declination from L379IRS3
(18 29 24.80, -15 15 49.0, J2000)
9- 18 F10.3 MHz Freq Frequency
20- 31 A12 --- Mol Molecule
33- 61 A29 --- Trans Transition
63- 71 E9.5 K.km/s Int(TRdV) Integrated emission
74- 77 F4.2 K.km/s e_Int(TRdV) rms uncertainty on IntTRdV
80- 84 F5.2 km/s VLSR LSR velocity
87- 90 F4.2 km/s e_VLSR rms uncertainty on VLSR
93- 99 F7.3 km/s DV Velocity dispersion
102-106 F5.2 km/s e_DV rms uncertainty on DV
109-116 E8.4 K TR Radiation temperature
118-121 F4.2 K e_TR ? rms uncertainty on TR
124-128 F5.3 10+14cm-2 Nmol ? Column density
130-143 A14 --- Notes Notes (1)
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Note (1): Notes as follows:
4 MHz = line was observed with a resolution of 4 MHz
bl = spectral feature is a blend of several lines of the same molecule,
with the strongest line indicated in column Trans
bw = the line has a blue wing
cte = the column density was calculated assuming equal abundances of the
cis and trans isomers
hfs = line has hyperfine structure
hr = line arises in a hot region
md = marginal detection
ml = the table gives the parameters of the main hyperfine-splitting
component
new = line is absent from the fourth version of the Lovas catalog
pf = poor Gaussian fitting
rw = line has a red wing
w = line has wings
ui = unreliable identification
the chemical formula for a molecule (CH3OH, CH133CN, etc.) indicates
that the line is blended with one or more lines of this molecule.
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Nomenclature Notes:
In the original paper, L379IRS1 is a misprint for L379IRS3
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-May-2016