J/A+A/625/A147 80-116GHz spectrum of L483 (Agundez+, 2019)
A sensitive λ 3 mm line survey of L483.
A broad view of the chemical composition of a core around a Class 0 object.
Agundez M., Marcelino N., Cernicharo J., Roue E., Tafalla M.
<Astron. Astrophys. 625, A147 (2019)>
=2019A&A...625A.147A 2019A&A...625A.147A (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Spectroscopy
Keywords: astrochemistry - line: identification - ISM: clouds - ISM: molecules -
radio lines: ISM
Abstract:
An exhaustive chemical characterization of dense cores is mandatory to
our understanding of chemical composition changes from a starless to a
protostellar stage. However, only a few sources have had their
molecular composition characterized in detail. Here we present a 3mm
line survey of L483, a dense core around a Class 0 protostar, which
was observed with the IRAM 30m telescope in the 80-116GHz frequency
range. We detected 71 molecules (140 including different isotopologs),
most of which are present in the cold and quiescent ambient cloud
according to their narrow lines (FWHM∼0.5km/s) and low rotational
temperatures (≲10K). Of particular interest among the detected
molecules are the cis isomer of HCOOH, the complex organic molecules
HCOOCH3, CH3OCH3, and C2H5OH, a wide variety of carbon
chains, nitrogen oxides like N2O, and saturated molecules like
CH3SH, in addition to eight new interstellar molecules (HCCO, HCS,
HSC, NCCNH+, CNCN, NCO, H2NCO+, and NS+) whose detection has
already been reported. In general, fractional molecular abundances in
L483 are systematically lower than in TMC-1 (especially for carbon
chains), tend to be higher than in L1544 and B1-b, and are similar to
those in L1527. Apart from the overabundance of carbon chains in
TMC-1, we find that L483 does not have a marked chemical
differentiation with respect to starless/prestellar cores like TMC-1
and L1544, although it does chemically differentiate from Class 0 hot
corino sources like IRAS 16293-2422. This fact suggests that the
chemical composition of the ambient cloud of some Class 0 sources
could be largely inherited from the dark cloud starless/prestellar
phase. We explore the use of potential chemical evolutionary
indicators, such as the HNCO/C3S, SO2/C2S, and CH3SH/C2S
ratios, to trace the prestellar/protostellar transition. We also
derived isotopic ratios for a variety of molecules, many of which show
isotopic ratios close to the values for the local interstellar medium
(remarkably all those involving 34S and 33S), while there are also
several isotopic anomalies like an extreme depletion in 13C for one
of the two isotopologs of c-C3H2, a drastic enrichment in 18O
for SO and HNCO (SO being also largely enriched in 17O), and
different abundances for the two 13C substituted species of C2H
and the two 15N substituted species of N2H+. We report the first
detection in space of some minor isotopologs and quantify for the
first time the deuterium fractionation for HDCCO and c-C3D. The
exhaustive chemical characterization of L483 presented here, together
with similar studies of other prestellar and protostellar sources,
should allow us to identify the main factors that regulate the
chemical composition of cores along the process of formation of
low-mass protostars.
Description:
The FITS file contains the full spectrum from 80 to 116 GHz of L483
observed with the IRAM 30m telescope, shown in Figures 2 and A.1 of
the article.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
18 17 35 -04 39.8 L483 = LDN 483
-----------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 136 1 Information of fits spectrum
tablea1.dat 124 636 Line parameters of assigned lines in L483
fits/* . 1 fits spectrum
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 25 I6 --- Nx Number of pixels along X-axis
27- 49 A23 "datime" Obs.Date Observation date
51- 55 F5.1 GHz Freq Rest frequency
57- 64 F8.4 GHz bFreq Lower value of frequency interval,
relative to Freq
66- 72 F7.5 GHz BFreq Upper value of frequency interval,
relative to Freq
74- 80 F7.1 Hz dFreq Frequency resolution
82- 85 I4 Kibyte size Size of FITS file
87-105 A19 --- FileName Name of FITS file, in subdirectory fits
107-136 A30 --- Title Title of the FITS file
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Mol Molecule
15- 67 A53 --- Trans Transition
70- 79 F10.3 MHz Freq Frequency
81- 84 F4.2 km/s VLSR ?=- LSR velocity
86- 87 I2 10-2km/s e_VLSR ? rms uncertainty on VLSR
90- 93 F4.2 km/s Deltav ?=- Line width
95- 96 I2 10-2km/s e_Deltav ? rms uncertainty on Deltav
98-103 F6.3 K T*Apeak ?=- Peak antenna temperature
104-111 F8.4 K.km/s IntT*Adv ?=- Velocity-integrated intensity
113-115 I3 10-3K.km/s e_IntT*Adv ? rms uncertainty on IntT*Adv
118-124 A7 --- Notes Notes (1)
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Note (1): Notes as follows:
1 = Complex line profile. Impossible to fit to Gaussian function
2 = Line affected by frequency switching negative artifact of other line
3 = Line blended. Only one component could be fitted
4 = Line blended. Several components could be fitted
5 = Marginal detection
6 = Hyperfine components resolved in astronomical spectrum but not
in the laboratory
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Acknowledgements:
Marcelino Agundez,marcelino.agundez(at)csic.es
(End) Marcelino Agundez [CSIC, Spain], Patricia Vannier [CDS] 25-Apr-2019