J/A+A/628/A72 C2O and C3O in low-mass star-forming regions (Urso+, 2019)
C2O and C3O in low-mass star-forming regions.
Urso R.G., Palumbo M.E., Ceccarelli C., Balucani N., Bottinelli S.,
Codella C., Fontani F., Leto P., Trigilio C., Vastel C., Bachiller R.,
Baratta G.A., Buemi C.S., Caux E., Jaber Al-Edhari A., Lefloch B.,
Lopez-Sepulcre A., Umana G., Testi L.
<Astron. Astrophys. 628, A72 (2019)>
=2019A&A...628A..72U 2019A&A...628A..72U (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; Spectroscopy
Keywords: astrochemistry - ISM: molecules - ISM: abundances -
methods: observational - methods: laboratory: solid state -
techniques: spectroscopic
Abstract:
C2O and C3O belong to the carbon chain oxides family. Both
molecules have been detected in the gas phase towards several
star-forming regions, and to explain the observed abundances,
ion-molecule gas-phase reactions have been invoked. On the other hand,
laboratory experiments have shown that carbon chain oxides are formed
after energetic processing of CO-rich solid mixtures. Therefore, it
has been proposed that they are formed in the solid phase in dense
molecular clouds after cosmic ion irradiation of CO-rich icy grain
mantles and released in the gas phase after their desorption.
In this work, we contribute to the understanding of the role of both
gas-phase reactions and energetic processing in the formation of
simple carbon chain oxides that have been searched for in various
low-mass star-forming regions.
We present observations obtained with the Noto-32m and IRAM-30m
telescopes towards star-forming regions. We compare these with the
results of a gas-phase model that simulates C2O and C3O formation
and destruction, and laboratory experiments in which both molecules
are produced after energetic processing (with 200 keV protons) of icy
grain mantle analogues.
New detections of both molecules towards L1544, L1498, and Elias 18
are reported. The adopted gas phase model is not able to reproduce the
observed C2O/C3O ratios, while laboratory experiments show that
the ion bombardment of CO-rich mixtures produces C2O/C3O ratios
that agree with the observed values.
Based on the results obtained here, we conclude that the synthesis of
both species is due to the energetic processing of CO-rich icy grain
mantles. Their subsequent desorption because of non-thermal processes
allows the detection in the gas-phase of young star-forming regions.
In more evolved objects, the non-detection of both C2O and C3O is
due to their fast destruction in the warm gas.
Description:
Data reported in Figure 1 correspond to newly detected C2O and C3O
lines towards: L1544 (panels A, B, C, D, E and F); L1498 (panels G and
H); and Elias 18 (panels I and J). Each panel reports the molecule and
its transition. The detection reported in panel G (performed with the
Noto-32m telescope) was acquired with a lower resolution than that
used for the observations reported in the other panels (IRAM-30m
telescope). For clarity we give a larger VLSR scale that allows a
better evaluation of the baseline.
Table 1 and Table 2 in the paper report information on the
spectroscopic parameters and telescope used.
Further details are given in Section 2 in the paper.
Files are given in FITS and ASCII format for each panel.
Objects:
-----------------------------------------------------
RA (2000) DE Designation(s)
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05 04 16.6 +25 10 48 L1544 = LDN 1544
04 11.0 +24 58 L1498 = LDN 1498
04 39 55.75 +25 45 01.9 Elias 18 = Elia 3-18
-----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 95 10 List of fits spectra
fits/* . 10 Individual fits spectra
sp/* . 10 Individual ascii spectra
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Nx Number of pixels along X-axis
5 I1 Kibyte size Size of FITS file
7- 22 A16 --- FileName Name of FITS file, in subdirectory fits
24- 33 A10 --- Table Name of the table, in subdirectory sp
35- 95 A61 --- Title Title of the FITS file
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 15 F15.11 km/s VLSR LSR velocity
16- 31 F16.12 mK Tmb Mean brightness temperature
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Acknowledgements:
Ricardo Urso, rurso(at)ias.u-psud.fr
Maria Palumbo, maria.palumbo(at)inaf.it
(End) Patricia Vannier [CDS] 17-Jul-2019