J/A+A/633/A118 3mm-band study of L183 and L1544 (Lattanzi+, 2020)
Molecular complexity in pre-stellar cores: a 3mm-band study of L183 and L1544.
Lattanzi V., Bizzocchi L., Vasyunin A.I., Harju J., Giuliano B.M.,
Vastel C., Caselli P.
<Astron. Astrophys. 633, A118 (2020)>
=2020A&A...633A.118L 2020A&A...633A.118L (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Millimetric/submm sources
Keywords: ISM molecules - line identification - molecular data -
molecular processes - radio lines: ISM
Abstract:
Pre-stellar cores (PSCs) are units of star formation. Besides
representing early stages of the dynamical evolution leading to the
formation of stars and planets, PSCs also provide a substrate for
incipient chemical complexity in the interstellar space. Our aim is to
understand the influence of external conditions on the chemical
composition of PSCs. For this purpose, we compared molecular column
densities in two typical PSCs, L183 and L1544, which are embedded in
different environments. A single-pointing survey of L183 at
λ=3mm was conducted using the IRAM 30-m single-dish antenna.
This led to the detection of more than 100 emission lines from 46
molecular species. The molecular column densities and excitation
temperatures derived from these lines were compared to the
corresponding parameters in L1544. The data for L1544 were obtained
from literature or publicly available surveys, and they were analysed
using the same procedure as adopted for L183. An astrochemical model,
previously developed for the interpretation of organic molecule
emissions towards the methanol peak of L1544, was used to interpret
the combined data. Our analysis reveals clear chemical differences
between the two PSCs. While L1544 is richer in carbon-bearing
species, in particular carbon chains, oxygen-containing species are
generally more abundant in L183. The results are well-reproduced by
our chemical model. The observed chemical differentiation between the
two PSCs is caused by the different environmental conditions: the core
of L183 is deeply buried in the surrounding cloud, whereas L1544 lies
close to the edge of the Taurus Molecular Cloud. The obscuration of
L183 from the interstellar radiation field (ISRF) allows the carbon
atoms to be locked in carbon monoxide, which ultimately leads to a
large abundance of O-bearing species. In contrast, L1544, being more
affected by the ISRF, can keep a fraction of carbon in atomic form,
which is needed for the production of carbon chains.
Description:
The FITS files represent the Herschel/SPIRE H2 column densities and
dust temperature maps of the two prestellar cores.
Objects:
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RA (2000) DE Designation(s)
-----------------------------------------
05 04 16.6 +25 10 48 L1544 = LDN 1544
15 54 12.2 -02 49 42 L183 = LDN 183
-----------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 115 4 List of fits maps
fits/* . 4 Individual fits maps
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 30 I3 Kibyte size Size of FITS file
32- 59 A28 --- FileName Name of FITS file, in subdirectory fits
61-115 A55 --- Title Title of the FITS file
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Acknowledgements:
Valerio Lattanzi, lattanzi(at)mpe.mpg.de
(End) Patricia Vannier [CDS] 10-Jan-2020