The first detection of SiC 2 in the interstellar medium
We report the first detection of SiC 2 in the interstellar medium. The molecule was identified through six rotational transitions toward G +0.693-0.027, a molecular cloud located in the Galactic center. The detection is based on a line survey carried out with the GBT, the Yebes 40m, and the IRAM 30m...
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Published in | Astronomy and astrophysics (Berlin) Vol. 678; p. A45 |
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Main Authors | , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
01.10.2023
|
Online Access | Get full text |
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Summary: | We report the first detection of SiC
2
in the interstellar medium. The molecule was identified through six rotational transitions toward G +0.693-0.027, a molecular cloud located in the Galactic center. The detection is based on a line survey carried out with the GBT, the Yebes 40m, and the IRAM 30m telescopes covering a range of frequencies from 12 to 276 GHz. We fit the observed spectra assuming local thermodynamic equilibrium and derive a column density of (1.02 ± 0.04) × 10
13
cm
−2
, which gives a fractional abundance of 7.5 × 10
−11
with respect to H
2
, and an excitation temperature of 5.9 ± 0.2 K. We conclude that SiC
2
can be formed in the shocked gas by a reaction between the sputtered atomic silicon and C
2
H
2
, or it can be released directly from the dust grains due to disruption. We also search for other Si-bearing molecules and detect eight rotational transitions of SiS and four transitions of Si
18
O. The derived fractional abundances are 3.9 × 10
−10
and 2.1 × 10
−11
, respectively. All Si-bearing species toward G+0.693−0.027 show fractional abundances well below what is typically found in late-type evolved stars. |
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ISSN: | 0004-6361 1432-0746 |
DOI: | 10.1051/0004-6361/202346822 |