The EDIBLES Survey. VII. A survey of C2 and C3 in interstellar clouds
| Autor: | Fan, Haoyu, Rocha, Carlos M. R., Cordiner, Martin, Linnartz, Harold, Cox, Nick L. J., Farhang, Amin, Smoker, Jonathan, Roueff, Evelyne, Ehrenfreund, Pascale, Salama, Farid, Foing, Bernard H., Lallement, Rosine, MacIsaac, Heather, Kulik, Klay, Sarre, Peter, van Loon, Jacco Th., Cami, Jan |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | A&A 681, A6 (2024) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202243910 |
| Popis: | We carried out a sensitive survey of C$_2$ and C$_3$ using the EDIBLES data set. We also expanded our searches to C$_4$, C$_5$, and $^{13}$C$^{12}$C isotopologue in the most molecule-rich sightlines. We fit synthetic spectra generated following a physical excitation model to the C$_2$ (2-0) Phillips band to obtain the C$_2$ column density ($N$) as well as the kinetic temperature ($T_\textrm{kin}$) and number density ($n$) of the host cloud. The C$_3$ molecule was measured through its $\tilde{A} - \tilde{X}$ (000-000) electronic origin band system. We simulated the excitation of this band with a double-temperature Boltzmann distribution. We present the largest combined survey of C$_2$ and C$_3$ to date in which the individual transitions can be resolved. In total we detected C$_2$ in 51 velocity components along 40 sightlines, and C$_3$ in 31 velocity components along 27 sightlines. The two molecules are detected in the same velocity components. We find a very good correlation between $N$(C$_2$) and $N$(C$_3$) with Pearson $r = 0.93$ and an average $N$(C$_2$)/$N$(C$_3$) ratio of 15.5$\pm$1.4. A comparison with the behaviour of the C$_2$ DIBs shows that there are no clear differences among sightlines with and without detection of C$_2$ and C$_3$. This is in direct contrast to the better-studied non-C$_2$ DIBs who have reduced strengths in molecule-rich environments. We also identify for the first time the $Q$(2), $Q$(3), and $Q$(4) transitions of the $^{13}$C$^{12}$C (2-0) Phillips band in a stacked average spectrum, and estimate the isotopic ratio of carbon $^{12}$C/$^{13}$C as 79$\pm$8. Our search for the C$_4$ and C$_5$ optical bands was unsuccessful. Comment: 31 pages, 23 figures. To appear in A&A |
| Databáze: | arXiv |
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