Detection of Interstellar C_2 and C_3 in the Small Magellanic Cloud

Abstract

We report the detection of absorption from interstellar C_2 and C_3 toward the moderately reddened star Sk 143, located in the near 'wing' region of the SMC, in optical spectra obtained with the ESO VLT/UVES. These detections of C_2 (rotational levels J=0-8) and C_3 (J=0-12) absorption in the SMC are the first beyond our Galaxy. The total abundances of C_2 and C_3 (relative to H_2) are similar to those found in diffuse Galactic molecular clouds -- as previously found for CH and CN -- despite the significantly lower average metallicity of the SMC. Analysis of the rotational excitation of C_2 yields an estimated kinetic temperature T_k ~ 25 K and a moderately high total hydrogen density n_H ~ 870 cm^-3 -- compared to the T_01 ~ 45 K and n_H ~ 85-300 cm^-3 obtained from H_2. The populations of the lower rotational levels of C_3 are consistent with an excitation temperature of about 34 K.

accepted to MNRAS; 10 pages, 6 figures

References in corpus (7)

• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• The VLT-FLAMES survey of massive stars: constraints on stellar evolution from the chemical compositions of rapidly rotating Galactic and Magellanic Cloud B-type stars
• The Spitzer Survey of the Small Magellanic Cloud: FIR Emission and Cold Gas in the SMC
• Abundances and Behavior of 12CO, 13CO, and C2 in Translucent Sight Lines
• VLT/UVES Observations of Interstellar Molecules and Diffuse Bands in the Magellanic Clouds
• The Structure of a Low-Metallicity Giant Molecular Cloud Complex
• Observation of interstellar lithium in the low-metallicity Small Magellanic Cloud

Cited by in corpus (17)

• 2021 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• 2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes
• ALCHEMI: an ALMA Comprehensive High-resolution Extragalactic Molecular Inventory. Survey presentation and first results from the ACA array
• Interstellar Gas-phase Element Depletions in the Small Magellanic Cloud: A Guide to Correcting for Dust in QSO Absorption Line Systems
• Diffuse Interstellar Bands vs. Known Atomic and Molecular Species in the Interstellar Medium of M82 toward SN 2014J
• Carbon-Chain Chemistry in the Interstellar Medium
• Thermal Pressures in the Interstellar Medium of the Magellanic Clouds
• Detection of vibronic bands of C${}_3$ in a translucent cloud towards HD 169454
• HD 62542: Probing the Bare, Dense Core of a Translucent Interstellar Cloud
• Dense molecular clouds in the SN2008fp host galaxy
• The $\lambda$6614 diffuse interstellar absorption band: evidence for internal excitation of the carrier
• The EDIBLES Survey. VII. A survey of C2 and C3 in interstellar clouds
• Extragalactic 85Rb/87Rb and 6Li/7Li ratios in the Small Magellanic Cloud
• The Bending of C${}_3$: Experimentally Probing the $l$-type Doubling and Resonance
• Probing the Interstellar Dust in Galaxies over > 10 Gyr of Cosmic History
• First detections of CO absorption in the Magellanic Clouds and direct measurement of the CO-to-H${}_2$ ratio