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Detection of interstellar C2 and C3 in the Small Magellanic Cloud

Daniel E. Welty ; J. Christopher Howk ; Nicolas Lehner ; John H. Black (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik)
Monthly notices of the Royal Astronomical Society (0035-8711). Vol. 428 (2013), 2, p. 1107-1115.
[Artikel, refereegranskad vetenskaplig]

We report the detection of absorption from interstellar C2 and C3 towards the moderately reddened star Sk 143, located in the near `wing' region of the SMC, in optical spectra obtained with the European Southern Observatory Very Large Telescope (VLT)/Ultraviolet and Visual Echelle Spectrograph. These detections of C2 (rotational levels J = 0-8) and C3 (J = 0-12) absorption in the SMC are the first beyond our Galaxy. The total abundances of C2 and C3 (relative to H2) 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 Small Magellanic Cloud. Analysis of the rotational excitation of C2 yields an estimated kinetic temperature Tk ˜ 25 K and a moderately high total hydrogen density nH ˜ 870 cm-3 - compared to the T01 ˜ 45 K and nH ˜ 85-300 cm-3 obtained from H2. The populations of the lower rotational levels of C3 are consistent with an excitation temperature of about 34 K.

Nyckelord: Interstellar matter: molecules, Interstellar matter: lines and bands, galaxies: Interstellar matter, Magellanic Clouds



Denna post skapades 2013-01-15. Senast ändrad 2014-09-02.
CPL Pubid: 170670

 

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Institutioner (Chalmers)

Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik (2010-2017)

Ämnesområden

Astronomi, astrofysik och kosmologi

Chalmers infrastruktur

Onsala rymdobservatorium