2015/04/30 by L. Velilla Prieto, L. Velilla-Prieto, J. Cernicharo +15 · 59 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Asymptotic giant branch #Atmospheric Ozone and Climate #Atomic physics #Circumstellar envelope #Emission spectrum #Envelope (radar) #Excitation #Excited state #Geometry #Ground state #Line (geometry) #Physics #Population #Spectral line #Stars #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.1088/2041-8205/805/2/l13
published in The Astrophysical Journal Letters 805(2), L13 (IOP Publishing) · 20 pages, 3 figures. Published in ApJL
openalex publication_date 2015/05/27 · arxiv created 2015/06/11 · arxiv updated 2015/06/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We report the detection of SiS rotational lines in high-vibrational states as well as SiO and SiC 2 lines in their ground vibrational state toward IRC+10216 during the Atacama Large Millimeter Array Cycle 0. The spatial distribution of these molecules shows compact emission for SiS and a more extended emission for SiO and SiC 2 and also proves the existence of an increase in the SiC 2 emission at the outer shells of the circumstellar envelope (CSE). We analyze the excitation conditions of the vibrationally excited SiS using the population diagram technique, and we use a large velocity gradient model to compare with the observations. We found moderate discrepancies between the observations and the models that could be explained if SiS lines detected are optically thick. Additionally, the line profiles of the detected rotational lines in the high-energy vibrational states show a decreasing linewidth with increasing energy levels. This may be evidence that these lines could be excited only in the inner shells, i.e., the densest and hottest, of the CSE of IRC+10216.