2002/11/27 by S. Thorwirth, Sven Thorwirth, F. Wyrowski +7 · 32 citations
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atomic physics #Circumstellar envelope #Emission spectrum #Envelope (radar) #Excited state #Line (geometry) #Maser #Molecular Spectroscopy and Structure #Nebula #Physics #Planetary nebula #Spectral line #Stars #astro-ph
paper · pdf · doi:10.1086/367629
published in The Astrophysical Journal 586(1), 338-343 (IOP Publishing) · 14 pages, 4 figures, to appear in ApJ
arxiv created 2002/11/27 · openalex publication_date 2003/03/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We report the detection of direct l -type transitions toward the proto-planetary nebula CRL 618 during a study of vibrationally excited carbon chains. The J = 8, 10, 11, 12, 13, and 14 Δ J = 0 transitions of HCN in its first excited bending mode v 2 = 1 were detected in absorption against the continuum of the central H II region, making use of the Effelsberg 100 m telescope and the Very Large Array. In addition, the J = 9 direct l -type transition was detected in emission, presumably indicating a weak maser. All lines are blueshifted with respect to the systemic velocity of CRL 618, indicating that the lines originate from a hot, expanding circumstellar envelope. The HCN column density along the line of sight in front of the continuum is 2 × 10 18 cm -2 .