2008/04/02 by J. R. Rizzo, F. M. Jimenez-Esteban, F. M. Jiménez‐Esteban +1
Biochemistry, Genetics and Molecular Biology · Computer Science · Physics and Astronomy · #Biomedical Text Mining and Ontologies #Dark nebula #H II region #Kinetic energy #Line (geometry) #Molecular cloud #Natural Language Processing Techniques #Nebula #Orion Nebula #Star formation #Stars #Text and Document Classification Technologies #astro-ph
paper · pdf · doi:10.1086/588455
26 pages, 6 figures. Accepted for publication in Astrophysical Journal
arxiv created 2008/04/02 · openalex publication_date 2008/07/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present for the first time the detection of mid- J CO line emission in the outskirts of an evolved massive star, which indicates the presence of warm and/or high-density molecular gas. Aiming to learn about the interplay between evolved massive stars and their surroundings, we have carried out CO J = 2→ 1, J = 3→ 2, and 13 CO J = 2→ 1 line observations in a 4 ' × 4 ' field around the ring nebula G79.29+0.46, which is illuminated by a strong LBV star candidate. The whole field shows extended predominant emission in both CO and 13 CO J = 2→ 1 lines, which probably comes from the large cloud which contains the star-forming region DR 15. When this large-scale emission is removed, minor-scale features become evident, particularly in the CO J = 3→ 2 line, strikingly coincident with the ring nebula. The high critical density of CO J = 3→ 2 (some 10 4 cm −3 ) gives additional support for the association with the massive star, since high-density molecular gas has more chances to survive in such a harsh environment. This structure may have been produced by the cumulative effect of a strong steady wind in the LBV stage or earlier, which has compressed the surviving parent molecular cloud. In addition, immersed within this CO feature, we have also discovered a higher density clump (at least several ~10 5 cm −3 ), unresolved by the telescope and probably having a higher kinetic temperature. Toward the clump, the presence of a jump of 14-16 km s −1 in the gas velocity may indicate the existence of a shock front. This clump may have been created by at least one mass eruption, 10 3 -10 4 yr ago. Thus, this work shows that not all the molecular gas is destroyed during massive star evolution, and consequently we are dealing with a new laboratory where one can learn about the mass-loss phenomena associated to the brief LBV stage.