ALMA observations of the vibrationally excited rotational CO transition v=1, J=3-2 towards five AGB stars

作者：Khouri T^*; Vlemmings W H T; Ramstedt S; Lombaert R; Maercker M; De Beck E

来源：Monthly Notices of the Royal Astronomical Society, 2016, 463(1): L74-L78.

DOI：10.1093/mnrasl/slw161

• line: profiles
• stars: AGB and post-AGB
• circumstellar matter

We report the serendipitous detection with the Atacama Large Millimeter/submillimeter Array (ALMA) of the vibrationally excited pure-rotational CO transition, J = 3 - 2 towards five asymptotic giant branch (AGB) stars, Cet, R Aqr, R Scl, W Aql, and pi(1) Gru. The observed lines are formed in the poorly understood region located between the stellar surface and the region where the wind starts, the so-called warm molecular layer. We successfully reproduce the observed lines profiles using a simple model. We constrain the extents, densities, and kinematics of the region where the lines are produced. R Aqr and R Scl show inverse P-Cygni line profiles which indicate infall of material on to the stars. The line profiles of Cet and R Scl show variability. The serendipitous detection towards these five sources shows that vibrationally excited rotational lines can be observed towards a large number of nearby AGB stars using ALMA. This opens a new possibility for the study of the innermost regions of AGB circumstellar envelopes.

• 出版日期2016-11-21