RT Journal Article
T1 CO line emission from circumstellar envelopes
A1 Teyssier, D.
A1 Lunar Hernández, María Del Rosario
A1 Bujarrabal, V.
A1 Yoshida, H.
A1 Phillips, T. G.
AB Aims.We present the results of a multi-transition CO observational program conducted on a sample of AGB and post-AGB stars envelopes. We have collected maps and single pointing observations of these envelopes in 5 rotational transitions ranging from J = 1–0 to J = 6–5, including in particular new observations of the CO line at 691 GHz at the CSO. The use of such a set of mm and submm CO line on stellar envelopes is rare and limited to the work of some authors on IRC+10216.Methods.Using a model for the CO emission of an AGB circumstellar envelope, in combination with a standard LVG approach, we have conducted a systematic modelling analysis using the whole set of CO data collected for a sample of 12 sources. We simultaneously fit all five transitions, taking into account the spatial information provided by the maps.Results.We find mass-loss rates in the range 1  10-7 to 4  10/yr, and envelope temperatures ranging from 20 K to 1000 K at a radius of 1016 cm. There seem to be a general anti-correlation between mass loss rates and temperature, the high mass loss rate AGBs having low temperatures, and vice versa. We show that most AGB data can be fitted using a constant mass loss rate, at least within the calibration uncertainties associated with the data collected at different frequencies. For some cases though (e.g. CIT 6, R Hya, χ Cyg), a change in the mass loss rate history needs to be invoked to reconcile data at low- and high-J, a scenario already mentioned by several authors to explain observations of WX Psc.
PB EDP Sciences
SN 0004-6361
YR 2006
FD 2006
LK https://hdl.handle.net/20.500.14352/107595
UL https://hdl.handle.net/20.500.14352/107595
LA eng
NO Teyssier, D., et al. «CO line emission from circumstellar envelopes». Astronomy & Astrophysics, vol. 450, n.º 1, abril de 2006, pp. 167-79. DOI.org (Crossref), https://doi.org/10.1051/0004-6361:20053759.
NO Ministerio de Ciencia y Tecnologia
DS Docta Complutense
RD 7 abr 2025