SIMBAD references

1997A&A...320..249D - Astronomy and Astrophysics, volume 320, 249-256 (1997/4-1)

Superwind in evolved OH/IR stars.


Abstract (from CDS):

We report observations of 13CO (J=1-0) and (J=2-1) emission towards 5 evolved OH/IR envelopes. Four of them are known to have very weak CO emission compared to their infrared flux, and an anomalously high (J=2-1)/(J=1-0) intensity ratio. Modeling of their 12CO and 13CO lines is used to test several possible explanations of this behaviour. We conclude that it is most likely due to the recent onset of a superwind phase. Another interesting result of the modeling is the very low 12C/13C isotopic ratios we derive in these envelopes, of the order of 3.5 and close to the equilibrium value of the CNO cycle. We interpret this as the signature of massive stars at the end of their AGB phase. The sixth envelope, which shows a much lower (J=2-1)/(J=1-0) intensity ratio, also has a low, marginally larger, 12C/13C isotopic ratio. We conclude that it also is a massive object, but in a slightly less evolved stage, just before the superwind phase.

Abstract Copyright:

Journal keyword(s): stars: circumstellar matter - stars: AGB, post-AGB - stars: mass loss - radio lines: stars

Simbad objects: 6

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