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1999MNRAS.306..954R - Mon. Not. R. Astron. Soc., 306, 954-974 (1999/July-2)
Maser mapping of small-scale structure in the circumstellar envelope of S Persei.
RICHARDS A.M.S., YATES J.A. and COHEN R.J.
Abstract (from CDS):
The water masers show evidence for significant acceleration of the wind, and this continues with a shallower gradient into the hydroxyl regions at up to 9.3x1013 m. These results are consistent with a wind driven by radiation pressure on dust, but the ongoing acceleration implies that the dust surface absorption efficiency increases throughout the maser zones. Dust momentum is more efficiently coupled to the gas in the denser clouds, and the drift velocity is greater in less dense regions, consistent with conditions (such as a longer velocity resonance length) required by 1612-MHz masers.
The circumstellar envelope appears to be spherical but irregularly filled. The mas resolution at 22 GHz allows the radial distribution of maser brightness to be related to AAVSO light curves. An anomalously dim region in the centre of the shell corresponds to low-amplitude periods in the 1930s; such behaviour is thought to reduce mass-loss and dust formation efficiency.
Abstract Copyright: 1999 RAS
Journal keyword(s): masers - circumstellar matter - stars: individual: S Per - stars: kinematics - stars: late - stars: mass-loss
Simbad objects: 9
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