2018ApJ...860..162F -
Astrophys. J., 860, 162-162 (2018/June-3)
The maser-emitting structure and time variability of the SiS lines J = 14-13 and 15-14 in IRC+10216.
FONFRIA J.P., FERNANDEZ-LOPEZ M., PARDO J.R., AGUNDEZ M., SANCHEZ CONTRERAS C., VELILLA PRIETO L., CERNICHARO J., SANTANDER-GARCIA M., QUINTANA-LACACI G., CASTRO-CARRIZO A. and CURIEL S.
Abstract (from CDS):
We present new high angular resolution interferometer observations of the v = 0 J = 14-13 and 15-14 SiS lines toward IRC+10216, carried out with the Combined Array for Research in Millimeter-wave Astronomy and the Atacama Large Millimeter Array. The maps, with angular resolutions of ≃0.''25 and 0.''55, reveal (1) an extended, roughly uniform, and weak emission with a size of ≃0.''5; (2) a component elongated approximately along the east-west direction peaking at ≃0.''13 and 0.''17 at both sides of the central star; and (3) two blue- and redshifted compact components peaking around 0.''07 to the NW of the star. We have modeled the emission with a 3D radiation transfer code, finding that the observations cannot be explained only by thermal emission. Several maser clumps and one arc-shaped maser feature arranged from 5 to 20 R* from the central star, in addition to a thin shell-like maser structure at ≃13 R*, are required to explain the observations. This maser-emitting set of structures accounts for 75% of the total emission, while the other 25% is produced by thermally excited molecules. About 60% of the maser emission comes from the extended emission, and the rest comes from the set of clumps and the arc. The analysis of a time monitoring of these and other SiS and 29SiS lines carried out with the IRAM 30 m telescope from 2015 to present suggests that the intensity of some spectral components of the maser emission strongly depends on the stellar pulsation, while other components show a mild variability. This monitoring evidences a significant phase lag of ≃0.2 between the maser and near-IR light curves.
Abstract Copyright:
© 2018. The American Astronomical Society. All rights reserved.
Journal keyword(s):
circumstellar matter - masers - stars: AGB and post-AGB - stars: individual: IRC+10216 - stars: oscillations - techniques: interferometric
Simbad objects:
7
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