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Paper: VLA Observations of Hi in the Circumstellar Envelopes of AGB Stars
Volume: 378, Why Galaxies Care About AGB Stars: Their Importance as Actors and Probes
Page: 319
Authors: Matthews, L.D.; Reid, M.J.
Abstract: We present the results of a VLA search for HI emission in the circumstellar envelopes of five nearby AGB stars: RS Cnc, IRC+10216, EP Aqr, R Cas, and R Aqr. We have detected emission coincident in both position and velocity with RS Cnc, implying that the emission arises from its extended envelope. For R Cas, we detected weak (5 σ) emission that peaks at the stellar systemic velocity and overlaps with the location of its circumstellar dust shell and thus is probably related to the star. Toward IRC+10216 and EP Aqr, we detected multiple, arcminute-scale HI emission features at velocities consistent with the circumstellar envelopes, but spatially offset from the stellar positions; in these cases we cannot determine unambiguously if the emission is related to the stars. In the case of IRC+10216, we were unable to confirm the detection of HI in absorption against the cosmic background previously reported by Le Bertre & Gérard. We detected our fifth target, R Aqr (a symbiotic binary), in the 1.4 GHz continuum.
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