Coordinated Millimeter VLBI Array Observations of R Cassiopeiae: 86 GHz SiO Masers and Envelope Dynamics

摘要

Coordinated Millimeter VLBI Array measurements at 86 GHz have imaged the silicon monoxide masers of the nearby red giant R Cassiopeiae at two epochs separated by approximately 1/12 the stellar pulsation period. The v = 1, J = 2 → 1 transition comes from a ring at 1.5 to 2 stellar radii. Doppler velocity patterns are ordered over scales up to ~1 AU but are not consistent with simple models such as global rotation. One major masing region disappeared in the interval between the two epochs.