Evidence of a Mira-like tail and bow shock about the semi-regular variable V CVn from four decades of polarization measurements

Abstract

Polarization is a powerful tool for understanding stellar atmospheres and circumstellar environments. Mira and semi-regular variable stars have been observed for decades and some are known to be polarimetrically variable, however, the semi-regular variable V Canes Venatici displays an unusually large, unexplained amount of polarization. We present ten years of optical polarization observations obtained with the HPOL instrument, supplemented by published observations spanning a total interval of about forty years for V CVn. We find that V CVn shows large polarization variations ranging from 1 - 6%. We also find that for the past forty years the position angle measured for V CVn has been virtually constant suggesting a long-term, stable, asymmetric structure about the star. We suggest that this asymmetry is caused by the presence of a stellar wind bow shock and tail, consistent with the star's large space velocity.

8 pages, 5 figures, 1 table. Accepted for publication in A&A

References in corpus (4)

• Runaway and hypervelocity stars in the Galactic halo: Binary rejuvenation and triple disruption
• Discovery of an HI Counterpart to the Extended Tail of Mira
• An edge-on translucent dust disk around the nearest AGB star L2 Puppis - VLT/NACO spectro-imaging from 1.04 to 4.05 microns and VLTI interferometry
• VLA Observations of HI in the Circumstellar Envelopes of Asymptotic Giant Branch Stars

Cited by in corpus (2)

• Polarization simulations of stellar wind bow shock nebulae. II. The case of dust scattering
• A Multi-Year Photopolarimetric Study of the Semi-Regular Variable V CVn and Identification of Analogue Sources