Polarimetry of evolved stars

II. The carbon star R Scl

¹ Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, 196140 Saint-Petersburg, Russia e-mail: ruslan61@hotmail.com
² Isaac Newton Institute of Chile, St.-Petersburg Branch
³ Department of Physics, Keele University, Keele, Staffordshire, ST5 5BG, UK

Corresponding author: A. Evans, ae@astro.keele.ac.uk

Received: 24 January 2002
Accepted: 3 June 2002

Abstract

We present broadband optical polarimetry of the carbon star R Scl, primarily in the bands. Polarimetric variability was detected on time-scales from hours to years. The polarization of R Scl showed a ~ wavelength-dependence, which we attribute to scattering by small amorphous carbon dust grains. We deduce the properties of the circumstellar condensations in which the scattering takes place, and find consistency with infrared data if the condensations move in eccentric orbits. We also conclude that the condensations are tidally dispersed on a time-scale ~1 day. On longer time-scales, polarimetric variations may possibly be linked with photometric variations.