EDP Sciences
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Volume 391, Number 2, August IV 2002
Page(s) 625 - 631
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20020823

A&A 391, 625-631 (2002)
DOI: 10.1051/0004-6361:20020823

Polarimetry of evolved stars

II. The carbon star R Scl
R. V. Yudin1, 2 and A. Evans3

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

(Received 24 January 2002 / Accepted 3 June 2002)

We present broadband optical polarimetry of the carbon star R Scl, primarily in the $VR_{\rm C}I_{\rm C}$ bands. Polarimetric variability was detected on time-scales from hours to years. The polarization of R Scl showed a ~ $\lambda^{-4}$ 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.

Key words: polarization -- stars: circumstellar matter -- stars: carbon -- stars: individual: R Scl -- stars: variables: general

Offprint request: A. Evans, ae@astro.keele.ac.uk

© ESO 2002