Issue |
EAS Publications Series
Volume 64, 2013
Setting a New Standard in the Analysis of Binary Stars
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Page(s) | 375 - 376 | |
Section | Posters | |
DOI | https://doi.org/10.1051/eas/1364052 | |
Published online | 25 February 2014 |
K. Pavlovski, A. Tkachenko and G. Torres (eds)
EAS Publications Series, 64 (2013) 375–376
Broad-band and multi-band polarimetric observations of post-AGB and RV Tauri stars
1 Institute of Astronomy, Astrophysics, Space Applications & Remote Sensing, National Observatory of Athens
2 Instituto de Astronomia, Universidad Nacional Autónoma de México, Ensenada, México
We present optical broad-band (UBVRI) aperture polarimetry of 52 post-AGB stars, selected from De Ruyter et al. (2006) and the Torun Catalog, based on the shape of their SED and near-infrared excess. We find 10 (19%) of the stars in our sample to have high polarization (P > 5%), 30 (56%) intermediate/low polarization (1% < P < 5%) and 13 (25%) very low (or non–polarized) polarization (P < 1%). Our observations show clear evidence of asymmetric circumstellar envelopes or equatorial density enhancement around post-AGB stars, probably formed at the beginning of the AGB phase. Some stars exhibit wavelength-independent polarization suggesting scattered light by large dust grains or free electrons (Thomson scattering), while others show wavelength-dependent polarization originated from scattering by small dust grains (Rayleigh scattering). Finally, we conclude that highly polarized sources (P > 3%), show systematically [12] − [25] > 1.5, J − H > 0.5 and J − K > 0.5, clearly separated from the group of RV Tauri stars, which are found to have very low polarization (P < 3%).
© EAS, EDP Sciences, 2014