Polarization and Variability of Brown Dwarfs

Knight, Cynthia; Goldman, B.; Stephens, D.; Pitann, J.; Zapatero Osorio, M.; Bejar, V. S. B.; Henning, T.
Bibliographical reference

American Astronomical Society, AAS Meeting #215, #606.01; Bulletin of the American Astronomical Society, Vol. 36, p.1129

Advertised on:
1
2010
Number of authors
7
IAC number of authors
1
Citations
0
Refereed citations
0
Description
L-type brown dwarfs (Teff = 1400-2100K) are known for their dusty photospheres. Brown dwarfs may have asymmetric surfaces arising from rotationally-induced flattening or large-scale cloud cover and patchiness. This broken symmetry may prevent polarization by dust-scattering to to cancel out, resulting in a non-zero polarization. Therefore, studying polarization provides useful insights into surface heterogeneities in brown dwarfs. Zapatero Osorio et al.(2005),Ménard et al. (2002), and Goldman et al. (2009) report that some brown dwarfs have small polarization degrees on the order of 0.1%. Their results also suggest variability. This project aims to confirm past results through investigating previous targets as well as expanding the sample size. We also aim to search for variability in the ultra-cool dwarfs in our survey. We used the CAFOS camera on the 2.2 meter telescope at the Calar Alto Observatory in Spain. In this poster, we present the data and analysis from 15 nights of observation of 22 brown dwarfs.