Low-gravity L Dwarfs Are Likely More Variable

Abstract

In the Weather on Other Worlds Spitzer Exploration Science program, we surveyed 44 nearby L3-T8 dwarfs for spot-induced rotational variability. Among single L3-L9.5 dwarfs, we found that 80% are variable at >0.2% in the 3-5 μm wavelength range, while 36% of T0-T8 were variable at >0.4%. Taking into account viewing angle and sensitivity considerations, both of these findings are consistent with spots being present on ∼100% of L3-T8 dwarfs. Intriguingly, we find a tentative association (92% confidence) between low surface gravity and high-amplitude variability among L3-L5.5 dwarfs. Although we can not confirm whether lower gravity is also correlated with a higher incidence of variables, the result is promising for the characterization of directly imaged young extrasolar planets through variability.

Department(s)

Physics, Astronomy, and Materials Science

Document Type

Conference Proceeding

DOI

https://doi.org/10.1017/S1743921315006523

Keywords

brown dwarfs, stars: low-mass, stars: starspots, stars: variables: general, stars:rotation, techniques: photometric

Publication Date

1-1-2015

Journal Title

Proceedings of the International Astronomical Union

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