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Low-gravity L Dwarfs Are Likely More Variable

Published online by Cambridge University Press:  27 January 2016

Stanimir Metchev
Affiliation:
The University of Western Ontario, Centre for Planetary Science and Exploration, Canada email: (smetchev@uwo.ca) Stony Brook University, USA
Aren Heinze
Affiliation:
Stony Brook University, USA
Daniel Apai
Affiliation:
The University of Arizona, USA
Davin Flateau
Affiliation:
The University of Arizona, USA
Jacqueline Radigan
Affiliation:
Space Telescope Science Institute, USA
Adam Burgasser
Affiliation:
University of California San Diego, Center for Astrophysics and Space Science, USA
Mark Marley
Affiliation:
NASA Ames Research Center, USA
Étienne Artigau
Affiliation:
Université de Montréal, Canada
Peter Plavchan
Affiliation:
Missouri State University, USA
Bertrand Goldman
Affiliation:
Max-Planck-Institut für Astronomie, Germany
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Abstract

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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.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2016 

References

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Metchev, S. M.et al. 2015, ApJ, 799, 154CrossRefGoogle Scholar