Low-gravity L Dwarfs Are Likely More Variable

• Published in: Proceedings of the International Astronomical Union Vol. 10; no. S314; pp. 121 - 123
• Main Authors: Metchev, Stanimir, Heinze, Aren, Apai, Daniel, Flateau, Davin, Radigan, Jacqueline, Burgasser, Adam, Marley, Mark, Artigau, Étienne, Plavchan, Peter, Goldman, Bertrand
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.11.2015
• Subjects: Astronomy; Brown dwarfs; Climatology; Confidence intervals; Contributed Papers; Exploration; Extrasolar planets; Gravitation; Spots; Stars & galaxies; Sunspots; Wavelengths; Weather; brown dwarfs – stars: low-mass – stars:rotation – stars: starspots – stars: variables: general – techniques: photometric
• ISSN: 1743-9213; 1743-9221
• DOI: 10.1017/S1743921315006523

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.