A SEARCH FOR PHOTOMETRIC VARIABILITY IN L- AND T-TYPE BROWN DWARF ATMOSPHERES
- Center for Astrophysics and Space Sciences, University of California, San Diego, CASS, M/C 0424 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States)
- Department of Astronomy/Steward Observatory University of Arizona, 933 North Cherry Avenue, Rm. N204, Tucson, AZ 85721-0065 (United States)
Using the Gemini infrared camera on the 3 m Shane telescope at Lick Observatory, we have searched for broadband J and K' photometric variability for a sample of 15 L- and T-type brown dwarfs, including 7 suspected spectral binaries. Four of the dwarfs-2MASS J0939-2448, 2MASS J1416+1348A, 2MASS J1711+2232, and 2MASS J2139+0220-exhibit statistically significant variations over timescales ranging from {approx}0.5 hr to 6 days. Our detection of variability in 2MASS J2139+0220 confirms that reported by Radigan et al., and periodogram and phase dispersion minimization analysis also confirms a variability period of approximately 7.6 {+-} 0.2 hr. Remarkably, two of the four variables are known or candidate binary systems, including 2MASS J2139+0220, for which we find only marginal evidence of radial velocity variation over the course of a year. This result suggests that some spectral binary candidates may appear as such due to the blending of cloudy and non-cloudy regions in a single ''patchy'' atmosphere. Our results are consistent with an overall variability fraction of 35% {+-} 5%, with no clear evidence of greater variability among brown dwarfs at the L dwarf/T dwarf transition.
- OSTI ID:
- 22130883
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 145, Issue 3; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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