Observations of rotational modulations of brown dwarfs and giant exoplanets allow the characterization of condensate cloud properties. As of now, rotational spectral modulations have only been seen in three L-type brown dwarfs. We report here the discovery of rotational spectral modulations in LP261-75B, an L6-type intermediate surface gravity companion to an M4.5 star. As a part of the Cloud Atlas Treasury program, we acquired time-resolved Wide Field Camera 3 grism spectroscopy (1.1-1.69 mu m) of LP261-75B. We find gray spectral variations with the relative amplitude displaying only a weak wavelength dependence and no evidence for lower-amplitude modulations in the 1.4. mu m water band than in the adjacent continuum. The likely rotational modulation period is 4.78 +/- 0.95. hr, although the rotational phase is not well sampled. The minimum relative amplitude in the white light curve measured over the whole wavelength range is 2.41% +/- 0.14%. We report an unusual light curve, which seems to have three peaks approximately evenly distributed in rotational phase. The spectral modulations suggests that the upper atmosphere cloud properties in LP261-75B are similar to two other mid-L dwarfs of typical infrared colors, but differ from that of the extremely red L-dwarf WISE0047.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/626404 |
| Date | 11 December 2017 |
| Creators | Manjavacas, Elena, Apai, Dániel, Zhou, Yifan, Karalidi, Theodora, Lew, Ben W. P., Schneider, Glenn, Cowan, Nicolas, Metchev, Stan, Miles-Páez, Paulo A., Burgasser, Adam J., Radigan, Jacqueline, Bedin, Luigi R., Lowrance, Patrick J., Marley, Mark S. |
| Contributors | Univ Arizona, Dept Astron, Steward Observ |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/1538-3881/155/i=1/a=11?key=crossref.db5bcad93f49b97c5367c60dc227b807 |
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