2017/10/23 by Elena Manjavacas, Dániel Apai, Daniel Apai +13
Physics and Astronomy · #Amplitude #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Brown dwarf #Exoplanet #Grism #Infrared #Light curve #Spectroscopy #Stellar classification #Stellar, planetary, and galactic studies #Wavelength #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.3847/1538-3881/aa984f
arxiv created 2017/10/23 · openalex created_date 2017/11/10 · openalex publication_date 2017/12/11 · arxiv updated 2017/12/27 · openalex updated_date 2026/08/05
Abstract 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 μ 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 μ 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.