Revealing the Vertical Cloud Structure of a Young Low-mass Brown Dwarf, an Analog to the β-Pictoris b Directly Imaged Exoplanet, through Keck I/MOSFIRE Spectrophotometric Variability
- 6 October 2021
- journal article
- research article
- Published by American Astronomical Society in The Astronomical Journal
- Vol. 162 (5), 179
- https://doi.org/10.3847/1538-3881/ac174c
Abstract
Young brown dwarfs are analogs to giant exoplanets, as they share effective temperatures, near-infrared colors, and surface gravities. Thus, the detailed characterization of young brown dwarfs might shed light on the study of giant exoplanets that we are currently unable to observe with a sufficient signal-to-noise to allow a precise characterization of their atmospheres. 2MASS J22081363+2921215 is a young L3 brown dwarf, and a member of the beta-Pictoris young moving group (23 +/- 3 Myr), which shares its effective temperature and mass with the beta Pictoris b giant exoplanet. We performed a similar to 2.5 hr spectrophotometric J-band monitoring of 2MASS J22081363+2921215 with the MOSFIRE multi-object spectrograph, installed at the Keck I telescope. We measured a minimum variability amplitude of 3.22 +/- 0.42% for its J-band light curve. The ratio between the maximum and the minimum flux spectra of 2MASS J22081363+2921215 shows a weak wavelength dependence, and a potentially enhanced variability amplitude in its alkali lines. Further analysis suggests that the variability amplitudes of the alkali lines are higher than its overall variability amplitude (4.5%-11%, depending on the lines). The variability amplitudes of these lines are lower if we degrade the resolution of the original MOSFIRE spectra to R similar to 100, which explains why this potentially enhanced variability of the alkali lines had not been found previously in Hubble Space Telescope (HST)/WFC3 light curves. Using radiative-transfer models, we obtained the different cloud layers that might be introducing the spectrophotometric variability we observe for 2MASS J22081363+2921215, which further supports the measured enhanced variability amplitudes of the alkali lines. We provide an artistic recreation of the vertical cloud structure of this beta-Pictoris b analog.Keywords
This publication has 63 references indexed in Scilit:
- Models of very-low-mass stars, brown dwarfs and exoplanetsPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2012
- YOUNG L DWARFS IDENTIFIED IN THE FIELD: A PRELIMINARY LOW-GRAVITY, OPTICAL SPECTRAL SEQUENCE FROM L0 TO L5The Astronomical Journal, 2009
- A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf “Lithium Test” at Early AgesThe Astrophysical Journal, 2008
- Ophiuchus 1622−2405: Not a Planetary‐Mass BinaryThe Astrophysical Journal, 2007
- LP 261‐75/2MASSW J09510549+3558021: A Young, Wide M4.5/L6 BinaryPublications of the Astronomical Society of the Pacific, 2006
- Binarity in Brown Dwarfs: T Dwarf Binaries Discovered with theHubble Space TelescopeWide Field Planetary Camera 2The Astrophysical Journal, 2003
- 67 Additional L Dwarfs Discovered by the Two Micron All Sky SurveyThe Astronomical Journal, 2000
- A prescription for period analysis of unevenly sampled time seriesThe Astrophysical Journal, 1986
- Studies in astronomical time series analysis. II - Statistical aspects of spectral analysis of unevenly spaced dataThe Astrophysical Journal, 1982
- Estimating the Dimension of a ModelThe Annals of Statistics, 1978