Magellan Adaptive Optics First-light Observations of the Exoplanet β Pic b. II. 3-5 μm Direct Imaging with MagAO+Clio, and the Empirical Bolometric Luminosity of a Self-luminous Giant Planet

Journal
Date Issued
2015
Author(s)
Morzinski, Katie M.
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Males, Jared R.
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Skemer, Andy J.
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Close, Laird M.
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Hinz, Phil M.
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Rodigas, T. J.
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•
•
•
•
•
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Bailey, Vanessa P.
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Follette, Katherine B.
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Kopon, Derek
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Weinberger, Alycia J.
•
Wu, Ya-Lin
DOI
Description
We thank the Magellan and Las Campanas Observatory staff for making this well-engineered, smoothly operated telescope and site possible. We would especially like to thank Povilas Palunas for help over the entire MagAO commissioning run. Juan Gallardo, Patricio Jones, Emilio Cerda, Felipe Sanchez, Gabriel Martin, Maurico Navarrete, Jorge Bravo, Victor Merino, Patricio Pinto, Gabriel Prieto, Mauricio Martinez, Alberto Pasten, Jorge Araya, Hugo Rivera, and the whole team of technical experts helped perform many exacting tasks in a very professional manner. Glenn Eychaner, David Osip, and Frank Perez all gave expert support which was fantastic. The entire logistics, dining, housekeeping, and hospitality staff provide for an excellent, healthy environment that ensured the wellness of our team throughout the commissioning runs. It is a privilege to be able to commission an AO system with such a fine staff and site. The MagAO system was developed with support from the NSF, MRI and TSIP programs. The VisAO camera was developed with help from the NSF ATI program. K.M.M. and J.R.M. were supported under contract with the California Institute of Technology, funded by NASA through the Sagan Fellowship Program. J.R.M. is grateful for the generous support of the Phoenix ARCS Foundation. L.M.C.'s and Y.-L.W.'s research were supported by NSF AAG and NASA Origins of Solar Systems grants. V.B. was supported in part by the NSF Graduate Research Fellowship Program (DGE-1143953). We thank the anonymous referee for a careful, timely review that significantly improved the manuscript. Facility: Magellan:Clay (MagAO+Clio) .
Abstract
Young giant exoplanets are a unique laboratory for understanding cool, low-gravity atmospheres. A quintessential example is the massive extrasolar planet β Pic b, which is 9 AU from and embedded in the debris disk of the young nearby A6V star β Pictoris. We observed the system with first light of the Magellan Adaptive Optics (MagAO) system. In Paper I we presented the first CCD detection of this planet with MagAO+VisAO. Here we present four MagAO+Clio images of β Pic b at 3.1 μm, 3.3 μm, L′, and {M}\prime , including the first observation in the fundamental CH4 band. To remove systematic errors from the spectral energy distribution (SED), we re-calibrate the literature photometry and combine it with our own data, for a total of 22 independent measurements at 16 passbands from 0.99 to 4.8 μm. Atmosphere models demonstrate the planet is cloudy but are degenerate in effective temperature and radius. The measured SED now covers >80% of the planet’s energy, so we approach the bolometric luminosity empirically. We calculate the luminosity by extending the measured SED with a blackbody and integrating to find log({{L}}{bol}/{{L}}☉ ) \=\-3.78+/- 0.03. From our bolometric luminosity and an age of 23 ± 3 Myr, hot-start evolutionary tracks give a mass of 12.7 ± 0.3 {{M}}{Jup}, radius of 1.45 ± 0.02 {{R}}{Jup}, and Teff of 1708 ± 23 K (model-dependent errors not included). Our empirically determined luminosity is in agreement with values from atmospheric models (typically -3.8 dex), but brighter than values from the field-dwarf bolometric correction (typically -3.9 dex), illustrating the limitations in comparing young exoplanets to old brown dwarfs.
Volume
815
Issue
2
Start page
108
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...815..108M
Rights
open.access
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