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A Combined Subaru/VLT/MMT 1-5 Micrometer Study of Planets Orbiting HR 8799: Implications For Atmospheric Properties, Masses and FormationWe present new 1-1.25 micron (z and J band) Subaru/IRCS and 2 micron (K band) VLT/NaCo data for HR 8799 and a rereduction of the 3-5 micron MMT/Clio data first presented by Hinz et al. Our VLT/NaCo data yield a detection of a fourth planet at a projected separation of approximately 15 AU--"HR 8799e ." We also report new, albeit weak detections of HR 8799b at 1.03 micron and 3.3 micron. Empirical comparisons to field brown dwarfs show that at least HR 8799b and HR 8799c, and possibly HR 8799d, have near-to-mid-IR colors/ magnitudes significantly discrepant from the L/T dwarf sequence. Standard cloud deck atmosphere models appropriate for brown dwarfs provide only (marginally) statistically meaningful fits to HR 8799b and c for unphysically small radii. Models with thicker cloud layers not present in brown dwarfs reproduce the planets' spectral energy distributions far more accurately and without the need for resealing the planets' radii. Our preliminary modeling suggests that HR 8799b has log(g) = 4-4.5, T(sub eff) = 900 K. while HR 8799c, d, and (by inference) e have log(g) = 4-4.5, T(sub eff) = 1000-1200 K. Combining results from planet evolution models and new dynamical stability limits implies that the masses of HR 8799b, c, d, and e are 6-7 M(sub j), 7-10 M(sub j), 7-10 M(sub j), and 7-10 M(sub j). "Patchy" cloud prescriptions may provide even better fits to the data and may lower the estimated surface gravities and masses. Finally, contrary to some recent claims, forming the HR 8799 planets by core accretion is still plausible, although such systems are likely rare.
Document ID
20110007998
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Currie, Thayne
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Burrows, Adam
(Princeton Univ. Princeton, NJ, United States)
Itoh, Yoichi
(Kobe Univ. Japan)
Matsumura, Soko
(Maryland Univ. College Park, MD, United States)
Fukagawa, Misato
(Osaka Univ. Osaka, Japan)
Apai, Daniel
(Space Telescope Science Inst. Baltimore, MD, United States)
Madhusudhan, Nikku
(Princeton Univ. Princeton, NJ, United States)
Hinz, Philip M.
(Arizona Univ. Tucson, AZ, United States)
Rodigas, T. J.
(Arizona Univ. Tucson, AZ, United States)
Kasper, Markus
Pyo, T.-S.
(National Astronomical Observatory Tokyo, Japan)
Ogino, Satoshi
(Kobe Univ. Japan)
Date Acquired
August 25, 2013
Publication Date
January 1, 2011
Subject Category
Astronomy
Funding Number(s)
CONTRACT_GRANT: HST-GO-12181.04-A
CONTRACT_GRANT: NNX07AG80G
Distribution Limits
Public
Copyright
Other

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