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Title: M-band imaging of the HR 8799 planetary system using an innovative LOCI-based background subtraction technique

Multi-wavelength observations/spectroscopy of exoplanetary atmospheres are the basis of the emerging exciting field of comparative exoplanetology. The HR 8799 planetary system is an ideal laboratory to study our current knowledge gap between massive field brown dwarfs and the cold 5 Gyr old solar system planets. The HR 8799 planets have so far been imaged at J- to L-band, with only upper limits available at M-band. We present here deep high-contrast Keck II adaptive optics M-band observations that show the imaging detection of three of the four currently known HR 8799 planets. Such detections were made possible due to the development of an innovative LOCI-based background subtraction scheme that is three times more efficient than a classical median background subtraction for Keck II AO data, representing a gain in telescope time of up to a factor of nine. These M-band detections extend the broadband photometric coverage out to ~5 μm and provide access to the strong CO fundamental absorption band at 4.5 μm. The new M-band photometry shows that the HR 8799 planets are located near the L/T-type dwarf transition, similar to what was found by other studies. Finally, we also confirm that the best atmospheric fits are consistent with lowmore » surface gravity, dusty, and non-equilibrium CO/CH 4 chemistry models.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3]
  1. Herzberg Institute of Astrophysics, Victoria, BC (Canada); Univ. de Montreal, Montreal, QC (Canada)
  2. Herzberg Institute of Astrophysics, Victoria, BC (Canada)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Lowell Observatory, Flagstaff, AZ (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-490367
Journal ID: ISSN 2041-8205
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 739; Journal Issue: 2; Journal ID: ISSN 2041-8205
Publisher:
Institute of Physics (IOP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; instrumentation: high angular resolution; methods: data analysis; methods: observational; planetary systems; planets and satellites: atmospheres; techniques: image processing
OSTI Identifier:
1343819