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Title: M-BAND IMAGING OF THE HR 8799 PLANETARY SYSTEM USING AN INNOVATIVE LOCI-BASED BACKGROUND SUBTRACTION TECHNIQUE

Abstract

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 {approx}5 {mu}m and provide access to the strong CO fundamental absorption band at 4.5 {mu}m. 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. We also confirm that the best atmospheric fits are consistent with low surfacemore » gravity, dusty, and non-equilibrium CO/CH{sub 4} chemistry models.« less

Authors:
;  [1]; ;  [2];  [3]
  1. National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada)
  2. Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States)
  3. Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)
Publication Date:
OSTI Identifier:
21565438
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 739; Journal Issue: 2; Other Information: DOI: 10.1088/2041-8205/739/2/L41
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; CARBON MONOXIDE; METHANE; PHOTOMETRY; PLANETARY ATMOSPHERES; PLANETS; SOLAR SYSTEM; ALKANES; ATMOSPHERES; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; HYDROCARBONS; ORGANIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; SORPTION

Citation Formats

Galicher, Raphael, Marois, Christian, Macintosh, Bruce, Konopacky, Quinn, and Barman, Travis, E-mail: raphael.galicher@nrc-cnrc.gc.ca. M-BAND IMAGING OF THE HR 8799 PLANETARY SYSTEM USING AN INNOVATIVE LOCI-BASED BACKGROUND SUBTRACTION TECHNIQUE. United States: N. p., 2011. Web. doi:10.1088/2041-8205/739/2/L41.
Galicher, Raphael, Marois, Christian, Macintosh, Bruce, Konopacky, Quinn, & Barman, Travis, E-mail: raphael.galicher@nrc-cnrc.gc.ca. M-BAND IMAGING OF THE HR 8799 PLANETARY SYSTEM USING AN INNOVATIVE LOCI-BASED BACKGROUND SUBTRACTION TECHNIQUE. United States. doi:10.1088/2041-8205/739/2/L41.
Galicher, Raphael, Marois, Christian, Macintosh, Bruce, Konopacky, Quinn, and Barman, Travis, E-mail: raphael.galicher@nrc-cnrc.gc.ca. 2011. "M-BAND IMAGING OF THE HR 8799 PLANETARY SYSTEM USING AN INNOVATIVE LOCI-BASED BACKGROUND SUBTRACTION TECHNIQUE". United States. doi:10.1088/2041-8205/739/2/L41.
@article{osti_21565438,
title = {M-BAND IMAGING OF THE HR 8799 PLANETARY SYSTEM USING AN INNOVATIVE LOCI-BASED BACKGROUND SUBTRACTION TECHNIQUE},
author = {Galicher, Raphael and Marois, Christian and Macintosh, Bruce and Konopacky, Quinn and Barman, Travis, E-mail: raphael.galicher@nrc-cnrc.gc.ca},
abstractNote = {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 {approx}5 {mu}m and provide access to the strong CO fundamental absorption band at 4.5 {mu}m. 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. We also confirm that the best atmospheric fits are consistent with low surface gravity, dusty, and non-equilibrium CO/CH{sub 4} chemistry models.},
doi = {10.1088/2041-8205/739/2/L41},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 739,
place = {United States},
year = 2011,
month =
}
  • 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 developmentmore » 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 low surface gravity, dusty, and non-equilibrium CO/CH 4 chemistry models.« less
  • The discovery of three planetary companions around HR 8799 marked a significant epoch in direct imaging of extrasolar planets. Given the importance of this system, we re-analyzed H-band images of HR 8799 obtained with the Subaru 36-elements adaptive optics (AO) in 2002 July. The low-order AO imaging combined with the classical point-spread function (PSF) subtractions even revealed the extrasolar planet, HR 8799b. Our observations in 2002 confirmed that it has been orbiting HR 8799 in a counterclockwise direction. The flux of HR 8799b was consistent with those in the later epochs within the uncertainty of 0.25 mag, further supporting themore » planetary mass estimate by Marois et al.« less
  • We present a pre-discovery H-band image of the HR 8799 planetary system that reveals all three planets in 2007 August. The data were obtained with the Keck adaptive optics system, using angular differential imaging and a coronagraph. We confirm the physical association of all three planets, including HR 8799d, which had only been detected in 2008 images taken two months apart, and whose association with HR 8799 was least secure until now. We confirm that the planets are 2-3 mag fainter than field brown dwarfs of comparable near-infrared colors. We note that similar underluminosity is characteristic of young substellar objectsmore » at the L/T spectral type transition, and is likely due to enhanced dust content and non-equilibrium CO/CH{sub 4} chemistry in their atmospheres. Finally, we place an upper limit of approx>18 mag arcsec{sup -2} on the >120 AU H-band dust-scattered light from the HR 8799 debris disk. The corresponding integrated scattered light flux is <10{sup -4} times the photospheric level, 24 times fainter than for the debris ring around HR 4796A.« less
  • The extrasolar planetary system around HR 8799 is the first multiplanet system ever imaged. It is also, by a wide margin, the highest mass system with >27 Jupiters of planetary mass past 25 AU. This is a remarkable system with no analog in any other known planetary system. In the first part of this paper, we investigated the nature of two faint objects imaged near the system. These objects are considerably fainter (H = 20.4 and 21.6 mag) and more distant (projected separations of 612 and 534 AU) than the three known planetary companions b, c, and d (68-24 AU).more » It is possible that these two objects could be lower mass planets (of mass approx5M{sub Jup} and approx3M{sub Jup}) that have been scattered to wider orbits. We make the first direct comparison of newly reduced archival Gemini adaptive optics images to archival Hubble Space Telescope/NICMOS images. With nearly a decade between these epochs, we can accurately assess the proper motion nature of each candidate companion. We find that both objects are unbound to HR 8799 and are background. We estimate that HR 8799 has no companions of H < 22 from approx5'' to 15''. Any scattered giant planets in the HR 8799 system are >600 AU or less than 3 M{sub Jup} in mass. In the second part of this paper, we search for any sign of a 'reverse parallax signature' in the astrometric residuals of HR 8799b. No such signal was found and we conclude, as expected, that HR 8799b has the same parallax as HR 8799A. In the third part of this paper, we carry out a search for wider common proper motion objects. We found one object within 1 deg{sup 2} in the Palomar Observatory Sky Survey-Digitized Sky Survey images with similar (<2sigma) proper motions to HR 8799 at a separation of 4.'0. We conclude that it is not likely a bound companion to HR 8799 based on available photometry.« less