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Title: HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b

Abstract

The nearby star GJ 1214 hosts a planet intermediate in radius and mass between Earth and Neptune, resulting in some uncertainty as to its nature. We have observed this planet, GJ 1214b, during transit with the high-resolution, near-infrared NIRSPEC spectrograph on the Keck II telescope, in order to characterize the planet's atmosphere. By cross-correlating the spectral changes through transit with a suite of theoretical atmosphere models, we search for variations associated with absorption in the planet atmosphere. Our observations are sufficient to rule out tested model atmospheres with wavelength-dependent transit depth variations {approx}> 5 x 10{sup -4} over the wavelength range 2.1-2.4 {mu}m. Our sensitivity is limited by variable slit loss and telluric transmission effects. We find no positive signatures but successfully rule out a number of plausible atmospheric models, including the default assumption of a gaseous, H-dominated atmosphere in chemical equilibrium. Such an atmosphere can be made consistent if the absorption due to methane is reduced. Clouds can also render such an atmosphere consistent with our observations, but only if they lie higher in the atmosphere than indicated by recent optical and infrared measurements. When taken in concert with other observational constraints, our results support a model in whichmore » the atmosphere of GJ 1214b contains significant H and He, but where CH{sub 4} is depleted. If this depletion is the result of photochemical processes, it may also produce a haze that suppresses spectral features in the optical.« less

Authors:
;  [1];  [2]
  1. Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095 (United States)
  2. Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)
Publication Date:
OSTI Identifier:
21578245
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/736/2/132; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABSORPTION SPECTROSCOPY; INFRARED SPECTRA; NEAR INFRARED RADIATION; PLANETARY ATMOSPHERES; PLANETS; STARS; VARIATIONS; WAVELENGTHS; ATMOSPHERES; ELECTROMAGNETIC RADIATION; INFRARED RADIATION; RADIATIONS; SORPTION; SPECTRA; SPECTROSCOPY

Citation Formats

Crossfield, I. J. M., Hansen, Brad M. S., and Barman, Travis, E-mail: ianc@astro.ucla.edu. HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/2/132.
Crossfield, I. J. M., Hansen, Brad M. S., & Barman, Travis, E-mail: ianc@astro.ucla.edu. HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b. United States. doi:10.1088/0004-637X/736/2/132.
Crossfield, I. J. M., Hansen, Brad M. S., and Barman, Travis, E-mail: ianc@astro.ucla.edu. Mon . "HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b". United States. doi:10.1088/0004-637X/736/2/132.
@article{osti_21578245,
title = {HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b},
author = {Crossfield, I. J. M. and Hansen, Brad M. S. and Barman, Travis, E-mail: ianc@astro.ucla.edu},
abstractNote = {The nearby star GJ 1214 hosts a planet intermediate in radius and mass between Earth and Neptune, resulting in some uncertainty as to its nature. We have observed this planet, GJ 1214b, during transit with the high-resolution, near-infrared NIRSPEC spectrograph on the Keck II telescope, in order to characterize the planet's atmosphere. By cross-correlating the spectral changes through transit with a suite of theoretical atmosphere models, we search for variations associated with absorption in the planet atmosphere. Our observations are sufficient to rule out tested model atmospheres with wavelength-dependent transit depth variations {approx}> 5 x 10{sup -4} over the wavelength range 2.1-2.4 {mu}m. Our sensitivity is limited by variable slit loss and telluric transmission effects. We find no positive signatures but successfully rule out a number of plausible atmospheric models, including the default assumption of a gaseous, H-dominated atmosphere in chemical equilibrium. Such an atmosphere can be made consistent if the absorption due to methane is reduced. Clouds can also render such an atmosphere consistent with our observations, but only if they lie higher in the atmosphere than indicated by recent optical and infrared measurements. When taken in concert with other observational constraints, our results support a model in which the atmosphere of GJ 1214b contains significant H and He, but where CH{sub 4} is depleted. If this depletion is the result of photochemical processes, it may also produce a haze that suppresses spectral features in the optical.},
doi = {10.1088/0004-637X/736/2/132},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 736,
place = {United States},
year = {2011},
month = {8}
}