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Title: Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the Hot Jupiter WASP-4b

Abstract

We present the complete optical transmission spectrum of the hot Jupiter WASP-4b from 440 to 940 nm at R  ∼ 400–1500 obtained with the Gemini Multi-Object Spectrometers (GMOS); this is the first result from a comparative exoplanetology survey program of close-in gas giants conducted with GMOS. WASP-4b has an equilibrium temperature of 1700 K and is favorable to study in transmission due to its large scale height (370 km). We derive the transmission spectrum of WASP-4b using four transits observed with the MOS technique. We demonstrate repeatable results across multiple epochs with GMOS, and derive a combined transmission spectrum at a precision about twice above photon noise, which is roughly equal to one atmospheric scale height. The transmission spectrum is well fitted with a uniform opacity as a function of wavelength. The uniform opacity and absence of a Rayleigh slope from molecular hydrogen suggest that the atmosphere is dominated by clouds with condensate grain sizes of ∼1  μ m. This result is consistent with previous observations of hot Jupiters since clouds have been seen in planets with similar equilibrium temperatures to WASP-4b. We describe a custom pipeline that we have written to reduce GMOS time-series data of exoplanet transits, and present a thoroughmore » analysis of the dominant noise sources in GMOS, which primarily consist of wavelength- and time-dependent displacements of the spectra on the detector, mainly due to a lack of atmospheric dispersion correction.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6]
  1. CASA, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States)
  2. API, University of Amsterdam, P.O. Box 94249, 1090 GE Amsterdam (Netherlands)
  3. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
  4. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
  5. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  6. NOAO and Gemini Observatory, present address Palo Alto, CA (United States)
Publication Date:
OSTI Identifier:
22663246
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 154; Journal Issue: 3; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTRA; CLOUDS; CORRECTIONS; EQUILIBRIUM; GRAIN SIZE; HYDROGEN; JUPITER PLANET; NOISE; OPACITY; PHOTONS; SATELLITE ATMOSPHERES; SATELLITES; SCALE HEIGHT; SILICON OXIDES; TIME DEPENDENCE; TRANSMISSION; WAVELENGTHS

Citation Formats

Huitson, C. M., Désert, J.-M., Bean, J. L., Fortney, J. J., Stevenson, K. B., and Bergmann, M., E-mail: catherine.huitson@colorado.edu. Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the Hot Jupiter WASP-4b. United States: N. p., 2017. Web. doi:10.3847/1538-3881/AA7F72.
Huitson, C. M., Désert, J.-M., Bean, J. L., Fortney, J. J., Stevenson, K. B., & Bergmann, M., E-mail: catherine.huitson@colorado.edu. Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the Hot Jupiter WASP-4b. United States. doi:10.3847/1538-3881/AA7F72.
Huitson, C. M., Désert, J.-M., Bean, J. L., Fortney, J. J., Stevenson, K. B., and Bergmann, M., E-mail: catherine.huitson@colorado.edu. Fri . "Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the Hot Jupiter WASP-4b". United States. doi:10.3847/1538-3881/AA7F72.
@article{osti_22663246,
title = {Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the Hot Jupiter WASP-4b},
author = {Huitson, C. M. and Désert, J.-M. and Bean, J. L. and Fortney, J. J. and Stevenson, K. B. and Bergmann, M., E-mail: catherine.huitson@colorado.edu},
abstractNote = {We present the complete optical transmission spectrum of the hot Jupiter WASP-4b from 440 to 940 nm at R  ∼ 400–1500 obtained with the Gemini Multi-Object Spectrometers (GMOS); this is the first result from a comparative exoplanetology survey program of close-in gas giants conducted with GMOS. WASP-4b has an equilibrium temperature of 1700 K and is favorable to study in transmission due to its large scale height (370 km). We derive the transmission spectrum of WASP-4b using four transits observed with the MOS technique. We demonstrate repeatable results across multiple epochs with GMOS, and derive a combined transmission spectrum at a precision about twice above photon noise, which is roughly equal to one atmospheric scale height. The transmission spectrum is well fitted with a uniform opacity as a function of wavelength. The uniform opacity and absence of a Rayleigh slope from molecular hydrogen suggest that the atmosphere is dominated by clouds with condensate grain sizes of ∼1  μ m. This result is consistent with previous observations of hot Jupiters since clouds have been seen in planets with similar equilibrium temperatures to WASP-4b. We describe a custom pipeline that we have written to reduce GMOS time-series data of exoplanet transits, and present a thorough analysis of the dominant noise sources in GMOS, which primarily consist of wavelength- and time-dependent displacements of the spectra on the detector, mainly due to a lack of atmospheric dispersion correction.},
doi = {10.3847/1538-3881/AA7F72},
journal = {Astronomical Journal (Online)},
number = 3,
volume = 154,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 2017},
month = {Fri Sep 01 00:00:00 EDT 2017}
}