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A search for methane in the atmosphere of GJ 1214b via GTC narrow-band transmission spectrophotometry

Wilson, P. A. and Colόn, K. D. and Sing, D. K. and Ballester, G. E. and Désert, J.-M. and Ehrenreich, D. and Ford, E. B. and Fortney, J. J. and des Etangs, A. Lecavelier and Lόpez-Morales, M. and Morley, C. V. and Pettitt, A. R. and Pont, F. and Vidal-Madjar, A. (2014) A search for methane in the atmosphere of GJ 1214b via GTC narrow-band transmission spectrophotometry. Monthly Notices of the Royal Astronomical Society, 438 (3). pp. 2395-2405. ISSN 0035-8711.

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We present narrow-band photometric measurements of the exoplanet GJ 1214b using the 10.4 m Gran Telescopio Canarias and the Optical System for Imaging and low Resolution Integrated Spectroscopy instrument. Using tuneable filters, we observed a total of five transits, three of which were observed at two wavelengths nearly simultaneously, producing a total of eight individual light curves, six of these probed the possible existence of a methane absorption feature in the 8770–8850 Å region at high resolution. We detect no increase in the planet-to-star radius ratio across the methane feature with a change in radius ratio of ΔR = -0.0007 ± 0.0017 corresponding to a scaleheight (H) change of −0.5 ± 1.2H across the methane feature, assuming a hydrogen-dominated atmosphere. We find that a variety of water and cloudy atmospheric models fit the data well, but find that cloud-free models provide poor fits. These observations support a flat transmission spectrum resulting from the presence of a high-altitude haze or a water-rich atmosphere, in agreement with previous studies. In this study, the observations are pre-dominantly limited by the photometric quality and the limited number of data points (resulting from a long observing cadence), which make the determination of the systematic noise challenging. With tuneable filters capable of high-resolution measurements (R ≈ 600–750) of narrow absorption features, the interpretation of our results are also limited by the absence of high-resolution methane models below 1 μm.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper 10.1093/mnras/stt2356DOIArticle
Désert, J.-M.0000-0002-0875-8401
Ehrenreich, D.0000-0001-9704-5405
Ford, E. B.0000-0001-6545-639X
Fortney, J. J.0000-0002-9843-4354
Morley, C. V.0000-0002-4404-0456
Pont, F.0000-0003-0076-5444
Additional Information:© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 December 3. Received 2013 December 2; in original form 2013 May 31. First published online: January 10, 2014. We thank the entire GTC staff and in particular Antonio Cabrera Lavers and Robert C. Morehead for their help in conducting these observations. This work is based on observations made with the GTC, installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias on the island of La Palma. The GTC is a joint initiative of Spain (led by the Instituto de Astrofísica de Canarias), the University of Florida and Mexico, including the Instituto de Astronomía de la Universidad Nacional Autόnoma de México (IA-UNAM) and Instituto Nacional de Astrofísica, Optica y Electrόnica (INAOE). PAW, DKS and ARP acknowledge support from the UK Science and Technology Facilities Council (STFC). FP is grateful for the STFC grant and Halliday fellowship (ST/F011083/1). KDC and RCM were supported by the National Science Foundation (NSF) Graduate Research Fellowships. GEB acknowledges support from STScI through grants HST-GO-12473.01-A. This work was also aided by the National Geographic Society’s Young Explorers Grant, awarded to KDC. The authors would like to acknowledge the anonymous referee for their useful comments.
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/F011083/1
Space Telescope Science InstituteUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
National Geographic SocietyUNSPECIFIED
Subject Keywords:techniques: photometric, stars: individual: GJ 1214, planetary systems.
Issue or Number:3
Record Number:CaltechAUTHORS:20140407-085754564
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Official Citation: P. A. Wilson, K. D. Colón, D. K. Sing, G. E. Ballester, J.-M. Désert, D. Ehrenreich, E. B. Ford, J. J. Fortney, A. Lecavelier des Etangs, M. López-Morales, C. V. Morley, A. R. Pettitt, F. Pont, and A. Vidal-Madjar A search for methane in the atmosphere of GJ 1214b via GTC narrow-band transmission spectrophotometry MNRAS (March 01, 2014) Vol. 438 2395-2405 first published online January 10, 2014 doi:10.1093/mnras/stt2356
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44679
Deposited By: Ruth Sustaita
Deposited On:07 Apr 2014 16:44
Last Modified:09 Mar 2020 13:19

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