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The Emergent 1.1-1.7 μm Spectrum of the Exoplanet CoRoT-2b as Measured Using the Hubble Space Telescope

Wilkins, Ashlee N. and Deming, Drake and Madhusudhan, Nikku and Burrows, Adam and Knutson, Heather and McCullough, Peter R. and Ranjan, Sukrit (2014) The Emergent 1.1-1.7 μm Spectrum of the Exoplanet CoRoT-2b as Measured Using the Hubble Space Telescope. Astrophysical Journal, 783 (2). Art. No. 113. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20140617-134424051

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Abstract

We have used Hubble/WFC3 and the G141 grism to measure the secondary eclipse of the transiting, very hot Jupiter CoRoT-2b in the 1.1-1.7 μm spectral region. We find an eclipse depth averaged over this band equal to 395^(+69)_(-45) parts per million, equivalent to a blackbody temperature of 1788 ± 18 K. We study and characterize several WFC3 instrumental effects, especially the "hook" phenomenon described by Deming et al. We use data from several transiting exoplanet systems to find a quantitative relation between the amplitude of the hook and the exposure level of a given pixel. Although the uncertainties in this relation are too large to allow us to develop an empirical correction for our data, our study provides a useful guide for optimizing exposure levels in future WFC3 observations. We derive the planet's spectrum using a differential method. The planet-to-star contrast increases to longer wavelength within the WFC3 bandpass, but without water absorption or emission to a 3σ limit of 85 ppm. The slope of the WFC3 spectrum is significantly less than the slope of the best-fit blackbody. We compare all existing eclipse data for this planet to a blackbody spectrum, and to spectra from both solar abundance and carbon-rich (C/O = 1) models. A blackbody spectrum is an acceptable fit to the full data set. Extra continuous opacity due to clouds or haze, and flattened temperature profiles, are strong candidates to produce quasi-blackbody spectra, and to account for the amplitude of the optical eclipses. Our results show ambiguous evidence for a temperature inversion in this planet.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://iopscience.iop.org/0004-637X/783/2/113PublisherArticle
http://dx.doi.org/10.1088/0004-637X/783/2/113DOIArticle
http://arxiv.org/abs/1401.4464arXivDiscussion Paper
ORCID:
AuthorORCID
Deming, Drake0000-0001-5727-4094
Madhusudhan, Nikku0000-0002-4869-000X
Burrows, Adam0000-0002-3099-5024
Knutson, Heather0000-0002-0822-3095
McCullough, Peter R.0000-0001-9165-9799
Alternate Title:The Emergent 1.1-1.7 Micron Spectrum of the Exoplanet CoRoT-2b as Measured Using the Hubble Space Telescope
Additional Information:© 2014 American Astronomical Society. Received 2013 October 18; accepted 2014 January 16; published 2014 February 21.
Subject Keywords:planets and satellites: atmospheres; planets and satellites: individual (CoRoT-2b); stars: individual (CoRoT-2); techniques: photometric; techniques: spectroscopic
Issue or Number:2
Record Number:CaltechAUTHORS:20140617-134424051
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140617-134424051
Official Citation:The Emergent 1.1-1.7 μm Spectrum of the Exoplanet CoRoT-2b as Measured Using the Hubble Space Telescope Ashlee N. Wilkins et al. 2014 ApJ 783 113
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46311
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:17 Jun 2014 21:09
Last Modified:14 Oct 2019 22:27

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