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A Search for a Sub-Earth-Sized Companion to GJ 436 and a Novel Method to Calibrate Warm Spitzer IRAC Observations

Ballard, Sarah and Charbonneau, David and Deming, Drake and Knutson, Heather A. and Christiansen, Jessie L. and Holman, Matthew J. and Fabrycky, Daniel and Seager, Sara and A'Hearn, Michael F. (2010) A Search for a Sub-Earth-Sized Companion to GJ 436 and a Novel Method to Calibrate Warm Spitzer IRAC Observations. Publications of the Astronomical Society of the Pacific, 122 (897). pp. 1341-1352. ISSN 0004-6280. https://resolver.caltech.edu/CaltechAUTHORS:20130219-133505285

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Abstract

We discovered evidence for a possible additional 0.75 R_⊕ transiting planet in the NASA EPOXI observations of the known M dwarf exoplanetary system GJ 436. Based on an ephemeris determined from the EPOXI data, we predicted a transit event in an extant Spitzer Space Telescope 8 μm data set of this star. Our subsequent analysis of those Spitzer data confirmed the signal of the predicted depth and at the predicted time, but we found that the transit depth was dependent on the aperture used to perform the photometry. Based on these suggestive findings, we gathered new warm Spitzer observations of GJ 436 at 4.5 μm spanning a time of transit predicted from the EPOXI and Spitzer 8 μm candidate events. The 4.5 μm data permit us to rule out a transit at high confidence, and we conclude that the earlier candidate transit signals resulted from correlated noise in the EPOXI and Spitzer 8 μm observations. In the course of this investigation, we developed a novel method for correcting the intrapixel sensitivity variations of the 3.6 and 4.5 μm channels of the Infrared Array Camera (IRAC) instrument. We demonstrate the sensitivity of warm Spitzer observations of M dwarfs to confirm sub-Earth-sized planets. Our analysis will inform similar work that will be undertaken to use warm Spitzer observations to confirm rocky planets discovered by the Kepler mission.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1086/657159DOIArticle
http://www.jstor.org/stable/10.1086/657159JSTORArticle
https://arxiv.org/abs/1009.0755arXivDiscussion Paper
ORCID:
AuthorORCID
Ballard, Sarah0000-0002-3247-5081
Charbonneau, David0000-0002-9003-484X
Deming, Drake0000-0001-5727-4094
Knutson, Heather A.0000-0002-0822-3095
Christiansen, Jessie L.0000-0002-8035-4778
Holman, Matthew J.0000-0002-1139-4880
Fabrycky, Daniel0000-0003-3750-0183
Seager, Sara0000-0002-6892-6948
Additional Information:© 2010 The Astronomical Society of the Pacific. Received 2010 August 12; accepted 2010 September 3; published 2010 October 1.
Subject Keywords:Extrasolar Planets
Issue or Number:897
Record Number:CaltechAUTHORS:20130219-133505285
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130219-133505285
Official Citation:A Search for a Sub-Earth-Sized Companion to GJ 436 and a Novel Method to Calibrate Warm Spitzer IRAC Observations Sarah Ballard, David Charbonneau, Drake Deming, Heather A. Knutson, Jessie L. Christiansen, Matthew J. Holman, Daniel Fabrycky, Sara Seager, and Michael F. A’Hearn Publications of the Astronomical Society of the Pacific, Vol. 122, No. 897 (November 2010), pp. 1341-1352 Published by: The University of Chicago Press on behalf of the Astronomical Society of the Pacific Article DOI: 10.1086/657159 Article Stable URL: http://www.jstor.org/stable/10.1086/657159
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36985
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:20 Feb 2013 18:59
Last Modified:09 Mar 2020 13:18

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