The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b
The hot Jupiter HD 209458b is particularly amenable to detailed study as it is among the brightest transiting exoplanet systems currently known (V-mag = 7.65; K-mag = 6.308) and has a large planet-to-star contrast ratio. HD 209458b is predicted to be in synchronous rotation about its host star with...
| Main Authors: | , , , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/92801 |
| _version_ | 1811002259771752448 |
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| author | Zellem, Robert T. Knutson, Heather A. Griffith, Caitlin A. Showman, Adam P. Fortney, Jonathan J. Cowan, Nicolas B. Agol, Eric Burrows, Adam Charbonneau, David Deming, Drake Laughlin, Gregory Langton, Jonathan Lewis, Nikole |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Zellem, Robert T. Knutson, Heather A. Griffith, Caitlin A. Showman, Adam P. Fortney, Jonathan J. Cowan, Nicolas B. Agol, Eric Burrows, Adam Charbonneau, David Deming, Drake Laughlin, Gregory Langton, Jonathan Lewis, Nikole |
| author_sort | Zellem, Robert T. |
| collection | MIT |
| description | The hot Jupiter HD 209458b is particularly amenable to detailed study as it is among the brightest transiting exoplanet systems currently known (V-mag = 7.65; K-mag = 6.308) and has a large planet-to-star contrast ratio. HD 209458b is predicted to be in synchronous rotation about its host star with a hot spot that is shifted eastward of the substellar point by superrotating equatorial winds. Here we present the first full-orbit observations of HD 209458b, in which its 4.5 μm emission was recorded with Spitzer/IRAC. Our study revises the previous 4.5 μm measurement of HD 209458b's secondary eclipse emission downward by ~35% to $0.1391%[+0.0072% over -0.0069%], changing our interpretation of the properties of its dayside atmosphere. We find that the hot spot on the planet's dayside is shifted eastward of the substellar point by 40.°9 ± 6.°0, in agreement with circulation models predicting equatorial superrotation. HD 209458b's dayside (T bright = 1499 ± 15 K) and nightside (T [subscript bright] = 972 ± 44 K) emission indicate a day-to-night brightness temperature contrast smaller than that observed for more highly irradiated exoplanets, suggesting that the day-to-night temperature contrast may be partially a function of the incident stellar radiation. The observed phase curve shape deviates modestly from global circulation model predictions potentially due to disequilibrium chemistry or deficiencies in the current hot CH[subscript 4] line lists used in these models. Observations of the phase curve at additional wavelengths are needed in order to determine the possible presence and spatial extent of a dayside temperature inversion, as well as to improve our overall understanding of this planet's atmospheric circulation. |
| first_indexed | 2024-09-23T15:45:42Z |
| format | Article |
| id | mit-1721.1/92801 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:45:42Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/928012024-05-15T02:13:29Z The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b Zellem, Robert T. Knutson, Heather A. Griffith, Caitlin A. Showman, Adam P. Fortney, Jonathan J. Cowan, Nicolas B. Agol, Eric Burrows, Adam Charbonneau, David Deming, Drake Laughlin, Gregory Langton, Jonathan Lewis, Nikole Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Lewis, Nicole The hot Jupiter HD 209458b is particularly amenable to detailed study as it is among the brightest transiting exoplanet systems currently known (V-mag = 7.65; K-mag = 6.308) and has a large planet-to-star contrast ratio. HD 209458b is predicted to be in synchronous rotation about its host star with a hot spot that is shifted eastward of the substellar point by superrotating equatorial winds. Here we present the first full-orbit observations of HD 209458b, in which its 4.5 μm emission was recorded with Spitzer/IRAC. Our study revises the previous 4.5 μm measurement of HD 209458b's secondary eclipse emission downward by ~35% to $0.1391%[+0.0072% over -0.0069%], changing our interpretation of the properties of its dayside atmosphere. We find that the hot spot on the planet's dayside is shifted eastward of the substellar point by 40.°9 ± 6.°0, in agreement with circulation models predicting equatorial superrotation. HD 209458b's dayside (T bright = 1499 ± 15 K) and nightside (T [subscript bright] = 972 ± 44 K) emission indicate a day-to-night brightness temperature contrast smaller than that observed for more highly irradiated exoplanets, suggesting that the day-to-night temperature contrast may be partially a function of the incident stellar radiation. The observed phase curve shape deviates modestly from global circulation model predictions potentially due to disequilibrium chemistry or deficiencies in the current hot CH[subscript 4] line lists used in these models. Observations of the phase curve at additional wavelengths are needed in order to determine the possible presence and spatial extent of a dayside temperature inversion, as well as to improve our overall understanding of this planet's atmospheric circulation. United States. National Aeronautics and Space Administration. Sagan Fellowship Program 2015-01-12T19:44:06Z 2015-01-12T19:44:06Z 2014-07 2014-03 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/92801 Zellem, Robert T., Nikole K. Lewis, Heather A. Knutson, Caitlin A. Griffith, Adam P. Showman, Jonathan J. Fortney, Nicolas B. Cowan, et al. “The 4.5 Μm Full-Orbit Phase Curve of the Hot Jupiter HD 209458b.” The Astrophysical Journal 790, no. 1 (July 2, 2014): 53. © 2014 The American Astronomical Society en_US http://dx.doi.org/10.1088/0004-637X/790/1/53 Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Zellem, Robert T. Knutson, Heather A. Griffith, Caitlin A. Showman, Adam P. Fortney, Jonathan J. Cowan, Nicolas B. Agol, Eric Burrows, Adam Charbonneau, David Deming, Drake Laughlin, Gregory Langton, Jonathan Lewis, Nikole The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b |
| title | The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b |
| title_full | The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b |
| title_fullStr | The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b |
| title_full_unstemmed | The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b |
| title_short | The 4.5 mm full-orbit phase curve of the hot Jupiter HD 209458b |
| title_sort | 4 5 mm full orbit phase curve of the hot jupiter hd 209458b |
| url | http://hdl.handle.net/1721.1/92801 |
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