DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS
The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measu...
| Main Authors: | , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
IOP Publishing
2015
|
| Online Access: | http://hdl.handle.net/1721.1/93205 |
| _version_ | 1826202263955177472 |
|---|---|
| author | Showman, Adam P. Fortney, Jonathan J. Lewis, Nikole Shabram, Megan |
| 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 Showman, Adam P. Fortney, Jonathan J. Lewis, Nikole Shabram, Megan |
| author_sort | Showman, Adam P. |
| collection | MIT |
| description | The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation—and Doppler signature—of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows toward Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blueshifted and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps these waves and inhibits jet formation. As a result, this second regime exhibits a circulation dominated by high-altitude, day-to-night airflow, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art circulation models including non-gray radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that cool planets like GJ 436b lie in the first regime, HD 189733b is transitional, while planets hotter than HD 209458b lie in the second regime. Moreover, we show how the amplitude of the Doppler shifts constrains the strength of frictional drag in the upper atmospheres of hot Jupiters. If due to winds, the ~2 km s[superscript –1] blueshift inferred on HD 209458b may require drag time constants as short as 10[superscript 4]-10[superscript 6] s, possibly the result of Lorentz-force braking on this planet's hot dayside. |
| first_indexed | 2024-09-23T12:04:46Z |
| format | Article |
| id | mit-1721.1/93205 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T12:04:46Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/932052022-09-27T23:57:36Z DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS Showman, Adam P. Fortney, Jonathan J. Lewis, Nikole Shabram, Megan Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Lewis, Nikole The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation—and Doppler signature—of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows toward Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blueshifted and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps these waves and inhibits jet formation. As a result, this second regime exhibits a circulation dominated by high-altitude, day-to-night airflow, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art circulation models including non-gray radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that cool planets like GJ 436b lie in the first regime, HD 189733b is transitional, while planets hotter than HD 209458b lie in the second regime. Moreover, we show how the amplitude of the Doppler shifts constrains the strength of frictional drag in the upper atmospheres of hot Jupiters. If due to winds, the ~2 km s[superscript –1] blueshift inferred on HD 209458b may require drag time constants as short as 10[superscript 4]-10[superscript 6] s, possibly the result of Lorentz-force braking on this planet's hot dayside. 2015-01-29T19:08:18Z 2015-01-29T19:08:18Z 2012-12 2012-07 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/93205 Showman, Adam P., Jonathan J. Fortney, Nikole K. Lewis, and Megan Shabram. “DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS.” The Astrophysical Journal 762, no. 1 (December 12, 2012): 24. © 2013 The American Astronomical Society en_US http://dx.doi.org/10.1088/0004-637x/762/1/24 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 | Showman, Adam P. Fortney, Jonathan J. Lewis, Nikole Shabram, Megan DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS |
| title | DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS |
| title_full | DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS |
| title_fullStr | DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS |
| title_full_unstemmed | DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS |
| title_short | DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS |
| title_sort | doppler signatures of the atmospheric circulation on hot jupiters |
| url | http://hdl.handle.net/1721.1/93205 |
| work_keys_str_mv | AT showmanadamp dopplersignaturesoftheatmosphericcirculationonhotjupiters AT fortneyjonathanj dopplersignaturesoftheatmosphericcirculationonhotjupiters AT lewisnikole dopplersignaturesoftheatmosphericcirculationonhotjupiters AT shabrammegan dopplersignaturesoftheatmosphericcirculationonhotjupiters |