The Oblique Orbit of WASP-107b from K2 Photometry
Observations of nine transits of WASP-107 during the K2 mission reveal three separate occasions when the planet crossed in front of a starspot. The data confirm the stellar rotation period to be 17 days - approximately three times the planet's orbital period - and suggest that large spots persi...
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| Format: | Article |
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American Astronomical Society
2017
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| Online Access: | http://hdl.handle.net/1721.1/112255 https://orcid.org/0000-0002-8958-0683 |
| _version_ | 1826198380169134080 |
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| author | Winn, Joshua N. Dai, Fei |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Winn, Joshua N. Dai, Fei |
| author_sort | Winn, Joshua N. |
| collection | MIT |
| description | Observations of nine transits of WASP-107 during the K2 mission reveal three separate occasions when the planet crossed in front of a starspot. The data confirm the stellar rotation period to be 17 days - approximately three times the planet's orbital period - and suggest that large spots persist for at least one full rotation. If the star had a low obliquity, at least two additional spot crossings should have been observed. They were not observed, giving evidence for a high obliquity. We use a simple geometric model to show that the obliquity is likely in the range 40°-140°, i.e., both spin-orbit alignment and anti-alignment can be ruled out. WASP-107 thereby joins the small collection of relatively low-mass stars with a high obliquity. Most such stars have been observed to have low obliquities; all of the exceptions, including WASP-107, involve planets with relatively wide orbits ("warm Jupiters," with a[subscript min]/R∗ ≳ 8). This demonstrates a connection between stellar obliquity and planet properties, in contradiction to some theories for obliquity excitation. |
| first_indexed | 2024-09-23T11:03:58Z |
| format | Article |
| id | mit-1721.1/112255 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T11:03:58Z |
| publishDate | 2017 |
| publisher | American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/1122552022-09-27T16:56:03Z The Oblique Orbit of WASP-107b from K2 Photometry Winn, Joshua N. Dai, Fei Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Dai, Fei Observations of nine transits of WASP-107 during the K2 mission reveal three separate occasions when the planet crossed in front of a starspot. The data confirm the stellar rotation period to be 17 days - approximately three times the planet's orbital period - and suggest that large spots persist for at least one full rotation. If the star had a low obliquity, at least two additional spot crossings should have been observed. They were not observed, giving evidence for a high obliquity. We use a simple geometric model to show that the obliquity is likely in the range 40°-140°, i.e., both spin-orbit alignment and anti-alignment can be ruled out. WASP-107 thereby joins the small collection of relatively low-mass stars with a high obliquity. Most such stars have been observed to have low obliquities; all of the exceptions, including WASP-107, involve planets with relatively wide orbits ("warm Jupiters," with a[subscript min]/R∗ ≳ 8). This demonstrates a connection between stellar obliquity and planet properties, in contradiction to some theories for obliquity excitation. 2017-11-20T20:16:04Z 2017-11-20T20:16:04Z 2017-04 2017-03 2017-10-19T13:45:11Z Article http://purl.org/eprint/type/JournalArticle 1538-3881 0004-6256 http://hdl.handle.net/1721.1/112255 Dai, Fei, and Joshua N. Winn. “The Oblique Orbit of WASP-107b from K2 Photometry.” The Astronomical Journal, vol. 153, no. 5, Apr. 2017, p. 205. © 2017 The American Astronomical Society https://orcid.org/0000-0002-8958-0683 http://dx.doi.org/10.3847/1538-3881/AA65D1 The Astronomical 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 American Astronomical Society IOP Publishing |
| spellingShingle | Winn, Joshua N. Dai, Fei The Oblique Orbit of WASP-107b from K2 Photometry |
| title | The Oblique Orbit of WASP-107b from K2 Photometry |
| title_full | The Oblique Orbit of WASP-107b from K2 Photometry |
| title_fullStr | The Oblique Orbit of WASP-107b from K2 Photometry |
| title_full_unstemmed | The Oblique Orbit of WASP-107b from K2 Photometry |
| title_short | The Oblique Orbit of WASP-107b from K2 Photometry |
| title_sort | oblique orbit of wasp 107b from k2 photometry |
| url | http://hdl.handle.net/1721.1/112255 https://orcid.org/0000-0002-8958-0683 |
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