EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS
One possible diagnostic of planet formation, orbital migration, and tidal evolution is the angle ψ between a planet's orbital axis and the spin axis of its parent star. In general, ψ cannot be measured, but for transiting planets one can measure the angle λ between the sky projections of the tw...
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| Format: | Article |
| Language: | en_US |
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American Astronomical Society
2010
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| Online Access: | http://hdl.handle.net/1721.1/51895 https://orcid.org/0000-0002-4265-047X |
| _version_ | 1811090217096970240 |
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| author | Fabrycky, Daniel C. Winn, Joshua Nathan |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Fabrycky, Daniel C. Winn, Joshua Nathan |
| author_sort | Fabrycky, Daniel C. |
| collection | MIT |
| description | One possible diagnostic of planet formation, orbital migration, and tidal evolution is the angle ψ between a planet's orbital axis and the spin axis of its parent star. In general, ψ cannot be measured, but for transiting planets one can measure the angle λ between the sky projections of the two axes via the Rossiter-McLaughlin effect. Here, we show how to combine measurements of λ in different systems to derive statistical constraints on ψ. We apply the method to 11 published measurements of λ, using two different single-parameter distributions to describe the ensemble. First, assuming a Rayleigh distribution (or more precisely, a Fisher distribution on a sphere), we find that the peak value is less than 22° with 95% confidence. Second, assuming that a fraction f of the orbits have random orientations relative to the stars, and the remaining fraction (1 – f) are perfectly aligned, we find f < 0.36 with 95% confidence. This latter model fits the data better than the Rayleigh distribution, mainly because the XO-3 system was found to be strongly misaligned while the other 10 systems are consistent with perfect alignment. If the XO-3 result proves robust, then our results may be interpreted as evidence for two distinct modes of planet migration. |
| first_indexed | 2024-09-23T14:38:29Z |
| format | Article |
| id | mit-1721.1/51895 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:38:29Z |
| publishDate | 2010 |
| publisher | American Astronomical Society |
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| spelling | mit-1721.1/518952022-10-01T21:54:24Z EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS Fabrycky, Daniel C. Winn, Joshua Nathan Massachusetts Institute of Technology. Department of Physics Winn, Joshua Nathan Winn, Joshua Nathan One possible diagnostic of planet formation, orbital migration, and tidal evolution is the angle ψ between a planet's orbital axis and the spin axis of its parent star. In general, ψ cannot be measured, but for transiting planets one can measure the angle λ between the sky projections of the two axes via the Rossiter-McLaughlin effect. Here, we show how to combine measurements of λ in different systems to derive statistical constraints on ψ. We apply the method to 11 published measurements of λ, using two different single-parameter distributions to describe the ensemble. First, assuming a Rayleigh distribution (or more precisely, a Fisher distribution on a sphere), we find that the peak value is less than 22° with 95% confidence. Second, assuming that a fraction f of the orbits have random orientations relative to the stars, and the remaining fraction (1 – f) are perfectly aligned, we find f < 0.36 with 95% confidence. This latter model fits the data better than the Rayleigh distribution, mainly because the XO-3 system was found to be strongly misaligned while the other 10 systems are consistent with perfect alignment. If the XO-3 result proves robust, then our results may be interpreted as evidence for two distinct modes of planet migration. National Aeronautics and Space Administration Origins program National Aeronautics and Space Administration, Keck PI Data Analysis Fund 2010-03-02T19:36:22Z 2010-03-02T19:36:22Z 2009-04 2008-12 Article http://purl.org/eprint/type/SubmittedJournalArticle 0004-637X http://hdl.handle.net/1721.1/51895 Fabrycky, Daniel C., and Joshua N. Winn. “EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS.” The Astrophysical Journal 696.2 (2009): 1230-1240. https://orcid.org/0000-0002-4265-047X en_US http://dx.doi.org/10.1088/0004-637x/696/2/1230 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 American Astronomical Society Josh Winn |
| spellingShingle | Fabrycky, Daniel C. Winn, Joshua Nathan EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS |
| title | EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS |
| title_full | EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS |
| title_fullStr | EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS |
| title_full_unstemmed | EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS |
| title_short | EXOPLANETARY SPIN-ORBIT ALIGNMENT: RESULTS FROM THE ENSEMBLE OF ROSSITER-MCLAUGHLIN OBSERVATIONS |
| title_sort | exoplanetary spin orbit alignment results from the ensemble of rossiter mclaughlin observations |
| url | http://hdl.handle.net/1721.1/51895 https://orcid.org/0000-0002-4265-047X |
| work_keys_str_mv | AT fabryckydanielc exoplanetaryspinorbitalignmentresultsfromtheensembleofrossitermclaughlinobservations AT winnjoshuanathan exoplanetaryspinorbitalignmentresultsfromtheensembleofrossitermclaughlinobservations |