LOW STELLAR OBLIQUITIES IN COMPACT MULTIPLANET SYSTEMS
Autor: | John Asher Johnson, Simon Albrecht, Geoffrey W. Marcy, Joshua N. Winn, Howard Isaacson, Andrew W. Howard |
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Přispěvatelé: | Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Albrecht, Simon H., Winn, Joshua Nathan |
Rok vydání: | 2013 |
Předmět: |
Earth and Planetary Astrophysics (astro-ph.EP)
Physics 010504 meteorology & atmospheric sciences Isotropy FOS: Physical sciences Astronomy and Astrophysics Astrophysics Planetary system Rotation 01 natural sciences Spectral line Wavelength Stars Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Planet 0103 physical sciences Astrophysics::Earth and Planetary Astrophysics Transit (astronomy) 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics - Earth and Planetary Astrophysics 0105 earth and related environmental sciences |
Zdroj: | arXiv |
ISSN: | 1538-4357 0004-637X |
Popis: | We measure the sky-projected stellar obliquities (λ) in the multiple-transiting planetary systems KOI-94 and Kepler-25, using the Rossiter-McLaughlin effect. In both cases, the host stars are well aligned with the orbital planes of the planets. For KOI-94 we find λ = –11° ± 11°, confirming a recent result by Hirano and coworkers. Kepler-25 was a more challenging case, because the transit depth is unusually small (0.13%). To obtain the obliquity, it was necessary to use prior knowledge of the star's projected rotation rate and apply two different analysis methods to independent wavelength regions of the spectra. The two methods gave consistent results, λ = 7° ± 8° and –0[° over .]5 ± 5[° over .]7. There are now a total of five obliquity measurements for host stars of systems of multiple-transiting planets, all of which are consistent with spin-orbit alignment. This alignment is unlikely to be the result of tidal interactions because of the relatively large orbital distances and low planetary masses in the systems. In this respect, the multiplanet host stars differ from hot-Jupiter host stars, which commonly have large spin-orbit misalignments whenever tidal interactions are weak. In particular, the weak-tide subset of hot-Jupiter hosts has obliquities consistent with an isotropic distribution (p = 0.6), but the multiplanet hosts are incompatible with such a distribution (p ~ 10[superscript –6]). This suggests that high obliquities are confined to hot-Jupiter systems, and provides further evidence that hot-Jupiter formation involves processes that tilt the planetary orbit. United States. National Aeronautics and Space Administration (Origins Award NNX09AB33G) National Science Foundation (U.S.) (Grant 1108595) |
Databáze: | OpenAIRE |
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