The Rossiter-McLaughlin Effect of the Transiting Exoplanet XO-4b
Author(s)
Narita, Norio; Hirano, Teruyuki; Sanchis Ojeda, Roberto; Winn, Joshua Nathan; Holman, Matthew J.; Sato, Bunei; Aoki, Wako; Tamura, Motohide; ... Show more Show less
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We report photometric and radial velocity observations of the XO-4 transiting planetary system, conducted with the FLWO 1.2 m telescope and the 8.2 m Subaru Telescope. Based on the new light curves, the refined transit ephemeris of XO-4b is $P$ $=$ 4.1250828$\ \pm\ $0.0000040 d and $T_{\rm c}$ [BJD$_{\rm TDB}$] $=$ 2454485.93323$\ \pm\ $0.00039. We measured the Rossiter–McLaughlin effect of XO-4b and estimated the sky-projected angle between the stellar spin axis and the planetary orbital axis to be $\lambda$ $=$ $-$46$^\circ\!\!\!.$7 $\ ^{{+8^\circ\!\!\!.1}}_{{\ -6^\circ\!\!\!.1}}$. This measurement of $\lambda$ is less robust than in some other cases because the impact parameter of the transit is small, causing a strong degeneracy between $\lambda$ and the projected stellar rotational velocity. Nevertheless, our finding of a spin–orbit misalignment suggests that the migration process for XO-4b involved few-body dynamics rather than interaction with a gaseous disk. In addition, our result conforms with the pattern reported by Winn et al. (2010, ApJ, 718, L145) that high obliquities are preferentially found for stars with effective temperatures hotter than 6250 K.
Date issued
2010-12Department
Massachusetts Institute of Technology. Department of Physics; MIT Kavli Institute for Astrophysics and Space ResearchJournal
Publications of the Astronomical Society of Japan
Publisher
Astronomical Society of Japan
Citation
Narita, Norio. et al. "The Rossiter-McLaughlin Effect of the Transiting Exoplanet XO-4b." Publ. Astron. Soc. Japan 62, L61–L65, 2010 December 25
(c) 2010. Astronomical Society of Japan
Version: Author's final manuscript
ISSN
0004-6264