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XO-2b: a Prograde Planet with a Negligible Eccentricity, and an Additional Radial Velocity Variation

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 Added by Norio Narita
 Publication date 2011
  fields Physics
and research's language is English




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We present precise radial velocities of XO-2 taken with the Subaru HDS, covering two transits of XO-2b with an interval of nearly two years. The data suggest that the orbital eccentricity of XO-2b is consistent with zero within 2$sigma$ ($e=0.045pm0.024$) and the orbit of XO-2b is prograde (the sky-projected spin-orbit alignment angle $lambda=10^{circ}pm72^{circ}$). The poor constraint of $lambda$ is due to a small impact parameter (the orbital inclination of XO-2b is almost 90$^{circ}$). The data also provide an improved estimate of the mass of XO-2b as $0.62pm0.02$ $M_{rm Jup}$. We also find a long-term radial velocity variation in this system. Further radial velocity measurements are necessary to specify the cause of this additional variation.



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66 - N. C. Hara , G. Boue , J. Laskar 2019
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286 - Anina Timmermann 2020
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