HAT-P-1 spin-orbit angle measured.

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HAT-P-1 spin-orbit angle measured.

Post by Sirius_Alpha on 22nd June 2008, 12:36 am

Measurement of the Spin-Orbit Angle of Exoplanet HAT-P-1b
http://arxiv.org/abs/0806.1734

Abstract wrote:We present new spectroscopic and photometric observations of the HAT-P-1 planetary system. Spectra obtained during three transits exhibit the Rossiter-McLaughlin effect, allowing us to measure the angle between the sky projections of the stellar spin axis and orbit normal, \lambda = 3.7 +/- 2.1 degrees. The small value of \lambda for this and other systems suggests that the dominant planet migration mechanism preserves spin-orbit alignment. Using two new transit light curves, we refine the transit ephemeris and reduce the uncertainty in the orbital period by an order of magnitude. We find a upper limit on the orbital eccentricity of 0.067, with 99% confidence, by combining our new radial-velocity measurements with those obtained previously.

There's lots of good information in there. Updated planet radius and mass values, as well as planet orbital period, and star mass and radius.

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Re: HAT-P-1 spin-orbit angle measured.

Post by Edasich on 22nd June 2008, 5:05 am

Orbit keeps being nearly circular. Not alike HAT-P-2 which is quite eccentric (e=0.5)
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