2008 Proceedings of the Second HELAS International Conference
Hatzes and Zechmeister performed very thorough observations of HD13189, Beta Gem, and Iota Dra, stars with confirmed exo-planets, to better characterize the jitter and oscillation modes of the stars. They compared their results with formulas from Kjeldsen & Bedding, and they were consistent for Beta Gem and Iota Dra, but not for HD13189. The discrepency in HD13189 is thought to arise from the predictive power of Kjeldsen & Bedding's formulas primarily in higher order modes, where HD13189 is pulsating in approximately the second mode. They also mention the possibility of constraining stellar masses based on the properties of oscillation modes.
HD13189 also has a very large scatter of 50 m/s, and its mass is also imprecise to the range of 1-7 solar masses. But it has a predicted jitter amplitude of 500 m/s, it actually smaller than predicted.
Other interesting facts in the article: it took 26 years of observations to confirm the planet around Beta Gem. The mass estimate also started out 2.8, but then it got switched to 1.7.
No comments:
Post a Comment