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Astronomy Colloquium - Jamie Lloyd

Artist's conception of an exoplanetary system [NASA Image]
April 9, 2015
2:30 pm - 3:30 pm
Smith Lecture Room, PRB

"Retired" Planet Hosts: Not So Massive, Maybe Just Portly After Lunch

Jamie Lloyd (Cornell University)


Studies of the planet abundance as a function of stellar mass have shown a strong increase in the frequency of radial velocity planet detection around stars more massive than 1.5 times the mass of the sun, and that such stars are deficit in short period planets. These planet searches have relied on subgiant and giant stars for a sample of high mass stars, which are otherwise hostile to precision Doppler measurements while on the main sequence due to rotation and activity. However, there is now controversy as to the whether the mass determinations of subgiant RV planet hosting stars are robust based on population synthesis and kinematic arguments.  It is clear that the mass distribution of main sequence radial velocity samples is insufficiently distinct from the subgiant radial velocity samples to account for the dramatic changes in planet frequency and orbital characteristics by stellar mass alone. The deficit of the shortest period planets can be explained by the effect of stellar tides, however I will argue that the desert of planets out to 0.5 AU requires a new migration mechanism to take effect around subgiant stars evolved from 1-1.4 solar mass stars.

Coffee and Donuts will be served at 2:00pm in MP4054
 

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