[Baps] BU Seminar by John Johnson on Retired A Stars and Their Planets

[Paul Withers]

-------- Original Message --------
Subject: [Announce] IAR seminar *Wednesday*
Date: Mon, 26 Oct 2009 15:54:17 -0400
From: Kimberly Paci <kpaci at bu.edu>
To: announce at bu-ast.bu.edu


*Please note special day!

The Institute for Astrophysical Research presents:

Dr. John Johnson, California Institute of Technology

"Retired A Stars and Their Planets"




Wednesday, October 28, 2009

4pm, Room 502

725 Commonwealth Ave.

Coffee at 3:45



ABSTRACT:

I will present the recent results from our search for planets orbiting
massive subgiants. The decreased rotation rates and cooler surface
temperatures of these "retired" A-type stars make them ideal proxies
for their massive (1.5 to 2 solar-mass) main-sequence progenitors. Our
results indicate that A stars such as Sirius are significantly more
likely than Sun-like stars to have a Jupiter-sized planet, which
confirms one of the predictions of the core accretion theory of planet
formation. Also, the collection of planets detected from our sample
displays a puzzling lack of semimajor axes smaller than 1 AU, as well
as lower eccentricities and higher minimum masses than planets found
around Sun-like stars. These are findings that have important implications
for future planet search efforts, and inform the various theories of planet
formation and inward orbital migration.