Brendan P. Bowler et al. 2010 ApJ 709 396 doi:10.1088/0004-637X/709/1/396
Brendan P. Bowler1, John Asher Johnson1,7, Geoffrey W. Marcy2, Gregory W. Henry3, Kathryn M. G. Peek2, Debra A. Fischer4, Kelsey I. Clubb4, Michael C. Liu1, Sabine Reffert5, Christian Schwab5 and Thomas B. Lowe6
Show affiliationsWe present an analysis of ~5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass (IM) subgiants (1.5
M */M ☉
2.0) with the goal of measuring the occurrence rate of Jovian planets around (evolved) A-type stars and comparing the distributions of their orbital and physical characteristics to those of planets around Sun-like stars. We provide updated orbital solutions incorporating new radial velocity measurements for five known planet-hosting stars in our sample; uncertainties in the fitted parameters are assessed using a Markov-Chain Monte Carlo method. The frequency of Jovian planets interior to 3 AU is 26+9 –8%, which is significantly higher than the 5%-10% frequency observed around solar-mass stars. The median detection threshold for our sample includes minimum masses down to {0.2, 0.3, 0.5, 0.6, 1.3} M Jup within {0.1, 0.3, 0.6, 1.0, 3.0} AU. To compare the properties of planets around IM stars to those around solar-mass stars we synthesize a population of planets based on the parametric relationship dN
M α P β dlnMdlnP, the observed planet frequency, and the detection limits we derived. We find that the values of α and β for planets around solar-type stars from Cumming et al. fail to reproduce the observed properties of planets in our sample at the 4σ level, even when accounting for the different planet occurrence rates. Thus, the properties of planets around A stars are markedly different than those around Sun-like stars, suggesting that only a small (~50%) increase in stellar mass has a large influence on the formation and orbital evolution of planets.
planetary systems: formation; stars: individual (HD 167042, HD 192699, HD 210702, kappa CrB, 6 Lyn); techniques: radial velocities
Issue 1 (2010 January 20)
Received 2009 June 10, accepted for publication 2009 December 3
Published 2009 December 31
Brendan P. Bowler et al. 2010 ApJ 709 396
Carme Rovira 2003 J. Phys.: Condens. Matter 15 S1809
Ted von Hippel et al. 2003 ApJ 595 794
Yang Jin et al 2006 Chinese Phys. Lett. 23 2838
D Hechtfischer 1987 J. Phys. E: Sci. Instrum. 20 143
Guanghong Wei et al 2004 J. Phys.: Condens. Matter 16 S5047
A M Ignatov et al 2003 J. Phys. D: Appl. Phys. 36 L83
C P Malone et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 225202
J C Phillips et al 2003 Rep. Prog. Phys. 66 2111
Y Ballini 1978 J. Phys. C: Solid State Phys. 11 2039