Transit Photometry of the Core-dominated Planet HD 149026b
Abstract
We report g, V, and r photometric time series of HD 149026 spanning predicted times of transit of the Saturn-mass planetary companion, which was recently discovered by Sato and collaborators. We present a joint analysis of our observations and the previously reported photometry and radial velocities of the central star. We refine the estimate of the transit ephemeris to Tc=(2,453,527.87455+0.00085-0.00091)+(2.87598+0.00012-0.00017)N (HJD). Assuming that the star has a radius of 1.45+/-0.10 Rsolar and a mass of 1.30+/-0.10 Msolar, we estimate the planet radius to be (0.726+/-0.064)RJup, which implies a mean density of 1.07+0.42-0.30 g cm-3. This density is significantly greater than predicted for models that include the effects of stellar insolation and in which the planet has only a small core of solid material. Thus, we confirm that this planet likely contains a large core and that the ratio of core mass to total planet mass is more akin to that of Uranus and Neptune than to either Jupiter or Saturn.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2006
- DOI:
- 10.1086/497959
- arXiv:
- arXiv:astro-ph/0508051
- Bibcode:
- 2006ApJ...636..445C
- Keywords:
-
- Stars: Planetary Systems;
- stars: individual (HD 149026);
- Techniques: Photometric;
- Astrophysics
- E-Print:
- 18 pages, 4 figures, submitted to ApJ