2mass-allsky

Improved Orbital Parameters and Transit Monitoring for HD 156846b

May 2011 • 2011ApJ...733...28K

Authors • Kane, Stephen R. • Howard, Andrew W. • Pilyavsky, Genady • Mahadevan, Suvrath • Henry, Gregory W. • von Braun, Kaspar • Ciardi, David R. • Dragomir, Diana • Fischer, Debra A. • Jensen, Eric • Laughlin, Gregory • Ramirez, Solange V. • Wright, Jason T.

Abstract • HD 156846b is a Jovian planet in a highly eccentric orbit (e = 0.85) with a period of 359.55 days. The pericenter passage at a distance of 0.16 AU is nearly aligned to our line of sight, offering an enhanced transit probability of 5.4% and a potentially rich probe of the dynamics of a cool planetary atmosphere impulsively heated during close approach to a bright star (V = 6.5). We present new radial velocity (RV) and photometric measurements of this star as part of the Transit Ephemeris Refinement and Monitoring Survey. The RV measurements from the Keck-High Resolution Echelle Spectrometer reduce the predicted transit time uncertainty to 20 minutes, an order of magnitude improvement over the ephemeris from the discovery paper. We photometrically monitored a predicted transit window under relatively poor photometric conditions, from which our non-detection does not rule out a transiting geometry. We also present photometry that demonstrates stability at the millimagnitude level over its rotational timescale.

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David Ciardi

Senior Scientist