NPOI Observations of the Exoplanet Host kappa Coronae Borealis and Their Implications for the Star's and Planet's Masses and Ages

TL;DR

This study precisely measured the star kappa CrB's physical properties using optical interferometry, refining its age, mass, and habitable zone, and updating the exoplanet's mass estimates.

Contribution

The paper provides new interferometric measurements of kappa CrB's diameter and derived properties, improving estimates of its age, mass, and planetary companion characteristics.

Findings

Measured star's angular diameter as 1.543 mas

Determined star's radius as 5.06 R_Sun

Estimated planetary mass range as 1.61-1.88 M_Jup

Abstract

We used the Navy Precision Optical Interferometer to measure the limb-darkened angular diameter of the exoplanet host star kappa CrB and obtained a value of 1.543 +/- 0.009 mas. We calculated its physical radius (5.06 +/- 0.04 R_Sun) and used photometric measurements from the literature with our diameter to determine kappa CrB's effective temperature (4788 +/- 17 K) and luminosity (12.13 +/- 0.09 L_Sun). We then placed the star on an H-R diagram to ascertain the star's age (3.42 +0.32/-0.25 Gyr) and mass (1.47 +/- 0.04 M_Sun) using a metallicity of [Fe/H] = +0.15. With this mass, we calculated the system's mass function with the orbital elements from a variety of sources, which produced a range of planetary masses: m_p sin i = 1.61 to 1.88 M_Jup. We also updated the extent of the habitable zone for the system using our new temperature.