Dynamical Packing in the Habitable Zone: The Case of Beta CVn

TL;DR

This study investigates the potential for multiple terrestrial planets in the habitable zone of Beta CVn, combining dynamical constraints with 20 years of radial velocity data to assess the likelihood of stable, detectable planets.

Contribution

It provides a detailed analysis of the dynamical packing of habitable zone planets around Beta CVn using long-term RV data and explores implications for direct imaging detection.

Findings

Dynamical constraints suggest up to 6 Earth-mass planets in the HZ for stars >0.7 M_sun.

Radial velocity data exclude planets more massive than Saturn within 10 AU.

Nearby stars like Beta CVn are promising targets for habitable zone planet detection.

Abstract

Uncovering the occurrence rate of terrestrial planets within the Habitable Zone (HZ) of their host stars has been a particular focus of exoplanetary science in recent years. The statistics of these occurrence rates have largely been derived from transiting planet discoveries, and have uncovered numerous HZ planets in compact systems around M dwarf host stars. Here we explore the width of the HZ as a function of spectral type, and the dynamical constraints on the number of stable orbits within the HZ for a given star. We show that, although the Hill radius for a given planetary mass increases with larger semi-major axis, the width of the HZ for earlier-type stars allows for more terrestrial planets in the HZ than late-type stars. In general, dynamical constraints allow $\sim$6 HZ Earth-mass planets for stellar masses $\gtrsim 0.7 M_\odot$, depending on the presence of farther out giant planets. As an example, we consider the case of Beta CVn, a nearby bright solar-type star. We present 20 years of radial velocities (RV) from the Keck/HIRES and APF instruments and conduct an injection-recovery analysis of planetary signatures in the data. Our analysis of these RV data rule out planets more massive than Saturn within 10~AU of the star. These system properties are used to calculate the potential dynamical packing of terrestrial planets in the HZ and show that such nearby stellar targets could be particularly lucrative for HZ planet detection by direct imaging exoplanet missions.