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

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 semimajor 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 ∼6 HZ Earth-mass planets for stellar masses 0.7M e , 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 yr of radial velocities (RV) from the Keck/High Resolution Echelle Spectrometer (HIRES) and Automated Planet Finder (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.

The Fundamental Connections between the Solar System and Exoplanetary Science

“…Giant planet. also hold most of the planetary mass and angular momentum of their respective planetary systems, making them key players in determining the final architectures of planetary systems generally (e.g., Childs et al., 2019; Kane, Turnbull, et al., 2020; Morbidelli et al., 2007). Schematics of the interiors of the Solar System's giant planets are shown in Figure 3 and indicate why these worlds are termed “gas giants” and “ice giants.” Most of Jupiter and Saturn consist of some form of H and He, including metallic hydrogen, with traces of heavier gases and possibly even some rock and ice at their centers.…”

Starshade Imaging Simulation Toolkit for Exoplanet Reconnaissance

“…12 A recent analysis based on ancillary radial velocity data and dynamical stability shows that β CVn could harbor several terrestrial planets in its Habitable Zone. 33 More precise catalogs exist, e.g., Gaia, 34 that are not provided with SISTER although one may pick up any star by setting its properties, such as stellar type, distance to Earth, apparent V magnitude, stellar mass, radius, coordinates, and proper motion. SISTER's handbook 35 provides full details on how to set up the host star properties.…”

“…( 23) and ( 35) in Gladman. 70 Even though a recent analysis based on radial velocity ancillary data has ruled out the presence of a Jupiter-like planet within 10 AU of β CVn, 33 we include it here at 5.2 AU for the sake of showing the relative intensity of these three major types of planets at three representative distances from the host star. The system is inclined at 35 deg.…”

Special Section on Starshades: Overview and a Dialogue

“…The system has a visual inclination of 30 deg, is dynamically stable, and is consistent with recent RV analysis. 80 The instrumental effects include an imperfect starshade with 10 −10 contrast at the IWA, formation flying misalignments, solar glint, and optical throughput 81 and detector noise 82 consistent with the Roman telescope end of life. The integration time is less than a week.…”