Instability of mass transfer in a planet-star system

Abstract

We show that the angular momentum exchange mechanism governing the evolution of mass transferring binary stars does not apply to Roche-lobe filling planets, because most of the angular momentum of the mass transferring stream is absorbed by the host star. Apart from a correction for the difference in specific angular momentum of the stream and the centre of mass of the planet, the orbit does not expand much on Roche-lobe overflow. We explore the conditions for dynamically unstable Roche-lobe overflow as a function of planet mass and mass and radius (age) of host star and equation of state of planet. For a Sun-like host, gas giant planets in a range of mass and entropy can undergo dynamical mass transfer. Examples of the evolution of the mass transfer process are given. Dynamic mass transfer of rocky planets depend somewhat sensitively on equation of state used. Silicate planets in the range $1M_{\oplus }<M_{\mathrm{p}}<10M_{\oplus }$ typically go through a phase of dynamical mass transfer before settling to slow overflow when their mass drops to less than $1M_{\oplus }$.

13 pages, 17 figures. One figure (Figure 15) has been added. The text has been improved (major revisions for Section 2 and Section 4). Matches version published in MNRAS

References in corpus (7)

• Mass-Radius Relationships for Solid Exoplanets
• Tidal dissipation in stars and giant planets
• The Magnetic Fields of Classical T Tauri Stars
• Observable Consequences of Planet Formation Models in Systems with Close-in Terrestrial Planets
• Falling Transiting Extrasolar Giant Planets
• Why is there a Dearth of Close-In Planets around Fast-Rotating stars?
• From Hot Jupiters to Super-Earths via Roche Lobe Overflow

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