Tides, planetary companions, and habitability: Habitability in the habitable zone of low-mass stars

C. Van Laerhoven, R. Barnes, R. Greenberg

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Earth-scale planets in the classical habitable zone (HZ) are more likely to be habitable if they possess active geophysics. Without a constant internal energy source, planets cool as they age, eventually terminating tectonic activity. Planets orbiting low-mass stars can be very old, due to the longevity of such stars, so they may be rendered sterile to life in this way. However, the presence of an outer companion could generate enough tidal heat in the HZ planet to prevent such cooling. The range of mass and orbital parameters for the companion that give adequate long-term heating of the inner HZ planet, while avoiding very early total desiccation, is probably substantial. We locate the ideal location for the outer of a pair of planets, under the assumption that the inner planet has the same incident flux as Earth, orbiting example stars: a generic late M dwarf (Teff = 2670 K) and the M9V/L0 dwarf DEN1048. Thus discoveries of Earth-scale planets in the HZ zone of old small stars should be followed by searches for outer companion planets that might be essential for current habitability.

Original languageEnglish (US)
Pages (from-to)1888-1898
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume441
Issue number3
DOIs
StatePublished - Jun 2014

Keywords

  • Astrobiology
  • Celestial mechanics
  • Planetary systems

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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