2 items with the tag “m dwarfs

  • Stellar Effects on Planetary Habitability and the Limits of the Habitable Zone
    NAI 2013 VPL at University of Washington Annual Report

    In this task VPL Team members explore the interactions between a planet and its parent star and how these interactions affect whether or not the planet can support life. These interactions can be radiative, with light from the star affecting the planet’s climate, or UV from stellar flares affecting the radiation environment at the planet’s surface. Or they interactions can be gravitational, with the star periodically deforming planets on elliptical orbits and thereby transferring energy into the planet. Both radiative and gravitational effects can input too much heat into a planet’s environment and cause it to lose the ability to maintain liquid water at the surface. Research this year included looking at the limits of the habitable zone with new calculations, exploring how gravitational tidal energy could cause a planet to lose its ocean, and understanding the effects that tidal deformation and incoming stellar radiation would have on the habitability of exomoons.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1
  • Stellar Effects on Planetary Habitability and the Limits of the Habitable Zone
    NAI 2014 VPL at University of Washington Annual Report

    In this task, VPL team members studied the interaction between stellar radiation (including light) and planetary atmospheres to better understand the limits of planetary habitability and the effects of stellar radiation on planetary evolution. Work this year included using climate models to recalculate the boundaries of the surface liquid water habitable zone planets of different masses, an exploration of the effect of a star’s spectrum on the rate at which a planet can exit a snowball state, and calculation of water loss from terrestrial planets with different fractions of atmospheric carbon dioxide. Atmospheric escape models were also used to illustrate how the pre-main sequence evolution of M-dwarf stars could strip the gaseous envelopes from mini-Neptune planets, transforming them into potentially-habitable, Earth-sized rocky bodies. In pioneering work, VPL researchers also showed that the pre-main sequence phase of an M-dwarf can lead to strong atmospheric escape of water on otherwise potentially habitable worlds, potentially rendering them uninhabitable. Observational work was also undertaken to characterize the frequency and characteristics of stellar flares on M dwarf stars from Kepler data, as input to future work on characterizing the effect of stellar flares on habitability.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1