4:00 PM - 4:15 PM
[PAE17-15] Evaluation of CHZ considering higher energetic particles emission around exoplanets
Keywords:Fluense, Stellar Energetic Particle, Habitable zone
Regarding the redefinition of the habitable zone (CHZ) around the G/K and M dwarf, we have been developing new framework by predicting the scale of possible maximum flare for those stars.
In this study, we re-evaluated these exoplanet systems by applying the fluence of stellar high-energetic particles mass ejection evaluated from the maximum energy of the assumed flare. The new fluence is characterized by a high proportion of energy bands above the GeV order and a significantly higher penetration into the planetary atmosphere than ordinary fluence obtained based on the analogy from solar CME. The analytical method for the evaluation of planetary impact focuses on exoplanets with significant atmospheric escape rates. Evaluation is made from flare occurrence frequency of one month and once a year, as well as from its sunspot area and surface temperature. Three different atmospheres (N2 + O2, Atmospheric showers for CO2, H2) were calculated and the exposure dose for each altitude was estimated. As a result, even on habitable planets around G and K type stars, which were considered safe at past evaluations, fatal radiation doses for terrestrial lifeform were predicted at thin atmospheric pressure (1/10 air pressure). For some of the habitable planets around the high M-type stars, fatal exposures have been estimated even at terrestrial atmospheric pressure.
In this study, we re-evaluated these exoplanet systems by applying the fluence of stellar high-energetic particles mass ejection evaluated from the maximum energy of the assumed flare. The new fluence is characterized by a high proportion of energy bands above the GeV order and a significantly higher penetration into the planetary atmosphere than ordinary fluence obtained based on the analogy from solar CME. The analytical method for the evaluation of planetary impact focuses on exoplanets with significant atmospheric escape rates. Evaluation is made from flare occurrence frequency of one month and once a year, as well as from its sunspot area and surface temperature. Three different atmospheres (N2 + O2, Atmospheric showers for CO2, H2) were calculated and the exposure dose for each altitude was estimated. As a result, even on habitable planets around G and K type stars, which were considered safe at past evaluations, fatal radiation doses for terrestrial lifeform were predicted at thin atmospheric pressure (1/10 air pressure). For some of the habitable planets around the high M-type stars, fatal exposures have been estimated even at terrestrial atmospheric pressure.