HABITABLE ZONES OF POST-MAIN SEQUENCE STARS

ABSTRACT Once a star leaves the main sequence and becomes a red giant, its Habitable Zone (HZ) moves outward, promoting detectable habitable conditions at larger orbital distances. We use a one-dimensional radiative-convective climate and stellar evolutionary models to calculate post-MS HZ distances...

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Bibliographic Details
Published in:The Astrophysical journal 2016-05, Vol.823 (1), p.6-6
Main Authors: Ramirez, Ramses M., Kaltenegger, Lisa
Format: Article
Language:English
Subjects:
Astronomical models
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ASYMPTOTIC SOLUTIONS
Atmospheric models
Atmospherics
COMPARATIVE EVALUATIONS
DETECTION
Extrasolar planets
INTERACTIONS
MAIN SEQUENCE STARS
MASS TRANSFER
METALLICITY
ONE-DIMENSIONAL CALCULATIONS
ORBITS
Phases
planet-star interactions
PLANETS
planets and satellites: atmospheres
planets and satellites: detection
Red giant stars
SATELLITE ATMOSPHERES
stars: winds, outflows
STELLAR WINDS
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Summary:ABSTRACT Once a star leaves the main sequence and becomes a red giant, its Habitable Zone (HZ) moves outward, promoting detectable habitable conditions at larger orbital distances. We use a one-dimensional radiative-convective climate and stellar evolutionary models to calculate post-MS HZ distances for a grid of stars from 3700 to 10,000 K (∼M1 to A5 stellar types) for different stellar metallicities. The post-MS HZ limits are comparable to the distances of known directly imaged planets. We model the stellar as well as planetary atmospheric mass loss during the Red Giant Branch (RGB) and Asymptotic Giant Branch (AGB) phases for super-Moons to super-Earths. A planet can stay between 200 million years up to 9 Gyr in the post-MS HZ for our hottest and coldest grid stars, respectively, assuming solar metallicity. These numbers increase for increased stellar metallicity. Total atmospheric erosion only occurs for planets in close-in orbits. The post-MS HZ orbital distances are within detection capabilities of direct imaging techniques.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/823/1/6