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Title: THE HABITABLE ZONES OF PRE-MAIN-SEQUENCE STARS

Abstract

We calculate the pre-main-sequence habitable zone (HZ) for stars of spectral classes F-M. The spatial distribution of liquid water and its change during the pre-main-sequence phase of protoplanetary systems is important for understanding how planets become habitable. Such worlds are interesting targets for future missions because the coolest stars could provide habitable conditions for up to 2.5 billion years post-accretion. Moreover, for a given star type, planetary systems are more easily resolved because of higher pre-main-sequence stellar luminosities, resulting in larger planet-star separation for cool stars than is the case for the traditional main-sequence (MS) HZ. We use one-dimensional radiative-convective climate and stellar evolutionary models to calculate pre-main-sequence HZ distances for F1-M8 stellar types. We also show that accreting planets that are later located in the traditional MS HZ orbiting stars cooler than a K5 (including the full range of M stars) receive stellar fluxes that exceed the runaway greenhouse threshold, and thus may lose substantial amounts of water initially delivered to them. We predict that M-star planets need to initially accrete more water than Earth did, or, alternatively, have additional water delivered later during the long pre-MS phase to remain habitable. Our findings are also consistent with recent claimsmore » that Venus lost its water during accretion.« less

Authors:
;  [1]
  1. Institute for Pale Blue Dots, Cornell University, Ithaca, NY (United States)
Publication Date:
OSTI Identifier:
22364785
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 797; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; DISTANCE; EARTH PLANET; LUMINOSITY; MAIN SEQUENCE STARS; PROTOPLANETS; PROTOSTARS; SATELLITE ATMOSPHERES; SATELLITES; SPATIAL DISTRIBUTION; VENUS PLANET; WATER

Citation Formats

Ramirez, Ramses M., and Kaltenegger, Lisa. THE HABITABLE ZONES OF PRE-MAIN-SEQUENCE STARS. United States: N. p., 2014. Web. doi:10.1088/2041-8205/797/2/L25.
Ramirez, Ramses M., & Kaltenegger, Lisa. THE HABITABLE ZONES OF PRE-MAIN-SEQUENCE STARS. United States. https://doi.org/10.1088/2041-8205/797/2/L25
Ramirez, Ramses M., and Kaltenegger, Lisa. 2014. "THE HABITABLE ZONES OF PRE-MAIN-SEQUENCE STARS". United States. https://doi.org/10.1088/2041-8205/797/2/L25.
@article{osti_22364785,
title = {THE HABITABLE ZONES OF PRE-MAIN-SEQUENCE STARS},
author = {Ramirez, Ramses M. and Kaltenegger, Lisa},
abstractNote = {We calculate the pre-main-sequence habitable zone (HZ) for stars of spectral classes F-M. The spatial distribution of liquid water and its change during the pre-main-sequence phase of protoplanetary systems is important for understanding how planets become habitable. Such worlds are interesting targets for future missions because the coolest stars could provide habitable conditions for up to 2.5 billion years post-accretion. Moreover, for a given star type, planetary systems are more easily resolved because of higher pre-main-sequence stellar luminosities, resulting in larger planet-star separation for cool stars than is the case for the traditional main-sequence (MS) HZ. We use one-dimensional radiative-convective climate and stellar evolutionary models to calculate pre-main-sequence HZ distances for F1-M8 stellar types. We also show that accreting planets that are later located in the traditional MS HZ orbiting stars cooler than a K5 (including the full range of M stars) receive stellar fluxes that exceed the runaway greenhouse threshold, and thus may lose substantial amounts of water initially delivered to them. We predict that M-star planets need to initially accrete more water than Earth did, or, alternatively, have additional water delivered later during the long pre-MS phase to remain habitable. Our findings are also consistent with recent claims that Venus lost its water during accretion.},
doi = {10.1088/2041-8205/797/2/L25},
url = {https://www.osti.gov/biblio/22364785}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 797,
place = {United States},
year = {Sat Dec 20 00:00:00 EST 2014},
month = {Sat Dec 20 00:00:00 EST 2014}
}