Cited by 1,615Stellar, planetary, and galactic studiesSpace Science and Extraterrestrial LifePlanetary Science and Exploration

HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES

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Kopparapu, Ravi Kumar, Ramirez, Ramses, Kasting, James F., Eymet, Vincent, Robinson, Tyler D., Mahadevan, Suvrath, Terrien, Ryan C., Domagal-Goldman, Shawn +2 more·2013·The Astrophysical Journal

Abstract

Identifying terrestrial planets in the habitable zones (HZs) of other stars is one of the primary goals of ongoing radial velocity (RV) and transit exoplanet surveys and proposed future space missions. Most current estimates of the boundaries of the HZ are based on one-dimensional (1D), cloud-free, climate model calculations by Kasting et al. However, this model used band models that were based on older HITRAN and HITEMP line-by-line databases. The inner edge of the HZ in the Kasting et al. model was determined by loss of water, and the outer edge was determined by the maximum greenhouse provided by a CO 2 atmosphere. A conservative estimate for the width of the HZ from this model in our solar system is 0.95–1.67 AU. Here an updated 1D radiative–convective, cloud-free climate model is used to obtain new estimates for HZ widths around F, G, K, and M stars. New H 2 O and CO 2 absorption coefficients, derived from the HITRAN 2008 and HITEMP 2010 line-by-line databases, are important improvements to the climate model. According to the new model, the water-loss (inner HZ) and maximum greenhouse (outer HZ) limits for our solar system are at 0.99 and 1.70 AU, respectively, suggesting that the present Earth lies near the inner edge. Additional calculations are performed for stars with effective temperatures between 2600 and 7200 K, and the results are presented in parametric form, making them easy to apply to actual stars. The new model indicates that, near the inner edge of the HZ, there is no clear distinction between runaway greenhouse and water-loss limits for stars with T eff ≲ 5000 K, which has implications for ongoing planet searches around K and M stars. To assess the potential habitability of extrasolar terrestrial planets, we propose using stellar flux incident on a planet rather than equilibrium temperature. This removes the dependence on planetary (Bond) albedo, which varies depending on the host star's spectral type. We suggest that conservative estimates of the HZ (water-loss and maximum greenhouse limits) should be used for current RV surveys and Kepler mission to obtain a lower limit on η ⊕ , so that future flagship missions like TPF-C and Darwin are not undersized. Our model does not include the radiative effects of clouds; thus, the actual HZ boundaries may extend further in both directions than the estimates just given.

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Crossref · 10.1088/0004-637x/765/2/131

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  • The new Kopparapu et al. (2013) habitable zone model recalculates the classic Kasting et al. (1993) habitable zone with updated model inputs, and its habitable zone extends from 0.99 to 1.70 AU.

    “The new Kopparapu et al. (2013) habitable zone model recalculates the classic Kasting et al. (1993) habitable zone with updated model inputs, and its habitable zone extends from 0.99 to 1.70 AU.”

    From The Astrobiology Primer v2.0 (2016) · cites this paper as Kopparapu et al. (2013)

    The Conclusions (page unavailable) say the model updates Kasting et al. (1993) and originally give solar-system habitable-zone limits of 0.99 and 1.70 AU. However, the correction in Additional information (page unavailable) changes the Table 1 maximum-greenhouse outer limit from 1.70 to 1.67 AU, so the unqualified 1.70 AU endpoint does not reflect the corrected value. (LLM, conf=0.86)

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  • The Kopparapu et al. (2013) study did not include the effects of clouds or circulation of moisture, either of which could stabilize a planet at the inner edge of the habitable zone.

    “However, this study did not include the effects of clouds or circulation of moisture, either of which could stabilize a planet at the inner edge of the habitable zone.”

    From The Astrobiology Primer v2.0 (2016) · cites this paper as Kopparapu et al. (2013)

    The Model Description (Section 2; page unavailable) says the study used a 1D cloud-free model, and the Discussion (Section 5; page unavailable) says water clouds could increase albedo and make the modeled inner-edge limit appear less stable than it is. The copy does not establish that circulation of moisture would stabilize a planet at the inner edge, so that part of the claim is unsupported. (LLM, conf=0.85)

    Experimental — accuracy not yet measured
  • In the updated conservative estimation, Earth is very near the inner edge of the current habitable zone.

    “In this updated conservative estimation, Earth is very near the inner edge of the current habitable zone.”

    From The Astrobiology Primer v2.0 (2016) · cites this paper as Kopparapu et al. (2013)

  • The location of the habitable zone depends on how bright the star is; for brighter stars, the habitable zone is shifted outward, and for dimmer stars, the habitable zone is shifted inward.

    “The location of the habitable zone depends on how bright the star is (Kopparapu et al., 2013); for brighter stars, the habitable zone is shifted outward because planets must be farther away from these stars to maintain temperatures necessary for liquid water, and for dimmer stars, the habitable zone is shifted inward (Fig. 18).”

    From The Astrobiology Primer v2.0 (2016) · cites this paper as Kopparapu et al., 2013

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2 of the 95 references couldn’t be matched to a known paper.

Research works printed but not linked: 4

  1. [9]9. Batalha, N. M., Rowe, J. F., Bryson, S. T., et al. 2012, ApJS, submitted (arXiv:1202.5852) · arXiv
  2. [61]61. Mahadevan, S., Ramsey, L., Bender, C., et al. 2012, Proc. SPIE, 8446, 84461S
  3. [69]69. Peale, S. J. 1977, in Planetary Satellites, Rotational Histories of the Natural Satellites, ed. J. A. Burns (Tucson, AZ: Univ. Arizona Press)
  4. [72]72. A. Sozzetti, M. G. Lattanzi, & A. P. Boss (Cambridge: Cambridge Univ. Press), 13

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Authors
Kopparapu, R. K., Ramirez, R., Kasting, J. F., Eymet, V., Robinson, T. D., Mahadevan, S., Terrien, R. C., Domagal-Goldman, S., Meadows, V., & Deshpande, R.
Affiliations
  • Pennsylvania State University (US)
  • Laboratoire d'Astrophysique de Bordeaux (FR)
  • NASA Astrobiology Institute (US)
  • Goddard Space Flight Center (US)
Venue
The Astrophysical Journal
Published
2013-02-26
Volume
765
Issue
2
Pages
131
ISSN
  • 0004-637X (ISSN-L)
  • 1538-4357
OpenAlex
W2047751764
Cited by
1,615
References
95
Citations by year
2026: 89 · 2025: 115 · 2024: 119 · 2023: 125 · 2022: 110 · 2021: 112 · 2020: 157 · 2019: 177 · 2018: 149 · 2017: 109 · 2016: 115 · 2015: 83 · 2014: 95 · 2013: 55 · 2012: 1
FWCI
61.44
Type
journal article
Language
en
Open access
Locations
  • The Astrophysical Journal (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • HAL (submittedVersion)
  • Oskar-Bordeaux (Universite de Bordeaux) (submittedVersion)
  • arXiv (Cornell University)
Funders
  • National Science Foundation (1126413, 1006676)
  • National Aeronautics and Space Administration (NNH05ZDA001C)
  • Pennsylvania Space Grant Consortium
  • Oak Ridge Associated Universities
  • University of Pennsylvania
  • University of Washington
  • Pennsylvania State University
  • NASA Astrobiology Institute
  • NASA Headquarters
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Space Science and Extraterrestrial Life
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Planetary Science and Exploration
Keywords
habitable zone, main-sequence stars, terrestrial exoplanets, water loss, runaway greenhouse, stellar effective temperature, stellar flux, M dwarfs, K stars, F and G stars

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