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Cited by 297Stellar, planetary, and galactic studiesAstro and Planetary ScienceHistory and Developments in Astronomy

Transonic hydrodynamic escape of hydrogen from extrasolar planetary atmospheres

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Tian, Feng, Toon, Owen B., Pavlov, Alexander A., De Sterck, H.·2005·The Astrophysical Journal
DOI 10.1086/427204
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Abstract

Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Transonic steady state solutions of the time-independent hydrodynamic equations are difficult to find because of the existence of a singularity point. A numerical model is developed to study the hydrodynamic escape of neutral gas from planetary atmospheres by solving the time-dependent hydrodynamic equations. The model is validated against an analytical solution of the escape from an isothermal atmosphere. The model uses a two-dimensional energy deposition calculation instead of the single-layer heating assumption, which is not sufficiently accurate for hydrodynamic escape from a hydrogen-rich planetary atmosphere. When applied to the atmospheres of extrasolar planets, the model results are in good agreement with observations of the transiting extrasolar planet HD 209458b. The model predicts that hydrogen is escaping from HD 209458b at a maximum rate of 6 × 10 10 g s -1 . The extrasolar planet is stable under the hydrodynamic escape of hydrogen. The rate of hydrogen hydrodynamic escape from other possible extrasolar planets is investigated using the model. The importance of hydrogen hydrodynamic escape for the long-term evolution of extrasolar planets is discussed. Simulation shows that through hydrodynamic escape of hydrogen, a planet at the orbit of Mercury (0.4 AU) and with 0.5 Uranus mass can lose about 10% of its mass within 850 million yr if the solar EUV radiation is 10 times the present level. This calculation provides an indication of how Mercury may have evolved during the early days of the solar system.

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Crossref · 10.1086/427204

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  • For high XUV fluxes, the thermosphere can be heated to high temperatures and the upper atmosphere expands efficiently so that losses cause a large-scale outward flow, and adiabatic cooling counters the strong heating to some extent.

    “For high XUV fluxes the thermosphere can be heated to high temperatures and the upper atmosphere starts to expand very efficiently so that losses at the exobase cause a large scale outward flow of material, and the resulting adiabatic cooling to some extent counters the strong heating (Tian et al. 2005; Tian et al. 2008; Murray-Clay et al. 2009).”

    From The young Sun's XUV-activity as a constraint for lower CO2-limits in the Earth's Archean atmosphere (2021) · cites this paper as Tian et al. 2005

    Section 5 reports a hot, extended upper atmosphere with a fast escape flow, and Section 4 states that the flow produces adiabatic cooling and that a larger escape rate lowers upper-atmosphere temperatures. The paper does not establish the more specific claim that losses at the exobase cause the large-scale outward flow. (LLM, conf=0.83)

    Experimental — accuracy not yet measured

  • The differences attributable to CO2-related photochemistry included in Zahnle et al. (2019) but neglected by Tian et al. (2005) and Kuramoto et al. (2013) were more or less negligible.

    “The differences that are attributable to the CO 2 -related photochemistry that was included in the model of Zahnle et al. (2019) but neglected by Tian et al. (2005) and Kuramoto et al. (2013) were more or less negligible.”

    From The young Sun's XUV-activity as a constraint for lower CO2-limits in the Earth's Archean atmosphere (2021) · cites this paper as Tian et al. (2005)

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Research works printed but not linked: 2

  1. De Sterck, H. 1999, Ph.D. thesis, Katholieke Univ. Leuven
  2. Walter, F. M., & Barry, D. C. 1991, in The Sun in Time, ed. C. P. Sonett, M. S. Giampapa, & M. S. Matthews ( Tucson: Univ. Arizona Press), 633

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Authors
Tian, F., Toon, O. B., Pavlov, A. A., & De Sterck, H.
Affiliations
University of Colorado Boulder (US)
ORCID
Venue
The Astrophysical Journal
Publisher
American Astronomical Society
Published
2005-03-10
Volume
621
Issue
2
Pages
1049-1060
ISSN
  • 0004-637X (ISSN-L)
  • 1538-4357
DOI
10.1086/427204
OpenAlex
W2036200834
Cited by
297
References
34
Citations by year
2026: 1 · 2025: 11 · 2024: 8 · 2023: 8 · 2022: 5 · 2021: 15 · 2020: 16 · 2019: 7 · 2018: 40 · 2017: 14 · 2016: 16 · 2015: 26 · 2014: 13 · 2013: 23 · 2012: 11
FWCI
7.56
Type
journal article
Language
en
Open access
Locations
The Astrophysical Journal (publishedVersion)
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astro and Planetary Science
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › History and Developments in Astronomy
Keywords
hydrodynamic escape, transonic flow, exoplanets, planetary atmospheres, hydrogen escape, HD 209458b, atmospheric escape, energy deposition, isothermal atmosphere, extreme ultraviolet radiation

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