The response of atmospheric chemistry on earthlike planets around F, G and K Stars to small variations in orbital distance

Grenfell, John Lee; Stracke, Barbara; Paris, Philip von; Patzer, B; Titz, Ruth; Segura, Antígona; Rauer, H.

doi:10.1016/j.pss.2006.09.002

Cited by 117 publications

(100 citation statements)

References 22 publications

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“…One approach used in these models is to adjust the surface albedo in the model (e.g., Kasting et al 1993;Grenfell et al 2007b;Goldblatt et al 2009a) so that the models reproduce prescribed reference scenarios (e.g. modern Earth with a surface temperature of 288 K).…”

Section: Properties Of the Planet Gl 581dmentioning

confidence: 99%

“…The simulation to which the runs from Table A.1 were compared included an adjustment of the model surface albedo in a way that modern Earth reference calculations yield a surface (Grenfell et al 2007b, when using the RRTM radiative transfer scheme developed by Mlawer et al 1997) upon excluding the greenhouse effect provided by methane, ozone, and nitrous oxide. The model surface albedo is 0.24, which is slightly higher than the value of 0.21 from von Paris et al (2008), but still compatible with surface albedos of other cloud-free models in the literature (e.g., Goldblatt et al 2009a;Haqq-Misra et al 2008, both studies using 0.23 as their surface albedo value).…”

Section: A1 Runsmentioning

confidence: 99%

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The extrasolar planet Gliese 581d: a potentially habitable planet?

Paris

Gebauer

Godolt

et al. 2010

A&A

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Aims. The planetary system around the M star Gliese 581 contains at least three close-in potentially low-mass planets, Gl 581c, d, and e. In order to address the question of the habitability of Gl 581d, we performed detailed atmospheric modeling studies for several planetary scenarios. Methods. A 1D radiative-convective model was used to calculate temperature and pressure profiles of model atmospheres, which we assumed to be composed of molecular nitrogen, water, and carbon dioxide. The model allows for changing surface pressures caused by evaporation/condensation of water and carbon dioxide. Furthermore, the treatment of the energy transport has been improved in the model to account in particular for high CO 2 , high-pressure Super-Earth conditions. Results. For four high-pressure scenarios of our study, the resulting surface temperatures were above 273 K, indicating a potential habitability of the planet. These scenarios include three CO 2 -dominated atmospheres (95% CO 2 concentration with 5, 10, and 20 bar surface pressure) and a high-pressure CO 2 -enriched atmosphere (5% CO 2 concentration with 20 bar surface pressure). For all other considered scenarios, the calculated Gl 581d surface temperatures were below the freezing point of water, suggesting that Gl 581d would not be habitable then. The results for our CO 2 -dominated scenarios confirm very recent model results by Wordsworth et al. (2010). However, our model calculations imply that also atmospheres that are not CO 2 -dominated (i.e., 5% vmr instead of 95% vmr) could result in habitable conditions for Gl 581d.

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Section: Properties Of the Planet Gl 581dmentioning

confidence: 99%

Section: A1 Runsmentioning

confidence: 99%

The extrasolar planet Gliese 581d: a potentially habitable planet?

Paris

Gebauer

Godolt

et al. 2010

A&A

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“…For example, Grenfell et al (2007b) look at the response of biosignature chemistry (e.g. ozone) on varying planetary and stellar parameters (orbital distance and stellar type: F, G, and K).…”

Section: Spectral Signature Of Biosignature Moleculesmentioning

confidence: 99%

Galactic cosmic rays on extrasolar Earth-like planets

Grießmeier

Vakili

Stadelmann

et al. 2016

A&A

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Context. Theoretical arguments indicate that close-in terrestial exoplanets may have weak magnetic fields. As described in the companion article (Paper I), a weak magnetic field results in a high flux of galactic cosmic rays to the top of the planetary atmosphere. Aims. We investigate effects that may result from a high flux of galactic cosmic rays both throughout the atmosphere and at the planetary surface. Methods. Using an air shower approach, we calculate how the atmospheric chemistry and temperature change under the influence of galactic cosmic rays for Earth-like (N 2 -O 2 dominated) atmospheres. We evaluate the production and destruction rate of atmospheric biosignature molecules. We derive planetary emission and transmission spectra to study the influence of galactic cosmic rays on biosignature detectability. We then calculate the resulting surface UV flux, the surface particle flux, and the associated equivalent biological dose rates. Results. We find that up to 20% of stratospheric ozone is destroyed by cosmic-ray protons. The effect on the planetary spectra, however, is negligible. The reduction of the planetary ozone layer leads to an increase in the weighted surface UV flux by two orders of magnitude under stellar UV flare conditions. The resulting biological effective dose rate is, however, too low to strongly affect surface life. We also examine the surface particle flux: For a planet with a terrestrial atmosphere (with a surface pressure of 1033 hPa), a reduction of the magnetic shielding efficiency can increase the biological radiation dose rate by a factor of two, which is non-critical for biological systems. For a planet with a weaker atmosphere (with a surface pressure of 97.8 hPa), the planetary magnetic field has a much stronger influence on the biological radiation dose, changing it by up to two orders of magnitude. Conclusions. For a planet with an Earth-like atmospheric pressure, weak or absent magnetospheric shielding against galactic cosmic rays has little effect on the planet. It has a modest effect on atmospheric ozone, a weak effect on the atmospheric spectra, and a noncritical effect on biological dose rates. For planets with a thin atmosphere, however, magnetospheric shielding controls the surface radiation dose and can prevent it from increasing to several hundred times the background level.

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“…A detailed description of the model is given in Kitzmann et al (2010). The profiles of the major chemical species were obtained with a detailed photochemical model representing the modern Earth's atmosphere (Grenfell et al 2007) and are used for all model calculations. The empirical relative humidity distribution of Manabe & Wetherald (1967) is used for the relative humidity in.…”

Section: Scenariosmentioning

confidence: 99%

Infrared radiative transfer in atmospheres of Earth-like planets around F, G, K, and M stars

Vasquez

Schreier

García

et al. 2013

A&A

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Context. The atmosphere of Earth-like extrasolar planets orbiting different types of stars is influenced by the spectral dependence of the incoming stellar radiation. The changes in structure and composition affect atmospheric radiation, hence the spectral appearance of these exoplanets. Aims. We provide a thorough investigation of infrared radiative transfer in cloud-free exoplanets atmospheres by not only analyzing the planetary spectral appearance but also discussing the radiative processes behind the spectral features in detail and identifying the regions in the atmosphere that contribute most at a given wavelength. Methods. Using cloud-free scenarios provided by a one-dimensional radiative-convective steady-state atmospheric model, we computed high-resolution infrared transmission and emission spectra, as well as weighting functions for exoplanets located within the habitable zone of F, G, K, and M stars by means of a line-by-line molecular absorption model and a Schwarzschild solver for the radiative transfer. The monochromatic spectra were convolved with appropriate spectral response functions to study the effects of finite instrument resolution. Results. Spectra of the exoplanets of F, G, K, and M stars were analyzed in the 4.5 µm N 2 O band, the 4.3 µm and 15 µm CO 2 bands, the 7.7 µm CH 4 band, the 6.3 µm H 2 O band, and the 9.6 µm O 3 band. Differences in the state of the atmosphere of the exoplanets clearly show up in the thermal infrared spectra; absorption signatures known from Earth can be transformed to emission features (and vice versa). Weighting functions show that radiation in the absorption bands of the uniformly mixed gases (CO 2 , CH 4 , N 2 O) and (to some extent) ozone comes from the stratosphere and upper troposphere, and also indicate that changes in the atmospheres can shift sources of thermal radiation to lower or higher altitudes. Molecular absorption and/or emission features can be identified in the high-resolution spectra of all planets and in most reduced resolution spectra. Conclusions. Insight into radiative transfer processes is essential for analyzing exoplanet spectral observations; for instance, understanding the impact of the temperature profile (nb. non-existence of an inversion) on the CO 2 bands facilitates their interpretation and can help avoid false positive or negative estimates of O 3 . The detailed analysis of the radiation source and sink regions could even help give an indication about the feasibility of identifying molecular signatures in cloud-covered planets, i.e. radiation mainly coming from the upper atmosphere is less likely to be hidden by clouds. Infrared radiative transfer and biomarker detectability in cloud-covered exoplanets will be presented in a companion paper.

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The response of atmospheric chemistry on earthlike planets around F, G and K Stars to small variations in orbital distance

Cited by 117 publications

References 22 publications

The extrasolar planet Gliese 581d: a potentially habitable planet?

The extrasolar planet Gliese 581d: a potentially habitable planet?

Galactic cosmic rays on extrasolar Earth-like planets

Infrared radiative transfer in atmospheres of Earth-like planets around F, G, K, and M stars

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