High stellar FUV/NUV ratio and oxygen contents in the atmospheres of potentially habitable planets

Tian, Feng; Linsky, Jeffrey L.; Mauas, P. J. D.; Vieytes, M.

doi:10.1016/j.epsl.2013.10.024

Cited by 180 publications

(246 citation statements)

References 32 publications

Supporting

Mentioning

237

Contrasting

Order By: Relevance

“…Selsis et al (2002) were the first to study the potential for O 2 and O 3 to accumulate on planets devoid of life, but their work did not properly account for sinks of these gases (Segura et al, 2003). Tian et al (2014) found a similar result using the spectrum of the M dwarf GJ876. Neither of those studies systematically studied the effects of atmospheric composition on the accumulation of detectable O 2 and O 3 , and did not include hotter-type stars in the study.…”

Section: Introductionsupporting

confidence: 51%

Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic Earth

Domagal-Goldman

Segura

Claire

et al. 2014

ApJ

204

258

View full text Add to dashboard Cite

Abstract:The search for life on planets outside our solar system will use spectroscopic identification of atmospheric biosignatures. The most robust remotely-detectable potential biosignature is considered to be the detection of oxygen (O 2 ) or ozone (O 3 ) simultaneous to methane (CH 4 ) at levels indicating fluxes from the planetary surface in excess of those that could be produced abiotically. Here, we use an altitude-dependent photochemical model with the

show abstract

Section: Introductionsupporting

confidence: 51%

Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic Earth

Domagal-Goldman

Segura

Claire

et al. 2014

ApJ

204

258

View full text Add to dashboard Cite

show abstract

“…However, even RDP oceans are not immune to evaporation by the radiation from the host RD during its extended pre-Main Sequence phase, causing a runaway greenhouse effect. During this early runaway phase, photolysis of water from RDPs in the habitable zone (for Earth-size and smaller planets) could result in hydrogen/oxygen escape to space of large quantities of water, up to several times that of all the Earth's oceans (Tian et al 2014;Luger and Barnes 2015). This does not necessarily preclude the existence of surface water on all RDPs during later stages.…”

Section: Liquid Water and Tidal Locking Within Habitable Zones Of Rd mentioning

confidence: 99%

“…by near UV radiation splitting water molecules). This abiotic oxygen could also produce a false biosignature (Tian 2014;Luger and Barnes 2015). Earth's oxygen-rich atmosphere has been both good and bad for life in general and for plants in particular (Gale, 2009).…”

Section: The Importance Of Oxygenic Photosynthesis For the Evolution mentioning

confidence: 99%

The potential of planets orbiting red dwarf stars to support oxygenic photosynthesis and complex life

Gále

Wandel

2016

International Journal of Astrobiology

View full text Add to dashboard Cite

We review and reassess the latest findings on the existence of extra-solar system planets and their potential of having environmental conditions that could support Earth-like life. Within the last two decades, the multi-millennial question of the existence of extra-Solarsystem planets has been resolved with the discovery of numerous planets orbiting nearby stars, many of which are Earth-sized (and some even with moderate surface temperatures).Of particular interest in our search for clement conditions for extra-solar system life are planets orbiting Red Dwarf (RD) stars, the most numerous stellar type in the Milky Way galaxy. We show that including RDs as potential life supporting host stars could increase the probability of finding biotic planets by a factor of up to a thousand, and reduce the estimate of the distance to our nearest biotic neighbor by up to 10. We argue that multiple star systems need to be taken into account when discussing habitability and the abundance of biotic exoplanets, in particular binaries of which one or both members are RDs. Early considerations indicated that conditions on RD planets would be inimical to life, as their Habitable Zones (where liquid water could exist) would be so close as to make planets tidally locked to their star. This was thought to cause an erratic climate and expose life forms to flares of ionizing electro-magnetic radiation and charged particles. Moreover, it has been argued that the lesser photon energy of the radiation of the relatively cool RDs would not suffice for Oxygenic Photosynthesis (OP) and other related energy expending reactions. Recent calculations show that these negative factors are less severe than originally thought. Numerous authors suggest that OP on RD planets may evolve to utilize photons in the infrared. We however argue, by analogy to the evolution of OP and the environmental

show abstract

“…While this is based on photolysis of e.g., CO 2 and H 2 O and is thus limited in extent, a sustainable production of abiotic O 3 which could build up to a detectable level has been suggested by Domagal-Goldman & Meadows (2010) for a planet within the habitable zone of AD Leonis with a specific atmospheric composition. Indeed, other studies confirm that abiotic buildup of ozone is possible (e.g., Hu et al 2012;Tian et al 2014); however, detectable levels are unlikely if liquid water is abundant, as e.g. rainout of oxidized species would keep atmospheric O 2 and O 3 low , unless the CO 2 concentration is high and both H 2 and CH 4 emissions are low (Hu et al 2012).…”

Section: Spectral Signature Of Biosignature Moleculesmentioning

confidence: 80%

“…Of course, care has to be taken to avoid combinations of biosignature molecules which can be generated abiotically together (see e.g. Tian et al 2014). The detectability of biosignature molecules is discussed, e.g.…”

Section: Spectral Signature Of Biosignature Moleculesmentioning

confidence: 99%

Galactic cosmic rays on extrasolar Earth-like planets

Grießmeier

Vakili

Stadelmann

et al. 2016

A&A

View full text Add to dashboard Cite

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.

show abstract

High stellar FUV/NUV ratio and oxygen contents in the atmospheres of potentially habitable planets

Cited by 180 publications

References 32 publications

Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic Earth

Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic Earth

The potential of planets orbiting red dwarf stars to support oxygenic photosynthesis and complex life

Galactic cosmic rays on extrasolar Earth-like planets

Contact Info

Product

Resources

About