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#biosignature

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Mikko Tuomi

Astronomers have detected the most promising signs yet of a possible #biosignature outside the solar system, although they remain cautious.

They have detected the chemical fingerprints of dimethyl sulfide and/or dimethyl disulfide, in the #atmosphere of the #exoplanet K2-18b, which orbits its star in the #habitable zone.

On Earth, theyare only produced by #life, primarily microbial life such as marine phytoplankton.

#astronomy #astrobiology
cam.ac.uk/stories/strongest-hi

University of CambridgeStrongest hints yet of biological activity outside the solar systemAstronomers have detected the most promising signs yet of a possible biosignature outside the solar system, although they remain cautious.
Public
Daniel Fischer

What if we Find Nothing? Bayesian Analysis of the Statistical Information of Null Results in Future Exoplanet Habitability and #Biosignature Surveys: iopscience.iop.org/article/10. -> What if we find nothing in our search for life beyond Earth? seti.org/press-release/what-if -> In the search for life on exoplanets, finding nothing is something too: phys.ethz.ch/news-and-events/d - what insights can be gained from a 'no life detected' scenario in future exoplanet surveys.

iopscience.iop.orgRadware Bot Manager Captcha
Public
Mikko Tuomi

The upcoming extremely large telescopes will provide the first opportunity to search for signs of #habitability and #life on non-transiting #terrestrial #exoplanets.

For the most accessible nearby target, #Proxima Centauri b, we may be able to rule out a sub-Neptune #atmosphere in as little as a single hour of observing, and some #biosignature disequilibrium pairs may be accessible in 10 hours.

#astronomy #astrobiology
arxiv.org/abs/2503.08592

arXiv.orgThere's more to life in reflected light: Simulating the detectability of a range of molecules for high-contrast, high-resolution observations of non-transiting terrestrial exoplanetsThe upcoming extremely large telescopes will provide the first opportunity to search for signs of habitability and life on non-transiting terrestrial exoplanets using high-contrast, high-resolution instrumentation. However, the suite of atmospheric gases in terrestrial exoplanet environments that are accessible to ground-based reflected light observations has not been thoroughly explored. In this work, we use an upgraded Extremely Large Telescope (ELT) detectability pipeline to simulate the detectability of gases that can serve as habitability markers, potential biosignatures, and false positive discriminants in the atmospheres of Earth-sized and sub-Neptune planets. We calculate molecular detectability for five photochemically self-consistent atmosphere types, including the modern and Archean Earth, uninhabited biosignature ``false positive'' environments, and a sub-Neptune, over a grid of observational configurations for non-transiting targets within 10pc of Earth. For the most accessible nearby target, Proxima Centauri b, our results suggest that we may be able to rule out a sub-Neptune atmosphere in as little as a single hour of observing, and two biosignature disequilibrium pairs (O$_2$/CH$_4$ and CO$_2$/CH$_4$) may be accessible in $\sim 10$ hours for the most optimistic scenario. It may also be possible to discriminate uninhabited worlds, and rule out biosignature false positives by identifying contextual indicators (CO and H$_2$O) of abiotic O$_2$ and/or CH$_4$ buildup on similar timescales. In the near term, ELT reflected light observations will likely allow us to characterize multiple nearby terrestrial atmospheres, and ultimately search for signs of habitability and life.
Public
Norobiik @Norobiik@noc.social

"We cannot say right now that we have discovered #LifeOnMars,” Katie Stack Morgan, the deputy project scientist, said. "But what we are saying is that we have a potential #biosignature, which is a set of features that could have a biological origin but do need further study and more data.

#NASA's #Perseverance rover found a rock on #Mars that could indicate #AncientLife
msn.com/en-us/news/technology/

A close-up of a reddish rock discovered by Perseverance rover on Mars
Public
Mikko Tuomi

Chemical disequilibrium quantified using the available free energy has previously been proposed as a potential #biosignature.

Atmospheric retrieval coupled with thermodynamical modelling can help assess the detectability of chemical disequilibrium signatures of Earth-like #exoplanets.

Such approaches could yield the first biosignature detections in #exoplanet atmospheres.

#astrobiology #astronomy
nature.com/articles/s41550-023

NatureInferring chemical disequilibrium biosignatures for Proterozoic Earth-like exoplanets - Nature AstronomyChemical disequilibrium is a known biosignature, and it is important to determine the conditions for its remote detection. A thermodynamical model coupled with atmospheric retrieval shows that a disequilibrium can be inferred for a Proterozoic Earth-like exoplanet in reflected light at a high O2/CH4 abundance case and signal-to-noise ratio of 50.
Public
Mikko Tuomi

We are inching closer and closer to reliably detecting #biosignatures on distant #planets.

Much of the focus is on determining which chemicals indicate #life's presence.

But life can also create free energy in a system, and excess energy can create chemical disequilibrium. That's what happened on Earth when life got going.

Could chemical disequilibrium be a #biosignature?

#astronomy #astrobiology #exoplanets
phys.org/news/2023-11-life-eas

Paper by Young et al. (2023):
arxiv.org/abs/2311.06083

Phys.org · Life might be easiest to find on planets that match an earlier EarthBy Evan Gough
Public
Matt Willemsen

Mid-Phanerozoic Exoplanets Might Be Easier to Detect than Modern Earth
In a new study, astronomers modeled the atmospheric composition and transmission spectra of five stages in Earth’s Phanerozoic Eon. Two key biosignature pairs — oxygen and methane, and ozone and methane — appeared stronger in models of Earth roughly 100 million to 300 million years ago, when oxygen levels were significantly higher.
sci.news/astronomy/mid-phanero #MidPhanerozoic #Exoplanets #Detection #biosignature #oxygen #methane #ozone

Sci.News: Breaking Science News · Mid-Phanerozoic Exoplanets Might Be Easier to Detect than Modern Earth | Sci.NewsIn a new study, astronomers modeled the atmospheric composition and transmission spectra of five stages in Earth’s Phanerozoic Eon.
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