Biosignatures & Paleobiology

Hypotheses for Near-surface Exchange of Methane on Mars

Hypotheses for Near-surface Exchange of Methane on Mars

The Curiosity rover recently detected a background of 0.7 ppb and spikes of 7 ppb of methane on Mars. This in situ measurement reorients our understanding of the Martian environment and its potential for life, as the current theories do not entail any geological source or sink of methane that varies sub-annually.

Biosignatures & Paleobiology

Debris Disks and the Search for Life in the Universe

Debris Disks and the Search for Life in the Universe

Circumstellar debris disks are the extrasolar analogues of the asteroid belt and the Kuiper belt. They consist of comets and leftover planetesimals that continuously collide and produce circumstellar dust that can be observed as infrared excess or in resolved imaging.

Astrogeology

Effects of Mg/Si on Exoplanetary Refractory Oxygen Budget

Effects of Mg/Si on Exoplanetary Refractory Oxygen Budget

Solar photospheric abundances of refractory elements mirror the Earth's to within ~10 mol% when normalized to the dominant terrestrial planet-forming elements Mg, Si and Fe. This allows for the adoption of Solar composition as an order-of-magnitude proxy for Earth's.

Astronomy

Hiding in the Sunshine: The Search for Other Earths

Hiding in the Sunshine: The Search for Other Earths

We humans might not be the only ones to ponder our place in the universe. If intelligent aliens do roam the cosmos, they too might ask a question that has gripped humans for centuries: Are we alone?

Astrobiology (general)

Are We Alone? Setting Some Limits to Our Uniqueness

Are We Alone? Setting Some Limits to Our Uniqueness

Are humans unique and alone in the vast universe? This question-- summed up in the famous Drake equation--has for a half-century been one of the most intractable and uncertain in science.

Extrasolar Planets

Giant Planets in the Habitable Zone

Giant Planets in the Habitable Zone

We report the discovery of three new substellar companions to solar-type stars, HD191806, HD214823, and HD221585, based on radial velocity measurements obtained at the Haute-Provence Observatory.

Astrochemistry

Herschel Detects Oxygen in the beta Pictoris Debris Disk

Herschel Detects Oxygen in the beta Pictoris Debris Disk

The young star beta Pictoris is well known for its dusty debris disk, produced through the grinding down by collisions of planetesimals, kilometre-sized bodies in orbit around the star.

Extremeophiles and Extreme Environments

Hydrothermal Systems Show Spectrum of Extreme Life on Earth

Hydrothermal Systems Show Spectrum of Extreme Life on Earth

The Danakil Depression in Ethiopia is one of the most inhospitable places on Earth.

Titan

A Closer Look At Titan's Methane Seas

A Closer Look At Titan's Methane Seas

Saturn's largest moon is covered in seas and lakes of liquid hydrocarbons and one sea has now been found to be filled with pure methane, with a seabed covered by a sludge of organic-rich material, and possibly surrounded by wetlands.

Astrochemistry

Identifying Planetary Biosignature Impostors

Identifying Planetary Biosignature Impostors

In order to identify inhabited worlds beyond the Solar System, scientists are exploring the possibility of detecting gases that could serve as biosignatures in the atmospheres of extrasolar planets.

Extrasolar Planets

Habitability of Planets on Eccentric Orbits: Limits of the Mean Flux Approximation

Habitability of Planets on Eccentric Orbits: Limits of the Mean Flux Approximation

Contrary to Earth, which has a small orbital eccentricity, some exoplanets discovered in the insolation habitable zone (HZ) have high orbital eccentricities (e.g., up to an eccentricity of ∼0.97 for HD~20782~b).

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