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Extrasolar Planets: April 2017


When it comes to exploring exoplanets, it may be wise to take a snorkel along. A new study, published in a paper in the journal Monthly Notices of the Royal Astronomical Society, has used a statistical model to predict that most habitable planets may be dominated by oceans spanning over 90% of their surface area.

Earth-like, potentially habitable exoplanets are prime targets in the search for extraterrestrial life. Information about their atmosphere and surface can be derived by analyzing light of the parent star reflected by the planet.

H2O is a key molecule in characterizing atmospheres of temperate terrestrial planets, and observations of transmission spectra are expected to play a primary role in detecting its signatures in the near future.

Current protoplanetary dust coagulation theory does not predict dry silicate planetesimals, in tension with the Earth. While remedies to this predicament have been proposed, they have generally failed numerical studies, or are in tension with the Earth's (low, volatility dependent) volatile and moderately volatile elemental abundances.

M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy [1]. The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy when the planets pass in front of these stars [2,3].

An exoplanet orbiting a red dwarf star 40 light-years from Earth may be the new holder of the title "best place to look for signs of life beyond the Solar System". Using ESO's HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered a "super-Earth" orbiting in the habitable zone around the faint star LHS 1140.

The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date.

We have just discovered a transiting terrestrial planet in a small nearby star's habitable zone. Due to the proximity of the host star and the size of the transit depth, possible constituents for this planet's atmosphere can be detected with the Hubble Space Telescope. Here we propose to use STIS to obtain observations of the host star at Lyman-alpha.

With two suns in its sky, Luke Skywalker's home planet Tatooine in "Star Wars" looks like a parched, sandy desert world.

The Kepler mission has revealed that Earth-sized planets are common, and dozens have been discovered to orbit in or near their host star's habitable zone. A major focus in astronomy is to determine which of these exoplanets are likely to have Earth-like properties that are amenable to follow-up with both ground- and future space-based surveys, with an ultimate goal of probing their atmospheres to look for signs of life. Venus-like atmospheres will be of particular interest in these surveys.

Astronomers have detected an atmosphere around the super-Earth GJ 1132b. This marks the first detection of an atmosphere around a low-mass Super-Earth, in terms of radius and mass the most Earth-like planet around which an atmosphere has yet been detected.