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Extrasolar Planets: November 2013


The biosignatures of life on Earth do not remain static, but change considerably over the planet's habitable lifetime.

You may have thought that NASA's Kepler spacecraft was finished. Well, think again. A repurposed Kepler Space telescope may soon start searching the sky again.

Charged dust grains in the atmospheres of exoplanets may play a key role in the formation of prebiotic molecules, necessary to the origin of life. Dust grains submerged in an atmospheric plasma become negatively charged and attract a flux of ions that are accelerated from the plasma.

Researchers from Bern have developed a method to simplify the search for Earth-like planets: By using new theoretical models they rule out the possibility of Earth-like conditions, and therefore life, on certain planets outside our solar system -- and limit their search by doing so.

Possible Climates on Terrestrial Exoplanets

What kind of environment may exist on terrestrial planets around other stars? In spite of the lack of direct observations, it may not be premature to speculate on exoplanetary climates, for instance to optimize future telescopic observations, or to assess the probability of habitable worlds.

On the Radius of Habitable Planets

The conditions that a planet must fulfill to be habitable are not precisely known. However, it is comparatively easier to define conditions under which a planet is very likely not habitable.

Planet Packing in Circumbinary Systems

The recent discovery of planets orbiting main sequence binaries will provide crucial constraints for theories of binary and planet formation.

The Kepler space telescope has detected transits of objects as small as the Earth's Moon, and moons as small as 0.2 Earth masses can be detected in the Kepler data by transit timing and transit duration variations of their host planets.

Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, as in the Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population.

This shows the relative sizes of the orbits and planets in the multi-transiting planetary systems discovered by Kepler up to Nov. 2013. The colors simply go by order from the star (the most colorful is the 7-planet system KOI-351). The terrestrial planets of the Solar System are shown in gray.

The ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected, and the efforts of future missions are placed on the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars.

Eclipsing systems, such as transiting exoplanets, allow one to measure the mean stellar density of the host star under various idealized assumptions. Asterodensity Profiling (AP) compares this density to an independently determined value in order to check the validity of the assumptions and ultimately extract useful information on the nature of the target system.

We present the results of a search for potential transit signals in four years of photometry data acquired by the Kepler Mission. The targets of the search include 111,800 stars which were observed for the entire interval and 85,522 stars which were observed for a subset of the interval.

We use moderate-resolution spectra of nearby late K and M dwarf stars with parallaxes and interferometrically determined radii to refine their effective temperatures, luminosities, and metallicities.

he proportions of oxygen, carbon and major rock-forming elements (e.g. Mg, Fe, Si) determine a planet's dominant mineralogy. Variation in a planet's mineralogy subsequently affects planetary mantle dynamics as well as any deep water or carbon cycle.

NASA's Kepler spacecraft, now crippled and its four-year mission at an end, nevertheless provided enough data to complete its mission objective: to determine how many of the 100 billion stars in our galaxy have potentially habitable planets.