Extrasolar Planets: July 2013

We use the sample of known stars and brown dwarfs within 5 pc of the Sun, supplemented with AFGK stars within 10 pc, to determine which stellar spectral types provide the most habitable real estate - defined to be locations where liquid water could be present on Earth-like planets.

High-precision eclipse spectrophotometry of transiting terrestrial exoplanets represents a promising path for the first atmospheric characterizations of habitable worlds and the search for life outside our solar system.

Most stars and their planets form in open clusters. Over 95 per cent of such clusters have stellar densities too low (less than a hundred stars per cubic parsec) to withstand internal and external dynamical stresses and fall apart within a few hundred million years.

Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions.

An International Collaboration of FACom researchers and astronomers of the University of Texas (El Paso) and New Mexico State University have discovered a physical mechanism that could make binary stars more hospitable to habitable planets than single stars.

Moons orbiting extrasolar planets are the next class of object to be observed and characterized for possible habitability. Like the host-planets to their host-star, exomoons have a limiting radius at which they may be gravitationally bound, or the Hill radius.

We describe the contents and functionality of the NASA Exoplanet Archive, a database and tool set funded by NASA to support astronomers in the exoplanet community.

Transmission spectroscopy of exoplanets is a tool to characterize rocky planets and explore their habitability. Using the Earth itself as a proxy, we model the atmospheric cross section as a function of wavelength, and show the effect of each atmospheric species, Rayleigh scattering and refraction from 115 to 1000nm.

Red dwarf stars are the commonest type of stars, making up about 75% of the stars in our galaxy. They are much smaller and much less massive than our Sun and for that reason a lot dimmer. If planets are found around these stars, then given the number of red dwarfs, life could then be commonplace.

A new study that calculates the influence of cloud behavior on climate doubles the number of potentially habitable planets orbiting red dwarfs, the most common type of stars in the universe. This finding means that in the Milky Way galaxy alone, 60 billion planets may be orbiting red dwarf stars in the habitable zone.