Global Climate & Habitability: July 2013

It might be easier than previously thought for a planet to overheat into the scorchingly uninhabitable "runaway greenhouse" stage, according to new research by astronomers at the University of Washington and the University of Victoria published July 28 in the journal Nature Geoscience.

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.

Conventional scientific wisdom has it that plants and other creatures have only lived on land for about 500 million years, and that landscapes of the early Earth were as barren as Mars.

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.

Stars interact with their close-in planets through radiation, gravitation, and magnetic fields. We investigate the energy input to a planetary atmosphere by reconnection between stellar and planetary magnetic fields and compare it to the energy input of the extreme ultraviolet (EUV) radiation field of the star.

Solving the "faint young Sun paradox" -- explaining how early Earth was warm and habitable for life beginning more than 3 billion years ago even though the Sun was 20 percent dimmer than today -- may not be as difficult as believed, says a new University of Colorado Boulder study.

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.