Image: An artist’s impression of the ‘super-Earth’ HD 85512 b. Is it possible that a planet like this is warmer internally than the Earth, allowing life to form over a wider habitable zone? Credit: ESO/M. Kornmesser.


Widening the Habitable Zone

by PAUL GILSTER on DECEMBER 12, 2012

Finding a way to extend the classical habitable zone, where liquid water can exist on the surface of a planet, is a project of obvious astrobiological significance. Now a team of astronomers and geologists from Ohio State University is making the case that their sample of eight stars shows evidence for just such an extension. The stars in question, drawn from a dataset created by the High Accuracy Radial Velocity Planet Searcher spectrometer at the European Southern Observatory in Chile, were selected because they match up well with the Sun in terms of size, age and composition. Seven of the eight, however, show signs of much more thorium than found in our star.

It’s an interesting result, as seen in this Ohio State news release. The slow radioactive decay of elements like thorium, potassium and uranium, all found in the Earth’s mantle, helps to heat the planet. These are elements present at planetary formation and, according to Ohio State’s Wendy Panero, they are involved in producing enough heat to drive plate tectonics, which some believe to be a factor in maintaining our planet’s oceans. All this is in addition to the sources of heat convection found in the Earth’s core, which play a comparable role in crustal movement.

Read more: Widening the Habitable Zone — Centauri Dreams.

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