Some extrasolar planets that one might assume are too cold to host life could in fact be made habitable by a squishing effect from their stars, a new study found.
A planet’s midsection gets stretched out by its star’s gravity so that its shape is slightly more like a cigar than a sphere. Some planets travel non-circular, or elongated paths around their stars. As such a world moves closer to the star, it stretches more, and when it moves farther away, the stretching decreases.
When a planet’s orbit is particularly oblong, the stretching changes are so great that its interior warms up in a process called tidal heating.
“It’s basically the same effect as when you bend a paper clip, and it gets hot inside,” said researcher Brian Jackson of the University of Arizona’s Lunar and Planetary Laboratory.
Jackson and colleagues created a computer model to simulate this effect on exoplanets, and found that the process could shift the range and distance of the “habitable zone” around a star in which planets would have the right temperatures needed to harbor life.