Life in the Milky Way may be less rare than one thinks: there would in fact be hundreds of millions of planets orbiting at the right distance from their star to have liquid water and therefore be able to host life forms. This is indicated by the study published in the journal of the American Academy of Sciences (PNAS) by Sarah Ballard, professor of astronomy at the University of Florida, and by PhD student Sheila Sagear.
The two astronomers measured the eccentricity of the orbit of a sample of over 150 planets revolving around some of the most common low-mass stars in the galaxy, the M-type dwarfs, smaller and colder than our Sun. Thanks to the data collected by NASA’s Kepler telescope and the European Space Agency’s Gaia satellite, the two scholars discovered that around stars with several planets it is more probable that circular orbits are traversed which allow them to remain at the right distance to keep water in a liquid state.
When there is only one planet, however, it is more probable that the orbit is so eccentric that it gets so close to the star that the gravitational force exerted deforms it and the consequent friction generates so much heat as to sterilize its surface. Given that a third of the observed planets orbit in the potentially habitable zone, then it is possible that hundreds of millions of planets exist in the Milky Way that constitute a promising research target for life ‘hunters’.
According to Sagear, first author of the study, this result will be “very important for the next decade of exoplanet research”.
Source: Ansa
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