Planetary Habitability Laboratory | University of Puerto Rico at Arecibo | 2017 Feb 23
There Might be More Planets in the Habitable Zone
[img3="Rocky planets in elliptical orbit experience hot and cold periods sometimes crossing the habitable zone. The new study provides a way to quantify whether these planets are able to support surface liquid water. Credit: PHL @ UPR Arecibo."]http://www.hpcf.upr.edu/~abel/phl/coolo ... lorbit.jpg[/img3][hr][/hr]A common assumption in the search for habitable abodes beyond Earth is that the average temperature of planets always increases the more elliptical their orbit is. Now, scientists from the Planetary Habitability Laboratory (PHL) and the Arecibo Observatory in Puerto Rico have shown that planets in elliptical orbits are generally colder than previously believed.
Planets can move around their parent star in orbits that are not perfectly circular. These elliptical orbits put planets sometimes significantly closer or farther from their star, thus contributing to extreme temperature changes. This is not the case of Earth, and probably for the exoplanets orbiting the stars Proxima Centauri or TRAPPIST-1, but true for many known planets around other stars.
In the past, scientists assumed the average equilibrium temperature of a planet would increase with eccentricity because the average energy received from its star, the stellar flux, also increases with eccentricity. A new study provides a new model that shows this is not always the case. ...
The Equilibrium Temperature of Planets in Elliptical Orbits - Abel Méndez, Edgard G. Rivera-Valentín
- Astrophysical Journal Letters 837(1):L1 (2017 Mar 01) DOI: 10.3847/2041-8213/aa5f13 (preprint)
