Sunday, January 3, 2016

Scientists Use New Way To Measure Stellar Gravity To Find Habitable Exoplanets

Artist conception of an exoplanet

Scientists have found a new way to measure the pull of gravity at the surface of distant stars that could help identify which exoplanets are capable of sustaining life, according to a new study published in Science Advances.

"If you don't know the star, you don't know the planet," said study co-author, Professor Jaymie Matthews. "The size of an exoplanet is measured relative to the size of its parent star. If you find a planet around a star that you think is Sun-like but is actually a giant, you may have fooled yourself into thinking you've found a habitable Earth-sized world. Our technique can tell you how big and bright is the star, and if a planet around it is the right size and temperature to have water oceans, and maybe life."

The new technique is called the autocorrelation function timescale technique, or timescale technique for short, which uses subtle variations in the brightness of distant stars recorded by satellites like Canada's MOST and NASA's Kepler missions.

"The timescale technique is a simple but powerful tool that can be applied to the data from these searches to help understand the nature of stars like our Sun and to help find other planets like our Earth," said University of Vienna's Thomas Kallinger, the study's lead author.

The new method allows scientists to measure surface gravity with an accuracy of about four percent for stars too distant and too faint to apply current techniques. Since surface gravity depends on the star's mass and radius (just as your weight on Earth depends on its mass and radius), this technique would enable astronomers to better gauge the masses and sizes of distant stars. 

Future space satellites could hunt for planets in the 'Goldilocks Zones' of their stars - not too hot, not too cold, but just right for liquid water oceans and possibly life. Future exoplanet surveys would need the best possible information about the stars they search, if they're to correctly characterize any planets they find.

ABOVE IMAGE: This artist's concept show a distant exoplanet orbiting its yellow-orange star. Image Credit: NASA, ESA, and G. Bacon (STScI)