In Hunt For Planets Like Earth, Vandy Student Discovers Useful Clue

Two Vanderbilt experts on astronomy and physics have found a more accurate way to calculate the gravity of many distant stars – which is handy information for scientists on the hunt for habitable planets similar to Earth.

Launch of the Kepler telescope, which spent years continuously watching distant stars in search of passing planets.  Bastien's work can use data gathered by Kepler on the stars' light to better estimate their surface gravity, which helps unlock details about planets near them. (Credit Jason Rowe / flickr)

Launch of the Kepler telescope, which spent years continuously watching distant stars in search of passing planets. Bastien’s work can use data gathered by Kepler on the stars’ light to better estimate their surface gravity, which is crucial to unlocking details about planets near them. (Credit Jason Rowe / flickr)

Looking at a planet faraway in space, an observer might wonder whether it’s made of poisonous clouds, or if it has swimmable lakes, like Earth. Vanderbilt’s Keivan Stassun says the question comes down to density:

“So for example, suppose you have discovered a planet, and you would like to know, what kind of world is it? Is it a gas-giant planet like Jupiter, or is it a rocky, watery world like the Earth? What you really want to know is, what is the density of that planet? Because the density of the planet then tells us, what kind of a world is it—what is it made out of.”

A key variable in figuring this out is the surface gravity of whatever star the planet is orbiting. Scientists already have ways to estimate this by analyzing what kinds of light those stars give off, comparing brightness and colors. But Fabienne Bastien, a Vandy grad student who got her Master’s from Fisk and who works with Stassun, found a better way.

Bastien saw a subtle pattern in existing data on how each star flickers. The pattern, caused by roiling gases that behave differently depending on the star’s gravity, points to a simple, accurate new method. It may yield the best estimates yet for tens of thousands of stars, one of which might be warming a cozy planet similar to ours.


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