New Way of Discovering Exoplanets Announced.

New Method Aids Search for Dazzling Alien Worlds

A group of astronomers is using a new method to search for hard to spot alien planets: By measuring the difference between the amount of light coming from the planets' daysides and nightsides, astronomers have spotted 60 new worlds thus far. The researchers used data from NASA's Kepler space telescope to apply their technique.

 From article, (Traditionally, scientists have relied on a handful of methods to hunt for planets. One technique, called the radial velocity (RV) method, was the first to reveal a distant world, tracking how a massive planet can cause its parent star to wobble. And using another technique, called the direct imaging method, researchers snap photos of exoplanets, but that method can be applied only to large worlds orbiting far from their stars.

But thanks to the Kepler space telescope, the transit method rules the exoplanet roost. Over the course of its primary mission, which lasted about four years, Kepler revealed thousands of potential and confirmed worlds.

But the transit method of searching for exoplanets also has limitations. For a planet to block the light of its star, it must orbit along the line of sight between Earth and the parent star. For every planet Kepler has spotted, there are likely another 99 that it couldn't see, according to an estimate by astronomy blogger and astrophysicist Ethan Siegel. That's an awful lot of missed worlds.

Millholland and Laughlin weren't content to leave all of those planets hidden. They used the Kepler data to look for worlds lit up by their parent stars, just like the sun lights up the face of the moon and the planets in our solar system (which is why planets in our solar system look like "stars" in the night sky). When an alien planet is on the near side of its star, it radiates a dim light from its nightside (from retained heat), and when the exoplanet is on the far side of the star, it reflects light from its parent star (the dayside). If those variations appear in the Kepler data, they can reveal a planet's presence.

After ensuring that the program could identify already-known, hot gas giants by their glow, the researchers turned their program loose on over 140,000 Kepler stars. The new technique turned up 60 previously unidentified gas giant candidates that don't transit their sun. 

Due to limitations in its precision, Kepler can hunt only for the glow of close-in gas giant planets — the so-called hot Jupiters. Future instruments with increased precision could extend the method to smaller worlds, Millholland said.

Compared to the dazzling searchlight glow of a star, the glow from a planet is extremely faint. Stellar activity, such as sunspots and flares, have the potential to give false positives in the search for planets. That's why, Millholland said, any detections made with the new method should be followed up with RV-method measurements; they have not yet used RV to follow up on the 60 detections reported in the new study.)

Me, "As time progresses, new methods for discovering exoplanets are discovered. Exoplanet discovery really is an amazing an advancing field because it teaches us so much about how planets form, what are they made of, can they hold life, and what are the major kinds in the universe. This knowledge can then be compared to planets, in our own solar system. And, of course, motivate us to find ways of one day getting to them."