New planet-hunting tool to refine exoplanet search

Scientists have developed a new refined tool to search for exoplanets orbiting distant stars or confirming other planetary detections.
One of the most popular and successful techniques for finding and confirming planets is called the radial velocity method. A planet is influenced by the gravity of the star it orbits - that is what keeps it in orbit, researchers said.
This technique takes advantage of the fact that the planet's gravity also affects the star in return. As a result, astronomers are able to detect the tiny wobbles the planet induces as its gravity tugs on the star. Using this method, astronomers have detected hundreds of exoplanets.

For certain kinds of low-mass stars, however, there are limitations to the standard radial velocity method, which can cause false positives - in other words, find something that looks like a planet, but is not.
To address this issue, researchers decided to use the radial velocity technique, but they examined a different, longer wavelength of light.
"Switching from the visible spectrum to the near-infrared, the wobble effect caused by an orbiting planet will remain the same regardless of wavelength," said Jonathan Gagne from Carnegie Institution for Science in the US.

"But looking in the near-infrared will allow us to reject false positives caused by sunspots and other phenomena that will not look the same in near-infrared as they do in visible light," said Gagne.

Radial velocity work in the near-infrared wavelengths has been conducted before, but it has trailed behind planet hunting in the visible spectrum, partially due to technical challenges, researchers said.
They were able to develop a better calibration tool to improve the overall technology for near-infrared radial velocity work, which should make it a better option going forward.
Researchers examined 32 low-mass stars using this technological upgrade at the NASA Infrared Telescope Facility in Hawaii.
Their findings confirmed several known planets and binary systems, and also identified a few new planetary candidates.
"Our results indicate that this planet-hunting tool is precise and should be a part of the mix of approaches used by astronomers going forward," said Peter Gao from California Institute of Technology.

"It is amazing to think that two decades ago we had only just confirmed exoplanets actually existed and now we are able to refine and improve those methods for further discoveries," said Gao.
The findings were published in the Astrophysical Journal.