red dwarf exoplanets

NASA’s Kepler along with a pair of telescopes on Earth confirmed 15 new exoplanets recently. All of them orbiting red dwarf stars.

One of the brighter red dwarfs, dubbed K2-155, is home to three super-Earths. The two closest planets don’t look too good for life, but the one furthest out could be sitting within the star’s habitable zone. This is the area where the water could exist on the planet’s surface in liquid form. Not too far away to become an icy ball. And not too close for all the water to boil away.

This planet, named K2-155d has a radius about 1.6 times of Earth.

Preliminary simulations suggest “the atmosphere and the composition of the planet were assumed to be Earth-like,” according to the research team’s leader Teruyuki Hirano. But Hirano cautions that the simulations could be wrong. Follow-up studies to gather more precise measurements of the radius and temperature of the planet’s host star are needed before scientist can say with confidence that this planet sits in the habitable zone.

K2-155d sits within what researchers call the radius gap. When examining the planets around solar-type stars and now red dwarfs, researchers noticed a dip in planets between 1.5 and 2 times the size of Earth.

Here’s a chart showing this ‘radius gap.’ Note the dip between 1.5 and 2.

radius gap exoplanets

Credit: Tokyo Institute of Technology/Astronomical Journal

Telescopes in Hawaii and Spain help confirm the planets

While NASA’s Kepler helps spot potential planets, it’s often a group effort to confirm them. For this batch of exoplanets, the Subaru Telescope in Hawaii and the Nordic Optical Telescope in Spain were used for follow-up observations.

subaru telescope hawaii

Subaru Telescope.

The Subaru Telescope sits atop Mauna Kea in Hawaii. Fun fact, it’s one of the few telescopes of its class ever to be used with the naked eye. During its dedication in 1999, an eyepiece was crafted so Princess Sayako of Japan could look through it directly. After a few days of what had to be breathtaking views, the team on-site replaced the eyepiece with the telescope’s more sophisticated instruments.

The Nordic Optical Telescope calls La Palma in the Canary Islands home. It’s been regularly starting into the night since 1990.

Researchers are about to get a new tool with TESS

NASA’s Transiting Exoplanet Survey Satellite, or TESS, is set to launch next month. This exoplanet hunter will watch for dips in brightness across more than 500,000 stars during its two-year mission. According to NASA, these stars will be 30 to 100 times brighter than the stars Kepler looks at.

The ultimate goal for TESS is to create a catalog of the closest and brightest stars with exoplanets orbiting them for other telescopes to conduct follow-up observations on. Future telescopes, like the James Webb Space Telescope, could then give researchers detailed measurements from a planet’s mass to what type of atmosphere it has.

A SpaceX Falcon 9 will have the honor of lifting TESS off the ground from Cape Canaveral, Florida and place it into its orbit. Right now, the launch date is set for April 16.

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