Brand new multi-planet system discovered just 10 parsecs from Earth

Brand new multi-planet system discovered just 10 parsecs from Earth

Brand new multi-planet system discovered just 10 parsecs from Earth

Brand new multi-planet system discovered just 10 parsecs from Earth

Artist impression of exoplanets. Image Credit: Aleksandr Kukharskiy/

A team of astronomers from the Massachusetts Institute of Technology (MIT) has discovered one of the closest multiplanetary systems. Two super-Earths orbit the cool M dwarf star HD 260655, and the entire system is 10 parsecs, or about 33 light-years, away from us.

The first planet, HD 260655 b, orbits the star every 2.8 days and is about 1.2 times the size of Earth, but about twice as massive. HD 260655 c is further away. It orbits the star in 5.7 days, has a mass of about three Earths and is 1.5 times larger. The discovery was presented at the 240th meeting of the American Astronomical Society.

Despite the fact that the dwarf star is much cooler than our sun, the planets are still too close to it, so they are very hot, putting them outside the “habitable zone.” The inner planet is estimated to have scorching temperatures of 437°C (818°F), while the outer planet is around 287°C (548°F).

“We consider that range beyond the habitable zone, too hot for liquid water to exist on the surface,” said Michelle Kunimoto, a postdoctoral fellow in MIT’s Kavli Institute for Astrophysics and Space Research and one of the discovery’s lead scientists. in a statement.

The planets may not be habitable, but their relative proximity to us and the brightness of their stars allow astronomers to study them in detail and perhaps even work out the properties of any atmosphere they might possess.

“Both planets in this system are each considered to be among the best targets for atmospheric study because of the brightness of their star,” Kunimoto explains. “Is there a volatile-rich atmosphere around these planets? And are there any signs of water- or carbon-based species? These planets are fantastic testbeds for those explorations.”

And that’s not all. Perhaps these two worlds do not stand alone.

“But there could be more planets in the system,” co-author Avi Shporer added. “There are a lot of multiplanet systems with five or six planets, especially around small stars like this one. Hopefully we’ll find more, and maybe one is in the habitable zone. That’s optimistic thinking.”

The system was first identified using NASA’s planet hunter, the Transiting Exoplanet Survey Satellite (TESS), which identifies dips in brightness when planets regularly pass in front of their star. To confirm that the planets were really there, the team had to use an independent method. They looked at observations of the star HD 260655 to determine possible wobble due to the gravitational pull of the planets.

“Any planet orbiting a star will exert a little gravitational pull on its star,” explains Kunimoto. “What we’re looking for is any little movement of that star that could indicate that an object of planetary mass is pulling on it.”

They found evidence for this in data collected by the High-Resolution Echelle Spectrometer (HIRES), an instrument that works as part of the Keck Observatory in Hawaii, and by CARMENES, a private data set at the Calar Alto Observatory in Spain. The planets are real.