Barnard’s star has at least one planet orbiting it

A red dwarf star known as Barnard’s Star, located just six light-years from our solar system, has at least one — and possibly a handful — of small rocky planets orbiting it, a new study suggests. .

Barnard’s Star, which is about one-sixth the mass of our sun, is the closest individual star to our solar system. Only three stars in the Alpha Centauri system are closer. Because of its proximity to Earth, Barnard’s star has long been a target of astronomers searching for exoplanets (SN: 12/1/73, SN: 12/7/23).

Now, after several false starts over the decades, researchers may have finally hit the dirt. Jonay González Hernández, an astrophysicist at the Instituto de Astrofísica de Canarias in Tenerife, Spain, and his team reviewed more than 150 observations made by a telescope in South America over four years. Specifically, they looked for tiny wobbles that would betray the presence of planets gravitationally pulling the star back and forth as they orbited.

The strongest wobbles occur every 3.15 days, the team reports online Oct. 1 Astronomy & Astrophysics. It’s probably caused by the roughly circular orbit of a small rocky planet about three times the mass of Mars, says González Hernández.

The researchers have done a good job of ruling out other possible sources of the wobble, such as the rotation of the star or the movement of the telescope during the observations, says astronomer Jennifer Burt. Those efforts, plus the high precision of the instruments used to collect the team’s data, “will convince scientists that this discovery is real,” notes Burt, of NASA’s Jet Propulsion Laboratory in Pasadena, California. . This, in turn, should inspire other teams to revisit all past observations they’ve made of Barnard’s star.

Indeed, the new study suggests there are more discoveries to be made. González Hernández and his colleagues have observed smaller oscillations that are superimposed on the larger oscillation. Although they have not yet been confirmed, they likely represent the presence of three smaller orbs that circle the star at periods of 2.34 days, 4.12 days, and 6.74 days. All four of these putative planets are too close to Barnard’s star to support life as we know it, the researchers suggest.