Second-closest 'super-Earth' found orbiting sun's stellar twin

Second-closest 'super-Earth' found orbiting sun's stellar twin

Second-closest 'super-Earth' found orbiting sun's stellar twin

Data from a worldwide array of telescopes, including ESO's planet-hunting HARPS instrument, have revealed this frozen, dimly lit world.

The planet, designated Barnard's Star b, now steps in as the second-closest known exoplanet to Earth [1].

Now continues the study of super-earths with spectometry HIRES. Proxima Centauri is the closest star to have a known exoplanet in orbit, Proxima Centauri b. It's actually the closest single star to us; the three stars closer are all part of the same Alpha Centauri ternary star system. Astronomers have long tried to find around exoplanets. It is a type of faint, low-mass star called a red dwarf.

For most of human history, it was thought that the positions of the stars were fixed, but to modern astronomers, Barnard's Star is virtually zipping across the sky.

The discovery is also something of a vindication for Dutch astronomer Peter van de Kamp, who predicted that there were planets orbiting Barnard's Star after seeing wobbles similar to those which prompted today's announcement.

The planet's surface temperature is estimated to be around minus 170 degrees Celsius, meaning it is likely to be a frozen world which is uninviting to Earth-like life, they said.

The potential planet is an excellent candidate for directing imaging and astrometric observations because of its wide orbit, researchers say, which could give us a look at the planet's surface. It might be cold, inhospitable and all but invisible but the new planet has one thing going for it: it's really close.

"A light source that comes towards us would have its wavelength slightly blue shifted, while a light source that moves away from us has its wavelength slightly red shifted", Ribas said.

Barnard's star is one of the least active known red dwarfs.

This image shows the surroundings of Barnard's Star.

It's the first time a planet this small and distant from its star has been detected using the radial velocity technique, which Butler helped pioneer.

In the coming decade, the next generation of astronomical observatory will revolutionise our ability to peer into the space close to the nearest stars, looking for the dim glow of their planets, reflecting the light of their host stars.

Every time GAIA observes Barnard's Star, it measures its location with a precision far greater than any previous observatory could manage.

The timing of the signal indicates that the planet orbits at about the same distance as Mercury orbits our Sun.

The fact that Barnard's star moves across the sky faster than any other (not counting the Sun), which greatly complicates its study. In each case, the additional data made the roughly 230-day signal grow stronger and more significant. "The combination of all data led to a total of 771 measurements", Ribas said.

Barnard's Star b appears to have an orbital period of 233 days.

This image shows an artist's impression of the planet's surface.

"We used observations from seven different instruments, spanning 20 years of measurements", Ignasi Ribas, the team's lead scientist (Institute of Space Studies of Catalonia and the Institute of Space Sciences, CSIC in Spain), said in a statement.

Still, over the years, a lot of astronomers have observed Barnard's Star. Knowing the star's mass, we can then determine the planet's mass of 3.2 times the Earth's (this is found by how much the planet tugs on the star). This effect causes the star's velocity to change only minutely, but it can be enough to single out an orbiting planet.

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