Image copyright ESO/M. Kornmesser Image caption Artwork: Barnard's Star b is thought to be quite cold

Astronomers have discovered a planet around one of the closest stars to our Sun.

Nearby planets like this are likely to be prime targets in the search for signatures of life, using the next generation of telescopes.

The planet's mass is thought to be 3.2 times that of our own, placing it in a category of world known as a "super-Earth".

It orbits Barnard's star, which sits "just" six light-years away.

The star is an extremely faint "red dwarf" that's about 3% as bright as the Sun.

The research is published in the journal Nature.

Co-author Guillem Anglada Escudé said the newly discovered world was "possibly a mostly rocky planet with a massive atmosphere. It's probably very rich in volatiles like water, hydrogen, carbon dioxide - things like this. Many of them are frozen on the surface".

The Sun's closest neighbours

Image copyright IEEC/Science-Wave - Guillem Ramisa

Dr Anglada Escudé, from Queen Mary University of London, added: "The closest analogue we may have in the Solar System might be the moon of Saturn called Titan, which also has a very thick atmosphere and is made of hydrocarbons. It has rain and lakes made of methane."

The planet, Barnard's Star b, is about as far away from its star as Mercury is from the Sun. It's the second closest exoplanet to Earth after Proxima Centauri b, whose discovery was announced in 2016.

The planet orbits past a boundary called the "snow line", beyond the traditional habitable zone where water can remain liquid on the surface.

On distance alone, it's estimated that temperatures would be about -150C on the planet's surface. However, a massive atmosphere could potentially warm the planet, making conditions more hospitable to life.

Image copyright ESO/M. Kornmesser Image caption Artwork: It's thought the planet is rocky, with a massive atmosphere

The researchers used the radial velocity method for their detection. The technique can detect "wobbles" in a star caused by the gravitational pull of an orbiting planet.

These wobbles also affect the light coming from the star. As it moves towards Earth its light appears shifted towards the blue part of the spectrum and, as it moves away, it appears shifted towards the red.

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"This planet is particularly complicated because the orbital period (the time to complete one full orbit of the host star) is 233 days. In one year, you only see one part of the cycle, and you have to cover it over many years to be sure that it's repeating," Dr Anglada Escudé told me.

The team re-examined archived data obtained from two astronomical surveys over a 20-year period. They also added new observations with the Carmenes spectrometer in Almeria, Spain, the Eso/Harps instrument in Chile and the Harps-N instrument in the Canary Islands.

It's the first time the radial velocity technique has been used to detect a planet this small so far away from its host star.

Image copyright NAture Image caption The planet lies at about the same distance as Mercury orbits the Sun

"We couldn't get a single experiment that would detect it unambiguously, so we had to combine all the data very carefully," said the Queen Mary University of London astronomer.

"We found a lot of systematic errors from several of the instruments that were producing "ghost signals". It was not only about getting new data but also about understanding the systematic effects. Only when we had done that did the signal become very clear and obvious."

When the next generation of telescopes come online, scientists will be able to characterise the planet's properties. This will likely include a search for gases like oxygen and methane in the planet's atmosphere, which might be markers for biology.

"The James Webb Space Telescope might not help in this case, because it was not designed for what's called high contrast imaging. But in the US, they are also developing WFirst - a small telescope that's also used for cosmology," said Dr Anglada Escudé.

"If you take the specs of how it should perform, it should easily image this planet. When we have the image we can then start to do spectroscopy - looking at different wavelengths, in the optical, in the infrared, looking at whether light is absorbed at different colours, meaning there are different things in the atmosphere."

Image copyright NASA Image caption Artwork: The next generation telescope WFirst, should have the capability to produce a direct image of the new planet

This is not the first time there have been claims of a planet around Barnard's Star. In the 1960s, the Dutch astronomer Peter van de Kamp, working in the US, published his evidence for a planetary companion, based on perturbations in the motion of the star.

However, van de Kamp's claims proved controversial, as other scientists were not able to reproduce his finding.

"The new planet is impossible for Peter van de Kamp to have detected. The signal would have been too small for the technique he was using," said Guillem Anglada Escudé.

However, the new data contain tentative hints of a second planet orbiting Barnard's Star even further out than the Super-Earth.

"The new data does show evidence for a long period object. That object... has a very low probability of being the van de Kamp planet. But it's a long shot," said Anglada Escudé.

In a separate article published in Nature, Rodrigo Diaz, from the Institute of Astronomy and Space Physics in Buenos Aires, Argentina, who was not involved with the study, said the discovery "gives us a key piece in the puzzle of planetary formation and evolution, and might be among the first low-mass exoplanets whose atmospheres are probed in detail".

He added: "Difficult detections such as this one warrant confirmation by independent methods and research groups... a signal for the planet might be detectable in astrometric data - precision measurements of stellar positions - from the Gaia space observatory that are expected to be released in the 2020s."

The star is named after the American astronomer E E Barnard, who measured properties of its motion in 1916.

Follow Paul on Twitter.</s>PARIS: A "Super-Earth" has been discovered orbiting the closest single star to our Sun, scientists said Wednesday (Nov 14) in a breakthrough that could shine a light on Earth's nearest planetary neighbours.

Astronomers studied Barnard's Star, a red dwarf just six light years away - practically in our back garden, galactically speaking - and noticed the presence of a "frozen, dimly lit world" at least 3.2 times heavier than Earth.

The planet, known for now as Barnard's Star b, is the second nearest to Earth outside the solar system and orbits its host star once every 233 days.

"It's important because it's really our nextdoor neighbour and we like to meet our neighbours in general," Ignasi Ribas, from the Institute of Space Studies of Catalonia and Spain's Institute of Space Sciences, told AFP.

Despite being relatively close to its parent star, the planet receives less than 2 per cent of the energy Earth gets from the Sun, and the team estimates it has a surface temperature of -170 degrees Celsius - far too cold to support life as we know it.

"It's definitely not in the habitable zone, no liquid water. If it has any water or gas this is probably in solid form so that's why we call it frozen," said Ribas.

In mankind's bid to map the planets in the night sky, most historic research has focused on brighter, newer stars, which produce more light and increase the chances of scientists noticing anything orbiting them.

But since Barnard's Star is a red dwarf, a small and cooling star probably about twice as old as the Sun, it produces relatively little light making it hard to discern any bodies in its orbit.

To find Barnard's Star b, Ribas and the team studied more than 20 years' worth of observations from seven separate instruments.

They then used a phenomenon known as the Doppler effect to track the impact of its gravitational pull on its parent star.

Astronomers can use this technique to measure a planet's velocity and, therefore, mass.

"We have all worked very hard on this breakthrough," said Guillem Anglada Escude, from London's Queen Mary University, who co-authored the study published in the journal Nature.

The team worked with the European Southern Observatory using astronomical instruments so accurate they can detect changes in a star's velocity as small as 3.5kph - a gentle walking pace.

It's thought that Barnard's Star is tearing through space at around 500,000kph, making it the fastest-moving known object in the universe.

Ribas said that although stargazers could predict its size and orbit with relative accuracy using the Doppler effect, any attempt at this stage to find out what the new planet looked like would be "guesswork".

"It's sort of in a fuzzy area with respect to its properties. We've seen planets of this mass be rocky, meaning that it could look like Earth with a solid surface with potentially some atmosphere or some frozen layer on top," he said.

"Or it may be what we call a mini-Neptune, like a scaled-down version of the gas giants of our solar system."

It might be cold, inhospitable and all but invisible but the new planet has one thing going for it: It's really close.

The only known exoplanet closer to Earth was discovered in 2016 orbiting one of a cluster of stars in the Alpha Centauri system, just over four light years away.

"There's not so many stars in our immediate neighbourhood. The investment to find them is expensive," said Ribas.

"It's really near and therefore if you have the hope - like I do - of eventually seeing these planets to study them in detail we have to start with the immediate ones. It could lead potentially to other discoveries."</s>We've observed an alien world orbiting Barnard's Star, a tiny red dwarf that's only six light-years away, making it the second-closest known exoplanet beyond our solar system. Known as a "super-Earth," the planet (designated Barnard's Star b, or GJ 699 b) is thought to be at least 3.3 times the mass of Earth and orbits its star once every 233 days.

Barnard's Star is the fourth-closest star to our sun. Alpha Centauri's triple-star system (including Alpha Centauri A and B, plus Proxima Centauri) are the only stars nearer. Proxima Centauri is the closest star to have a known exoplanet in orbit, Proxima Centauri b. That world is slightly more massive than Earth, is located only 4.2 light-years away and has been pelted by solar flares, dashing hopes of it hosting life.

While an exciting (and historic) find, you can forget about Barnard's Star b bearing any resemblance to our planet. Barnard's Star is a very low mass and dim red dwarf that produces only 0.4 percent of the radiant power our sun generates. That means its "habitable zone" is extremely compact, and the exoplanet orbits beyond the star's "snow line." The snow line around any star is the distance beyond which water cannot exist in a liquid state on a planet's surface. The exoplanet has a predicted surface temperature of -170 degrees Celsius (-274 F), making it wholly incompatible for life (as we know it, anyway).

Still, this new exoplanetary discovery is exciting. Super-Earths are like nothing we have in our solar system and have only been discovered orbiting other stars more distant than Barnard's Star. These alien worlds occupy the mass range between the small rocky planets (like Earth, Mars and Venus) and the larger gaseous planets (like Neptune). Knowing that we have one of these strange exoplanets so nearby could allow us to get to know this planetary species a little better.

Although it's on our interstellar doorstep, discovering the Barnard's Star super-Earth took an international team of astronomers using decades of spectroscopic data of the star to find it.

"For the analysis we used observations from seven different instruments, spanning 20 years, making this one of the largest and most extensive datasets ever used for precise radial velocity studies," said Ignasi Ribas, of the Institut de Ciènces de l'Espai (ICE, CSIC), Spain, in a statement. Ribas is the first author of the study published in the journal Nature.

The radial velocity method used in exoplanet hunting requires precise observations of a star's spectrum. When starlight is received by telescopes, its spectrum can be split into its component wavelengths — such as infrared, visible and ultraviolet. However, if astronomers record observations of this starlight over many years, they may notice slight periodic frequency shifts. This is how we find exoplanets actually: As they orbit their host stars, their gravity causes their stars to wobble, pulling them toward and away from the telescope on Earth, creating a frequency shift that corresponds to the exoplanet's mass orbital period. Unlike NASA's Kepler and new Transiting Exoplanet Survey Satellite (TESS) – which both detect the slight dimming of starlight as an exoplanet orbits in front of its host star (known as a "transit") – the radial velocity method doesn't depend on detecting this dip in light to realize the presence of exoplanets around stars.

"This technique has been used to find hundreds of planets," said collaborator Paul Butler, of Carnegie Institution for Science and one of the pioneers of the radial velocity method, in a statement, "We now have decades of archival data at our disposal. The precision of new measurements continues to improve, opening the doors to new parameters of space, such as super-Earth planets in cool orbits like Barnard's Star b."

Since this exoplanet is so close, astronomers hope that they will be able to use it as a target for the next generation of space telescopes, such as the planned NASA Wide Field Infrared Survey Telescope (WFIRST). This makes Barnard's Star b a prime candidate for us to use powerful spectroscopic techniques to, one day, peer into its atmosphere (if it has one) and understand what it's really made of.</s>For most of human history, people wondered if there were other planets out there in the unfathomable reaches of space. It turns out there are some very close to Earth, though. A team of astronomers has revived interest in Barnard’s Star, which hangs in space just six light years away. After dismissing evidence for an exoplanet orbiting this star in the 1970s, the team now says there’s a very good chance Barnard’s Star does indeed host a super-Earth.

Barnard’s Star is a red dwarf and one of the closest stars to Earth. Only the Centauri system is closer, and we know there’s at least one exoplanet there. Astronomers announced the discovery of Proxima Centauri b with great fanfare in 2016. At just 4.4 light years away, this planet will make an excellent target for future observation. The planet orbiting Barnard’s Star is just a little bit more distant, but it’s still close enough to be key to understanding exoplanets.

The tale of planet hunting around Barnard’s Star starts in the 1960s when astronomer Peter van de Kemp released compelling data supporting the existence of an exoplanet. However, other teams were unable to confirm, and by the 1970s we knew the discovery was merely a product of defective instruments. Scientists kept looking at the star, and now astronomers from the Institute of Space Studies of Catalonia and the Institute of Space Sciences in Spain have assembled 20 years of data to reveal Barnard’s Star b.

The newly published study lays out the basics of the exoplanet. Barnard’s Star b completes an orbit of the star every 233 Earth days. It’s about as far away from Barnard’s Star as Mercury is from Earth, but Barnard’s Star is much cooler. So, it’s distinctly outside the habitable zone with a surface temperature of -170 degrees Celsius (-274 degrees Fahrenheit). It’s the equivalent of a planet orbiting between Mars and Jupiter in our solar system. Barnard’s Star b has a mass about three times that of Earth, but we don’t know its size or composition yet. We suspect it’s rocky, though.

Barnard’s Star b does not transit in front of its host star from Earth’s perspective — that would have made detection vastly simpler. Instead, the team used the radial velocity method. They watched for small counter movements in the star that indicate a massive body (a planet) is in orbit. A smaller star like Barnard’s Star wobbles more than a more massive one, so even a small-ish planet like this one had some detectable effect.

The team claims high confidence that Barnard’s Star b is real, but other teams will need to confirm. We don’t want another van de Kemp scenario.

Now read: There’s an Earthlike planet orbiting our nearest neighbor, Proxima Centauri – but how might we actually get there?, Massive Solar Flares Diminish Chance of Finding Life on Proxima Centauri, and So Long, and Thanks for All the Planets: NASA Retires the Kepler Telescope</s>Astronomers have found a telltale sign that something is tugging at the movements of Barnard's star - so it looks like we could soon be adding a planetary neighbour to the local directory of our corner of the Milky Way.

Barnard's star is a red dwarf that was already hanging out in space before our Solar System was even born. At almost 6 light-years away, it is the closest solitary star to our Sun - only the three stars in the Alpha Centauri system are closer.

Red dwarf stars are much smaller and cooler than our Sun and can have volatile magnetic activity, from dimming starspots to blazing solar flares, but Barnard's star is one of the quietest red dwarfs known.

Its relatively mild stellar weather and its proximity to us made Barnard's star seem like the perfect place to find exoplanets.

Except, for a long time, a clear sign of the existence of such a planet remained elusive - despite researchers throwing multiple detection techniques at it. There were tantalising hints though, suggesting a "wobble" in the star's movement.

"It was not a 'eureka' moment," astrophysicist Ignasi Ribas from the Institute of Space Sciences in Spain told ScienceAlert.

"Back in 2015 we were already seeing a signal arise from the data using archival observations from various facilities. But the statistical significance was low."

After observing the star more intensively to narrow the nature of the signal, the large team of researchers from around the world eventually got more confident about what they were seeing.

They analysed two decades of radial-velocity measurements from seven different spectrometers, carefully ruling out statistical flukes or interference from the instruments.

"We are quite certain that the periodic wobble of the star with an amplitude of 1.2 metres per second and 233-day period is there," Ribas explained.

"However, there are stellar phenomena that could be responsible for similar kind of signals."

To rule out other stellar phenomena, the team exhaustively ran simulations to test how likely alternate explanations might be. They estimated that the chance of the 233-day signal being due to starspot activity was less than 0.8 percent.

"After all the tests, the signal survived both in its significance and nature and we therefore concluded that the most likely explanation is the result of Keplerian reflex motion caused by a planet. Well, we are, at least, 99.2 percent sure..." Ribas told us.

The potential Super-Earth - a planet with a mass larger than Earth but smaller than ice giants like Uranus - was detected close to the 'snow-line' of Barnard's star. This is the closest distance to a star that planetary ingredients like water and other gases are able to clump together into a potential baby planet, and also near where most of these ingredients would be found.

However, details of this potential body are still very much a mystery: "We know very little about the properties of the planet," Ribas explained.

"Its mass is likely to be around 4 Earth masses and therefore it could be a rocky planet or perhaps a puffier mini-Neptune. In any case, it is almost certainly a frozen world because its equilibrium temperature is about -170 degrees Celsius."

That doesn't sound at all life-as-we-know-it friendly, but after this initial discovery, there could be potential to find planets around Barnard's star that are more Earth-like.

Excitingly, the next generation of observatory instruments due to start work during the 2020s should be able to take direct pictures and light spectrum measurements from Earth of relatively close planets like those around Barnard's star. This will help us learn much more about these exoplanets.

Ribas and his colleagues will continue collecting data on Barnard's star's movements to keep increasing their ability to detect other types of planets that might be orbiting around the red dwarf.

This study has been published in Nature.</s>Astronomers have discovered a frozen with a mass over three times that of the Earth, orbiting the closest solitary star to the

The potentially rocky planet, known as Barnard's star b, is a 'super-Earth' and orbits around its host star once every 233 days, said researchers from Queen in the UK.

The findings, published in the journal Nature, show the lies at a distant region from the star known as the 'snow line'.

This is well beyond the habitable zone in which liquid water, and possibly life, could exist, researchers said.

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.

However, if the has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable.

"Barnard's star is an infamous object among astronomers and exoplanet scientists, as it was one of the first stars where planets were initially claimed but later proven to be incorrect. Hopefully we got it right this time," said Guillem Anglada Escude from Queen Mary's School of Physics and

At nearly six light-years away Barnard's star is the next closest star to the after the Centauri triple system.

It is a type of faint, low-mass star called a red dwarf. Red dwarfs are considered to be the best places to look for exoplanet candidates, which are planets outside our solar system.

Barnard's star b is the second closest known exoplanet to our The closest lies just over four light-years from

That exoplanet, called Proxima b, orbits around the red dwarf star

The researchers used the radial velocity method during the observations that led to the discovery of Barnard's star b.

This technique detects wobbles in a star which are likely to be caused by the gravitational pull of an orbiting planet.

These wobbles affect the light coming from the star.

As the star moves towards the its spectrum appears slightly shifted towards the blue and, as it moves away, it is shifted towards the red.

This is the first time that this technique has been used to detect a planet this small so far away from its host star.</s>A "Super Earth" – a planet much bigger and colder than our world – has been discovered in orbit around a nearby star, scientists announced in a study published Wednesday.

How big? Over three times the mass of the Earth. How cold? A chilly temperature of about 238 degrees below zero. Super-Earths are planets with masses larger than the Earth, but not as big as the ice giants in our solar system, such as Neptune and Uranus.

The planet and its star are nearby in cosmic terms only: At 30 trillion miles from Earth, Barnard's Star is the closest single star to our solar system. For decades, astronomers have looked for planets around the star.

The newly discovered planet, dubbed Barnard's Star b, is the second-closest known exoplanet to the Earth and orbits the fastest-moving star in the night sky. Exoplanets are planets outside of our solar system.

"After a very careful analysis, we are 99 percent confident that the planet is there," said the study's lead scientist, Ignasi Ribas of Spain's Institute of Space Sciences, in a statement.

Data from a worldwide array of telescopes revealed the frozen, dimly lit world. "We used observations from seven different instruments, spanning 20 years of measurements, making this one of the largest and most extensive data sets ever used," Ribas said.

An artist’s impression of the surface of the planet that's orbiting Barnard's Star, the nearest single star to the sun. Data from a worldwide array of telescopes have revealed this frozen, dimly lit world.

The planet lies at a distant region from the star known as the "snow line," according to the study. This is well beyond the habitable zone in which liquid water, and possibly life, could exist.

It's a barren, frigid world because light from Barnard's Star provides it with only 2 percent of the energy the Earth receives from the sun.

“This is an extremely exciting new planet candidate,” Sarah Ballard, an MIT scientist not involved with the research, told Sky and Telescope. However, she cautioned that "I wouldn't buy a ticket to Barnard's Star just yet, knowing that there's a 1 percent chance the planet isn't there.”

The star's nearby status has made it a long-running candidate in the hunt for exoplanets. However, none of the previous searches have led to a discovery.

"This remarkable planet gives us a key piece in the puzzle of planetary formation and evolution," noted Rodrigo Díaz, an astronomer at the University of Buenos Aires in Argentina in an article accompanying the study.

The study was published Wednesday in the peer-reviewed British journal Nature.

The distances to the nearest stars from the sun. Barnard’s star is the second closest star system, and the nearest single star to us.</s>TEHRAN (Tasnim) – A planet has been discovered by astronomers in orbit around one of the closest stars to the sun, Barnard’s star.

The potentially rocky planet, known as Barnard’s star b, is a ‘super-Earth’ with a mass of at least 3.2 times that of the Earth, and it orbits around its host star once every 233 days.

The results, published in the journal Nature, show the planet lies at a distant region from the star known as the ‘snow line’. This is well beyond the habitable zone in which liquid water, and possibly life, could exist.

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

However, if the planet has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable.

Dr. Guillem Anglada Escudé, from Queen Mary’s School of Physics and Astronomy, said: “Barnard’s star is an infamous object among astronomers and exoplanet scientists, as it was one of the first stars where planets were initially claimed but later proven to be incorrect. Hopefully we got it right this time.”

At nearly six light-years away Barnard’s star is the next closest star to the Sun after the Alpha Centauri triple system.</s>The nearest single star to the sun apparently hosts a big, icy planet.

Astronomers have found strong evidence of a frigid alien world about 3.2 times more massive than Earth circling Barnard's Star, a dim red dwarf that lies just 6 light-years from the sun. Barnard's Star is our sun's nearest neighbor, apart from the three-star Alpha Centauri system, which is about 4.3 light-years away.

The newly detected world, known as Barnard's Star b, remains a planet candidate for now. But the researchers who spotted it are confident the alien planet will eventually be confirmed. [Barnard's Star b: What We Know About the "Super-Earth' Candidate]

"After a very careful analysis, we are 99 percent confident that the planet is there," Ignasi Ribas, of the Institute of Space Studies of Catalonia and the Institute of Space Sciences in Spain, said in a statement.

"However, we'll continue to observe this fast-moving star to exclude possible, but improbable, natural variations of the stellar brightness which could masquerade as a planet," added Ribas, the lead author of a new study announcing the detection of Barnard's Star b. That study was published online today (Nov. 14) in the journal Nature.

Barnard's Star b, if confirmed, will not be the nearest exoplanet to Earth. That designation is held by the roughly Earth-size world Proxima b, which orbits Proxima Centauri, one of the Alpha Centauri trio.

NASA's Kepler space telescope showed that small planets are common in the Milky Way galaxy at large. Together, Proxima b and Barnard's Star b strongly suggest that such worlds "are also common in our neighborhood," study co-author Johanna Teske, of the Department of Terrestrial Magnetism at the Carnegie Institution for Science in Washington, D.C., told Space.com. "And that is super-exciting."

Barnard's Star is named after the American astronomer E.E. Barnard, who in 1916 discovered the speediness Ribas mentioned. No other star moves faster across Earth's sky than Barnard's Star, which travels about the width of the full moon every 180 years. [Gallery: The Strangest Alien Planets]

This unparalleled apparent motion is a consequence of the proximity of Barnard's Star and its high (but not record-setting) velocity of 310,000 mph (500,000 km/h) relative to the sun.

And Barnard's Star is getting closer to us every day: In about 10,000 years, the red dwarf will take over the nearest-star mantle from the Alpha Centauri system. At that time, just 3.8 light-years will separate Barnard's Star from the sun.

Barnard's Star is about twice as old as Earth's sun, one-sixth as massive and just 3 percent as luminous. Because Barnard's Star is so dim, its "habitable zone" — the range of distances where liquid water may be possible on a world's surface — lies extremely close-in. Indeed, researchers estimate that zone to be a sliver that lies 0.06 AU to 0.10 AU from the star. (One AU, or astronomical unit, is the Earth-sun distance — about 93 million miles, or 150 million kilometers.)

The habitable-zone concept is a tricky one, of course. Gauging a world's true habitability requires a strong working knowledge of its atmospheric composition and thickness, among other characteristics. And such information is hard to come by for exoplanets.

Barnard's Star has long been a target of exoplanet hunters, but their searches have always come up empty — until now.

And the new detection wasn't easy: Ribas and his team analyzed huge amounts of data, both archival and newly gathered, before finally digging up Barnard's Star b.

They used the "radial velocity" method, which looks for changes in starlight caused by the gravitational tug of an orbiting planet. Such tugs cause a star to wobble slightly, shifting its light toward red wavelengths at times and toward the blue end of the spectrum at others, as seen from Earth. [7 Ways to Discovery Alien Planets]

"We used observations from seven different instruments, spanning 20 years of measurements, making this one of the largest and most extensive datasets ever used for precise radial-velocity studies," Ribas said in the same statement. "The combination of all data led to a total of 771 measurements — a huge amount of information!"

Never before had the radial velocity method been used to find such a small planet in such a distant orbit, study team members said. (Big, close-in planets tug their host stars more powerfully and therefore cause more dramatic, and more easily detectable, light shifts.)

Those seven instruments were the High Accuracy Radial Velocity Planet Searcher (HARPS), at the European Southern Observatory's (ESO) La Silla Observatory in Chile; the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope, at ESO's Paranal Observatory in Chile; HARPS-North, at the Galileo National Telescope in the Canary Islands; the High Resolution Echelle Spectrometer, at the Keck 10-meter telescope in Hawaii; the Carnegie Institute's Planet Finder Spectrograph, at the Magellan 6.5-m telescope at Las Campanas Observatory in Chile; the Automated Planet Finder at the 2.4-m telescope at the University of California's Lick Observatory; and& CARMENES, at the Calar Alto Observatory in Spain.

The researchers also detected hints of another possible planet in the system, orbiting farther out than Barnard's Star b — way farther out, with an orbital period of 6,600 Earth days. But this second signal is too weak to be deemed a planet candidate, Teske said.

"There's not enough data," she told Space.com.

Barnard's Star b is at least 3.2 times more massive than our own planet, making it a "super-Earth" — the class of worlds that are significantly larger than Earth but smaller than "ice giants" such as Neptune and Uranus.

The newfound planet candidate lies 0.4 AU from its host star and completes one orbit every 233 Earth days, according to the new study.

This orbital distance is similar to that of radiation-blasted Mercury in our own solar system. But, because Barnard's Star is so dim, the potential planet lies right around the system's "snow line" — the region where volatile materials such as water can condense into solid ices.

"Until now, only giant planets had been detected at such a distance from their stars," Rodrigo Diaz, of the Institute of Astronomy and Space Physics at the National Council of Scientific and Technical Research and the University of Buenos Aires in Argentina, said in an accompanying "News and Views" article that was also published today in Nature.

"The authors' discovery of a low-mass planet near the snow line places strong constraints on formation models for this type of planet," added Diaz, who was not involved in the new study.

Barnard's Star b, if it does indeed exist, is not a very promising abode for life as we know it, at least not on the surface. The potential planet is likely very cold, with an estimated surface temperature of about minus 275 degrees Fahrenheit (minus 170 degrees Fahrenheit), study team members said.

Confirmation of Barnard's Star b is unlikely to come from additional radial-velocity measurements, Diaz wrote. But super-precise measurements of star positions, such as those now being made by the European Space Agency's Gaia spacecraft, may do the job in the next few years, he added.

"Even more excitingly, the next generation of ground-based instrumentation, also coming into operation in the 2020s, should be able to directly image the reported planet, and measure its light spectrum," Diaz wrote.

"Using this spectrum, the characteristics of the planet’s atmosphere — such as its winds and rotation rate — could be inferred," he added. "This remarkable planet therefore gives us a key piece in the puzzle of planetary formation and evolution, and might be among the first low-mass exoplanets whose atmospheres are probed in detail."

WANT MORE STORIES ABOUT EXOPLANETS?
• Hottest exoplanet ever discovered has metallic skies, rain like lava
• Interstellar 'porch light' just might help us find space aliens</s>The study was co-led by researchers from Queen Mary University of London, and from the Institut d'Estudis Espacials de Catalunya and the Institute of Space Sciences/CSIC in Spain.

The potentially rocky planet, known as Barnard's star b, is a 'super-Earth' with a mass of at least 3.2 times that of the Earth, and it orbits around its host star once every 233 days.

The results, published in the journal Nature, show the planet lies at a distant region from the star known as the 'snow line'. This is well beyond the habitable zone in which liquid water, and possibly life, could exist.

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

However, if the planet has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable.

Dr. Guillem Anglada Escudé, from Queen Mary's School of Physics and Astronomy, said: "Barnard's star is an infamous object among astronomers and exoplanet scientists, as it was one of the first stars where planets were initially claimed but later proven to be incorrect. Hopefully we got it right this time."

At nearly six light-years away Barnard's star is the next closest star to the Sun after the Alpha Centauri triple system.

It is a type of faint, low-mass star called a red dwarf. Red dwarfs are considered to be the best places to look for exoplanet candidates, which are planets outside our solar system.

Barnard's star b is the second closest known exoplanet to our Sun. The closest lies just over four light-years from Earth and was also discovered by a team led by Queen Mary's Dr. Anglada Escudé in 2016. That exoplanet, called Proxima b, orbits around the red dwarf star Proxima Centauri.

The researchers used the radial velocity method during the observations that led to the discovery of Barnard's star b. This technique detects wobbles in a star which are likely to be caused by the gravitational pull of an orbiting planet.

These wobbles affect the light coming from the star. As the star moves towards the Earth its spectrum appears slightly shifted towards the blue and, as it moves away, it is shifted towards the red.

This is the first time that this technique has been used to detect a planet this small so far away from its host star.

The researchers re-examined archive data obtained over a 20-year period, and added new observations with the latest generation of instruments, namely the CARMENES spectrometer in Spain, the ESO/HARPS instrument in Chile and the HARPS-N instrument in the Canary Islands.

This wealth of data provided the extraordinary accuracy needed to identify the influence of the planet with near certainty. The wobble observed in the star's motion corresponds to speeds of only just over 1 metre per second—about walking speed.

Dr. Ignasi Ribas, from Institut d'Estudis Espacials de Catalunya and the Institute of Space Sciences in Spain, said: "After a very careful analysis, we are over 99 per cent confident that the planet is there, since this is the model that best fits our observations. However, we must remain cautious and collect more data to nail the case in the future."

Further observations to increase the confidence of this result are already under way at various observatories, and the system is an excellent candidate for observation by the next generation of instruments specifically designed to image exoplanets directly, such as NASA's planned Wide Field Infra Red Survey Telescope (WFIRST).

If the planet can be observed directly it will provide vital information about its properties and extend our understanding of the kinds of planets that form around red dwarf stars.

An award-winning public engagement campaign, known as Pale Red Dot, allowed the public to follow in real time the observations and analysis that led to the discovery of Proxima b.

The public have also been able to follow the observations leading to this new discovery, a result of extending the search to other very nearby red dwarfs, via a similar web-based campaign known as the Red Dots project, @reddotsspace on Twitter).

The study includes contributions from Professor Richard Nelson and research student John Strachan, both members of Queen Mary's School of Physics and Astronomy.

This research was supported in part by the UK Science and Technology Facilities Council and a Queen Mary University of London Principal's Postgraduate Studentship.

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More information: I. Ribas et al. A candidate super-Earth planet orbiting near the snow line of Barnard's star, Nature (2018). DOI: 10.1038/s41586-018-0677-y
Astronomers announce, through the journal Nature, the discovery of Barnard's Star b, a Super-Earth exoplanet orbiting Barnard's Star, the fourth-nearest-known individual star to the Sun.