The single star closest to the sun is apparently hosting a large icy planet.
Astronomers have found solid evidence of an icy extraterrestrial world about 3.2 times more massive than the Barnard star surrounding Earth, a pale red dwarf located just 6 light years from the sun. The Barnard star is the nearest neighbor to our sun, apart from the Alpha Centauri three-star system, located about 4.3 light-years away.
The newly detected world, known as Barnard's Star B, remains for the moment a candidate for the planet. But the researchers who have spotted it are convinced that the extraterrestrial planet will finally be confirmed. [Barnard’s Star b: What We Know About the “Super-Earth’ Candidate]
"After a very thorough analysis, we are 99% convinced that the planet is there," said Ignasi Ribas, of the Institute for Space Studies of Catalonia and the Institute of Sciences of Catalonia. Space in Spain, in a statement.
"However, we will continue to observe this moving star to rule out possible, but unlikely, natural variations of stellar brightness that could pose as a planet," added Ribas, lead author of a new study announcing the detection of Barnard's disease. Star b. This study was published online today (14 November) in the journal Nature.
Barnard's star b, if confirmed, will not be the closest exoplanet to the Earth. This designation is owned by Proxima b, a world about the size of the Earth, which revolves around Proxima Centauri, one of the Alpha Centauri trios.
NASA's Kepler Space Telescope has shown that small planets are common in the Milky Way galaxy. Together, Proxima B and Barnard's Star B strongly suggest that such "worlds" are also common in our neighborhood, "said Johanna Teske, co-author of the study, Department of Magnetism at Space.com. of the Carnegie Institution for Science in Washington, DC. "And it's super exciting."
An almost solar neighbor
Barnard's Star owes its name to the American astronomer E. E. Barnard, who discovered in 1916 the speed mentioned by Ribas. No other star moves faster in the 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 unprecedented apparent movement is a consequence of the proximity of Barnard's star and its high speed (without reaching a record) of 310,000 km / h (500,000 km / h) compared to the sun.
RELATED: 2018 Space Calendar:
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Space calendar 2018
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January 1st, 2: Moon Supermoon / Full Wolf
The moon will come closer to Earth on New Year's Day and appear larger and brighter than usual, which will give it the distinction of "Supermoon".
In addition, the first full moon of a year wins the distinction "Full Wolf Moon". The term was coined by Native Americans in tribute to the howls of the wolves they often heard outside their villages in January.
Photo: Matt Cardy / Getty Images
January 3 and 4: meteor shower of quadrantides
The meteor shower Quadrantid, known to produce 50 to 100 meteors at its peak, is the first major meteor shower in 2018.
Unfortunately, the light of the near-full moon will block most of the show.
Photo: NurPhoto / NurPhoto via Getty Images
January 31: Total eclipse of the moon / blue moon
A blue moon is the term for the second full moon of the month with more than one full moon.
The blue moon of January also coincides with a total lunar eclipse.
Photo: REUTERS / Mike Hutchings
February 15: partial solar eclipse
This type of solar eclipse occurs when the moon casts a shadow that only covers a part of the sun.
The partial solar eclipse of February 15 will only be visible in parts of South America and Antarctica. Those who wish will have to wear special eye protection.
Photo: REUTERS / Tatyana Makeyeva TPX THE IMAGES OF THE DAY
March 2: Full Worm Moon
Another term invented by the Amerindians, "Full Worm Moon" is the distinction given to the first full moon in March.
As the temperature warms, the soil begins to soften and the earthworms begin to rise again.
Photo: NICHOLAS KAMM / AFP / Getty Images
March 15: Mercury reaches its largest eastern stretch
The mercury will reach its greatest elongation east of the sun (ie, its highest point above the horizon) on March 15th.
This will make the planet more visible than usual.
Photo: The Royal Observatory Greenwich, London
April 22 and 23: Lyrid Meteor Shower
The meteor shower Lyrid, which usually produces about 20 meteors an hour, will reach its peak between the night of April 22 and the morning of the 23rd.
Photo: Ye Aung Thu / AFP / Getty Images
April 30: Full Moon Rose
"Full Pink Moon" is another term supposed to have been invented by the Native American tribes.
In April, the weather finally begins to warm up and the flowers begin to appear, giving the full moon of the month its pretty name.
Photo: Ben Birchall / PA Images via Getty Images
6th and 7th May: Eta Aquarid meteor shower
The Eta Aquarids meteor shower, made up of dust particles left by Halley's comet, can produce up to 60 meteors per hour at its peak.
Although most of its activity can be observed in the southern hemisphere, northerners can still watch the show if weather conditions permit.
Photo: NASA
May 9: Jupiter reaches the opposition
The gas giant will be closer to the Earth on May 9, which will make it brighter than any other time of the year.
Photo: Universal History Archive via Getty Images
May 29: Full moon
Native American tribes gave this name to the May full moon because the beginning of the month is usually when the flowers are in full bloom.
Photo: REUTERS / Navesh Chitrakar TPX THE IMAGES OF THE DAY
June 27: Saturn reaches the opposition
Saturn will be closer to Earth on June 27, making it brighter than any other time of the year.
Photo: NASA / JPL-Caltech / Institute for Space Science / Distributed via REUTERS
June 28: full moon with strawberries
The last star of the spring, astronomers can expect it to be big and bright – but unlike its name, it is not red.
The strawberry season peaks in June, giving the first moon of the month its delicious name.
Photo: Matt Cardy / Getty Images
July 13: partial solar eclipse
This type of solar eclipse occurs when the Moon casts a shadow that only covers part of the Sun.
The partial solar eclipse of July 13 will only be visible in parts of southern Australia and Antarctica. Those who wish will have to wear special eye protection.
Photo: REUTERS / Mal Langsdon TPX THE IMAGES OF THE DAY
July 27: March reaches the opposition
You'll have guessed it – Mars will get closer to Earth on July 27, which will make it brighter and therefore more visible than any other time of the year.
Photo: NASA / Document via Reuters
July 27: Full Buck Moon
The full moon of July was nicknamed "Full Buck Moon" by the Native American tribes, as it appears at this time of the year, when male deer begin to grow their new woods.
Photo: REUTERS / Carlo Allegri
July 28th and 29th: total lunar eclipse
A total lunar eclipse occurs when the moon passes completely through the Earth's shadow, giving it a dark red appearance.
The lunar eclipse of July will be visible in North America, East Asia and Australia.
Photo: REUTERS / Kacper Pempel
August 11: partial solar eclipse
This type of solar eclipse occurs when the moon casts a shadow that only covers a part of the sun.
The partial solar eclipse of August 11 will only be visible in parts of Canada, Greenland, Northern Europe and North and East Asia. Those who wish will have to wear special eye protection.
Photo: REUTERS / Samrang Pring TPX THE IMAGES OF THE DAY
August 12 and 13: Perseid meteor shower
The Perseid meteorite shower, made up of the dust particles left by the Swift-Tuttle comet, can produce up to 60 meteors per hour at its peak.
The thin crescent moon on the night of August 12th will create favorable viewing conditions for the heavenly spectacle, which should be visible all over the world.
Photo: REUTERS / Paul Hanna
August 17: Venus reaches its largest eastern stretch
Venus will be closer to Earth on August 17, making it brighter and more visible than any other time of the year.
Photo: Photo12 / UIG via Getty Images
August 26: Full moon sturgeon
The August full moon earned this distinction from Native American tribes, sturgeons being the most easily caught during this month.
Photo: Pradita Utana / NurPhoto via Getty Images
September 7: Neptune reaches the opposition
Neptune will be closer to Earth on September 7th, making it brighter and more visible than any other time of the year.
However, because of its distance from the Earth, the blue planet will only appear as a small dot, even to those who use telescopes.
Photo: Time Life Pictures / NASA / LIFE Images Collection / Getty Images)
September 24th and 25th: harvest full moon
The name & # 39; Harvest Moon & # 39; refers to the full moon that occurs each year closest to the autumn equinox.
Photo: Santiago Vidal / LatinContent / Getty Images
October 8: draconid meteor shower
The Draconid meteor shower, composed of the dust particles left by comet 21P Giacobini-Zinner, produces only about ten meteors per hour at its peak.
However, the new moon in the night of 9 October will create extremely favorable viewing conditions for the shower, which should be visible worldwide.
Photo: NASA
October 21 and 22: Orionid meteor shower
Another shower produced by Halley's Comet, the Orionids will probably be at least partially blocked by the nearly full moonlight on October 21st.
Photo: Yuri Smityuk TASS via Getty Images
October 23: Uranus joins the opposition
Uranus will make its closest approach to Earth on October 23, making it more brilliant and therefore more visible than any other time of the year.
Unfortunately, it is so far from Earth that it will not be visible without a powerful telescope.
Photo: Time Life Pictures / NASA / Reaction Propulsion Laboratory / LIFE / Getty Images Collection
October 24: Hunter's full moon
The full moon of October has been dubbed "the hunter's moon" by the naive American tribes, as animals are more easily spotted during this time of year after the plants have lost their leaves.
Photo: PA Wire / PA Images
November 5 and 6: meteor shower Taurides
The Taurides are a small meteor shower that only produces 5 to 10 meteors per hour at its peak.
Photo: NASA
November 17 and 18: meteor shower Leonid
The meteor shower Leonid, which emanates from the constellation Leo, produces about 15 meteors per hour at its peak.
Photo: Ali Jarekji / Reuters
November 23: Full Beaver Moon
The Native American tribune gave its name to the November full moon, which would install beaver traps during the month in the hope of capturing the creatures for their warm fur.
Photo: Matt Cardy / Getty Images
December 13th and 14th: Geminids meteor shower
The meteorite rain of the Geminids, produced by the debris left by an asteroid known as 3200 Phaethon, is reputed to be one of the most spectacular of its kind.
The show can produce up to 120 meteors per hour at its peak and will be visible all over the planet on the night of December 13th.
Photo: REUTERS / Navesh Chitrakar
December 21st and 22nd: Ursides meteor shower
The Draconid meteor shower, made up of dust particles left by the Tuttle Comet, produces only about 10 meteors per hour at its peak.
Unfortunately, the full moon on December 22nd will probably create unfavorable conditions for the small show.
Photo: REUTERS / Daniel Aguilar DA / LA
December 22: Full Cold Moon
Unsurprisingly, December's full moon was named by Native American tribes after the cold and winter.
Photo: Matt Cardy / Getty Images
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And Barnard & # 39; s Star is getting closer to us every day: in about 10,000 years, the Red Dwarf will take over the Alpha Centauri system. At this time, only 3.8 light-years apart will separate Barnard's star from the sun.
The Barnard star is about twice as old as the Earth's sun, with one sixth of mass and 3% of light. As Barnard's star is so dark, its "habitable zone" – the range of distances where liquid water may be possible at the surface of the world – is extremely close. Indeed, the researchers estimate that this zone is a brightness located between 0,06 AU and 0,10 AU of the star. (An astronomical unit, or astronomical unit, is the Earth-Sun distance – about 93 million miles, or 150 million kilometers).
The concept of habitable zone is of course delicate. To measure the true livability of a world, one must, among other characteristics, be familiar with its atmospheric composition and thickness. And such information is difficult to obtain for exoplanets.
A long search
Barnard's Star has long been a target of exoplanet hunters, but their searches have always remained empty – until now.
And the new detection was not easy: Ribas and his team analyzed huge amounts of data, both archival and newly collected, before finally unearthing Barnard's Star b.
They used the "radial velocity" method, which searches for changes in starlight caused by the gravitational tug of a planet in orbit. Such tugs are slightly swinging a star, shifting its light towards the red wavelengths at times and towards the blue end of the spectrum in others, as seen from the Earth. [7 Ways to Discovery Alien Planets]
"We used observations from seven different instruments, spanning 20 years of measurements, making it one of the largest and most comprehensive data sets ever used for accurate radial velocity studies," he said. Ribas in the same release. "The combination of all the data has led to a total of 771 measurements – a huge amount of information!"
Never before has the method of radial velocity been used to find such a small planet in such a distant orbit, said members of the study team. (Large, closely spaced planets drive their host stars more powerfully and therefore cause more dramatic and easily detectable light offsets.)
These seven instruments were the high-precision Search Radial Velocity Planet Searcher (HARPS) at the La Silla Observatory of the European Southern Observatory (ESO) in Chile; Ultraviolet and visual scale spectrograph on the very large telescope, at the Paranal observatory of ESO in Chile; HARPS-North at Galileo National Telescope in the Canary Islands; the High Resolution Scale spectrometer at the 10-meter Keck telescope in Hawaii; the Carnegie Institute's Planet Finder Spectrograph, at the 6.5-meter Magellan Telescope at the Las Campanas Observatory in Chile; the automatic planet finder at the 2.4 m telescope of the Lick Observatory of the University of California; and & CARMENES, at the observatory of Calar Alto in Spain.
The researchers also detected allusions to another possible planet in the system, orbiting farther away than the more distant Barnard star, with an orbital period of 6,600 terrestrial days. But this second signal is too weak to be considered a candidate for the planet, said Teske.
"There is not enough data," she told Space.com.
An icy super-land
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 considerably larger than Earth but smaller than "giants" ice "such as Neptune and Uranus.
The new study indicates that the new candidate planet is 0.4 UA from its host star and orbits every 233 days on Earth.
This orbital distance is similar to that of radiation-treated mercury in our own solar system. But since Barnard's star is so dark, the potential planet is all around the system's "snow line" – the area where volatile materials such as water can condense into solid ice.
"Until now, only giant planets had been detected at a distance as far removed from their stars," said Rodrigo Diaz, of the Institute of Astronomy and Space Physics of the National Council of Scientific and Technical Research and the University of Buenos Aires in Argentina. an accompanying article "News and Views" which was also published today in Nature.
"The discovery by the authors of a low-mass planet near the snow line is severely undermining the training patterns of this type of planet," added Diaz, who did not participate in the new study.
Barnard & # 39; s Star B, if it does exist, is not a very promising home for life as we know it, at least not on the surface. The potential planet is probably very cold, with an estimated surface temperature of minus 275 degrees Fahrenheit (minus 170 degrees Fahrenheit), the study team members said.
It is unlikely that the confirmation of Barnard's star b will come from additional radial velocity measurements, wrote Diaz. But very precise measurements of the position of the stars, such as those currently carried out by the Gaia spacecraft of the European Space Agency, could do well in the coming years, he added.
"Even more exciting, the next generation of ground-based instruments, which will also come into service in the 2020s, should be able to directly image the reported planet and measure its light spectrum," wrote Diaz. .
"Using this spectrum, the characteristics of the planet's atmosphere – such as its winds and speed of rotation – could be deduced," he added. "This remarkable planet is therefore a key element in the puzzle of the formation and evolution of planets, and could be among the first small-scale exoplanets whose atmospheres are explored in detail."
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