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At barely six light-years away, the Barnard star has fascinated exoplanet hunters since the 1960s, largely because of its extreme proximity to us. It is the nearest single star closest to the sun and the second closest star system to the Alpha Centauri three-star system.
"The Barnard star is one of the neighboring red dwarfs, making it an ideal target to search for exoplanets that may one day be reached by future interstellar spacecraft," said co-author Steven Vogt, a professor Emeritus of Astronomy and Astrophysics at UC Santa Cruz. But the search for evidence of the existence of planets around this famous red dwarf star over the past 50 years has been unsuccessful until now.
As part of a historic discovery, an international team of astronomers led by Ignasi Ribas of the Institute of Space Studies of Catalonia (IEEC) and the Institute of Space Science (IEEC-CSIC) discovered a planet in orbit around Barnard's star.
Measurements made with the aid of high-precision instruments, including the High Resolution Resolution Spectrometer (HIRES) from the WM Keck Observatory in Hawaii, reveal that the candidate, named Barnard's star b ( or GJ 699 b), is a super-cold ground with a minimum of 3.2 Earth masses gravitate around its red dwarf star every 233 days. This would place the planet on the so-called snow line of the star, where it is likely that the world is frozen.
The results of the team are online in the November 14, 2018 issue of the journal Nature.
In the absence of an atmosphere, the temperature of the planet should be about -150 + C, which makes it unlikely that the planet can withstand liquid water on its surface . However, its features make it an excellent target for direct imaging using the next generation of instruments.
"This discovery is a stimulus for continuing to search for exoplanets around our nearest stellar neighbors, in the hope that we will one day find conditions conducive to life," said co-author Cristina Rodriguez- Lopez, researcher at the Instituto de Astrofisica de Andalucia (IAA, CSIC).
Barnard's star seems to move faster than any other star in the night sky of the Earth. Smaller and older than our sun, it is one of the least active red dwarfs known. "This is the most prevalent type of star in the galaxy.More than 70% of the Milky Way stars look like that of the dwarf star M," said Vogt. "Although this is extremely close, Barnard's star is too dim to be seen at the naked eye."
Methodology
The Vogt exoplanet research team began observing Barnard's star in 1997 with the help of HIRES instrument from the Keck Observatory, designed by Vogt. They used the radial velocity method to measure the subtle back and forth of the star caused by the gravitational tug of a planet in orbit.
However, detectable signals of a flicker from Earth-sized planets tugging at their host star are weak and largely submerged by the noise generated by the boiling surface activity of the stars themselves.
"We knew we had to be patient – we followed Barnard's star for 16 long years at Keck, amassing about 260 radial speeds from Barnard's star by 2013," said Vogt. . "Fortunately, our long-standing Keck planetary research program has provided us with the years necessary to collect sufficient precision radial velocity data with HIRES to begin to detect the presence of a planet."
In 2016, Vogt's European colleague, Mikko Tuomi, combined the team's HIRES data with publicly available data from the UVES and HARPS spectrometers of the Southern European Observatory, and began to hint at light indices of a periodicity of 230 days in the radial velocity data, index of a possible size planet.
However, at that time, the signal was still too weak for astronomers to claim to be significant and publish their results. Redoubling efforts, the Vogt team added 45 additional radial velocity measurements using the newly commissioned Automated Planet Finder (APF) automated telescope at the Lick Observatory. UC, 39 speeds of the PFS spectrometer (Planet Finder) of the Magellan II telescope at Las Campanas Observatory in Chile, and more data that have been made available to the public by HARPS in recent years. In each case, the additional data made the signal about 230 days more powerful and meaningful.
The final push came when the Ribas team decided to launch an intensive observational campaign from 2016 to 2017 aimed at confirming the suspected planet with CARMENES, a new planetary hunter spectrograph at the time. observatory of Calar Alto in Spain.
"The additional CARMENES data has strongly confirmed the signal and eliminated any lingering doubts about the reality of this planet," said Vogt.
"For analysis, we used observations from seven different instruments over a 20-year period, making it one of the largest and most comprehensive data sets ever used for studies. Accurate radial velocity The combination of all the data has generated 771 measurements, "he said.
A clear signal to a period of 233 days appeared again when a new analysis of all combined measurements. This signal implies that Barnard's star is approaching and moving away from us at about 1.2 meters per second – about the speed of a person's movement – and this movement is taking place. 39, explains better by the fact that a planet revolves around the star.
"After a very thorough analysis, we are more than 99% confident that the planet is present because it is the model that best fits our observations," Ribas said. "However, we must remain cautious and collect more data to solve the problem in the future, as natural variations in stellar brightness resulting from star spots may produce effects similar to those detected."
xNext Steps
Barnard star tracking observations are already taking place in different observatories. According to Vogt, current data may exclude the presence of giant planets of Jupiter's size closer to the star, but there may be additional planets slightly smaller than the more orbiting Earth mass. near that have not yet been detected.
Exoplanets so small and so far from their parent star had not been discovered before the use of the radial velocity technique. This means that astronomers are getting better at finding this type of planet outside our solar system.
"We have all worked very hard to achieve this result," said co-leader Guillem Anglada-Escude of Queen Mary University in London. "This is the result of extensive collaboration within the Red Dots project, which is why teams from around the world participated, including semi-professional astronomers coordinated by the American Association of Variable Star Observers."
"The super-Earth that we have detected is far too cold to be habitable, but it highlights the statistics on exoplanets that confirm that there are more planets in the universe than it is." There are stars, and there are more potentially habitable planets the size of an Earth's beaches on our planet! "Says Vogt.
Related Links
W. M. Keck Observatory
Lands Beyond Beyond – Additional Solar Planets – News & Science
Life beyond the earth
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A super-cold land just 6 light years from Barnard's Star
Heidelberg, Germany (SPX) Nov 15, 2018
An international group of astronomers, associated with the Max Planck Institute for Astronomy (MPIA) in Heidelberg, has successfully detected a planet around the Barnard star, located at six years -light of the day before.
The planet has a little more than three times the mass of the Earth and is slightly colder than Saturn. The discovery was made by measuring the periodic change in the radial velocity of the parent star. The CARMENES spectrograph, developed largely by the MPIA, played an important role in this discovery … read more
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