In just six light years away, Barnard's star has fascinated exoplanet hunters since the 1960s, largely because of its extreme…
In just six light years away, Barnard’s star has fascinated exoplanet hunters since the 1960s, largely because of its extreme proximity to us. It is the closest single star to the sun and the next closest star system only to the Alpha Centauri triple star.
“Barnard’s star is among the nearby red dwarves, representing an ideal goal to look for exoplanets that could ever be reached by future interstellar spacecraft,” said co-author Steven Vogt, Professor Emeritus of Astronomy and Astrophysics at UC Santa Cruz. But the search for evidence of planets around this famous voice star in the last 50 years has been successful, so far.
In a landmark’s discovery, an international team of astronomers of Ignasi Ribas from the Institute for Space Studies in Catalonia (IEEC) and the Institute of Space Sciences (IEEC-CSIC) led a candidate plan to circle Barnard’s star.
High Precision Instruments, including the High Resolution Echelle Spectrometer (HIRES) at the WM Keck Observatory in Hawaii, reveal that the candidate, named Barnard’s star b (or GJ 699b), is a cold super-earth with at least 3.2 earthquakes circles its red dwarf star every 233 days. This would place the planet at the star’s so-called snow line, where it is likely to become a frozen world.
The team’s results are displayed online in the newspaper Nature, November 1
In the absence of an atmosphere, the planet’s temperature is likely to be about -150 + C, making it unlikely that the planet can support liquid water on the surface. But its features make it an excellent goal for directing with the next generation of instruments.
“This discovery is an increase in continuing to look for exoplanets around our closest star children, hoping that we will ultimately come across one that has the right conditions to host life,” said co-author Cristina Rodriguez -Lopez, Researcher at the Instituto de Astrofisica de Andalucia (IAA, CSIC).
Barnard’s star seems to move across the earth’s night sky faster than any other star. Less and older than our sun, it is one of the least active red dwarves that are known. “It’s the most common type of star in the galaxy – over 70 percent of Milky Way stars are like this fog, M-dwarf star,” said Vogt. “Although it’s extremely close, Barnard’s star is too weak to see with the naked eye.”
Vogt’s exoplanet search team began to observe Barnard’s star in 1997 using the Keck Observatory’s HIRES instrument, which Vogt designed. They used the radial velocity method to measure the star’s subtle back and forth cradle caused by an angled plane’s gravity trains.
Detectable signals of a wobble from earthy planets that turn on its host star are weak,
“We knew we would have to be patient. We followed Barnard’s star for 16 long years at Keck and collected about 260 radial speeds in Barnard’s star by 2013, Sade Vogt. “Fortunately, our long-term Keck Planet Search program provided us with the years we needed to gather enough precision radial speed data with HIRES to begin to know the planet’s presence.”
In 2016, Vogt’s European colleague Mikko Tuomi combined the team’s HIRES data with widely available data from the European Southern Observatory’s UVES and HARPS spectrometers and began to see weak remarks about a 230-day periodicity in radial velocity data, indicating a possible planet in the ground.
At that time, the signal was still too weak for astronomers to claim it as significant and publish their findings. Redirecting their efforts The Vogt team provided 45 additional radial velocity measurements from the newly-ordered Automated Planet Finder (APF) telescope at the UC Lick Observatory, 39 speeds from the Carnegie Institution for Science Planet Finder Spectrograph (PFS) on the Magellan II Telescope at the Las Campanas Observatory in Chile and more data published in recent years from HARPS. In any case, they further increased the information that the approximately 230-day signal grew stronger and more significant.
The last press came when Riba’s team decided to launch an intensive observation campaign from 2016 to 2017 to confirm the suspicious planet with CARMENES, a new planetary hunter spectrograph at the Calar Alto Observatory in Spain.
“The additional information from CARMENES strongly confirmed the signal and removed serious doubts about the reality of this planet,” said Vogt.
“For analysis, we used observations from seven different instruments, extending over 20 years, making this one of the largest and most comprehensive datasets ever used for accurate radial velocity studies. The combination of all data led to a total of 771 measurements , says Ribas. 19659002] A clear signal of 233 days occurred again in a reassessment of all measurements combined. This signal means that Barnard’s star approaches and moves from us at about 1.2 meters per second – about one-time walking speed for one person – and this movement is best explained as a result of a planet that circles the star.
After a very careful analysis, we are over 99 percent convinced that the planet is there because this is the model that best suits our observations, says Ribas. “However, we must be careful and collect more data to spike the case in the future, because natural variations of s The starlight resulting from star stains can produce similar effects as those discovered. “
] The following observations of Barnard’s star are already taking place at different observatories. According to Vogt, current data can exclude the presence of the jupiter size giant planets closer to the star, but there may be further planets slightly less than the ground of the earth closer to what has not yet been discovered.
Exoplanets so small and so far away from their parent star have not been detected before radial velocity technology is used. This means that astronomers will be better at finding such planets outside our solar system.
“We have all worked very hard on this result,” said Co-Guillem Anglada-Escude at Queen Mary University of London. “This is the result of a large collaboration organized within the framework of the Red Dots project, why it has contributions from teams all over the world, including semi-professional astronomers coordinated by the American Association of Variable Star Observers.”
“Although the supersoil we discovered is far too cold to be probably habitable, it emphasizes the exoplanet statistics that confirm that there are more planets in the universe than there are stars and more potentially habitable earthy planets than sand grains on all the shores of our planet! “said Vogt.
W. M. Keck Observatory
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