Astronomers from the Breakthrough Watch Initiative use a newly developed system for middle-infrared exoplanet imaging and say that they can now use ground-based telescopes to directly take images of exoplanets about three times the size of Earth within the habitable zones of nearby stars. . Their first observations, made with ESO’s Very Large Telescope at the Paranal Observatory in Chile as part of the NEAR program (New-Earths in the AlphaCen Region), led to the discovery of a hot planet below the Neptune size. in the habitable region of Alpha Centauri A, part of the galaxy closest to Earth.
Mid-infrared images of Alpha Centauri AB: (a) high-pass filtered image without point distribution function (PSF) subtraction or removal of artifacts; the Alpha Centauri B on-coronagraph images were subtracted from the Alpha Centauri A coronagraph images, resulting in a central residual and two off-axis PSFs on the SE and NW of Alpha Centauri A and B, respectively; systematic artifacts marked 1-3 correspond to the detector’s persistence of Alpha Centauri A, Alpha Centauri B, and an optical ghost of Alpha Centauri A. (b) zoom in on the inner regions after removal of artifacts and PSF deduction; regions affected by detector retention are masked for clarity; the approximate interior of the habitable zone of Alpha Centauri A is indicated by the dotted circle; a candidate planet tracking is marked as ‘C1’. Image Credit: Wagner et al., doi: 10.1038 / s41467-021-21176-6.
Alpha Centauri, also known as Rigil Centaurus, Rigil Kent and Gliese 559, is the closest galaxy to Earth.
This triple system consists of the bright binary star formed by Alpha Centauri A and B, plus the dull red dwarf star Alpha Centauri C.
The two brighter components are about 4.35 light-years from us. Alpha Centauri C, better known as Proxima Centauri, is slightly closer to 4.23 light-years.
Compared to our sun, Alpha Centauri A is of the same star G2, but slightly larger. Alpha Centauri B, a K1-type star, is slightly smaller and less bright.
Alpha Centauri A and B orbit a common center of gravity once every 80 years, with a minimum distance of about 11 times the distance between the earth and the sun.
“We have achieved the ability to directly image planets about three times the size of the earth in the habitable zone of Alpha Centauri A,” said Dr. Olivier Absil, director of the PSILab (STAR Research Institute / Faculty of Sciences), at the Université de Liège.
In 2016, Breakthrough Watch and ESO launched a collaboration to build a thermal infrared coronagraph, designed to block most of the light coming down from the star and was optimized to absorb the infrared light emitted by the hot surface of orbiting an orbiting planet.
In addition to drastically reducing the target’s light and thus revealing the signatures of potential terrestrial exoplanets, the coronegraph modifies the existing instrumentation to optimize the sensitivity to infrared wavelengths so that it can detect potential heat signatures similar to those observed by the Earth. Earth is radiated.
Based on this progress, astronomers have been observing more than 100 hours since 2019 to search for exoplanets within the habitable zones of Alpha Centauri A and B.
This artist’s conception shows a hypothetical rocky exoplanet in the Alpha Centauri system. Image credit: Michael S. Helfenbein.
“We were surprised to find a signal in our data,” said Dr. Kevin Wagner, an astronomer at the University of Arizona, said.
“While the detection meets all the criteria for what a planet looks like, alternative explanations should be ruled out.”
“Verification can take a while and will require the involvement and ingenuity of the larger scientific community.”
“Only a few years ago, we were looking for possible terrestrial planets surrounding Alpha Centauri A and B,” said Dr. Pete Worden, executive director of the breakthrough initiatives, said.
‘We built the machinery that could do the job, and now a candidate planet has revealed itself. The power of collaborative, global scientific collaboration is quite astounding. ”
“As we work together globally, we discover new worlds, and we’re still making progress,” said Yuri Milner, founder of the Breakthrough Initiatives.
“Identifying a candidate-habitable zone planet in our heavenly backyard will continue our curiosity.”
The team’s report was published in the journal Nature communication.
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K. Wagner et al. 2021. Images of low-mass planets within the habitable zone of α Centauri. Nat Commun 12, 922; doi: 10.1038 / s41467-021-21176-6