US: Scientists have developed a new method that could revolutionise how they find and classify new planets that are very far away from Earth. They have detected an exoplanet using machine learning, a branch of Artificial Intelligence (A.I.).
A recent study by the University of Georgia research team showed that machine learning can correctly determine if an exoplanet is present by looking in protoplanetary disks, the gas around newly formed stars. The newly published findings represent a first step towards using machine learning to identify previously overlooked exoplanets.
“We confirmed the planet using traditional techniques, but our models directed us to run those simulations and showed us exactly where the planet might be,” said lead author of the study Jason Terry in a release.
“When we applied our models to a set of older observations, they identified a disk that wasn’t known to have a planet despite having already been analyzed. Like previous discoveries, we ran simulations of the disk and found that a planet could re-create the observation.”
According to Terry, the models suggested a planet’s presence, indicated by several images that strongly highlighted a particular region of the disk that turned out to have the characteristic sign of a planet - an unusual deviation in the velocity of the gas near the planet.
“This is an incredibly exciting proof of concept. We knew from our previous work that we could use machine learning to find known forming exoplanets,” said Cassandra Hall, assistant professor of computational astrophysics and principal investigator of the Exoplanet and Planet Formation Research Group at UGA. “Now, we know for sure that we can use it to make brand new discoveries.”
“This demonstrates that our models - and machine learning in general - have the ability to quickly and accurately identify important information that people can miss. This has the potential to dramatically speed up analysis and subsequent theoretical insights,” Terry said.
“It only took about an hour to analyze that entire catalog and find strong evidence for a new planet in a specific spot, so we think there will be an important place for these types of techniques as our datasets get even larger.”
Meanwhile, In 1992, astronomers discovered the first exoplanet, or planet outside our solar system. But it didn’t come in any form they’d really anticipated.
Neutron stars are the second densest type of object in the universe outside black holes. They form when a giant star dies and explodes outward as a result of the collapse of its core. Put simply, the star becomes too massive to go on and expels all its energy into the surrounding space. The core is a sort of ground zero of this detonation. When that core collapses, depending on the size of the star, it becomes either a neutron star or a black hole.
Some neutron stars are called pulsars, for the regular “pulses” they give off in radio frequencies. Think of many of them like a drummer — fast regular beats. Some pulsars, called millisecond pulsars, “drum” so fast that it would put Napalm Death’s drummer Danny Herrera to shame. Those pulses are so regular that if they don’t come at the right interval, astronomers know something is off.
A breakthrough in 1992 provided rock-solid evidence of planets. Astronomers Aleksander Wolszczan and Dale Frail tuned into the pulsar PSR B1257+12, 2300 light-years away. It should have pulsed every 0.006219 seconds, but every now and then, its pulses were a little off. Yet those off-beats came at regular intervals as well. After intensive study, Wolszczan and Frail came up with an explanation for why that was: it had two planets around it. One was three and the other four times the mass of Earth, and they rotated around every 67 and 98 days, rounded up.
Pulsar planets are somewhere in between a zombie and a chimera.
When a star explodes, usually the planets in that system are destroyed or flung out by a shockwave. But after the violence settles down, the gas and dust can recondense. This, in effect, means that the three planets in B1257 may be made out of parts of the planets that came before them. Given the extreme radiation in these systems, almost no one has ever thought that the B1257 system could host life.
So, while the 1992 discovery was major news, it meant astronomers had the first verified planets around another star, but no proof of planets around a main sequence star like the Sun. That kind of confirmation was still a few years away.
From the 1980s on, many groups had been on the hunt for the first planet around a Sun-like star. Some candidates came and went. Others required dozens or hundreds of observations to officially confirm.
But an observation in January 1995 proved to be the real deal. Didier Queloz, a grad student at the University of Geneva, was working with his advisor, Michel Mayor, on the search for extrasolar planets via radial velocity, in other words, wobbles.
Reportedly, his find was a chance coincidence. Out of a catalog of radial velocity signatures, he chose an F-type star called 51 Pegasi, roughly 50 light-years distant. He was trying to calibrate his planet finding code, opting for the star as one of a few promising candidates. It fell into place that night, a strong signal roughly every four days.
Measurements placed its minimum mass near Jupiter — meaning the object was without a doubt a planet. While astronomers considered it possible to have such periods, it wasn’t necessarily expected to find one in such a short period. “At this time, I was the only one in the world who knew I had found a planet,” Queloz told the BBC in 2016. “I was really scared, I can tell you.”
In 2016, a group of astronomers working under a thick veil of secrecy announced they had found the closest exoplanet system to Earth orbiting around the star Proxima Centauri. That team — calling itself Pale Red Dot — later rechristened themselves into Red Dots. Their work has added in other nearby systems, like Barnard’s Star, where in November 2018, they found tantalizing evidence of an exoplanet.
In a 2018 conference talk, MIT’s resident exoplanet expert, Sara Seager, mentioned that exoplanet astronomy is, in some ways, taking a turn back toward its beginnings. There will still be some large-scale surveys, but those will be intended to find a handful of candidates for future studies. Other projects like Red Dots will focus on a few stars at a time.
This is partly because, with much of the heavy lifting done on censuses of stars, we are at the edge of being able to know previously unfathomable details about planets and we may be studying them one by one with giant telescopes and better optic technology.
- NDTV
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