In the first half of 2020, Brazilian astrophysicist Stella Ichitani Silva received an alert in one of the systems she uses at work: the star she was observing had an unusual peak of light.
It was the beginning of a journey that would take the 28-year-old miner, who is a researcher at NASA (the US space agency), to lead a search that discovered a new planet – at least 26,000 light-years from Earth.
The star MOA-2020-BLG-135Lb was christened – an expletive you know by heart and scrambled, so proud that she stayed for a while. will lead The research, in which 36 scientists from around the world participated GlobalismIt is an exoplanet, that is, a star outside our solar system.
To get an idea of the distance of the planet you’ve discovered, 26,000 light-years means that if an airplane could travel at the speed of light, that’s 300,000 kilometers per second, it would take 26,000 years to travel from Earth to Earth. a star.
For four years as a research assistant at the Goddard Space Flight Center, a NASA laboratory in Washington, D.C., Stella says the idea of working for the famous US agency always seemed silly to her.
“When I decided to study physics, my family was joking, ‘But why, to work at NASA?'” And I thought, “How silly these people are, it’s not, nobody works at NASA,” says the researcher, who fulfilled the family’s prophecy after graduating in physics at UFMG in 2016.
From a lecture given by Brazilian astronomer Doulia de Mello, a professor at the Catholic University of America (also in Washington), Stella discovered that some people worked for NASA.
She passed her PhD from the same Catholic University — she did her doctorate in conjunction with her master’s degree, which she concluded in 2019 — and is meticulously examining how to facilitate the search for new planets outside the solar system through artificial intelligence, automating data from millions of observed stars.
In the case of the MOA-2020-BLG-135Lb, the light peak alerted by the Brazilian system indicated that A phenomenon called gravitational lensing.
“Have you ever seen a Whatsapp sticker where someone throws a ball over the net and the net sinks?” He interrogates the young woman when the report asks the researcher to explain the phenomenon.
What Stela is trying to explain is essentially Albert Einstein’s theory of general relativity, according to which the gravity of objects causes spacetime to twist. This curvature ends up acting as a kind of lens, increasing the amount of observed light coming from the star, as if it were a magnifying glass.
After months of searching, it became clear that the alert Stella received with an unusual light altitude was nothing more than a planet passing in front of the star, and the distortion of spacetime caused the device to pick up more light.
“It was the object’s gravity that generated the lens effect,” she explains. “This allows us to observe dimly lit objects, which we would hardly encounter without knowing this phenomenon.”
The gravitational lens also makes it easier to detect distant exoplanets – the distance of MOA-2020-BLG-135Lb varies from Earth by calculation, but is between 25,800 light-years and 27,100 light-years.
The first exoplanets were discovered in the early 1990s, and today NASA records 5071 of these stars, as well as another 8,870 candidates, which have yet to be confirmed.
There are different types of them. The planet discovered by Stela is of the class Neptune, as it is similar in size to the planet in the solar system. While Neptune has a mass of 17.1 times the mass of Earth, the exoplanet identified by the Brazilian has between 11.3 and 25 times the mass of Earth. Planets of this type usually have atmospheres dominated by hydrogen and helium with cores or heavier rocks and metals.
This is the first exoplanet discovered in a research led by Stela, but the Brazilian has already been involved in identifying a string of other stars with the research group that is part of it, the MOA (Micro Lens Observations in Astrophysics Collaboration), which brings together scientists in the US Japan and New Zealand.
In addition to the distant planets, the group was part of the discovery of the first isolated black hole – wandering without interacting with other objects – known to exist, about 5,000 light-years from Earth.
Outside of the Department of Agriculture, Stela has also been involved in work with other researchers, mostly at NASA, who have discovered 181 candidate exoplanets using artificial intelligence.
In this case, the method used to identify potential planets wasn’t gravitational lensing, but rather a technique called planetary transits, which is one of the most common ways to find exoplanets. In the case of planetary transits, when a planet passes between its star and the observer, it causes a kind of eclipse by blocking part of the light emitted by the star. By observing this decrease in the amount of light emitted, astronomers determine the possibility of a planet in that star.
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