For the first time, signs of a planet transiting a star beyond the Milky Way galaxy may have been discovered. The extraordinary finding has made it easier for NASA’s Chandra X-ray Observatory for searching of exoplanets at farther distances than ever before.
The potential exoplanet resides in the spiral galaxy called Messier 51, often known as the Whirlpool Galaxy because of its unique shape. Until now, scientists have found all known exoplanets in the Milky Way galaxy, most of them are 3,000 light-years away from Earth.
We’re attempting to open up a whole new field for discovering other worlds by looking for planet candidates at X-ray wavelengths, an approach that allows us to detect them in other galaxies, according to the study’s lead author, Rosanne Di Stefano.
This discovery is based on transits, which occur when a planet passes in front of a star and blocks some of the star’s light, causing a distinctive dip. Astronomers have looked for dips in optical light, electromagnetic radiation that humans can see, using both ground-based and space-based telescopes such as those on NASA’s Kepler and TESS missions, allowing the finding of hundreds of planets.
A few scientists were looking for a decrease in the brightness of X-rays released by X-ray bright binaries. These dazzling systems are frequently made up of a neutron star or black hole consuming gas from a nearby partner star. The material near a neutron star or black hole becomes superheated and emits X-rays.
As the zone which is emitting powerful X-rays is very small, a planet going close to it will block most of the X-rays, making the transition easier to detect because the X-rays may disappear totally.
The scientists utilized this strategy to find the exoplanet candidate in M51-ULS-1, a binary system. A black hole or neutron star orbits a companion star 20 times the mass of the Sun in this binary system. The X-ray transit that was found by Chandra data was only for three hours, for that time the X-ray output became zero. The researchers say that the exoplanet in M51-ULS-1 is around the size of Saturn and goes around the neutron star or black hole approximately twice as far as Saturn revolves around the Sun.
This is very interesting research, more findings are required to confirm the analysis as an extragalactic exoplanet. One difficulty is that the planet candidate’s huge orbit implies it will not cross in front of its binary partner again for nearly 70 years, preventing any efforts at confirmation for decades.
The researchers say there’s no clear explanation since the things that happened in the event which was seen in M51-ULS-1 are not constant for such a cloud. However, the model of a planet candidate is compatible with the evidence.
If there is a planet in this system, it has most certainly had a turbulent and violent history. A supernova explosion that formed the neutron star or black hole would have been required to be survived by an exoplanet in the system. The future might potentially be perilous. At some point, the star which is close to it may also explode as a supernova, blasting the planet with a lot of radiation once more.
Scientists used Chandra and the European Space Agency’s XMM-Newton telescopes to search for X-ray transits in three galaxies beyond the Milky Way. The research included 55 of the M51 systems, 64 of the Messier 101 systems, and 119 of the Messier 104 systems, generating a single exoplanet.