Astronomers have discovered a planet that could be the first exoplanet outside our galaxy.
Nearly 5,000 extrasolar exoplanets have been discovered so far, but no extragalactic exoplanets have been discovered.
Discovered by NASA’s Chandra X-ray Observatory (CXO) telescope, the Saturn-sized planet is located in the spiral galaxy Messier 51 (M51), about 28 million light-years from Earth.
Dr. Rosen Di Stefano of the Harvard-Smithsonian Center for Astrophysics (CfA) and his research team observed a temporary decrease in X-rays based on the technique of observing the decrease in starlight when an exoplanet passes through the celestial plane passing in front of the star. Candidates for extragalactic planets have been identified.
These observations have been used in the past to find thousands of exoplanets.
X-rays are usually emitted as they become superheated when a neutron star or black hole absorbs material from a nearby companion.
At this time, the X-ray emission area is not wide, so the planet passes through the celestial plane and completely obscures it.
The researchers used these observations to find candidates for exoplanets in the M51-ULS-1 binary system.
“The method we have developed and applied is currently the only viable way to discover planets from other galaxies,” Di Stefano told the BBC.
“This method is also the only suitable method for finding planets orbiting an X-ray binary star at a distance where the luminosity curve can be measured,” he added.
search for a future planet
This binary system consists of a black hole or neutron star and a pair of stars with a mass about 20 times that of the Sun.
A neutron star is a star formed when the nucleus of a star remaining after a supernova explosion degenerates through gravitational collapse, and the nucleus and electrons inside the atom merge to form a neutron.
The passage of the celestial surface on the X-ray observation data took about 3 hours, during which time the X-ray emission was completely obscured and dropped to zero.
Based on this information, the researchers estimated that the exoplanet was similar in size to Saturn and orbited a neutron star or black hole at twice the distance of the Sun and Saturn.
At the same time, the researchers admitted that verification of the findings today would not be easy.
It may have to wait about 70 more years for this planet to pass in front of its companion, so there is a possibility that it will not be confirmed until then.
On the other hand, it is also possible that the temporary brightness decrease in binary systems was caused by clouds of gas or dust.
However, given the data, this seems unlikely.
“We know for ourselves that we are making interesting and daring claims, so we expected astronomers to test their claims very carefully,” said Julia Berntson, PhD and co-author at Princeton University. I think that’s the way it works,” he said.
Di Stefano said the new optical and infrared telescopes will not be able to solve the problems of clustering and brightness, and X-ray wavelength observations will remain the main way to find extragalactic planets.
He added, however, that microlenses could also be used in future extragalactic planets discovery techniques.
The results of this study were published in the latest issue of the international academic journal ‘Nature Astronomy’.