Objects hanging in the vacuum of the cosmos orbiting a star have been detected throughout the galaxy, these exoplanets have been a source of enhancing our understanding of the conditions beyond our solar system. Astronomers have now gone a step further and detected the first planet not just beyond the solar system but beyond the entire stretch of the Milky Way Galaxy.
This is the first time that signs of a planet transiting a star beyond the Milky Way galaxy has been detected. The unique discovery was led by Nasa’s Chandra X-ray Observatory that has peaked into the spiral galaxy Messier 51 (M51), also called the Whirlpool Galaxy.
Astronomers have over the years detected over 4000 such exoplanets , some earth like some hot Jupiters and others decaying due to astronomical events in their region. Almost all of them are within the realm of the Milky Way, less than about 3,000 light-years from Earth. But the exoplanet in M51 would be about 28 million light-years away, meaning it would be thousands of times farther away than those in the Milky Way.
“We are trying to open up a whole new arena for finding other worlds by searching for planet candidates at X-ray wavelengths, a strategy that makes it possible to discover them in other galaxies,” said Rosanne Di Stefano of the Center for Astrophysics, who led the study
The team searched for dips in the brightness of X-rays from X-ray bright binaries, which usually contain a neutron star — when a massive star collapses — or black hole pulling in gas from a closely orbiting star. The material near the neutron star or black hole becomes superheated and glows in X-rays.
The region creating bright X-rays is small, and so a planet passing in front of it would be easy to spot, as it would block most, or all, of the X-rays. This allows exoplanets to be detected at much greater distances
“Unfortunately to confirm that we’re seeing a planet we would likely have to wait decades to see another transit,” co-author astrophysicist Nia Imara, of the University of California at Santa Cruz, said in a statement. “And because of the uncertainties about how long it takes to orbit, we wouldn’t know exactly when to look.”
The study was published in the journal Nature Astronomy.