Desk Report
Published: 06 Nov 2021, 11:53 pm
Signs of First Planet Found Outside Our Galaxy || Photo: Collected
Astronomers
have found hints of what could be the first planet ever to be discovered
outside our galaxy, reports BBC.
Nearly
5,000 "exoplanets" - worlds orbiting stars beyond our Sun - have been
found so far, but all of these have been located within the Milky Way galaxy.
The
possible planet signal discovered by Nasa's Chandra X-Ray Telescope is in the
Messier 51 galaxy.
This
is located some 28 million light-years away from the Milky Way.
This
new result is based on transits, where the passage of a planet in front of a
star blocks some of the star's light and yields a characteristic dip in
brightness that can be detected by telescopes.
This
general technique has already been used to find thousands of exoplanets.
Dr
Rosanne Di Stefano and colleagues searched for dips in the brightness of X-rays
received from a type of object known as an X-ray bright binary.
These
objects typically contain a neutron star or black hole pulling in gas from a
closely orbiting companion star. The material near the neutron star or black
hole becomes superheated and glows at X-ray wavelengths.
Because
the region producing bright X-rays is small, a planet passing in front of it
could block most or all of the X-rays, making the transit easier to spot.
The
team members used this technique to detect the exoplanet candidate in a binary
system called M51-ULS-1.
"The
method we developed and employed is the only presently implementable method to
discover planetary systems in other galaxies," Dr Di Stefano, from the
Harvard-Smithsonian Center for Astrophysics in Cambridge, US, told BBC News.
"It is a unique method, uniquely well-suited to finding planets around X-ray binaries at any distance from which we can measure a light curve."