TORONTO: 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.
have over the years detected over
4,000 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.
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 astronomers searched for dips in the
brightness of X-rays received from X-ray bright binary systems that typically
contain a neutron star or black hole pulling in gas from a closely orbiting
To locate exoplanets,
astronomers study the light emerging from the star and whenever a plant passes through
it, it blocks the light from the star producing a characteristic dip.
Astronomers using both ground-based and space-based telescopes have searched
for dips in optical light, electromagnetic radiation humans can see, enabling
the discovery of thousands of planets.
the newest candidate, astronomers studied X-rays. Since 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 because the X-rays can
completely disappear. The team used it to detect exoplanet candidates in a
binary system called M51-ULS-1, located in M51.
binary system contains a black hole orbiting a companion star with a mass about
20 times that of the Sun. Nasa said that The X-ray transit they found using
Chandra data lasted about three hours, during which the X-ray emission
decreased to zero. Based on this and other information, the researchers
estimate the exoplanet candidate in M51-ULS-1 would be roughly the size of
to confirm that we’re seeing a planet we would likely have to wait decades to
see another transit. And because of the uncertainties about how long it takes
to orbit, we wouldn’t know exactly when to look,” co-author Nia Imara of
the University of California said in a statement.
Astronomers speculate that if a
planet actually exists in this massive system it likely had a tumultuous history and violent
past since it would have had to survive a supernova explosion that created the
neutron star or black hole. They further speculate that at some point the
companion star could also explode as a supernova and blast the planet once
again with extremely high levels of radiation.