A new planet in another galaxy, do you think it’s possible? Researchers say they detected evidence of a world orbiting a pair of stars — one of which most likely underwent a supernova explosion — 23 million light-years from Earth.
Astronomers have spotted tantalizing signs of a planet in a star system outside the Milky Way, which, if it’s confirmed, would be the first-ever found in another galaxy.
The discovery, reported in a study published Monday in the journal Nature Astronomy, demonstrates a new technique for finding far-off worlds. In addition, it could significantly expand the search for so-called extragalactic exoplanets.
“It’s always fun when you find something that is the first of its kind,” said the study’s lead researcher, Rosanne Di Stefano, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. “Once we began to find planets locally, it made sense that there were planets in other galaxies, but this is humbling and exciting.”
The possible planet was discovered in a spiral galaxy called Messier 51, also known as the Whirlpool Galaxy, more than 23 million light-years from Earth.
A new planet in another galaxy
They may have detected Signs of a planet transiting a star outside of the Milky Way galaxy for the first time. Using NASA’s Chandra X-ray Observatory, this intriguing result opens up a new window to search for exoplanets at greater distances than ever before.
The possible exoplanet candidate is located in the spiral galaxy Messier 51 (M51), called the Whirlpool Galaxy, because of its distinctive profile.
Exoplanets are defined as planets outside of our Solar System. Until now, astronomers have found all other known exoplanets and exoplanet candidates in the Milky Way galaxy, almost all of them less than about 3,000 light-years from Earth. So, for example, an 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 | Harvard & Smithsonian (CfA) in Cambridge, Massachusetts, who led the study, which was published today in Nature Astronomy.
This new result is based on transits, events in which the passage of a planet in front of a star blocks some of the star’s light and produces a characteristic dip. Astronomers using ground-based and space-based telescopes – like those on NASA’s Kepler and TESS missions – have searched for dips in optical light, electromagnetic radiation humans can see, enabling the discovery of thousands of planets.
The nature of the stars made this feat possible. Because the researchers had to focus on binary X-ray light systems where the region of the light rays is relatively tiny, the crossing was much more accessible. In addition, conventional sensing of nearby stars requires more photosensitive sensing, as a planet can only block a small amount of light from a particular star.
The planet itself is thought to be the size of Saturn but orbits its hosts (a star 20 times the mass of the Sun plus a black hole or neutron star) at twice the distance.
The Bottom Line
The scientists did not think that clouds of gas or dust caused the dimming because that does not correspond to the event they recorded in M51. However, the planet will agree with the data.
The challenge, as you can imagine, is verifying that data. The planet’s large orbit could rule out another transit for about 70 years, and it won’t be clear exactly when astronomers will have to take a look. The three-hour transit of this candidate planet did not provide a large window. This also assumes that a “living” star does not explode and flood the Earth with radiation.
If there is any confirmation, the discovery will be very significant. Although there are not many doubts about the existence of planets in other galaxies, it would be helpful to have evidence of their existence. This could also significantly extend searches for future planets to galactic neighborhoods, not just nearby stars.