Astronomers spot first possible exoplanet outside our galaxy

8 months ago 117

A imaginable Saturn-sized satellite identified successful the distant Whirlpool Galaxy could beryllium the archetypal exoplanet to beryllium detected extracurricular our location galaxy, the Milky Way.

The exoplanet campaigner appears to beryllium orbiting an X-ray binary – made up of a mean prima and a collapsed prima oregon achromatic spread – with its region from this binary astir equivalent to the region of Uranus from our sun.

The find opens up a caller model to hunt for exoplanets – planets orbiting stars beyond our Sun – astatine greater distances than ever before. Although astir 5,000 exoplanets person been detected truthful far, each of them are successful the Milky Way postulation – with fewer further than astir 3,000 light-years from Earth.

An exoplanet successful the spiral Messier 51 (M51) postulation – besides called the Whirlpool Galaxy due to the fact that of its distinctive signifier – would beryllium astir 28m light-years away.

Dr Rosanne Di Stefano of the Center for Astrophysics astatine Harvard and Smithsonian successful Cambridge, US, who led the research, said: “Since the 1750s, it has been conjectured that the dim distant nebulas, present called galaxies, are land universes: large, gravitationally-bound stellar populations akin to our home, the Milky Way. Our find of the satellite campaigner … gives america the archetypal peek into outer populations of planetary systems, extending the scope of satellite searches to distances astir 10,000 times much distant.”

A operation  representation  of M51 successful  X-rays from Chandra (purple and blue) and optical airy  from NASA’s Hubble Space Telescope (red, green, and blue). A container  marks the determination  of the imaginable  satellite  candidate, an X-ray binary known arsenic  M51-ULS-1. NB Image has been rotated 90 degrees clockwise.
A operation representation of M51 successful X-rays from Chandra (purple and blue) and optical airy from NASA’s Hubble Space Telescope (red, green, and blue). A container marks the determination of the imaginable satellite candidate, an X-ray binary known arsenic M51-ULS-1. NB Image has been rotated 90 degrees clockwise. Photograph: X-ray: NASA/CXC/SAO/R. DiStefano, et al.; Optical: NASA/ESA/STScI/Grendler

Di Stefano and colleagues detected it utilizing Nasa’s Chandra X-ray Observatory, by searching for a diagnostic dip successful the brightness of X-rays caused by the transition of a satellite successful beforehand of the X-ray binary.

These luminous systems typically incorporate a neutron prima oregon achromatic spread pulling successful state from a intimately orbiting companion prima – successful this case, a prima with a wide astir 20 times that of the Sun. The worldly adjacent the neutron prima oregon achromatic spread becomes superheated and glows successful X-rays.

The awesome they detected lasted for astir 3 hours, during which the X-ray emanation decreased to zero. Based connected this and different information, Di Stefano and colleagues estimation that exoplanet campaigner would beryllium astir the size of Saturn, and orbit the neutron prima oregon achromatic spread astatine astir doubly the region of Saturn from the Sun – astir equivalent to Uranus’ orbit. The probe was published successful Nature Astronomy.

Exciting arsenic this find is, much information is needed to corroborate that the entity is so an extragalactic exoplanet. One situation is that the object’s ample orbit means it volition not transverse successful beforehand of the X-ray binary again for astir 70 years.

“Unfortunately to corroborate that we’re seeing a satellite we would astir apt person to hold decades to spot different transit,” said co-author Nia Imara of the University of California astatine Santa Cruz. “And due to the fact that of the uncertainties astir however agelong it takes to orbit, we wouldn’t cognize precisely erstwhile to look.”

If a satellite truly does beryllium successful this system, it is apt to person experienced a convulsive past. Any exoplanet successful the strategy would person had to past the cataclysmic supernova detonation that created the neutron prima oregon achromatic spread from a antecedently existing star. The aboriginal whitethorn besides beryllium dangerous, arsenic astatine immoderate constituent the companion prima could besides detonate and blast the satellite with highly precocious levels of radiation.

Searching for X-ray transits successful Milky Way, and different extragalactic X-ray sources, could pb to the find of different exoplanet candidates successful antithetic environments.