Giant black hole in Milky Way vomits spitballs as big as a planet

A monster black hole located in the centre of the Milky Way galaxy spews out spitballs as large as a planet, scientists have discovered. According to scientists, the fragments of stars shredded by the supermassive black hole have formed the spitballs.

An unlucky star comes too close to the black hole every thousand years. The powerful gravity of the black hole rips the star apart and in this process a long streamer of gas whips outwards.

The gas can gather itself into planet-size objects and those objects are then flung throughout the galaxy in the game of cosmic spitball, according to new research.

"A single shredded star can form hundreds of these planet-mass objects. We wondered: Where do they end up? How close do they come to us? We developed a computer code to answer those questions," said Eden Girma, undergraduate student at Harvard University in the US.

The closest of these planet-mass objects might be within a few hundred light-years of Earth, according to calculations.

It would have a weight somewhere between Neptune and several Jupiters. It would also glow from the heat of its formation, although not brightly enough to have been detected by previous surveys.

Large Synoptic Survey Telescope and James Webb Space Telescope, the future instruments, may discover these far-flung oddities, researchers said.

The vast majority of the planet-mass objects, about 95%, will leave the galaxy entirely due to their speeds of about 10,000 kilometres per second, Eden Girma said.

Same process may take place in other galaxies as well as most of them also have black holes at their cores.

"Other galaxies like Andromeda are shooting these spitballs at us all the time," said James Guillochon of the Harvard-Smithsonian Centre for Astrophysics (CfA).

Although they might be planet-size, these objects would be very different from a typical planet.

They are literally made of star-stuff, and since different ones would develop from different pieces of the former star, their compositions could vary.

They also form much more rapidly than a normal planet. It takes only a day for the black hole to shred the star (in a process known as tidal disruption), and only about a year for the resulting fragments to pull themselves back together.

This is in contrast to the millions of years required to create a planet like Jupiter from scratch.

Once launched, it would take about a million years for one of these objects to reach Earths neighbourhood.

The challenge will be to tell it apart from free-floating planets that are created during the more mundane process of star and planet formation.

"Only about one out of a thousand free-floating planets will be one of these second-generation oddballs," said Girma.

(With inputs from PTI)