A Distant Eruption observed as a Black Hole engulfed a Star

A Distant Eruption observed as a Black Hole engulfed a Star

Radio and Infrared telescopes were used to see what happens as a black hole rips apart a passing star.

The phrase ‘Humanity fears what it does not know’ fits best to Black Holes as we are unaware of their origin. Scientists are trying very hard to figure out the building block of this cosmic structure but they have had no luck until now. Having said that, they are confident that they are extremely dangerous due to the immense gravitational pull they possess. We don’t have a black hole critically closer to our solar system but occasional incidents in other parts of the universe remind us of the chaos they can cause. For the first time ever, scenes of a black hole destroying a star were captured by astronomers. Following the blasting of the star, a fast-moving material was ejected which was observed through various infrared and radio telescopes.

Two colliding galaxies called Arp299 were under observation when scientists found out that a black hole, which is 20 million times bigger than our Sun, exists in the center of one of these galaxies. The Very Long Baseline Array (VLBA) of National Science Foundation was also used for analyzing this historic event. Researchers concluded that the distant eruption was actually the shredded remains of a passing star, which had twice as much mass as the Sun of our solar system.

As the star got too close to the black hole, it was ripped apart by the strong gravitational attraction. The name given to this kind of stellar death is ‘Tidal Disruption Events (TDEs)’. Despite the fact that it was the first sighting of such an event, scientists have detected a handful of them. Miguel Perez-Torres, a representative of the Astrophysical Institute of Andalusia in Spain, confirmed that in the following words:

Never before have we been able to directly observe the formation and evolution of a jet from one of these events.”

It was a long time coming as astronomers got an indication about a TDE in January 2005. Researchers were observing colliding galaxies in the Canary Islands, by making use of the William Herschel Telescope, when they discovered that bright infrared emissions were coming out from the core of one of those galaxies. The stellar material was analyzed for a decade by the scientists and they suggested that black hole engulfing a passing star is quite common. However, we can’t see them often because the majority of the visible light is absorbed by the stellar dust. As a result, infrared and radio rays are needed to observe such eruptions from black holes. Seppo Mattila, one of the Lead Authors of the study from the University of Turku, acknowledged that by saying,

As time passed, the new object stayed bright at infrared and radio wavelengths, but not in visible light and X-rays. The most likely explanation is that thick interstellar gas and dust near the galaxy’s center absorbed the X-rays and visible light, then re-radiated it as infrared.”

VLBA came up with a new source of radio emission from the same location on 17th July 2005. Further studies were carried out as the European VLBI Network (EVN) and other powerful telescopes were used to analyze the jet-like emission of radio waves. It was observed that the stellar material moved at one-fourth of the speed of light. As radio waves are not absorbed by the galaxy, multiple radio antennas were installed at a distance of thousands of miles to see the fine details. The determination and patience of scientists were finally rewarded as they found the evidence of a jet.

According to the researching team, black holes are present in all the galaxies somewhere around the core. When these Supermassive black holes are pulling things towards themselves, a rotating disk is formed around the entrance and jets of particles are released. Fortunately, these black holes are not active most of the times but once a TDE takes place, stellar materials are ejected as massive speeds which can be observed through infrared and radio telescopes. Mattila mentioned exactly that as he said,

Because of the dust that absorbed any visible light, this particular tidal disruption event may be just the tip of the iceberg of what until now has been a hidden population. By looking for these events with infrared and radio telescopes, we may be able to discover many more, and learn from them.”

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