Black holes are among the most mysterious cosmic objects, much studied but not fully understood. In pursuit of understanding these celestial bodies, astronomers have stumbled upon a supermassive black hole, located a whopping 12.9 billion light-years from Earth, and it’s doing something pretty spectacular. The “blazar” is firing a super-powerful beam of energy straight towards us.

The energy beam from this black hole has travelled to us, just over 100 million years after the Big Bang took place — setting a new record for the distance from which we’ve observed such a phenomenon. The discovery also raises questions about how supermassive black holes grow so rapidly in the Universe’s infancy.

Named J0410-0139, the black hole has a mass of about 700 million Suns and is one of the oldest of its kind that scientists have ever observed. Detected using data from several telescopes, including NASA’s Chandra Observatory and Chile’s Very Large Telescope, the black hole has provided a new peek into the early universe.

“The alignment of J0410-0139’s jet with our line of sight allows astronomers to peer directly into the heart of this cosmic powerhouse. This blazar offers a unique laboratory to study the interplay between jets, black holes, and their environments during one of the Universe’s most transformative epochs,” said Dr Emmanuel Momjian, an astronomer at the National Radio Astronomy Observatory in Virginia, associated with the study, published in The Astrophysical Journal Letters.

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What is a blazar?

The universe is full of powerful supermassive black holes that create powerful jets of high-energy particles, creating sources of extreme brightness in the vastness of space. When one of those jets points directly at Earth, scientists call the black hole system a blazar, as per NASA.

The jets extending from these blazars can extend millions of light-years in length. They are exceedingly bright because as particles approach the speed of light, they give off a tremendous amount of energy and behave in weird ways that Albert Einstein predicted.

Up until now, a little less than 3,000 blazars have been discovered but most are located closer to Earth than J0410-0139. Despite decades of study, scientists still don’t fully grasp the physical processes that shape the dynamics and emission of blazar jets.

At the centre of the Milky Way is a supermassive black hole called Sagittarius A*. It is roughly 27,000 light years from Earth and 23.5 million kilometres in diameter.

In a world first, a team of astronomers led by Florian Peißker from the University of Cologne, Germany, have discovered a binary star system orbiting this black hole.

The system is known as D9. Its discovery, announced in a new paper published today in Nature Communications, sheds light on the extreme environment at the centre of our Milky Way galaxy.

It also helps explain a long-running cosmic mystery about why some stars hurtle through space much faster than others.

What Is A Binary Star System?

A binary star system is simply two stars orbiting each other.

Our Sun is not part of a binary, which is a good thing: we wouldn’t want another star wandering through our Solar System. It would disrupt the orbit of the Earth; we’d fry or freeze.

Observations show about two thirds of the stars in the Milky Way are single stars, and the remainder are part of a binary or multiple star system. Larger stars are more likely to be paired.

Binary star systems are useful to astronomers because their motion contains a wealth of information. For example, the speed and distance of the orbits tell us about the masses of the stars.

For a single star, by contrast, we usually work out its mass from how bright it is.

A Technically Challenging Discovery

Although scientists have previously predicted that binary star systems exist near supermassive black holes, they have never actually detected one.

This recent discovery was technically quite challenging. We can’t simply look at the system and see two stars, because it’s too far away. Rather, the astronomers used the European Southern Observatory’s Very Large Telescope to measure the shifting of the starlight – known as the Doppler effect. This showed that the stellar system’s light had a characteristic wobble, indicating an orbit.

But the team did much more than that.

Because binary stars contain a wealth of information, the astronomers could calculate that this particular system is approximately 2.7 million years old. That is, 2.7 million years ago, these stars first ignited.

They probably weren’t born in the black hole’s extreme surroundings, so unless they only recently wandered into this neighbourhood, they have lasted about a million years in their current environment.

This, in turn, tells us about the black hole’s ability to disrupt stars in its orbit. Black holes are mysterious beasts, but clues such as this are helping us unravel their nature.

Circling A Black Hole

The situation the astronomers discovered is quite familiar.

Think of the Moon: it orbits the Earth, and the Earth and the Moon together orbit the Sun. Because gravity is an attractive force, it can pull multiple celestial objects into complicated orbits. The complexity of this scenario inspired the recent book and Netflix series, The Three Body Problem.

If they are complicated, could the whole thing drift apart? The Moon–Earth–Sun arrangement is stable because two of the three bodies – the Earth and Moon – are much closer together than the other body, the Sun. The Moon and Earth are close enough that, so far as the Sun is concerned, it’s effectively a two-body system, which is stable.

But if all three bodies interact, the system can come apart. It is even possible for two of the bodies to eject the third body entirely.

Stars Of Unusual Speed

This mechanism probably explains a cosmic mystery: hypervelocity stars.

Most stars in the night sky are in a typical, almost-circular orbit around the centre of our galaxy. Orbital speeds are about 200 kilometres per second: very fast on Earth, but nothing special in space.

However, since 2005 we have discovered about 20 hypervelocity stars, which are hurtling through our galaxy at more than 1,000 kilometres per second. How?

Our best current idea is that hypervelocity stars were once part of a binary system orbiting our supermassive black hole. In time, the stars got too close to the black hole, and a complicated orbit resulted. In the kerfuffle, with a black hole calling the shots, one of the stars got ejected. It escaped to the outer Milky Way, where we see it as a hypervelocity star.

Finding The Hypervelocity Factory

It’s an interesting theory.

Theoretical calculations show the mechanism works and the speeds are about right. Observations show many of the known hypervelocity stars appear to be shooting away from the galactic centre, which is another plus for the theory. But how else could we test this idea?

An obvious way is to look for binary stars around our supermassive black hole.

Astronomers have been keeping a close eye on our galactic centre for decades. It’s not too difficult to find in the night sky, as you can see from the image below.

Here are two reliable methods to find Sagittarius A*. First, find Antares (bright and red), which is the centre of the back of Scorpio, and then follow the scorpion’s body to the tip of the tail, and that’s close-ish to the black hole. Alternatively, get a good night sky app on your phone; they’re amazing.

In the context of these theories, this recent discovery is very important. Astronomers found a binary star system around our supermassive black hole. An important piece of the hypervelocity puzzle falls into place.

(Author: Luke Barnes, Lecturer in Physics, Western Sydney University)

(Disclosure Statement: Luke Barnes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment)

This article is republished from The Conversation under a Creative Commons license. Read the original article.
 

The interaction between a supermassive black hole in a galaxy named 2MASX J02301709+2836050 and a star orbiting it is seen in this image captured by the Pan-STARRS telescope, in Hawaii, U.S., in an undated handout image provided by NASA.
| Photo Credit: Reuters

Black holes, celestial objects known for their gluttony, usually eat stars unlucky enough to stray too close to them in one big gulp, annihilating them with their enormous gravitational pull. But some, it turns out, tend to snack rather than gorge.

Researchers said they have observed a supermassive black hole at the center of a relatively nearby galaxy as it takes bites out of a star similar in size and composition to our sun, consuming material equal to about three times Earth’s mass each time the star makes a close pass on its elongated oval-shaped obit.

Black holes are extraordinarily dense objects with gravity so strong that not even light can escape.

The star is located about 520 million light years from our solar system. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). It was observed being plundered by a supermassive black hole at the heart of a spiral-shaped galaxy.

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As such black holes go, this one is relatively small, estimated to have a mass a few hundred thousand times larger than the sun. The supermassive black hole at the center of our galaxy, called Sagittarius A*, possesses about 4 million times the mass of our sun. Some other galaxies harbor supermassive black holes hundreds of millions times the mass of the sun.

Most galaxies have such black holes at their center, and the environment around them can be among the most violent places in the universe.

Most of the data used by the scientists in the new study came from NASA’s orbiting Neil Gehrels Swift Observatory.

The star was observed orbiting the black hole every 20 to 30 days. At one end of its orbit, it ventures near enough to the black hole to have some material from its stellar atmosphere sucked away, or accreted, each time it passes – but not so close as to have the whole star shredded. Such an event is called a “repeating partial tidal disruption.”

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The stellar material that falls into the black hole heats up to around 3.6 million degrees Fahrenheit (2 million degrees Celsius), unleashing an immense amount of X-rays. Those were detected by the space observatory.

“What’s most likely to happen is the star’s orbit will gradually decay and it will get closer and closer to the supermassive black hole until it gets close enough to be completely disrupted,” said astrophysicist Rob Eyles-Ferris of the University of Leicester in England, one of the authors of the study published this week in the journal Nature Astronomy.

“That process is likely to take years at least – more likely decades or centuries,” Eyles-Ferris added.

This marked the first time that scientists had observed a sun-like star being repeatedly snacked upon by a supermassive black hole.

“There are lots of unanswered questions about tidal disruption events and exactly how the orbit of the star affects them,” Eyles-Ferris said. “It’s a very fast-moving field at the moment. This one has shown us that new discoveries could come at any time.”