Scientific first! Black hole eats a star!

[Delta4Embassy]

http://phys.org/news/2015-11-scientists-glimpse-black-hole-star.html

"An international team of astrophysicists led by a Johns Hopkins University scientist has for the first time witnessed a star being swallowed by a black hole and ejecting a flare of matter moving at nearly the speed of light.

The finding reported Thursday in the journal Science tracks the star—about the size of our sun—as it shifts from its customary path, slips into the gravitational pull of a supermassive black hole and is sucked in, said Sjoert van Velzen, a Hubble fellow at Johns Hopkins.

"These events are extremely rare," van Velzen said. "It's the first time we see everything from the stellar destruction followed by the launch of a conical outflow, also called a jet, and we watched it unfold over several months."


Here's hoping the solar system was uninhabited.

 

[waltky]

Black hole caught 'burping' gas...

Black hole caught 'burping' galactic gas supply
Tue, 05 Jan 2016 - Astronomers have spotted two huge waves of gas being "burped" by the black hole at the heart of a nearby galaxy.

The swathes of hot gas, detected in X-ray images from Nasa's Chandra space telescope, appear to be sweeping cooler hydrogen gas ahead of them. This vast, rippling belch is taking place in NGC 5194 - a small, neglected sibling of the "Whirlpool Galaxy", 26 million light years away. That makes it one of the closest black holes blasting gas in this way.

The two waves of hot, X-ray emitting gas were seen in this image from Chandra​

The findings, presented at the 227th meeting of the American Astronomical Society (AAS) in Florida, are a dramatic example of "feedback" between a supermassive black hole and its host galaxy. "We think that feedback keeps galaxies from becoming too large," said Marie Machacek, a co-author of the study from the Harvard-Smithsonian Center for Astrophysics (CFA). "But at the same time, it can be responsible for how some stars form. This shows that black holes can create, not just destroy."

Ancient emissions

Black holes are well known for consuming gas and stars, but the two arcs of material glimpsed here are the equivalent of a burp after a big meal, the team said. The black hole at the centre of NGC 5194 probably gorged on gas that was delivered by the small galaxy's interaction with its much bigger, spiralling neighbour. As that matter fell into the black hole, huge amounts of energy would have been released - causing the outbursts. Eric Schlegel from the University of Texas at San Antonio, who led the study, explained that the crucial observation was the cooler hydrogen gas being propelled ahead of the hot, X-ray emitting waves. "This is the best example of snowplough material I've ever seen," he said.

NGC 5194 is a small companion galaxy to the huge "Whirlpool Galaxy" NGC 5195​

Deep red light, indicating the presence of hydrogen, was seen in a thin strip just in front of the outermost wave, in optical images from a telescope at the Kitt Peak National Observatory in Arizona. "If it had not been for the hydrogen-alpha image, I would have been somewhat sceptical," Dr Schlegel told BBC News. "I would have said, maybe this is mass going in, maybe it's mass coming out." But the patch of hydrogen, spread out in a thin shape closely matching the arc of hot gas seen in Chandra X-ray images, clinched this as a belch rather than a gulp.

MORE

 

[waltky]

Black hole's twin jets shine bright...

Black hole's twin jets shine bright, somehow
Tue, 02 Feb 2016 - Astronomers have published new images of a bright jet of material, long enough to cross the Milky Way three times, fired into space by the black hole at the heart of a distant galaxy. The observations confirm the existence of a second jet, blasting in the opposite direction.

The study uses this galaxy, Pictor A, to test ideas about what makes jets like these emit very bright X-rays. It appears in the Monthly Notices of the Royal Astronomical Society. To make their observations, the team combined 15 years of X-ray data, from Nasa's Chandra space telescope, with images taken in radio wavelengths by the Australia Telescope Compact Array.

The jets shine in X-ray wavelengths (shown in blue) while radio waves (red) reveal twin "lobes"​

Chandra has been in orbit since 1999 - and interest in Pictor A was sparked right back at the beginning of its mission, according to Martin Hardcastle from the University of Hertfordshire, UK. "The early images from Chandra showed there was this very bright jet," Prof Hardcastle, the study's lead author, told the BBC. "At that stage we didn't really understand it, because the data were good enough to make an image of the jet, but not to do this kind of detailed analysis." The new images have five or six times the resolution of our previous best views of Pictor A, he added, meaning that new features can be detected and the physics of the jet probed in detail.

Blowing up balloons

Most big galaxies have a supermassive black hole at their centre, and Pictor A - five million light-years from Earth - is no exception. In its case, the immense quantities of stuff swirling towards the black hole release so much energy that a beam of high-energy particles is spat across space, at very nearly light speed. A second jet, fired in the opposite direction, was only an indistinct shadow in previous images, Prof Hardcastle said. "In some work we did on an interim version of this data set, we thought we could see it. But now it's definitely there." This "counterjet" - to the left in the blue X-ray image - appears much fainter than its twin and the team believes this is because it is moving away from us, at the same breakneck speed. According to the principles of relativity, this makes it look dimmer. "It's like the Doppler effect only more so," said Prof Hardcastle. "In special relativity it actually effects the amplitude as well as the frequency of the emission."

X-ray image: The jet on the left is moving away from us, so appears fainter​

Blooming outwards from the twin beams are two clouds of hot material, clearly visible in the radio wave images (displayed in red in these images). These are created after the jets smash into the sparse, gaseous medium that separates galaxies. "The material goes up the jet at relativistic speeds and at some point it runs into the external medium. And when it does, it's like blowing up a balloon; the material that's come up the jet has to go somewhere and it inflates these lobes," Prof Hardcastle said. "It's basically pushing the hot intergalactic medium out of the way, so it blows these twin bubbles." At the end of the jet there is also a "hotspot", visible in both images, where the material first piles up in collision with that medium.

Mysterious acceleration