The flow of hot gas toward a black hole has been clearly imaged for the first time in X-rays.
The observations from Nasa’s Chandra X-ray Observatory will help tackle two of the most fundamental problems in modern astrophysics - understanding how black holes grow and how matter behaves in their intense gravity.
The black hole is at the centre of a large galaxy known as NGC 3115, located some 32million light-years from Earth.
A large amount of previous data has shown material falling towards and onto black holes, but none with this clear a signature of hot gas.
Composite: This image contains X-rays from Chandra (blue) and optical data from the VLT (gold) of the galaxy NGC 3115. Using the Chandra data, the flow of hot gas towards the supermassive black hole in the centre of this galaxy has been imaged - the first time that clear evidence for such a flow has been observed in any black hole
By imaging the hot gas at different distances from the supermassive black hole, scientists at the University of Alabama have observed a critical threshold where the motion of gas first becomes dominated by the black hole’s gravity and falls inward.
The distance from the black hole is known as the 'Bondi radius'.
Lead researcher Dr Ka-Wah Wong said: 'It’s exciting to find such clear evidence for gas in the grip of a massive black hole.
'Chandra’s resolving power provides a unique opportunity to understand more about how black holes capture material by studying this nearby object.'
As gas flows toward a black hole, it becomes squeezed, making it hotter and brighter, a signature now confirmed by the X-ray observations.
The researchers found the rise in gas temperature begins about 700 light-years from the black hole, giving the location of the Bondi radius.
This suggests the black hole in the center of NGC 3115 has a mass about two billion times that of the sun, making it the closest black hole of that size to Earth.
The Chandra data also show that the gas close to the black hole in the centre of the galaxy is denser than gas further out, as predicted.
Using the observed properties of the gas and theoretical assumptions, the team then estimated that each year gas weighing about 2 per cent the mass of the sun is being pulled across the Bondi radius toward the black hole.
Making certain assumptions about how much of the gas’s energy changes into radiation, astronomers would expect to find a source that is more than a million times brighter in X-rays than what is seen in NGC 3115.
'It’s exciting to find such clear evidence for gas in the grip of a massive black hole'
Dr Jimmy Irwin, from the University of Alabama and the study's co-author, said: 'A leading mystery in astrophysics is how the area around massive black holes can stay so dim, when there’s so much fuel available to light up.
'This black hole is a poster child for this problem.'
There are at least two possible explanations for this discrepancy. The first is that much less material actually falls onto the black hole than flows inside the Bondi radius.
Another possibility is that the conversion of energy into radiation is much less efficient than is assumed.
Different models describing the flow of material onto the black hole make different predictions for how quickly the density of the gas is seen to rise as it approaches the black hole.
A more precise determination of the rise in density from future observations should help astronomers rule out some of these models.
The research is published in the Astrophysical Journal Letters.
Keeping us company, the newly discovered asteroid leading the Earth around the Sun
Until now a tiny asteroid had secretly and silently run ahead of Earth on the planet's stroll around the Sun.
But scientists have found that for the coming hundreds of years we are certain not to only have the Moon for company on the year-long journey.
The discovery of this companion, known as Trojan 2010 TK7, which measures only about 300 yards across, makes Earth the fourth planet in the solar system that is known to share its orbit with an asteroid.
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Not alone: This artist's impression by NASA shows the trojan leading the Earth, and its extreme orbit around our planet is shown in green. Earth's orbit around the sun is indicated by blue dots
It well never get closer than 50-times the distance the moon sits from the us.
Currently, it is about 50 million miles away, and should come no closer than about 18 million miles.
'These objects are difficult to find from Earth, simply because they're not very big and they're pretty faint, and they're close to the Sun as seen from Earth,' explained Christian Veillet from the Canada-France-Hawaii Telescope and a co-author on the Nature study.
'But we can find them from space, and future satellites will likely find some more. We think that there are others which will be very close to the Earth and have motions that make them relatively easy to reach. So, they could be potential targets to go to with spacecraft,' he told BBC News.
The future: Scientists believe that astronauts could decide to land on Trojan 2010 TK7
Experts say in order to imagine its path, people should picture Earth and the asteroid travelling around a clock face, with the Sun in the middle.
Generally, the asteroid runs about two numbers ahead.
However, the asteroid sometimes ranges so far ahead that it's on the opposite side of the Sun from Earth, said Martin Connors of Canada's Athabasca University in Alberta.
He reports the discovery in today's issue of the journal Nature.
An asteroid of this type has previously only been detected only around Jupiter, Neptune and Mars.
There are few for Mars and Neptune and nearly 5,000 for Jupiter.
Spotting one in Earth's orbit is difficult from the ground because the potential locations are generally in the daytime sky, yet Connors and colleagues were able to focus a ground-based telescope in Hawaii on it in April, determining its orbit with enough precision to show it was a Trojan.
Donald K. Yeomans, manager of NASA's Near-Earth Object Program Office, who didn't participate in the discovery, agreed that the asteroid is a Trojan.
'Most scientists suspected Earth had them', he said, and 'I would guess there's others.'
'Hundreds of black holes that can swallow whole planets and solar systems roam galaxy'
Hundreds of invisible black holes powerful enough to swallow entire solar systems could be roaming the galaxy, say scientists.
The spiralling traps, created by the collapse of matter to an infinitely-dense state, are places where gravity is so strong it sucks in even light.
Now a new threat of 200 wandering "rogue" black holes has been predicted by supercomputer simulations of what happens when two black holes of different sizes or spin speeds collide.
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Black hole: The spiralling gravity traps can swallow entire solar systems and roam our galaxy
Scientists believe they would merge into a single black hole and be kicked into space at speeds as high as 2,500 miles per second.
Any star, planet or spacecraft that crossed the path of one of these black holes would be engulfed by its gravity, never to escape.
It would be difficult to see the danger coming, according to US astronomer Dr Kelly Holley-Bockelmann, from Vanderbilt University in Nashville.
"Rogue black holes like this would be very difficult to spot," she said.
"Unless it's swallowing a lot of gas, about the only way to detect the approach of such a black hole would be to observe the way in which its super-strength gravitational field bends the light that passes nearby.
"This produces an effect called gravitational lensing that would make background stars appear to shift and brighten momentarily."
Dr Holley-Bockelmann studied models of "intermediate mass" black holes that may reside in globular clusters - ancient collections of 100,000 to a million stars.
Black holes of this type, whose existence is controversial, would contain the equivalent of a few thousand Suns.
Dr Holley-Bockelmann's team investigated what would happen if an intermediate black hole collided with a smaller "stellar" black hole created by the explosion of a giant star at the end of its life.
The result is a "big kick" that would shoot the combined black hole out of the globular cluster at high velocity.
Astronomers have ample evidence for the existence of stellar black holes weighing less than 100 solar masses, which are thought to be plentiful in globular clusters.
A kick would also occur if black holes rotating at different speeds were to collide.
"We used different assumptions for the initial black hole mass, for the range of stellar black hole masses within a globular cluster, and assumed that the spins and spin orientations were distributed randomly," said Dr Holley-Bockelmann, who presented her findings today at a meeting of the American Astronomical Society in Austin, Texas.
"With our most conservative assumptions, we found that, even if every globular cluster started out with an intermediate-sized black hole, only about 30 per cent retain them through the merger epoch.
With our least conservative assumptions, less than 2 per cent of the globular clusters should contain intermediate mass black holes today."
Our galaxy, the Milky Way, contains roughly 200 globular clusters, leading Dr Holley-Bockelmann's team to conclude that hundreds of rogue black holes could be at large.
However the scientists say it is "extremely unlikely" that they will present any threat to us in the lifetime of the universe.
"Their danger zone, the Schwarzschild radius, is really tiny, only a few hundred kilometres," said Dr Holley-Bockelmann.
"There are far more dangerous things in our neighbourhood!"
Super-massive black hole devours a star and scientists watch it for the first time
A stunning cosmic jet from a super-massive black hole which shredded then swallowed a star has been observed by astronomers for the first time.
The extremely rare phenomenon caused by stellar debris being consumed by the hole has never been observed before.
Known as 'relativistic jets', they can reach hundreds of thousands of light years in length.
Stunning: This illustration shows plasma shooting out of the black hole after it devours a star. Such an event took place four billion light years from Earth
Swift's Ultraviolet/Optical (white, purple) and X-ray telescopes (yellow and red) showing the bursts
Most galaxies have super-massive black holes - regions of space that suck in everything nearby with their strong gravitation pull - at their core, with masses of millions or even billions of suns.
Scientists were first alerted to the phenomenon in March after Nasa's Swift telescope detected several bursts of X-rays from a quiet patch of sky.
Teams from both Pennsylvania State University and the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, said the bursts could be the remnants of a star pulled apart when it came too close to a black hole located 3.9billion light years away.
WHAT HAPPENS WHEN A STAR FALLS INTO A BLACK HOLE
As a star falls toward a black hole, it is ripped apart by intense tides.
The gas is corralled into an accretion disk that swirls around the black hole and becomes rapidly heated to temperatures of millions of degrees.
The innermost gas in the disk spirals toward the black hole, where rapid motion and magnetism create dual, oppositely directed 'funnels' through which some particles may escape.
Jets driving matter at velocities greater than 90 percent the speed of light form along the black hole's spin axis.
In the case of Swift J1644+57, one of these jets happened to point straight at Earth.
Dr David Burrows, from Pennsylvania State University which controls Swift, said chemical analysis of the bright flash's ultraviolet light show it comes from material being sucked into a black hole the size of a million suns.
Writing in Nature, they concluded that the Swift satellite just happened to be in the path of the jet of star remains that were shot out at 99.5 per cent the speed of light.
Dr Burrows said: 'Incredibly, this source is still producing X-rays and may remain bright enough for the Swift satellite to observe into next year. It behaves unlike anything we've seen before.'
The swallowing of a star by a black hole only happens once every one hundred million years in a galaxy.
The black hole is now believed to be even more powerful because of the additional mass from the swallowed star.
The absorption of large mass such as stars or even other black holes is what gives black holes growth and spawn the existence of super-massive black holes.Super-massive black holes could contain up to billions of solar masses.
By comparison, the sun is just one solar mass and the Earth is 1/332,950th of a solar mass.
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Moist black hole home to largest and farthest water reservoir ever detected in the universe
- Mass of water vapour is 140trillion times the size of all the water in the world's oceans combined
- The reservoir is 30billion trillion miles away
- It takes light 12billion years to reach Earth from there
The largest and farthest reservoir of water ever detected in the universe has been discovered 30billion trillion miles away.
Looking into a quasar - one of the brightest and most violent objects in the cosmos - researchers have found a mass of water vapour that's at least 140trillion times that of all the water in the world's oceans combined, and 100,000 times bigger than the sun.
Because the quasar is so far away, its light has taken 12billion years to reach Earth.
The observations therefore reveal a time when the universe was just 1.6billion years old.
An artist's impression of a quasar, or feeding black hole, similar to APM 08279+5255, where scientists have found the largest and farthest reservoir of water ever detected in the universe
Matt Bradford, a scientist at Nasa's Jet Propulsion Laboratory, said: 'The environment around this quasar is unique in that it's producing this huge mass of water.
'It's another demonstration that water is pervasive throughout the universe, even at the very earliest times.'
A quasar is powered by an enormous black hole that is steadily consuming a surrounding disk of gas and dust; as it eats, the quasar spews out huge amounts of energy.
Two teams of astronomers, each led by scientists at the California Institute of Technology, studied a particular quasar called APM 08279+5255, which harbours a black hole 20billion times more massive than the sun and produces as much energy as a thousand trillion suns.
Since astronomers expected water vapour to be present even in the early universe, the discovery of water is not itself a surprise, according to Mr Bradford.
There's water vapour in the Milky Way, although the total amount is 4,000 times less than in the quasar, as most of our galaxy's water is frozen.
Nevertheless, water vapour is an important trace gas that reveals the nature of the quasar.
In this particular quasar, the water vapour is distributed around the black hole in a gaseous region spanning hundreds of light-years - a light-year is about six trillion miles - and its presence indicates that the gas is unusually warm and dense by astronomical standards.
Although the gas is a chilly -53C (-63F) and is 300trillion times less dense than Earth's atmosphere, it's still five times hotter and ten to 100 times denser than what is typical in galaxies like the Milky Way.
The water vapour is just one of many kinds of gas that surround the quasar, and its presence indicates that the quasar is bathing the gas in both X-rays and infra-red radiation.
'It's another demonstration that water is pervasive throughout the universe, even at the very earliest times'
The interaction between the radiation and water vapour reveals properties of the gas and how the quasar influences it.
For example, analysing the water vapour shows how the radiation heats the rest of the gas.
Furthermore, measurements of the water vapour and of other molecules, such as carbon monoxide, suggest that there is enough gas to feed the black hole until it grows to about six times its size.
Whether this will happen is not clear as some of the gas may end up condensing into stars or may be ejected from the quasar.
Mr Bradford's team started making their observations in 2008, using an instrument called Z-Spec at the Caltech Submillimetre Observatory (CSO), a ten-metre telescope near the summit of Mauna Kea, Hawaii.
Z-Spec is an extremely sensitive spectrograph, requiring temperatures cooled to within 0.06C above absolute zero.
The instrument measures light in a region of the electromagnetic spectrum called the millimetre band, which lies between infra-red and microwave wavelengths.
The researchers' discovery of water was possible only because Z-Spec's spectral coverage is ten times larger than that of previous spectrometers operating at these wavelengths.
The astronomers made follow-up observations with the Combined Array for Research in Millimetre-Wave Astronomy, an array of radio dishes in the Inyo Mountains in southern California.
The research will be published in Astrophysical Journal Letters.
Saturn water mystery finally solved as scientists discover giant jets of vapour from moon are responsible
Water expelled from the moon Enceladus forms a giant torus of water vapour around Saturn, scientists have said.
The discovery by the European Space Agency's Herschel space telescope solves a 14-year mystery by identifying the source of the water in Saturn’s upper atmosphere.
It means that Enceladus is the only moon in the Solar System known to influence the chemical composition of its parent planet.
At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus. Light reflected off Saturn is illuminating the moon while the sun, almost directly behind Enceladus, is backlighting the plumes
Enceladus expels around 250kg of water vapour every second, through a collection of jets from the south polar region, known as the Tiger Stripes because of their distinctive surface markings.
These crucial observations reveal that the water creates a doughnut-shaped torus of vapour surrounding the ringed planet.
The total width of the torus is more than ten times the radius of Saturn, yet it is only about one Saturn radius thick.
Enceladus orbits the planet at a distance of about four Saturn radii, replenishing the torus with its jets of water.
Despite its enormous size, it has escaped detection until now because water vapour is transparent to visible light, but not at the infrared wavelengths Herschel was designed to see.
Saturn's atmosphere is known to contain traces of gaseous water in its deeper layers. A particular enigma has been the presence of water in its upper atmosphere.
Samples of ice spray shooting out of Enceladus were collected by Nasa's Cassini spacecraft. Scientists last month said they believe it is the strongest evidence yet that Enceladus has a large saltwater ocean lurking beneath its surface
First reported in 1997 by teams using ESA’s Infrared Space Observatory, the source of this water was unknown until now.
Computer models of these latest Herschel observations show that about 3 to 5 per cent of the water expelled by Enceladus ends up falling into Saturn.
Lead researcher Paul Hartogh, of the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, said: 'There is no analogy to this behaviour on Earth.
'No significant quantities of water enter our atmosphere from space. This is unique to Saturn.'
Although most of the water from Enceladus is lost into space, freezes on the rings or perhaps falls onto Saturn’s other moons, the small fraction that does fall into the planet is sufficient to explain the water observed in its upper atmosphere.
Herschel's infrared images have reveal that the water creates a doughnut-shaped torus of vapour surrounding the ringed planet
It is also responsible for the production of additional oxygen-bearing compounds, such as carbon dioxide.
Ultimately, water in Saturn's upper atmosphere is transported to lower levels, where it will condense but the amounts are so tiny that the resulting clouds are not observable.
Researcher Göran Pilbratt said: 'ESA’s Infrared Space Observatory found the water vapour in Saturn’s atmosphere. Then Nasa/ESA’s Cassini/Huygens mission found the jets of Enceladus.
'Now Herschel has shown how to fit all these observations together.'
Is this the biggest rock ever? Astronomers discover planet made of DIAMONDS
It is certainly what you could call a gem of a discovery.
Astronomers believe they have found an entire planet made of diamonds.
Scientists at the University of Manchester think they have unearthed a once-massive star in the Milky Way that has been transformed into a small planet made of the precious rock.
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Twinkle, twinkle little star: The diamond planet - the shrunken core of a once-huge star - is a chunk of crystallised carbon measuring 40,000 miles across, five times the diameter of Earth
The international research team first detected an unusual star, called a pulsar, and followed up their discovery with research using a telescope based in an observatory in Cheshire.
The findings led the scientists to discover the gravitational pull of a small companion planet orbiting the pulsar.
Pulsars are small spinning stars more than ten miles in diameter – the size of a small city – that emit a beam of radio waves.
The team, also made up of scientists from Australia, Germany, Italy and the United States, thinks that the ‘diamond planet’ is all that remains of the original star, most of whose matter was siphoned off towards the pulsar.
The companion planet is small, at less than 40,000 miles wide – about five times the diameter of Earth.
But it is so close to the pulsar that if it were any bigger it would be ripped apart by the gravitational force of the star, which rotates more than 10,000 times per minute and has a mass of about 1.4 times that of the sun.
Precious: The international research team found the diamond planet in our Milky Way (above) after first detecting an unusual star, called a pulsar. They think the planet is all that remains of the original star, most of whose matter was siphoned off towards the pulsar
Research team member Dr Michael Keith said: 'This remnant is likely to be largely carbon and oxygen, because a star made of lighter elements like hydrogen and helium would be too big to fit the measured orbiting times.'
The density means that this material is certain to be crystalline, that is, a large part of the star may be similar to a diamond.
The pulsar, dubbed PSR J1719-1438, and its planet are part of the Milky Way's plane of stars and lie 4,000 light-years away in the constellation of Serpens - the Snake.
The modulations in the radio pulses told astronomers a number of things about the planet.
It orbits the pulsar in just two hours and ten minutes, and the distance between the two objects is about 373,000 miles - a little less than the radius of our sun.
Despite its small size, the planet has slightly more mass than Jupiter.
About 70 per cent of millisecond pulsars have companions of some kind.
Astronomers think it is the companion that, in its star form, transforms an old, dead pulsar into a millisecond pulsar by transferring matter and spinning it up to a very high speed.
The result is a fast-spinning millisecond pulsar with a shrunken companion - most often a so-called white dwarf.
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