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Astronomers Uncover Mystery Of The Magnetic World Of Galaxies

September 6, 2017 by  
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Astronomers have detected the magnetic field of a galaxy located a whopping 5 billion light-years from Earth. 

“This finding is exciting,” Sui Ann Mao, an astronomer from the Max Planck Institute for Radio Astronomy in Germany, said in a statement. “It is now the record holder of the most distant galaxy for which we have this magnetic-field information.”

Mao led the team that made the find. The researchers used the Karl G. Jansky Very Large Array, a radio telescope network in New Mexico, to detect and characterize the magnetic field of the distant galaxy.

“This means that magnetism is generated very early in a galaxy’s life by natural processes, and thus that almost every heavenly body is magnetic,” study co-author Bryan Gaensler, a professor at the Dunlap Institute for Astronomy & Astrophysics at the University of Toronto, said in the same statement. “The implication is that we need to understand magnetism to understand the universe.”

Measuring the magnetic fields of other galaxies that are at different distances from Earth and are different ages can help astronomers better understand how cosmic magnetism evolves, study team members said. Since a faraway magnetic field can’t be detected directly, astronomers rely on observations of the magnetic fingerprint left on light passing through the field. This imprint is also known as Faraday rotation.

The astronomers discovered a quasar — an incredibly bright galactic core powered by a supermassive black hole — located beyond the galaxy being studied, along the same line of sight. As the bright light from the quasar passes through the galaxy’s magnetic field, it picks up the Faraday rotation fingerprint, providing astronomers with the information they need to learn more about the field’s strength and direction, the researchers said. 

“Nobody knows where cosmic magnetism comes from or how it was generated,” Gaensler said in the statement. “But now, we have obtained a major clue needed for solving this mystery, by extracting the fossil record of magnetism in a galaxy billions of years before the present day.”

Their findings were published today (Aug. 28) in the journal Nature Astronomy.


Astronomers Test Einsteins’s Relativity Theory With Star

August 16, 2017 by  
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A giant star near the center of our galaxy hints, once again, that Albert Einstein was correct about gravity.

A group of astronomers in Germany and the Czech Republic observed three stars in a cluster near the supermassive black hole at the center of the Milky Way galaxy. Using data from the Very Large Telescope in Chile, among others, the researchers tracked how the stars moved as they went around the monster black hole.

One of the stars, called S2, showed slight deviations in its orbit that might indicate relativistic effects, scientists said. If the observations are confirmed, then it shows that Einstein’s theory of general relativity holds even under extreme conditions — in gravity fields produced by objects like the galactic center’s black hole, which contains the mass of 4 million suns. General relativity says that massive objects bend the space around them, causing other objects to deviate from straight lines they would follow absent any forces on them.

The position of the supermassive black hole at the center of our Milky Way galaxy, as well as the giant star S2, are shown (inset) in this near-infrared image from the European Southern Observatory’s Very Large Telescope in Chile.The black hole’s position is marked with an orange cross.

“Most relativity tests are done with our sun and the stars, so they are in the 1-solar-mass or few-solar-mass[es] limit,” Andreas Eckart, a professor of experimental physics at the University of Cologne in Germany, who led the research team, told “Or with the [Laser Interferometer Gravitational-Wave Observatory] recently, that’s a few 10s of solar masses.” 

The stars used in the observations are so close to the black hole that they move at 1 or 2 percent the speed of light, Eckart said, and they approach to within only about 100 times the Earth-sun distance of the black hole itself, which is quite close by galactic standards, he said. (Pluto averages about 39 times the Earth’s distance from the sun, which is about 93 million

Using orbiting bodies to show relativistic effects is not new; observations of the planet Mercury in the 19th centuryshowed that its movements deviated from what Isaac Newton’s theory of gravity predicted. At first, astronomers thought they had evidence of another planet, which they dubbed Vulcan. Einstein was able to show in 1915 that relativity could explain the deviation.

Mercury’s motions proved Einstein correct, but the sun’s gravity is weak compared to that of a supermassive black hole. This is why Eckart and his team set out to see if Einstein’s theory held up in a more extreme environment. While gravitational lensing, the bending of light by massive objects, shows that massive objects bend space, the recent research is the first time anyone has taken precise measurements of any object orbiting so close to a black hole.

This artist’s illustration shows the orbits of three stars, including the giant star S2, around the supermassive black hole at the center of our Milky Way galaxy. Scientists say the stars’ orbits may show effects predicted by Einstein’s general theory of relativity.

The measurement itself is not as precise as it might be, Eckart said. Future work will get a better read on the stars’ positions and narrow down the result. He said one plan is to get better spectrographic measurements, which would reveal S2’s movement more precisely.


Astronomers Detect Weird Radio Signal From Red Dwarf

July 24, 2017 by  
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Strange radio signals have been spotted coming from the vicinity of a nearby star — but don’t get your hopes up that aliens are responsible.

On May 12, the 1,000-foot-wide (305 meters) Arecibo radio telescope in Puerto Rico detected “some very peculiar signals” apparently emanating from Ross 128, a red dwarf star that lies just 11 light-years from Earth.

“The signals consisted of broadband quasi-periodic nonpolarized pulses with very strong dispersion-like features,” Abel Mendez, director of the Planetary Habitability Laboratory at the University of Puerto Rico, wrote in a statement late last week.  

“We believe that the signals are not local radio frequency interferences (RFI) since they are unique to Ross 128, and observations of other stars immediately before and after did not show anything similar,” he added.

The three leading explanations for the signals, Mendez wrote, are solar flare-like emissions from Ross 128, emissions from some other object in the same field of view and a burst of some sort from a satellite orbiting high above Earth.

Each of these hypotheses has its issues, he said. For example, solar flares of the type that could be responsible generally occur at lower frequencies. In addition, Mendez wrote, there aren’t a lot of other objects in the Ross 128 field of view, “and we have never seen satellites emit bursts like that.”

But if you’re getting the urge to invoke E.T., temper it: “In case you are wondering, the recurrent aliens hypothesis is at the bottom of many other better explanations,” Mendez wrote.

Figuring out the signal’s source will require more data, and Mendez and his team already have some in hand. The researchers carried out a successful observation of Ross 128 — as well as of Barnard’s Star, a red dwarf located just 6 light-years from Earth — using the Arecibo dish yesterday (July 16), Mendez announced on Twitter yesterday. (These Arecibo observations are all part of a campaign to better understand the radiation and magnetic environments of red dwarfs, and to look for signs of undiscovered planets orbiting them, Mendez explained in his statement about the Ross 128 signals.)

Other research teams are following up as well. For example, scientists with the SETI (Search for Extraterrestrial Intelligence) Institute have already begun observing Ross 128 with the Allen Telescope Array, a network of 42 radio dishes in northern California, said Seth Shostak, a senior astronomer at the SETI Institute.

Like Mendez, Shostak said that aliens are unlikely to be the cause of the Ross 128 signal.

“It does look like the kind of broadband interference that you get in SETI experiments,” Shostak told

Astronomer Douglas Vakoch, president of the San Francisco-based nonprofit METI (Messaging Extraterrestrial Intelligence), shared similar sentiments.

“There’s nothing about these observations from May that resembles the sort of narrowband signal typically sought by radio SETI projects — a signal designed specifically to stand out against the cosmic static created by nature,” Vakoch told via email. “Beyond that, the signal hasn’t even been replicated — a fundamental requirement for a credible signal from an extraterrestrial civilization.”

In addition, Ross 128 has been studied repeatedly by SETI scientists, Vakoch said.

“On five separate occasions in the past, METI’s Optical SETI Observatory in Panama has scanned this star for brief laser pulses — all with no indication whatsoever that E.T. is calling,” he said. “If there’s an extraterrestrial civilization around this red dwarf in our galactic backyard, it seems like it’s staying very quiet.”

All of that being said, the E.T. hypothesis should not be dismissed, Shostak stressed.

“The historic lesson is clear — these things pop up, and you have to follow them up, because you never know what’s going to be the real one, or even if there will ever be a real one,” Shostak told “Following up is mandatory.”


Astronomers Suggest Billions Of Failed Stars Hiding In Our Milky Way

July 14, 2017 by  
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Brown dwarfs, or failed stars that resemble rogue planets, are far more abundant than astronomers previously thought. A whopping 100 billion of the small, dim celestial bodies could be lurking throughout the Milky Way, new research suggests. 

Like most stars, brown dwarfs form when clouds of interstellar gas and dust collapse under their own gravity. In main-sequence stars, the heat and pressure ignite the core through nuclear fusion. But some aspiring stars never reach that point: instead, they enter a stable state before fusion can begin. Without fusion, these failed stars don’t emit much light, and they can be difficult for astronomers to observe. A new study attempts to tally up how many brown dwarfs are hiding in the Milky Way, revealing a number that is much higher than expected.

Previous studies determined that there are about six stars for every brown dwarf in our cosmic neighborhood. Those studies only looked at brown dwarfs within a range of about 1,500 light-years from Earth, where such faint and tiny objects are easier to spot. However, the entire Milky Way spans a much greater distance of about 100,000 light-years, and it turns out that our neck of the woods isn’t exactly representative of the entire galaxy.

This false-color, near-infrared image of the star cluster RCW 38 reveals several small, faint brown-dwarf candidates. The image was taken using the NACO adaptive-optics camera at the European Southern Observatory’s Very Large Telescope.

Using deep-space observations by the European Southern Observatory’s Very Large Telescope in northern Chile, an international team of astronomers surveyed star clusters in the Milky Way to determine just how common these stealthy objects really are. The team, led by Koraljka Muzic from the University of Lisbon in Portugal and Aleks Scholz from the University of St Andrews in Scotland, began hunting for brown dwarfs in nearby star-forming regions in 2006.

While they were conducting their Substellar Objects in Nearby Young Clusters (SONYC) survey, the researchers discovered that the star cluster NGC 1333 contained an unusually high number of brown dwarfs. Rather than 1 brown dwarf for every 6 stars, there are about half as many brown dwarfs as there are stars in this star cluster — three times the previous estimate. 

At first, they weren’t sure if NGC 1333 was just a bizarre brown-dwarf hotspot, or if this observation had bigger implications. So the researchers expanded their brown-dwarf survey to look at a bigger chunk of the Milky Way. They then turned their telescope toward another star cluster named RCW 38, which lies 5,500 light-years away in the constellation Vela. Not only is this cluster about five times farther away from Earth than the previously surveyed regions, but it’s also more densely populated with bigger and brighter stars.

In order to detect the brown dwarfs in RCW 38, the researchers used a special adaptive optics camera on the European Southern Observatory’s Very Large Telescope called NACO. This instrument combines two technologies: the Nasmyth Adaptive Optics System (NAOS), which counteracts distortion caused by turbulence in Earth’s atmosphere, and the Near-Infrared Imager and Spectrograph (CONICA), an infrared camera and spectrometer. Because brown dwarfs emit red and infrared light, these technologies allowed researchers to see the distant, dim and tiny objects hiding among a crowd of large and brilliant stars.  

Again, the researchers counted about half as many brown dwarfs as actual stars in RCW 38. “This is in agreement with the values found in other young star-forming regions, leaving no evidence for environmental differences in the efficiency of the production of [brown dwarfs] and very-low mass stars possibly caused by high stellar densities or a presence of numerous massive stars,” the study’s authors wrote in a research paper, which was published online in the Monthly Notices of the Royal Astronomical Society.

“We’ve found a lot of brown dwarfs in these clusters. And whatever the cluster type, the brown dwarfs are really common,” Scholz said in a statement. “Brown dwarfs form alongside stars in clusters, so our work suggests there are a huge number of brown dwarfs out there.”

The researchers determined that the minimum number of brown dwarfs in the Milky Way is somewhere between 25 billion to 100 billion. But there are likely far more than that, the researchers suspect, because there are many more brown dwarfs in the galaxy that are too small and faint to be detected with today’s telescopes.

Scholz presented the new findings at the National Astronomy Meeting in Hull, England, on Thursday July 6.


Astronomers Speculate The Fate Of The First Stars In The Milky Way

July 12, 2017 by  
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When astronomers gaze at the center of the Milky Way, some 27,000 light years from our Solar System, a jumble of gas and dust obscures their view. Bursting through the mess, however, is a radio signal, immensely powerful, and keenly focused, unlike anything else in our galaxy. Astronomers are now very certain that the signal emanates from Sagittarius A*, an immense black hole 44 million kilometers in diameter (a little less than the closest distance from the Sun to Mercury) with a mass of four million Suns. Pretty much everything in our galaxy revolves around this gargantuan object.

But more amazing than Sagittarius A* itself is the story of how it came to be. What follows consists of learned speculation, inferences, and hypotheticals based on astronomical observations and cosmological theory. None of it has actually been seen… yet.

Long ago, perhaps just a hundred million years after the Big Bang, the formed. Born within the thick, gassy soup of the early Universe, these stars fed on the pristine hydrogen and helium from the Big Bang itself. Because there was so much elemental fuel, they gorged themselves into behemoths, growing hundreds of times more massive than our Sun, and far larger than any even the largest stars that exist today. They burned bright, but died young, living as few as two million years. For comparison, stars like our Sun persist for billions of years

But though deceased, these first stars were not finished affecting the Universe. In fact, they may litter the cosmos today, albeit in an unrecognizable form.

“These enormous stars are… thought to have left behind enormous black holes when they died…” Lehman College astrophysicist Matt O’Dowd explained on a recent episode of PBS Space Time. “Clusters of giant stars become clusters of giant black holes, which, in turn, would merge into monsters of thousands or tens of thousands of solar masses. Now, these were probably the seeds of the so-called supermassive black holes, with millions to billions of times the mass of the sun, that we find lurking in the centers of galaxies.”

So Sagittarius A*, essentially the heart of our galaxy, may be the blackened husk of some of the first stars in the Universe. The other two trillion galaxies in the Universe may also have formed around their remains.

There is a very good chance that this tale is true, but that is not enough. Actually seeing is infinitely better than simply believing. Scientists know this, which is why astronomers are busy building the telescopes of the future that could allow us to test cosmologists’ theories.

The launch of the James Webb Space Telescope is now just a little over a year away. At least one group of astronomers is hopeful that its gaze will be far-reaching enough to directly detect the Universe’s first stars. Doing so could bring the story of Sagittarius A* firmly into the realm of non-fiction, or it could tell us something completely unexpected. Whatever we end up seeing, it’s sure to be awe-inspiring.


Is Light Speed Really Slow

June 29, 2017 by  
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In 2015, a team of Scottish scientists announced they had found a way to slow the speed of light. By sending photons through a special mask, the researchers altered their shape. In this malformed state, these infinitesimal particles of light traveled slower than normal photons.

The difference in speed was almost imperceptible, but the accomplishment itself was stunning! At 299,792,458 meters per second, the speed of light has stood as an unbreakable, unchangeable speed limit. No longer.

But why would anybody want to slow down the speed of light? After all, it’s already slow enough!

As strange as that assertion may seem to humans accustomed to traveling a mere 70 miles per hour on the highway, it makes a lot of sense on a cosmic scale. Consider this: If the observable Universe was reduced to the size of planet Earth, traversing the Milky Way Galaxy would be roughly equivalent to walking three houses down the block to visit your neighbor. And yet, traveling at the cosmic speed limit of our smaller, Earth-size universe, that short jaunt would take 100,000 years!

This example showcases just how tediously slow exploring the galaxy would be for a ship traveling at the speed of light. Such a journey would span more than a hundred human generations!

Even if you don’t consider humanity’s self-centered wish for interstellar light-speed travel and instead think about photons dashing across our solar system, the speed of light still seems positively sluggish. As astrophysicist Brian Koberlein calculated, it takes 45 minutes for light from the Sun to reach Jupiter, and five hours for it to reach Pluto.

And of course, when gazing at the sky with the naked eye, we’re viewing some stars as they were more than 4,000 years in the past — that’s how long it takes their light to reach us!

So now that we’ve ascertained that light is not fast but rather is excruciatingly slow, we can now turn to a more pressing and difficult matter: Why?

Theoretical physicists can muse and cosmologists can measure, but all their learned tinkering currently leads back to an inescapable answer: Because.

Theoretical physicist Gennaro Tedesco provided a slightly more satisfying version:

The universe is made such that photons propagate with that velocity, there is no reason why it should be so, but it is just the way it is. Physics does not explain why things are what they are, rather it explains how to make predictions by using proven models.

Okay, so like in much of theoretical physics, the answer is effectively a non-answer, and we’re still stuck in a slow universe.

To salvage this situation, let’s examine a scenario where light is much faster. What would existence be like if, say, the speed of light was boosted by a factor of 1,000? Steve Jones explored the hypothetical. A light-speed vessel could cross the Milky Way in less than a century! A trip to Alpha Centauri, home to a potentially habitable planet, would take fewer than two days! Computers and networks would run faster thanks to enhanced optical speeds! We might be more likely to receive signals from extraterrestrials!

But – and this is a big but – the Sun would burn a million times hotter. We’d be cooked.

So you better learn to love our finely tuned speed of light, however slothlike it may be. If it were any faster, life on Planet Earth might not exist.


Astronomers Use Hubble To Capture Extremely Bright Galaxies

June 22, 2017 by  
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A glittering jackpot of ultrabright galaxies bursting with star formation has been revealed in a series of stunning images taken by the Hubble Space Telescope.  

The galaxies captured in these images sparkle like jewels of cosmic light. These massive collections of stars are each as much as 10,000 times more luminous than the Milky Way in the infrared range, or 10 trillion to 100 trillion times the brightness of the sun. They are also forming about 10,000 new stars each year, according to a statement from NASA. (By comparison, it is estimated that fewer than 10 stars form in the Milky Way each year.)

Viewers may also notice strange shapes, including rings and arcs of light. Those are mostly the result of a cosmic phenomenon known as gravitational lensing, in which a foreground galaxy acts as a lens, warping and magnifying the light from a more distant galaxy

This lensing has magnified the light from these very distant galaxies, giving scientists the opportunity to study in them in much finer detail than would be otherwise possible. 

“These ultra-luminous, massive, starburst galaxies are very rare,” James Lowenthal, an astronomy professor at Smith College in Massachusetts and lead researcher on the Hubble survey, said in the statement. “Gravitational lensing magnifies them so that you can see small details that otherwise are unimaginable. We can see features as small as about 100 light-years or less across. We want to understand what’s powering these monsters, and gravitational lensing allows us to study them in greater detail.”

The birth and death of so many stars generate a lot of new gas and dust, which obscures the galaxies in many wavelengths of light, including visible. But infrared light can penetrate those layers. These galaxies were first identified by the European Space Agency’s Planck satellite, and were subject to further study by other instruments, but the Hubble observations confirmed that gravitational lensing is making them brighter and more visible. 

The furious star formation in these galaxies coincides with the “peak of the universe’s star-making boom between 8 billion and 11.5 billion years ago,” according to the statement. Even so, only a few dozen of these star-forming, bright infrared galaxies existed in that period of the early universe, NASA said. 

In the nearby universe, researchers have identified so-called ultra-luminous infrared galaxies (ULIRGS), which are also massive, cloaked in dust, and have high rates of star formation. The star formation in those galaxies is “stoked by the merger of two spiral galaxies,” according to the statement. Such a collision could have brought together large amounts of gas and dust into a relatively small region, creating an environment ripe for star formation. 

But it’s not clear if similar galaxy mergers were taking place between 11.5 billion and 8 billion years ago, so scientists aren’t sure if the galaxies seen in this recent Hubble survey are fueled by the same mechanism as the nearby galaxies. 

“The early universe was denser, so maybe gas is raining down on the galaxies, or they are fed by some sort of channel or conduit, which we have not figured out yet,” Lowenthal said. “This is what theoreticians struggle with: How do you get all the gas into a galaxy fast enough to make it happen?”

To unlock the mysteries these galaxies may hold, scientists need to know if the strange features that appear in the Hubble images — the curves and arcs of light — are artificial features generated by the lensing effect, or if they are indicative of actual features around the galaxies. The researchers now need to separate artifice from reality to come up with some answers.


Astronomer Find The Building Blocks Of Life Found Around Baby Star

June 21, 2017 by  
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The young, triple-star system IRAS 16293-2422 is located approximately 400 light-years from Earth in the constellation of Ophiuchus. The infant stars in this system have a similar mass to the sun, but are still in the early stages of formation. 

Researchers have detected a complex organic molecule called methyl isocyanate near the stars. This is the first time that the molecule, which can be a precursor to life, has been found around sun-like protostars, according to a statement from the European Southern Observatory (ESO). [6 Most Likely Places for Alien Life in the Solar System]

Previously, astronomers found a simple form of sugar in the disk of gas and dust surrounding IRAS 16293-2422. The sugar, called glycolaldehyde, is linked to the formation of RNA, which is one of the building blocks of life. 

“This star system seems to keep on giving! Following the discovery of sugars, we’ve now found methyl isocyanate,” Niels Ligterink and Audrey Coutens, researchers at the Leiden Observatory in the Netherlands and University College London, respectively, said in the statement. “This family of organic molecules is involved in the synthesis of peptides and amino acids, which, in the form of proteins, are the biological basis for life as we know it.” Ligterink and Coutens make up one of two teams of astronomers who detected the new molecule; the findings are detailed in two studies that will be published in the Monthly Notices of the Royal Astronomical Society.

Using the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope in Chile, the astronomers found signatures of methyl isocyanate molecules in the inner regions of the dust and gas surrounding each of the stars, according to the ESO statement. “We are particularly excited about the result because these protostars are very similar to the sun at the beginning of its lifetime, with the sort of conditions that are well suited for Earth-sized planets to form,” Rafael Martín-Doménech and Víctor M. Rivilla, co-lead authors of the second study, said in the statement. “By finding prebiotic molecules in this study, we may now have another piece of the puzzle in understanding how life came about on our planet.”

Earth and other planets in the solar system formed from material left over after the formation of the sun. Therefore, studying young, sun-like stars like IRAS 16293-2422 can help astronomers learn more the early years of our solar system.

In addition to the ALMA data, both teams of researchers used computer chemical modeling to better understand the origin of the methyl isocyanate molecules.

Models suggest that the molecules likely formed on “icy particles under very cold conditions that are similar to those in interstellar space,” Ligterink said. 

“This implies that this molecule — and thus the basis for peptide bonds — is indeed likely to be present near most new young solar-type stars,” he added. 


Einstein’s Theory Used To Calculate The Mass Of A Star

June 16, 2017 by  
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The mass of Stein 2051 B, a white dwarf star located about 18 light-years from Earth, has been a subject of some controversy for over a century. Now, a group of astronomers has finally made a precise measurement of the star’s mass and settled a 100-year-old debate, using a cosmic phenomenon first predicted by Albert Einstein. 

The researchers calculated the star’s mass using carefully timed observations made by the Hubble Space Telescope, which studied Stein 2051 B when it eclipsed another, more distant star, as seen from Earth. During this transit, the background star appeared to change its position in the sky, moving ever so slightly to the side, even though its actual position on the sky had not changed at all. 

This cosmic optical illusion is broadly known as gravitational lensing, and its effects have been observed extensively throughout the universe, especially near very massive objects, such as entire galaxies. The effect occurs because a massive object warps the space around it and acts like a very large lens, bending the path of the light from the more distant object. In some cases, this creates the illusion that the background star has been displaced. 

(Water can also create this kind of displacement illusion; try placing a pencil in a glass of water, and note that the submerged half of the pencil appears disconnected from the dry half.)  

Einstein predicted that these displacement events could be used to measure individual stellar masses. That’s because the extent to which the background star’s position is offset depends on the mass of the foreground star. But telescopes at the time lacked the sensitivity to make that dream a reality. 

The scientists behind the new work said no one, before now, has ever used the displacement of a background star to calculate the mass of an individual star. In fact, there is only one other example of scientists measuring this displacement between individual stars: During the 1919 total solar eclipse, scientists saw the sun displace a few background stars. That measurement was possible only because of the sun’s proximity to Earth. 

A paper describing the new work was published online today in the journal Science.

Einstein’s theory of general relativity hypothesized that space is flexible rather than fixed, and that massive objects (like stars) create curves in space, sort of like a bowling ball creating a curve on the surface of a mattress. The degree to which an object warps space-time depends on how massive that object is (similarly, a heavier bowling ball puts a deeper imprint on a mattress).

A ray of light normally travels in a straight line through empty space, but if the ray passes close by a massive object, the curve in space created by the star acts like a bend in the road, causing the light ray to veer away from its formerly straight path. 

Einstein showed that this deflection could direct more light toward the observer, similar to how a magnifying glass can focus diffuse light from the sun down into a single spot. This effect causes the background object to appear brighter, or it creates a ring of bright light around the foreground object called an Einstein ring.  

Astronomers have observed Einstein rings and “brightening events” when very massive foreground lenses, like entire galaxies, create the phenomena. These have also been observed along the plane of the Milky Way galaxy, where individual stars likely cause the lensing effect. It has also been used to detect planets around other stars.  

In the new study, astronomers reported the first ever observation of so-called “asymmetric lensing” involving two stars outside Earth’s solar system, in which the position of the background star appeared to change. 

The degree of displacement is directly related to the foreground object’s mass. With relatively “light” objects, like stars, the displacement is extremely small and thus more difficult to detect, according to Kailash C. Sahu, an astronomer at the Space Telescope Science Institute in Baltimore, and the lead author on the new paper. In the case of Stein 2051 B, the displacement was about 2 milliarcseconds on the plane of the sky, or about equal to the width of a quarter seen from 1,500 miles (2,400 kilometers) away, Sahu said.

Measuring such a subtle change required a powerful instrument, like the Hubble telescope’s high-resolution camera, which was installed in 2009. This instrument also made it possible to pick out the light from the displaced star, which was somewhat overshadowed by the light from Stein 2051 B — like a firefly next to a lightbulb, Sahu said. 

The researchers took eight measurements between October 2013 and October 2015, so they could observe the white dwarf moving across the sky, eclipsing the background star and creating the displacement. The scientists also observed the actual position of the background star after the white dwarf had passed by. 

Many variables could affect whether scientists can observe more events like this. Those variables include the alignment of the two objects, the mass and proximity of the foreground object, the separation between the foreground and background object, and the sensitivity of the telescope. But Sahu said he thinks his team has demonstrated the effectiveness of the method and that scientists could use it to measure the masses of about two to four nearby stars per year. 

White dwarfs are stars that have stopped burning hydrogen in their cores and subsequently shed their outer layers. In each of these stars, the remaining mas has collapsed into a dense core known as a white dwarf. This collapse drives up the temperature on the surface of these objects, so they may burn hotter than “living” stars. 

“At least 97 percent of the stars in the sky, including the sun, will become or already are white dwarfs,” Terry Oswalt, a professor of engineering and physics at Embry-Riddle Aeronautical University in Daytona Beach, Florida, wrote in an accompanying Perspectives article in Science. “Because they are the fossils of all prior generations of stars, white dwarfs are key to sorting out the history and evolution of galaxies such as our own.”

The mass of Stein 2051 B has been “a source of controversy for over 100 years,” said Oswalt, who was not affiliated with the new research. 

The current picture that scientists have of white dwarfs suggests that the mass and radius of these objects reveals important information about how they formed, what they’re made of, and what kind of stars they formed from, according to Sahu. 

Previous measurements of the mass of Stein 2051 B suggested it was largely composed of iron, but that finding presented several problems based on accepted theories about white dwarf formation and stellar evolution, according to the research paper. For example, to form large amounts of iron, the star that would become Stein 2051 B would have to have been extremely massive, but the radius of Stein 2051 B suggests it formed from a star not much larger than the sun. 

If those measurements of Stein 2051’s mass were correct, it would have sent astrophysicists back to the drawing board to figure out how such an object could have formed. Sahu said astronomers realized their measurements of Stein 2051 B’s mass were probably incorrect, but they had no way to know for sure.  

Typically, the only way to measure the mass of a star is to observe how it interacts with another massive body. For example, in a binary system where two stars orbit each other, the heavier star will have a large influence on the motion of the lighter one, and by observing the two stars’ interaction over time, scientists can calculate more and more specific values for the stars’ masses. Stein 2051 B has a companion, but the two bodies orbit very far apart, so their influence on each other is minimal. 

The new result shows that Stein 2051 B is in fact a very normal white dwarf, and it fits in just fine with the accepted formation theory Sahu said. Its mass is about 0.68 times the mass of the sun, indicating it formed from a star about 2.3 times the mass of the sun, Sahu said. That’s compared to the previous measurement which placed the white dwarf’s mass at about 0.5 times the mass of the sun. Not very many white dwarfs have had both their masses and radii measured precisely, he added .

“It confirms white dwarf mass-radius relationship,” he said. “[Astrophysicists] have been using that theory, and it’s good to know it’s on solid footing.”


Astronomers Discover 3rd Black Hole Merger

June 13, 2017 by  
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It’s not a fluke: For the third time, scientists have detected ripples in space-time caused when two black holes circle each other at mind-bending speeds and collide.

The LIGO gravitational-wave detector spotted the space-time ripples on Jan. 4, members of the LIGO Scientific Collaboration announced today (June 1).

If this news sounds familiar, it’s because this is the third black-hole collision that LIGO has detected in less than two years. These three consecutive discoveries signal to astrophysicists that mergers between black holes in this mass range are so common in the universe that LIGO may detect as many as one per day when the observatory begins operating at its full sensitivity, members of the collaboration said during a news teleconference yesterday (May 31). 

“If we’d run for a long time and hadn’t seen a third black-hole merger … we would have started scratching our heads and saying, ‘Did we just get really lucky that we saw these two rare events?'” David Reitze, LIGO Laboratory executive director and a professor of physics at the California Institute of Technology, told “Now I think we can say safely that that’s not the case. I think that’s exciting.”

A batch of black-hole detections by LIGO could help scientists learn how black holes of this size — those with masses tens of times that of the sun, or so-called stellar-mass black holes — are born, and what causes them to come together and merge into a new, single black hole. A paper describing the new discovery includes a few clues about the spins of the original two black holes, which is an early step in learning about the environment where they formed and how they ended up colliding.  

Ripples in space-time

LIGO (which stands for Laser Interferometer Gravitational-Wave Observatory) was the first experiment in history to directly detect gravitational waves — ripples in the universal fabric known as space-time that were first predicted by Albert Einstein. The famous physicist showed that space and time are fundamentally linked, such that when space is distorted, time can either slow down or speed up.

Although LIGO first began taking data in 2002, it wasn’t until the observatory underwent a major upgrade, called Advanced LIGO, that it achieved the sensitivity necessary to make a detection. The first black-hole merger spotted by LIGO was announced in February 2016; the second was announced in June 2016.

This new merger spotted by LIGO took place between one black hole with a mass about 19 times that of the sun, and another with a mass about 31 times that of the sun. Those companions combined to form  a new black-hole with a mass of about 49 times that of the sun (some mass can be lost during the merger). The entire mass of that final black hole is packed into an object with a diameter of about 167 miles (270 kilometers), or about the width of the state of Massachusetts, according to the LIGO scientists.

This newly-formed black hole falls between the final masses of the black holes that LIGO previously detected, which were 62 solar masses and 21 solar masses.

The gravitational waves created by this new black hole collision had to travel across the universe for 3 billion years before they reached Earth. That means this new black hole merger occurred more than twice as far away from Earth as the first and second  black hole mergers detected by LIGO. The gravitational waves from those black hole collisions traveled for 1.3 billion and 1.4 billion years to reach Earth, respectively.

This map of the night sky shows the location of three confirmed black hole mergers detected by the LIGO gravitational wave experiment, as well as a fourth , unconfirmed event. The most recent detection is labelled GW170104. LIGO can only locate the source of a gravitational wave signal to a fairly large area on the sky. When more gravitational wave detectors come online, those experiments will be able to help LIGO narrow down the source of a signal.

Credit: LIGO/Caltech/MIT/Leo Singer (Milky Way image: Axel Mellinger)

However, as with the previous two detections, the LIGO detector can’t determine precisely where the newly formed black hole is located. Rather, the data only narrows down the source of the signal to an area of about 1,200 square degrees. (See the map of the sky above to see the area from which the signal could have come.)

Because black holes don’t radiate any light of their own (or reflect light from other sources), they are effectively invisible to light-based telescopes, unless regular matter nearby creates a secondary source of light. Black holes with masses between 20 and 100 solar masses aren’t expected to have much, if any, regular matter around them radiating light, and black holes in this mass range hadn’t been observed by astronomers prior to LIGO’s three discoveries.

But gravitational waves come directly from the black holes. This opens up a new realm of the universe that is visible to an instrument like LIGO, which was designed to detect gravitational waves, but invisible to other telescopes. The three mergers that LIGO detected not only confirm the existence of black holes in this mass range, but also show that they are fairly common throughout the universe, according to the collaboration members.

In the data from the new detection, the LIGO scientists managed to glean a little information about the spin of the two black holes. Those clues could hint at why the black holes wound up crashing into each other, LIGO collaboration members said.

Black holes spin on their axes just as the Earth, most planets and most moons do. Stellar-mass black holes are thought to form when massive stars run out of fuel and collapse. If two massive stars live in a “binary” system, they will typically spin along the same axis, like two tops spinning next to each other on the ground. When those stars become black holes, they will also spin along the same axis, researchers said in a statement from Caltech.

But if the black holes formed in different regions of a stellar cluster and come together later, they may not spin along the same axis. Those misaligned spins will slow the merger, said Laura Cadonati, the LIGO Scientific Collaboration’s deputy spokesperson and an associate professor of physics at the Georgia Institute of Technology.

“In our analysis, we cannot measure spins of individual black holes very well but can tell if they’re generally spinning in same direction,” Cadonati said during yesterday’s news teleconference. The LIGO data doesn’t provide a strong ruling about whether the black-hole spins were aligned or misaligned. The authors of the new research concluded that the data “disfavors” the identical spin alignment of the black-hole axis, according to the paper, which has been accepted for publication in the journal Physical Review Letters.

“This is the first time that we have evidence that the black holes may not be aligned, giving us just a tiny hint that binary black holes may form in dense stellar clusters,” Bangalore Sathyaprakash, a researcher at Pennsylvania State University and Cardiff University and one of the LIGO collaboration members who edited the new paper, said in the statement from Caltech.

Of course, black-hole mergers could arise from both scenarios. To get an idea of the most common origin story for solar-mass black-hole mergers, LIGO scientists will need more than three examples to study.

The discovery of three stellar-mass black-hole mergers in less than two years indicates that LIGO will be seeing a lot more of these types of events, Reitze told But three events are still not enough to know for sure exactly how frequently LIGO will begin to see these black-hole collisions once its sensitivity is increased. The optimistic estimate that Reitze and other collaboration members cite is one per day, but even the pessimistic estimates are around one per month. That means LIGO could collect data on tens to hundreds of black-hole mergers in three to five years of operations. With this collection of black-hole mergers, scientists will be able to learn about the general population rather than a few individuals.  

A large collection of black holes could also provide scientists with a deeper look at Einstein’s theory of general relativity. Black holes are “pure space-time,” according to Reitze, meaning that while they might have formed from regular matter, their interaction with the universe has none of the properties of regular matter. Rather, the characteristics of a black hole are described entirely in terms of how its gravity warps space-time or influences other objects.

The theory of relativity predicted the existence of space-time and gravitational waves, so LIGO’s detection of this phenomenon was another confirmation that the theory is accurate. But the study of black holes and gravitational waves could also reveal cracks in that theory.

For example, when light waves pass through a medium like glass, they may be slowed based on their wavelength — a process called dispersion. General relativity states that gravitational waves should not be dispersed as they travel through space, and the researchers saw no sign of dispersion in LIGO’s new data.

For now, it seems, Einstein was right. But one of the most exciting things that LIGO could potentially discover is a flaw in the theory, Reitze said. Einstein’s theory of gravity has withstood scrutiny for more than a century, but it also doesn’t match up with the theory of quantum mechanics. The lack of an obvious connection between gravity (which generally describes the universe on very large scales) and quantum mechanics (which describes the universe on very small scales) is one of the most significant unsolved problems in physics. That problem isn’t likely to go away unless it turns out there’s some still-undiscovered angle to one or both of those theories.

“The question is, where does [general relativity] break down,” Reitze said, and will LIGO’s data on black holes provide the right laboratory for answering that question?

The detection of a gravitational-wave signal is significant for LIGO because it confirms that the experiment is “moving from novelty to real gravitational-wave science,” David Shoemaker, a spokesperson for the LIGO Scientific Collaboration and a professor of physics at MIT, said during the news conference. This gravitational-wave-hunting machine has officially demonstrated its ability to illuminate a once-dark sector of the universe.


Astronomers Find Two Massive Black Holes On A Collision Course

June 6, 2017 by  
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Two monster black holes are apparently on a collision course near the heart of a nearby galaxy, a new study reports.

Astronomers have spotted an extremely bright object located about 1,500 light-years from the supermassive black hole known to occupy the heart of Cygnus A, an oft-studied galaxy that lies about 800 million light-years from Earth. 

“We think we’ve found a second supermassive black hole in this galaxy, indicating that it [the galaxy] has merged with another galaxy in the astronomically recent past,” study co-author Chris Carilli, of the National Radio Astronomy Observatory (NRAO) in New Mexico, said in a statement.

“These two would be one of the closest pairs of supermassive black holes ever discovered, likely themselves to merge in the future,” Carilli added.

The researchers studied Cygnus A in 2015 and 2016 using the Very Large Array (VLA), a system of radio telescopes in New Mexico. These observations revealed the mysterious bright object, which had not appeared in earlier VLA images of Cygnus A from the 1980s and 1990s.

The completion of a VLA upgrade in 2012 motivated the new imaging campaign, study team members said. 

“To our surprise, we found a prominent new feature near the galaxy’s nucleus that did not appear in any previous published images. This new feature is bright enough that we definitely would have seen it in the earlier images if nothing had changed,” co-author Rick Perley, also of the NRAO, said in the same statement. “That means it must have turned on sometime between 1996 and now.”

Additional observations made in 2016 by the radio telescopes of the Very Long Baseline Array, which is also located in New Mexico, detected the object as well. 

Infrared images captured by NASA’s Hubble Space Telescope and Hawaii’s Keck Observatory between 1994 and 2002 show a faint object in the same spot within Cygnus A. This mysterious body had originally been interpreted as a clump of stars, but the recent and dramatic brightening is forcing a rethink, study team members said.

There are only two viable possibilities that could explain the new observations, the researchers added: The object is either a supernova or a supermassive black hole in outburst mode.

The team favors the black-hole hypothesis, because no known type of supernova could stay so bright for so long, the researchers said. The second supermassive black hole probably became so active after stumbling onto a lot of material to gobble up — perhaps a star that strayed too close, or gas stirred up by the galaxy merger, the researchers said.

“Further observations will help us resolve some of these questions,” said study lead author Daniel Perley, of the Astrophysics Research Institute of Liverpool John Moores University in England (and Rick Perley’s son). “In addition, if this is a secondary black hole, we may be able to find others in similar galaxies.”

The new study has been accepted for publication in The Astrophysical Journal. 


Did Astronomers Find A Renegade Supermassive Black Hole

June 1, 2017 by  
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Astronomers have spied the possible aftermath of a colossal black hole collision that happened in the center of a galaxy far, far away.

Usually, researchers find supermassive black holes that are stationary objects, anchored in the cores of their galactic hosts. So astronomers became excited when they spotted a “renegade” supermassive black hole speeding through space, as reported in a new study.

The black hole, which is 160 million times the mass of Earth’s sun, appears to be the result of a collision with another black hole in a galaxy 3.9 billion light-years away from Earth.

Theory suggests that when two galaxies merge, supermassive black holes in the two galaxies’ cores orbit one another and eventually collide. The black hole pair may merge to create an even more massive supermassive black hole. But sometimes, the pair can violently recoil, and one of the black holes may be kicked in the opposite direction at great speed.

Researchers spotted what seems to be a “renegade” supermassive black hole speeding away from the site of a galactic merger.

The energy behind this powerful recoil is referred to as gravitational waves. As two black holes approach one other, they generate a lot of these ripples in space-time, and if the conditions are right, there might be a preponderance of gravitational waves blasted out in one direction, ejecting one of the black holes.

While searching through thousands of Sloan Digital Sky Survey (SDSS) observations in hopes of finding these recoiling black holes, the new study’s researchers noticed a very bright X-ray source at the center of one galaxy. This is a telltale sign that a black hole is active and growing, the researchers said in a statement. 

Then, using the Hubble Space Telescope, they discovered that the emissions were coming from two distinct objects. Further observations by NASA’s Chandra X-ray Observatory and the Keck telescope in Hawaii revealed that one of the two black holes is not in the center of its galaxy and is traveling at a different speed than its surroundings.

These clues suggest the object is a recoiling black hole, and the host galaxy itself also carries evidence of the merger that could have instigated it, the researchers said. The galaxy is forming stars at a high rate, for example, which is a sign that interstellar gases have been compressed. Also, the outer regions of the galaxy show signs of a massive disturbance.

Although the data supports a bona fide recoiling black hole, the researchers said in the statement, further observations are needed to rule out other explanations.

The study was recently accepted to The Astrophysical Journal and is available online on


Astronomers Find X-Ray Tsunami Rolling Through Galaxy Cluster

May 11, 2017 by  
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A wave of hot gas twice as wide as the Milky Way galaxy roils the nearby Perseus galaxy cluster, a new study indicates.

The wave, which measures 200,000 light-years across, likely formed billions of years ago, after a neighboring cluster clipped Perseus, researchers said. You can watch the monster wave roll in this awesome NASA video.

“The wave we’ve identified is associated with the flyby of a smaller cluster, which shows that the merger activity that produced these giant structures is still ongoing,” lead author Stephen Walker, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.

Galaxy clusters are the largest gravitationally bound structures in the universe. For example, Perseus — which lies 240 million light-years away from Earth, in the constellation of the same name — spans a vast 11 million light-years.

Most of the observable matter within galaxy clusters is superheated gas that glows in X-ray wavelengths, study team members said. Observations by NASA’s Chandra X-ray Observatory and other instruments have revealed many interesting formations in Perseus’ glowing gas, including an odd, 200,000-light-year-long concave feature dubbed “the bay.”

The bay generates no emissions, so — unlike some other features in the massive gas field — its origins don’t trace back to activity of the supermassive black hole at the core of Perseus’ central galaxy, NGC 1275, study team members said. And the bay’s shape doesn’t match those predicted by computer models that simulate normal gas sloshing, the scientists added.

So, the researchers re-analyzed Chandra images of the bay, filtering them to highlight edges and other important details. Then, the scientists compared these enhanced observations to computer simulations of merging galaxy clusters performed by astrophysicist John ZuHone, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

“Galaxy cluster mergers represent the latest stage of structure formation in the cosmos,” said ZuHone, who’s not a member of the new study’s team. (His simulations are available to other researchers in an online catalog.)

“Hydrodynamic simulations of merging clusters allow us to produce features in the hot gas and tune physical parameters, such as the magnetic field,” ZuHone said in the same statement. “Then we can attempt to match the detailed characteristics of the structures we observe in X-rays.”

Such comparative work led the researchers to identify a likely birth scenario for the bay. Long ago, Perseus’ gas had settled into two separate components: an interior “cold” region with temperatures around 54 million degrees Fahrenheit (30 million degrees Celsius) and a surrounding area three times hotter, the idea goes.

Then, a smaller cluster about 1,000 times more massive than the Milky Way galaxy grazed Perseus, coming within 650,000 light-years or so of its core, researchers said. This near miss roiled Perseus’ gas significantly, generating a spiral that expanded outward from the “cold” interior region.

years after the cluster flyby, this spiral reached 500,000 light-years from Perseus’ center and began producing huge waves in the cluster’s outer reaches. These features are basically enormous versions of “Kelvin-Helmholtz waves,” which appear at the interface of two fluids that are moving at different velocities, the researchers said.

“We think the bay feature we see in Perseus is part of a Kelvin-Helmholtz wave, perhaps the largest one yet identified, that formed in much the same way as the simulation shows,” Walker said. “We have also identified similar features in two other galaxy clusters, Centaurus and Abell 1795.”

The new study will appear in the June 2017 issue of the journal Monthly Notices of the Royal Astronomical Society.


Astronomers Find Supermassive Black Hole In Tiny Galaxy

April 25, 2017 by  
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An incredibly powerful supermassive black hole has been found at the center of a tiny galaxy that is merging with another larger galaxy, a new study shows.

NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) has imaged a system known as Was 49. The system consists of a large disk galaxy called Was 49a that is colliding with a smaller dwarf galaxy called Was 49b, located about 26,000 light-years from the larger galaxy’s center. 

Data from the NuSTAR mission, along with information from the Sloan Digital Sky Survey and the Discovery Channel Telescope in Arizona, show luminous, high-energy X-rays shooting out from 49b’s galactic core, suggesting it hosts an active supermassive black hole that comprises more than 2 percent of the galaxy’s entire mass, scientists say.

“This is a completely unique system and runs contrary to what we understand of galaxy mergers,” Nathan Secrest, lead author of the study and postdoctoral fellow at the U.S. Naval Research Laboratory in Washington, D.C., said in a statement from NASA. “We didn’t think that dwarf galaxies hosted supermassive black holes this big. This black hole could be hundreds of times more massive than what we would expect for a galaxy of this size, depending on how the galaxy evolved in relation to other galaxies.”

The powerful bursts of high-energy radiation emitted from dwarf galaxy 49b are fueled by the gas and dust being gobbled up by the black hole. Normally, however, it is the larger of two merging galaxies that hosts the active supermassive black hole, according to the NASA statement. 

“That is because, as galaxies approach each other, their gravitational interactions create a torque that funnels gas into the larger galaxy’s central black hole,” NASA officials said. “But in this case, the smaller galaxy hosts a more luminous AGN [active galactic nucleus] with a more active supermassive black hole, and the larger galaxy’s central black hole is relatively quiet.” 

The pink-colored emissions captured in the image represent the gas and dust surrounding the active supermassive black hole, while the large green cloud represents the starlight of Was 49a. Although scientists have yet to determine how the supermassive black hole of 49b grew to be so big, they expect that it will collide with the dormant black hole of 49a in several hundred million years to form one ginormous galactic beast, according to the NASA statement. 

“This study is important because it may give new insight into how supermassive black holes form and grow in such systems,” Secrest said in the statement. “By examining systems like this, we may find clues as to how our own galaxy’s supermassive black hole formed.”


Astronomers Begin Campaign To Photograph A Black Hole

April 18, 2017 by  
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The campaign to capture the first-ever image of a black hole has begun.

From today (April 5) through April 14, astronomers will use a system of radio telescopes around the world to peer at the gigantic black hole at the center of the Milky Way, a behemoth called Sagittarius A* (Sgr A*) that’s 4 million times more massive than the sun.

The researchers hope to photograph Sgr A*’s event horizon — the “point of no return” beyond which nothing, not even light, can escape. (The interior of a black hole can never be imaged, because light cannot make it out.) [The Strangest Black Holes in the Universe]

“These are the observations that will help us to sort through all the wild theories about black holes — and there are many wild theories,” Gopal Narayanan, an astronomy research professor at the University of Massachusetts Amherst, said in a statement. “With data from this project, we will understand things about black holes that we have never understood before.” 

The project, known as the Event Horizon Telescope (EHT), links up observatories in Hawaii, Arizona, California, Mexico, Chile, Spain and Antarctica to create the equivalent of a radio instrument the size of the entire Earth. Such a powerful tool is necessary to view the event horizon of Sgr A*, which lies 26,000 light-years from our planet, EHT team members said.

“That’s like trying to image a grapefruit on the surface of the moon,” Narayanan said.

During the current campaign, EHT is also eyeing the supermassive black hole at the core of the galaxy M87, which lies 53.5 million light-years from Earth. This monster black hole’s mass is about 6 billion times that of the sun, so its event horizon is larger than that of Sgr A*, Narayanan said.

These observations should help astronomers determine the mass, spin and other characteristics of supermassive black holes with better precision, team members said. The researchers also aim to learn more about how material accretes into disks around black holes, and the mechanics of the plasma jets that blast from these light-gobbling giants.

EHT could also reveal more about the “information paradox” — a long-standing puzzle about whether information about the material gobbled up by black holes can be destroyed — and other deep cosmological mysteries, team members said.

“At the very heart of Einstein’s general theory of relativity, there is a notion that quantum mechanics and general relativity can be melded, that there is a grand, unified theory of fundamental concepts,” Narayanan said. “The place to study that is at the event horizon of a black hole.”


Though the current observing campaign will be over soon, it will take a while for astronomers to piece together the images. For starters, so much information will be collected by the participating telescopes around the world that it will be physically flown, rather than transmitted, to the central processing facility at the Massachusetts Institute of Technology’s Haystack Observatory.

Then, the data will have to be calibrated to account for different weather, atmospheric and other conditions at the various sites. The first results from the campaign will likely be published next year, EHT team members said.


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