The dwarf planet Ceres keeps looking better and better as a possible home for alien life.
NASA’s Dawn spacecraft has spotted organic molecules — the carbon-containing building blocks of life as we know it — on Ceres for the first time, a study published today (Feb. 16) in the journal Science reports.
And these organics appear to be native, likely forming on Ceres rather than arriving via asteroid or comet strikes, study team members said.
“Because Ceres is a dwarf planet that may still preserve internal heat from its formation period and may even contain a subsurface ocean, this opens the possibility that primitive life could have developed on Ceres itself,” Michael Küppers, a planetary scientist based at the European Space Astronomy Centre just outside Madrid, said in an accompanying “News and Views” article in the same issue of Science.
“It joins Mars and several satellites of the giant planets in the list of locations in the solar system that may harbor life,” added Küppers, who was not involved in the organics discovery.
The $467 million Dawn mission launched in September 2007 to study Vesta and Ceres, the two largest objects in the main asteroid belt between Mars and Jupiter.
Dawn circled the 330-mile-wide (530 kilometers) Vesta from July 2011 through September 2012, when it departed for Ceres, which is 590 miles (950 km) across. Dawn arrived at the dwarf planet in March 2015, becoming the first spacecraft ever to orbit two different bodies beyond the Earth-moon system.
During its time at Ceres, Dawn has found bizarre bright spots on crater floors, discovered a likely ice volcano 2.5 miles (4 km) tall and helped scientists determine that water ice is common just beneath the surface, especially near the dwarf planet’s poles.
The newly announced organics discovery adds to this list of achievements. The carbon-containing molecules — which Dawn spotted using its visible and infrared mapping spectrometer instrument — are concentrated in a 385-square-mile (1,000 square km) area near Ceres’ 33-mile-wide (53 km) Ernutet crater, though there’s also a much smaller patch about 250 miles (400 km) away, in a crater called Inamahari.
And there could be more such areas; the team surveyed only Ceres’ middle latitudes, between 60 degrees north and 60 degrees south.
“We cannot exclude that there are other locations rich in organics not sampled by the survey, or below the detection limit,” study lead author Maria Cristina De Sanctis, of the Institute for Space Astrophysics and Space Planetology in Rome, told Space.com via email.
Dawn’s measurements aren’t precise enough to nail down exactly what the newfound organics are, but their signatures are consistent with tar-like substances such as kerite and asphaltite, study team members said.
“The organic-rich areas include carbonate and ammoniated species, which are clearly Ceres’ endogenous material, making it unlikely that the organics arrived via an external impactor,” co-author Simone Marchi, a senior research scientist at the Southwest Research Institute in Boulder, Colorado, said in a statement.
In addition, the intense heat generated by an asteroid or comet strike likely would have destroyed the organics, further suggesting that the molecules are native to Ceres, study team members said.
The organics might have formed via reactions involving hot water, De Sanctis and her colleagues said. Indeed, “Ceres shows clear signatures of pervasive hydrothermal activity and aqueous alteration,” they wrote in the new study.
Such activity likely would have taken place underground. Dawn mission scientists aren’t sure yet how organics generated in the interior could make it up to the surface and leave the signatures observed by the spacecraft.
“The geological and morphological settings of Ernutet are still under investigation with the high-resolution data acquired in the last months, and we do not have a definitive answer for why Ernutet is so special,” De Sanctis said.
It’s already clear, however, that Ceres is a complex and intriguing world — one that astrobiologists are getting more and more excited about.
“In some ways, it is very similar to Europa and Enceladus,” De Sanctis said, referring to ocean-harboring moons of Jupiter and Saturn, respectively.
“We see compounds on the surface of Ceres like the ones detected in the plume of Enceladus,” she added. “Ceres’ surface can be considered warmer with respect to the Saturnian and Jovian satellites, due to [its] distance from the sun. However, we do not have evidence of a subsurface ocean now on Ceres, but there are hints of subsurface recent fluids.”
For decades, astronomers have tracked black holes with masses millions of times that of the sun, as well as those with tens of solar masses. But black holes between those two extremes have proved elusive. Now, astronomers studying a globular cluster have found just such a black hole at its center, showing that intermediate-mass black holes could be hiding out in these compact agglomerations of stars.
Lead study author Bülent Kiziltan, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), and his co-authors Holger Baumgardt (of Australia’s University of Queensland) and Abraham Loeb (also of CfA) found a black hole between 1,400 and 3,700 solar masses at the center of 47 Tucanae, a globular cluster in the southern sky some 16,700 light-years from Earth.
Black holes are usually found because they emit massive amounts of X-rays as matter falls in. Midsize black-hole candidates have been found in galaxies; a group from the University of Maryland and NASA’s Goddard Space Flight Center found one in another galaxy in 2015, and there are about a dozen objects in total.
Kiziltan and his team found this one by measuring motions of pulsars within the cluster. They found the telltale signs of a compact, massive object in the cluster’s heart. The likeliest explanation for the motions was a black hole.
“Intermediate-mass black holes have been expected [in globular clusters] for many decades,” Kiziltan told Space.com. “But we’ve not been able to find one conclusively.”
Theorists think stellar-mass black holes form from stars that are at least a few dozen times the mass of the sun. When they run out of nuclear fuel, there is no longer enough energy from radiation to hold the star’s outer layers against its immense gravity. The star collapses, and then explodes as a supernova. (Supernovas can outshine the galaxies in which they reside.) What’s left of the star then shrinks into a tiny volume. A 100-solar-mass star, as a black hole, would have a radius of about 180 miles (290 kilometers). The former star’s escape velocity exceeds that of light, resulting in a black hole, from which nothing can escape.
A big question for astronomers is what the population of black holes looks like. Given that there are supermassive black holes, and stellar-mass ones, there should be a population of black holes with masses between those two. But there don’t seem to be as many as expected. The centers of globular clusters, which are agglomerations of old stars, seemed a good place to look, as earlier studies indicated they might be there, according to the new study.
The problem is, black holes are visible only when stuff falls in them. As such, the researchers needed another method that didn’t depend on picking up radio emissions.
That’s why Kiziltan and his colleagues decided to look at the pulsars that inhabit a globular cluster. Pulsars form from stars less massive than those that make black holes. After those stars go supernova, they collapse into neutron stars
Some neutron stars spin rapidly and emit radio waves along a line offset from their rotational axes. These are called pulsars. Earthbound observers see them if Earth is in the radio beam as it sweeps across the sky. Pulsars’ rotation rates change so little that they are precise timekeepers. They are precise enough that by timing the signal and looking for any Doppler shifts, it’s possible to measure a pulsar’s movement along one’s line of sight.
Kiziltan’s group tracked the movement of some two dozen pulsars and used computer simulations to model the cluster to track down their black-hole candidate.
“We’re proposing a brand-new approach to the study of globular clusters,” Kiziltan said. “It’s not only that we see the dynamical signature of a black hole, but how to probe the region near it without going too close to it.” Probing the centers of globular clusters is usually difficult, because the density of stars makes it hard to see what’s going on.
Finding the intermediate-mass black hole raises more questions about how these black holes form, said Cole Miller, a professor of astronomy at the University of Maryland who studies black-hole formation. “Let’s say it’s an intermediate-mass black hole,” he said. “How did it get there?”
“Globular clusters have small escape speeds,” he said. “So the stars should blow away all the gas.” There will be some as stars age, such as a red giant’s stellar winds. “But that amount of gas is nowhere close enough to make an intermediate-mass black hole.”
This differs from the supermassive black holes at galactic centers, he added, because one would expect lots of matter to accumulate there, feeding a black hole and allowing it to grow very fast.
Both Kiziltan and Cole said there are several ways to grow black holes early in a cluster’s history. “One of my favorites is runaway collisions of stars or stellar- mass black holes,” Miller said. “An interesting effect is, if you have a bunch of stars in a dense stellar region, the heaviest will start runaway collisions.” Once a black hole forms — perhaps when a star that’s absorbed a few neighbors dies ― all the matter that isn’t in a stable orbit around the black hole will fall in or get ejected from the cluster, he said. That puts an automatic stop on the black hole’s growth.
For scientists to get a better handle on how such black holes might form in clusters, more of them need to be found — but that won’t be easy, Kiziltan said. The only reason it worked for 47 Tucanae was that there were enough pulsars in it to begin with, and they were close enough to see. Not every globular cluster has the right combination of distance and bright pulsars.
The wandering black hole was discovered lurking just outside a supernova remnant, a shell of expelled material left behind after a massive star explodes. Using the Atacama Submillimeter Telescope Experiment (ASTE) in Chile and the 45-meter (148 feet) Radio Telescope at Nobeyama Radio Observatory, astronomers found that the black hole had been previously hidden by a compact gas cloud emerging from the remnant.
The cloud itself has now been named “the Bullet,” because of its long, cone shape and its incredible speed — part of the cloud is moving away from the supernova remnant at more than 60 miles per second [100 kilometers per second], “which exceeds the speed of sound in interstellar space by more than two orders of magnitude,” Nobeyama Radio Observatory scientists said in the statement. The researchers now suspect that the black hole might have played a role in forming the gaseous “bullet.”
The supernova remnant, called W44, is located 10,000 light-years from Earth. The Bullet, which is about 2 light-years long [11.76 trillion miles, or 18.9 trillion km], is so energetic that it moves backward against the rotation of the Milky Way galaxy, according to the Nobeyama Radio Observatory statement.
“Most of the Bullet has an expanding motion with a speed of 50 km/s [31 miles per second], but the tip of the Bullet has a speed of 120 km/s [75 miles per second],” Masaya Yamada, lead author of the new study and a graduate student at Keio University in Japan, said in the statement. “Its kinetic energy is a few tens of times larger than that injected by the W44 supernova. It seems impossible to generate such an energetic cloud under ordinary environments.”
So what could possibly send such a huge amount of molecular gas streaming out of the supernova remnant at such high speeds? The discovery of the hidden black hole may offer an explanation.
The researchers developed two possible scenarios for how the Bullet might have formed. The first, called the explosion model, suggests that the cloud passed by a static black hole and was pulled in by the black hole’s strong gravitational forces. This could have created a powerful explosion of gas that was spit back out into space, Nobeyama scientists said.
Another theory, called the irruption model, proposes that a high-speed black hole tore through the dense molecular cloud, and the black hole’s powerful gravitational pull left a stream of gas in its wake. Further research is required to determine which model best explains the origin of the Bullet, according to the study, published Dec. 29, 2016, in The Astrophysical Journal Letters.
Although millions of black holes are thought to exist in the Milky Way, it is often difficult to locate them because they are completely black. However, this study has revealed a new way for astronomers to detect these types of elusive, stray black holes — by their influence on molecular gas clouds — that would otherwise float alone in space and remain unnoticed with no observable emissions, the scientists said in the statement.
As astronomers work to learn more about the environment it, a new paper in Astrophysical Journal Letters makes predictions about what would happen to young, highly magnetized stars in Sgr A*’s vicinity. It’s the first time a star’s magnetic field has been included in simulations where a black hole tidally disrupted a star, meaning the star is pulled apart and stretched.
“Magnetic fields are a bit tricky numerically to simulate,” James Guillochon, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, told Seeker. In the past, it’s been hard to put magnetic fields in context with other influences on a star, such as gas pressure and gravity. This is especially true towards the boundary or atmosphere of the star.
The simulations show that if a star gets a “glancing blow” from a black hole, it can survive the encounter and its magnetic field amplifies strongly, by a factor of about 30. But if the star gets very close to the black hole, the star is tidally destroyed and the magnetic field maintains its strength.
“One of the immediate impacts is that we might see highly magnetized stars in the centers of galaxies, and that includes our own galactic center,” Guillochon added. “We also would expect this to affect the resulting flare that arises from the disruption of the star by the supermassive black hole. Half the matter of the star falls on to the black hole and feeds it, and that generates a luminous flare of a billion or 10 billion solar luminosities.”
A star disruption should theoretically be visible in our own galactic center, but Guillochon says that only happens about once every 10,000 years or so. Luckily, the stream of the disrupted star can persist for centuries, feeding the black hole.
Guillochon co-wrote a paper a couple of years ago about G2, a gas cloud falling into the galactic center in 2014 that produced far less activity than expected. It suggests that G2 could have been produced by the disruption of a red giant star, and its gas envelope is still feeding the black hole today.
He suggested that G2-like clouds would form by “clumping up” due to cooling instabilities, which would put regular deliveries of a G2-type cloud once every decade. When the material is highly magnetized, co-author Michael McCourt has previously suggested that the fields can help stabilize the clouds and prevent them from breaking apart. If the pattern holds true, highly magnetized clouds would continue to pass near the black hole over the next several decades.
That said, the challenge of learning about stars that survive disruption in the galactic center is they tend to be lower mass and hard to see. How many of them are magnetized, and how strongly, remains an open question, Guillochon said. Below is a short animation simulating a star’s magnetic field being torn apart by a black hole.
An international team of scientists tasked with fleshing out the main goals of the mission, which is known as Venera-D, is wrapping up its work and will deliver its final report to NASA and the Russian Academy of Sciences’ Space Research Institute by the end of the month, said David Senske, of NASA’s Jet Propulsion Laboratory in Pasadena, California.
“Is this the mission that’s going to fly? No, but we’re getting there,” Senske, the U.S. co-chair of this “joint science-definition team,” told Space.com last month at the annual fall meeting of the American Geophysical Union, in San Francisco.
Venera-D is led by Russia, which has been developing the project for more than a decade. The mission would mark a return to once-familiar territory for the nation; Russia’s forerunner state, the Soviet Union, launched a number of probes to Venus from the early 1960s through the mid-1980s, as part of its Venera and Vega programs. (“Venera” is the Russian name for Venus.)
“Russia has always been interested in going back to Venus,” Senske said.
NASA got involved about three years ago, when Russia asked if the U.S. space agency would be interested in collaborating on the mission, Senske added.
The joint science-definition team arose out of those initial discussions. The team stood down shortly thereafter; Russia’s March 2014 annexation of Crimea prompted NASA to suspend most cooperation with Roscosmos, Russia’s federal space agency (with activities involving the International Space Station being the most prominent exception).
But the collaboration was up and running again by August 2015, Senske said, and the team met in Moscow that October. More meetings are planned, including a workshop this May that will inform decisions about the mission’s scientific instruments, he added.
Venera-D is a large-scale mission, comparable in scope to NASA “flagship” efforts such as the $2.5 billion Curiosity Mars rover, Senske said. The baseline concept calls for an orbiter that will study Venus from above for at least three years, plus a lander that will operate for a few hours on the planet’s surface.
Mission planners said they had originally hoped the lander could survive for 30 days; the “D” in Venera-D stands for “dolgozhivushaya,” which means “long lasting” in Russian. But this goal was ultimately deemed too difficult and costly, given the blistering temperatures on Venus’ surface, according to RussianSpaceWeb.com (which outlines the mission’s tortuous history in rich detail).
Data gathered by the orbiter should help scientists better understand the composition, structure and dynamics of Venus’ atmosphere, including why the planet’s air rotates so much faster than the surface does, a mysterious phenomenon known as super-rotation, Senske said.
The lander will collect further atmospheric information while descending, then study the composition and morphology of the Venusian surface after touching down.
Venera-D could incorporate additional components as well. Some ideas on the drawing board include a handful of small, relatively simple ground stations that would gather surface data for a month or so (putting the “D” back in Venera-D) and a solar-powered, uncrewed aerial vehicle that would ply the Venusian skies.
The surface of Venus is far too hot to support life as we know it, but temperatures are much more hospitable at an altitude of 31 miles (50 kilometers) or so. Furthermore, the planet’s atmosphere sports mysterious dark streaks that some astronomers have speculated might be signs of microbial life. The UAV could hypothetically investigate this possibility, sampling the air while cruising along.
Engineers have already been thinking about how to build such an aircraft. For example, the U.S. aerospace company Northrop Grumman and partner L’Garde Inc. have been researching a concept vehicle called the Venus Atmospheric Maneuverable Platform (VAMP) for several years now.
It’s still too early to know exactly what Venera-D will look like, what it will do or when the mission will launch. A liftoff in 2025 or 2026 is possible under an “aggressive” time line, Senske said. “It depends when the Russians can get this into their federal space budget,” he said.
Some things are known, however. For instance, Russia will build the orbiter and the lander, and Venera-D will launch atop Russia’s in-development Angara A5 rocket, Senske said. If NASA remains involved in the mission — which is far from a given at this point — the U.S. space agency will likely contribute smaller items, such as individual scientific instruments.
“Russia is definitely in the driver’s seat,” Senske said. “NASA is the junior partner.”
New observations by NASA’s Hubble Space Telescope suggest that the gas, called Smith’s Cloud, was cast from the Milky Way long ago. A new NASA video describes the cloud’s discovery in 1963 and what researchers know.
“We don’t fully understand the Smith Cloud’s origin,” Andrew Fox, an astronomer at the Space Telescope Science Institute who led the research, said in a statement from NASA. “There are two leading theories. One is that it was blown out of the Milky Way, perhaps by a cluster of supernova explosions. The other is that the Smith Cloud is an extragalactic object that has been captured by the Milky Way.” Fox’s team examined the cloud using Hubble’s Cosmic Origins Spectrograph, and saw evidence of sulfur, which absorbs ultraviolet light from the cores of three galaxies lying beyond the cloud. The team found that the amount of sulfur in Smith’s Cloud is the same as that found in the outer disk of the Milky Way, suggesting that both objects came from the same family.
“The cloud appears to have been ejected from within the Milky Way and is now falling back,” Fox said. “The cloud is fragmenting and evaporating as it plows through a halo of diffuse gas surrounding our galaxy. It’s basically falling apart.
“This means that not all of the material in Smith’s Cloud will survive to form new stars,” he added. “But if it does survive, or some part of it does, it should produce an impressive burst of star formation.”
It’s still unclear what event tore this cloud from the Milky Way’s disk and how it stayed together so long, NASA officials said in the statement. What is known, however, is that in roughly 30 million years, it will crash into our galaxy’s Perseus Arm, one of the two major spiral arms in the Milky Way. When that happens, there will be a surge of star formation when clouds of gas in the spiral arm are compressed, NASA officials said.
There are some things in the universe that you simply can’t escape. Death. Taxes. Black holes. If you time it right, you can even experience all three at once.
Black holes are made out to be uncompromising monsters, roaming the galaxies, voraciously consuming anything in their path. And their name is rightly deserved: once you fall in, once you cross the terminator line of the event horizon, you don’t come out. Not even light can escape their clutches.
But in movies, the scary monster has a weakness, and if black holes are the galactic monsters, then surely they have a vulnerability. Right?
Black holes are strange regions where gravity is strong enough to bend light, warp space and distort time.
In the 1970s, theoretical physicist Stephen Hawking made a remarkable discovery buried under the complex mathematical intersection of gravity and quantum mechanics: Black holes glow, ever so slightly, and, given enough time, they eventually dissolve.
Wow! Fantastic news! The monster can be slain! But how? How does this so-called Hawking Radiation work?
Well, general relativity is a super-complicated mathematical theory. Quantum mechanics is just as complicated. It’s a little unsatisfying to respond to “How?” with “A bunch of math,” so here’s the standard explanation: the vacuum of space is filled with virtual particles, little effervescent pairs of particles that pop into and out of existence, stealing some energy from the vacuum to exist for the briefest of moments, only to collide with each other and return to nothingness.
Every once in a while, a pair of these particles pops into existence near an event horizon, with one partner falling in and the other free to escape. Unable to collide and evaporate, the escapee goes on its merry way as a normal non-virtual particle.
Voila: The black hole appears to glow, and in doing so — in doing the work to separate a virtual particle pair and promote one of them into normal status — the black hole gives up some of its own mass. Subtly, slowly, over the eons, black holes dissolve. Not so black anymore, huh?
Here’s the thing: I don’t find that answer especially satisfying, either. For one, it has absolutely nothing to do with Hawking’s original 1974 paper, and for another, it’s just a bunch of jargon words that fill up a couple of paragraphs but don’t really go a long way to explaining this behavior. It’s not necessarily wrong, just…incomplete.
First things first: “Virtual particles” are neither virtual nor particles. In quantum field theory — our modern conception of the way particles and forces work — every kind of particle is associated with a field that permeates all of space-time. These fields aren’t just simple bookkeeping devices. They are active and alive. In fact, they’re more important than particles themselves. You can think of particles as simply excitations — or “vibrations” or “pinched-off bits,” depending on your mood — of the underlying field.
Sometimes the fields start wiggling, and those wiggles travel from one place to another. That’s what we call a “particle.” When the electron field wiggles, we get an electron. When the electromagnetic field wiggles, we get a photon. You get the idea.
Sometimes, however, those wiggles don’t really go anywhere. They fizzle out before they get to do something interesting. Space-time is full of the constantly fizzling fields.
What does this have to do with black holes? Well, when one forms, some of the fizzling quantum fields can get trapped — some permanently, appearing unfortunately within the newfound event horizon. Fields that fizzled near the event horizon end up surviving and escaping. But due to the intense gravitational time dilation near the black hole, thy appear to come out much, much later in the future.
In their complex interaction and partial entrapment with the newly forming black hole, the temporary fizzling fields get “promoted” to become normal everyday ripples — in other words, particles.
So, Hawking Radiation isn’t so much about particles opposing into existence near a present-day black hole, but the result of a complex interaction at the birth of a black hole that persists until today.
One way or the other, as far as we can tell, black holes do dissolve. I emphasize the “as far as we can tell” bit because, like I said at the beginning, generality is all sorts of hard, and quantum field theory is a beast. Put the two together and there’s bound to be some mathematical misunderstanding.
But with that caveat, we can still look at the numbers, and those numbers tell us we don’t have to worry about black holes dying anytime soon. A black hole with the mass of the sun will last a wizened 10^67 years. Considering that the current age of our universe is a paltry 13.8 times 10^9 years, that’s a good amount of time. But if you happened to turn the Eiffel Tower into a black hole, it would evaporate in only about a day. I don’t know why you would, but there you go.
A giant blob of gas and dust far off in the universe mysteriously glows bright green, and astronomers have finally figured out why. Two huge galaxies were observed in the blob’s core, and they’re surrounded by a swarm of smaller galaxies in what appears to be the birth of a massive cluster of galaxies.
Astronomers spotted the blob’s central galaxies using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Telescope at the European Southern Observatory in Chile. The glowing space blob was first discovered in 2000, and the source of its light has been a mystery ever since.
One study published in 2011 suggested that polarized light emitted by the blob could have come from hidden galaxies. The new observations with ALMA and VLT allowed researchers to pinpoint two big galaxies as the sources of this light.
Further observations by the Hubble Space Telescope and the Keck Observatory in Hawaii revealed the swarm of small, faint galaxies surrounding the bigger two in the heart of the blob. Here, galaxies are forming stars at 100 times the rate of the Milky Way.
A giant green “space blob” – called the Lyman-alpha blob LAB-1 – is seen in this composite of two different images taken by the Very Large Telescope in Chile. The LAB-1 space blob is 300,000 light-years across, making it one of the largest known single objects in the universe.
Credit: ESO/M. Hayes
“For a long time, the origin of the extended Lyman-alpha light has been controversial,” Jim Geach, the study’s lead author, said in a statement. “But with the combination of new observations and cutting-edge simulations, we think we have solved a 15-year-old mystery.”
So-called “Lyman-alpha blobs” are some of the biggest things in space. This particular space blob, named SSA22-Lyman-alpha Blob 1 (LAB-1), is the largest of its kind. It measures about 300,000 light-years across, or three times the size of the Milky Way galaxy.
LAB-1 is located 11.5 billion light-years from Earth, so the light we observe from it is almost as old as the universe (13.8 billion years). This means that looking at LAB-1 provides a window into the early history of the universe.
Lyman-alpha blobs consist mainly of hydrogen gas and emit a particular wavelength of ultraviolet light called Lyman-alpha radiation. The light looks green to viewers on Earth, because its wavelength is stretched by the expanding universe during its long trip here.
This is a snapshot from a computer simulation of the evolution of a Lyman-alpha Blob similar to LAB-1. Gas within the dark matter halo is color- coded so that cold gas (mainly hydrogen) appears red and hot gas appears white. At the center of this system are two star-forming galaxies surrounded by hot gas and many smaller satellite galaxies that appear as small red clumps.
Once they had observed the sources of light from within the blob, the researchers created simulations of galaxy formation using NASA’s Pleiades supercomputer. They wanted to show that ultraviolet light — a byproduct of star formation — scatters off hydrogen gas to create a bright, glowing mega-blob like LAB-1.
“Think of a streetlight on a foggy night — you see the diffuse glow because light is scattering off the tiny water droplets,” Geach said in the same statement. “A similar thing is happening here, except the streetlight is an intensely star-forming galaxy and the fog is a huge cloud of intergalactic gas. The galaxies are illuminating their surroundings.”
The simulations also track gas and dark matter in the blob as it evolves into a galaxy. “Lyman-alpha Blob-1 is the site of formation of a massive elliptical galaxy that will one day be the heart of a giant cluster,” Geach added
Monster black holes can be millions of times more massive than the sun. If a star happens to wander too close, the black hole’s extreme gravitational forces can tear the star into shreds, in an event called “stellar tidal disruption.”
This kind of stellar destruction may also spit out a bright flare of energy in the form of ultraviolet and X-ray light. The two new studies examine how surrounding dust absorbs and re-emits the light from those flares, like a cosmic echo, according to a statement from NASA’s Jet Propulsion Laboratory (JPL).
“This is the first time we have clearly seen the infrared-light echoes from multiple tidal disruption events,” Sjoert van Velzen, a postdoctoral fellow at Johns Hopkins University and lead author of one study, said in the statement.
The new studies use data from NASA’s Wide-field Infrared Survey Explorer (WISE). The NASA study led by van Velzen used these “echoes” to identify three black holes in the act of devouring stars. The second study, led by Ning Jiang, a postdoctoral researcher at the University of Science and Technology of China, identified a potential fourth light echo.
Flares emitted from stellar tidal disruptions are extremely energetic and “destroy any dust” that is within the immediate neighborhood, according to NASA. However, a patchy, spherical web of dust that resides a few trillion miles (half a light-year) from the black hole can survive the flare and absorb light released from the star being gobbled up
“The black hole has destroyed everything between itself and this dust shell,” van Velzen said in the statement. “It’s as though the black hole has cleaned its room by throwing flames.”
The absorbed light heats the more distant dust, which in turn gives off infrared radiation that the WISE instrument can measure. These emissions can be detected for up to a year after the flare is at its brightest, the statement said. Scientists are able to characterize and locate the dust by measuring the delay between the original light flare and the subsequent echoes, according to the NASA study, which will be published in the Astrophysical Journal.
“Our study confirms that the dust is there, and that we can use it to determine how much energy was generated in the destruction of the star,” Varoujan Gorjian, an astronomer at JPL and co-author of the paper led by van Velzen, said in the statement.
Many supermassive black holes in the centers of galaxies possess a thick ring of material known as a torus. Appearing like a supersized doughnut, astronomers have long thought that these features were created by churned-up material from the galactic core itself, falling into the black hole’s gravitational well.
However, according to powerful new observations by the the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, this conventional model is, apparently, far too simple.
While studying the environment surrounding the supermassive black hole in the core of the barred spiral galaxy NGC 1068 47 million light-years away, ALMA was able to track clouds of material being flung outwards by the black hole, creating its own torus rather than material falling in.
WATCH VIDEO: The Race To See The Black Hole At Our Galaxy’s Core
“Think of a black hole as an engine,” said astronomer Jack Gallimore, of Bucknell University in Lewisburg, Pennsylvania, in a statement. “It’s fueled by material falling in on it from a flattened disk of dust and gas. But like any engine, a black hole can also emit exhaust.”
Black holes consuming matter possess accretion disks, which are basically flat and hot features that swirl around the black hole’s event horizon. The innermost section of the accretion disk is so hot that it generates X-ray and ultraviolet radiation, but further out, the disk is cooler and emits infrared and millimeter wavelength radiation. ALMA is very sensitive to the latter, allowing the observatory to track the motion of the gases in the outermost portion of NGC 1068’s accretion disk.
The torus of material harboring the supermassive black hole is highlighted in the pullout box. This region, which is approximately 40 light-years across, is the result of material flung out of the black hole’s accretion disk.
While following cool clouds of carbon monoxide gas inside this cooler accretion disk region, Gallimore’s team saw the clouds lift off the disk. As they become ionized by the superheated portion of the accretion disk, the clouds started to interact with the black hole’s powerful magnetic field. The gas was then flung away from the accretion disk at high speed, far faster than the rotational speed of the disk itself.
“These clouds are traveling so fast that they reach ‘escape velocity’ and are jettisoned in a cone-like spray from both sides of the disk,” said Gallimore. “With ALMA, we can for the first time see that it is the gas that is thrown out that hides the black hole, not the gas falling in.”
The vast majority of galaxies are known to contain supermassive black holes in their cores. They have a symbiotic relationship and the activity of black holes are known to have a powerful influence over the galaxies as a whole, even impacting the rate of star formation. Now, with observatories like ALMA, we’re beginning to see the intricacies of this relationship and their impact on the hearts of galaxies.
A star’s mysterious evolution recently came to light using the Hubble Space Telescope, which spotted the star cooling after a rapid temperature increase in the past. Th find is all the more extraordinary given that this sort of process usually exceeds a human lifetime, according to astronomers.
The researchers explained the process behind the rebirth of the star (called SAO 244567) in this new animation.
“SAO 244567 is one of the rare examples of a star that allows us to witness stellar evolution in real time,” Nicole Reindl, a postdoctoral researcher from the University of Leicester in the U.K. who led the study, said in a statement. “Over only 20 years the star has doubled its temperature, and it was possible to watch the star ionizing its previously ejected envelope [of dust and gas], which is now known as the Stingray Nebula.”
Astronomers have seen many changes in the star, which is 7,000 light-years from Earth, in the past 45 years. Between 1971 and 2002, they saw the surface temperature of the star increase by almost 72,000 degrees Fahrenheit (40,000 degrees Celsius). But the new observations with Hubble’s cosmic origins spectrograph reveal that the star is cooling and expanding.
In 2014, Reindl’s team proposed that SAO 244567 — whose low mass makes it hard to explain the rapid temperature fluctuations — may have just undergone a “helium-shell flash event,” which happens when helium briefly ignites outside the heart, or core, of the star. Once the heating flash completes, SAO 244567 should regress in its evolution and cool. The new observations suggest this 2014 theory was correct, Reindl said in the same statement.
“The release of nuclear energy by the flash forces the already very compact star to expand back to giant dimensions — the born-again scenario,” Reindl said.
She added that the team will need to refine their calculations to better explain SAO 244567’s behavior, which can’t be accounted for in current models of star evolution.
Hundreds of black holes could be lurking inside a cluster of stars that orbits the Milky Way galaxy, a new study shows.
NGC 6101 is a globular cluster (a dense, spherical collection of ancient stars) orbiting the center of the Milky Way. Using computer models, scientists recently showed that some strange characteristics of NGC 6101 could be explained by the presence of hundreds of black holes — something scientists have never observed in a globular cluster.
Black holes can form when massive stars die in a fiery explosion called a supernova. This type of blast is thought to kick the black hole away from its birth site, according to Mark Gieles, a professor of astrophysics at the University of Surrey in England and one of the authors of the new study. But the existence of so many black holes within the globular cluster would suggest that these “kicks” are not as powerful as scientists previously thought, Gieles said in a video detailing the new work.
Finding black holes is difficult, because astronomers can’t see them the same way they can see stars and other objects in the universe. That’s because black holes are so dense that not even light can escape the pull of their gravity.
While black holes may be difficult to spot, computer simulations can help predict where they might be hiding. Gieles and colleagues at the University of Surrey were inspired to create simulations of NGC 6101 after another group published their observations of the cluster last year.
The cluster’s structure didn’t make sense at first. Usually, in globular clusters, heavy stars move to the center, while lightweight stars tend to migrate to the periphery — a process known as “mass segregation.” But NGC 6101 has very few stars near its center. “We found that this is not at all what you would expect for a normal stellar system,” Gieles said in the video about the study.
“It reminded us of previous work where we looked at the influence black holes can have on globular clusters, and we had the idea, ‘Maybe we could explain it by simply putting some black holes into the cluster,'” Miklos Peuten, a Ph.D student in astrophysics at the University of Surrey and lead author of the research paper, said in the same video.
To make sense of the missing mass segregation, the team recreated the entire 13-billion-year evolution of the cluster. Without black holes, the simulation didn’t match their real observations of the system. But once they threw black holes into the mix, their simulations matched their observations perfectly. Black holes could be the missing piece of the NGC 6101 puzzle.
“The next step would be to look at other globular clusters which also have strange profiles” and see if black holes can explain those as well, Peuten said in the video, adding that this “would help us to understand how black holes are created and how black holes evolve.”
The star, located almost 11,000 light-years from Earth, has a mass 30 times that of the sun, and it’s still growing. Astronomers found that this star is still in the process of collecting material from its parent cloud of gas and dust, which means it is only a baby in cosmic terms and is expected to be even more massive by the time it grows up, according to a statement from the University of Cambridge, where the research was conducted. A young star such as this is also known as a protostar.
Due to their incredibly large size, protostars such as this are difficult to locate in Earth’s galaxy (the Milky Way) and are hard to study because they live fast and die young and are generally very far away.
“An average star like our sun is formed over a few million years, whereas massive stars are formed orders of magnitude faster — around 100,000 years,” John Ilee, lead author of the study from Cambridge’s Institute of Astronomy, said in the statement. “These massive stars also burn through their fuel much more quickly, so they have shorter overall life spans, making them harder to catch when they are infants.”
But the astronomers behind the new work were able to do just that: catch the star during a key stage of its birth. Their findings revealed that massive stellar bodies like this form from rotating discs of gas and dust, also known as the stars’ parent clouds. This process is very similar to the way that much smaller stars like Earth’s sun form, astronomers said in the statement.
Using the Submillimeter Array (SMA) in Hawaii and the Karl G. Jansky Very Large Array (VLA) in New Mexico, the astronomers found that the new protostar lives in an infrared dark cloud, which is an ideal region for star formation because it is very cold and dense.
With thick surrounding clouds of gas and dust, these areas are generally difficult to observe using telescopes. However, the astronomers were able to peer through the clouds and measure the radiation emitted from the dust around the star and its chemical signatures. Their findings revealed the presence of a “Keplerian” disc that’s rotating more quickly at its center.
“This type of rotation is also seen in the solar system — the inner planets rotate around the sun more quickly than the outer planets,” Ilee explained. “It’s exciting to find such a disc around a massive young star, because it suggests that massive stars form in a similar way to lower-mass stars, like our sun.”
The new findings were published Aug. 9 in the Monthly Notices of the Royal Astronomical Society.
Are black holes truly black? A new laboratory experiment points toward “no.”
Using a simulated black hole made from soundwaves, scientists have observed a phenomenon known as Hawking radiation: a faint energy emission that, in theory, is created right at the edge of a black hole’s event horizon, or the point beyond which even light cannot escape.
If Hawking radiation comes from astrophysical black holes (not just those created in a lab), it would mean these objects are not entirely dark. It could also help scientists solve a paradox posed by black holes, and perhaps shed light on one of the most significant problems facing modern physics.
Black holes are strange regions where gravity is strong enough to bend light, warp space and distort time
Jeff Steinhauer, an experimental physicist at the Technion — Israel Institute of Technology in Israel, and lead author on the new study, told Space.com.
According to Steinhauer, earlier calculations by cosmologist Stephen Hawking (who came up with the theory that bears his name) combined the theories of quantum physics and gravity. The current experiment tests those calculations, providing the first strong evidence that they are correct, Steinhauer said.
“A black hole is a testing ground for the laws of physics,” Steinhauer said.
Swimming against the current
There’s a tricky concept in physics that says that pairs of particles constantly blink into existence throughout space. One is a particle of normal matter and the other is its exact opposite, or antiparticle, so the two annihilate one another, and there’s no change to the universe’s energy balance sheet. These are called virtual particles. When this happens near the edge, or event horizon, of a black hole, the particles can avoid complete destruction; one can fall inside while the other escapes.
But observing such interactions in nature has remained difficult, the Hawking radiation around a black hole (if it exists) is so faint that it can’t be seen from Earth around known black holes (most of which are very far away). In addition to the distance, the Hawking radiation is likely overwhelmed by radiation from other sources, Steinhauer said.
“It makes it seemingly almost impossible to see this very slight radiation coming from the black hole,” he said.
The same problem applies in a laboratory, where any heat can create background radiation that overwhelms the lab-produced Hawking radiation. To eliminate that problem, Steinhauer’s experiment ran at less than a billionth of a degree above absolute zero.
In the analogue black hole, a line of cold rubidium atoms stream from a laser to create a form of matter known as a Bose-Einstein condensate. The cold gas flows faster than the speed of sound in one direction, so that a sound wave trying to go against the flow can’t manage to move forward. In this respect, the slower moving sound wave is like a particle trying to escape from a black hole.
“It’s like trying to swim against the river,” Steinhauer said. “If the river is going faster than you can swim, you go backwards, even though you feel like you’re going forward.”
The upstream attempt is analogous to light in a black hole trying to escape, he said. Sound waves trying to move forward instead fall backward. If two virtual particles were created near the edge of the event horizon, one particle could be consumed by the black hole (the fast-moving stream), while the other escapes, avoiding destruction. The escaping particles are called Hawking radiation.
A method of creating a black hole using sound waves was proposed in 1981, and since then scientists have struggled to simulate Hawking radiation in the lab. Two years ago, Steinhauer performed an experiment that measured Hawking radiation after something was deliberately crashed into the event horizon of the analogue black hole. This new experiment took more of a wait-and-see stance, waiting for the particle-antiparticle pair to appear without external stimulation, more like what happens in the depths of space.
Just as Hawking theorized, the simulated black hole spit out the predicted particles, a sign of Hawking radiation.
“What I saw suggests that a real black hole might emit something,” Steinhauer said.
The new finding also has larger implications for the field of physics, he said. One of the biggest mysteries in physics is why Einstein’s theory of gravity (which describes large-scale interactions in the universe) doesn’t seem to be compatible with quantum mechanics (which describes very small-scale interactions).
“Combining gravity with quantum physics is one of the main goals of physics today,” Steinhauer said. “Hawking made the first steps toward that.”
The simulated black hole tested Hawking’s equations.
“His calculations predicted there should be light from a black hole,” Steinhauer said. “It turns out his calculations were correct.”
One intriguing result of the artificial black hole involved insight into the information paradox. According to Einstein’s theory of general relativity, everything that crosses the event horizon of a black hole is consumed, including information. As the escaping particle steals energy from a black hole, the massive object can shrink over time, eventually evaporating into nothing. Of course, this assumes it has stopped consuming nearby material and thus isn’t putting on new weight. Theoretically, a black hole can shrink into nothing, taking with it the information carried by or about the particles it consumed.
“Information has vanished,” he said. “It’s like it goes into the black hole and disappears.”
Since quantum mechanics suggests that information can’t be lost, that raises a paradox.
According to Hawking’s calculations, the surviving particles contain no useful information about how the black hole formed and what it consumed, suggesting that information vanished with the black hole itself.
Steinhauer’s black hole revealed that the higher energy particle pairs remained entangled, even after one was swallowed by the event horizon. Entangled particles are able to share information instantaneously, even when they are separated by great distances, a phenomenon sometimes described as “spooky action at a distance.”
“Some of the solutions to this [paradox] probably rely on entanglement,” Steinhauer said.
Scientists not associated with the research who were interviewed by Nature News and Physics World both said that while the experiment appears to have measured Hawking radiation, it does not necessarily prove that Hawking radiation exists around black holes in space.
This research suggests that Ceres might still be warmed by radioactive material in its interior, scientists say.
With a diameter of about 585 miles (940 kilometers), Ceres is by far the biggest member of the asteroid belt located between Mars and Jupiter. Previous remote analysis of Ceres using ground- and space-based telescopes suggested that it was not as dense as other large asteroids such as Vesta. This suggested that Ceres was not made up solely of rock, but composed partly of both icy and rocky material.
However, scientists weren’t sure how the innards of Ceres were structured. Whereas Earth developed an onion-like structure fully differentiated into distinct layers — an outer crust, a central core and a mantle layer between the two — prior research suggested that Ceres might only be partially differentiated into more vague zones, or perhaps not differentiated at all. Shedding light on the structure of Ceres might, in turn, yield insight into how it and other asteroids and dwarf planets evolved over time.
One property of Ceres that might reveal more about its structure is how easy or difficult it is for the dwarf planet to spin. This property, technically known as the moment of inertia, is related to how mass is distributed within a celestial body: The lower the moment of inertia, the more dense material is concentrated in a body’s center.
To determine the moment of inertia of Ceres, scientists needed to analyze the dwarf planet’s gravity field. Anything that has mass has a gravity field that attracts objects toward it, and the strength of this field depends on a body’s mass. Because the mass of bodies such as Earth and Ceres is not spread out evenly, this means their gravity fields are stronger in some places on their surfaces and weaker in others.
The researchers examined gravity-field data that NASA’s Dawn spacecraft gathered from its close encounter with Ceres. Their work suggests that Ceres is only partially differentiated, with a core made of rock overlaid by a shell composed of a mix of icy, salty and rocky material that is about 43.5 to 120 miles (70 to 190 km) thick.
“The partial differentiation suggests that Ceres was hot at one point, but it did not fully separate the water and other volatiles from its rocky components,” study lead author Ryan Park, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, told Space.com.
The scientists also detected signs that Ceres’ interior might still be warm. This was a bit of a surprise, because previous research suggested that a body as small as Ceres should have cooled off a long time ago. This new finding indicates that Ceres might have a warm interior because of heat from radioactive material, Park said.