A huge telescope array will allow scientists to conduct the most sensitive and exhaustive search for signs of alien civilizations to date when it comes online, the project’s backers say.
The Square Kilometer Array (SKA), currently planned to begin construction in 2018, could enable the search for intelligent alien life to piggy-back on other scientific observations, scouring the galaxy with unprecedented precision.
“A unique aspect for the search of life in the universe is the question of whether advanced lifeevolves intelligence,” Andrew Siemion said at the Astrobiology Science Conference in Chicago in June. [13 Ways to Hunt Intelligent Alien Life]
Siemion, who holds joint appointments with the University of California, Berkeley, the Netherlands Institute for Radio Astronomy and Radbound University in the Netherlands, hunts for signs of alien technology in the universe.
“The only way to answer that in the foreseeable future is to look directly for evidence” of intelligence, Siemion said. “For that, you need a large telescope.”
The Square Kilometer Array is an enormous radio telescope that will be built in South Africa and Australia. Funded by a consortium of different countries, the SKA will combine thousands of small antennaeacross the globe instead of a single large dish, allowing unprecedented sensitivity in radio astronomy.
Using such a costly instrument for a single scientific study, especially one as speculative as the search for extraterrestrial intelligence (SETI), is unheard of in astronomy. But SETI scientists figured out a way to obtain significant telescope time nearly 30 years ago, when they began to piggy-back on other users’ observations at the enormous Arecibo Observatory in Puerto Rico, duplicating their observations with very little loss of sensitivity. Today, SETI researchers are able to obtain thousands of hours of observations annually, which they diligently scrutinize for radio signals from beyond Earth.
According to Siemion, data from the SKA could be similarly piggy-backed. But while Arecibo utilizes a single large dish, the SKA will be much larger than the biggest radio telescope operating today, allowing scientists to search for fainter signals.
Construction on the SKA should begin in 2018. The first phase, planned for completion by 2020, would allow for about 10 percent of the collecting area of the full instrument at low and mid-range frequencies.
According to a paper Siemion authored last fall, a five-year campaign by the first phase of the SKA could allow scientists to survey more than 10,000 stars. When completed, the SKA could detect signals as faint as those emitted by aircraft radars on Earth from every star within almost 200 light-years.
Earth began leaving its mark in the galaxy when humanity started transmitting signals by radio. These signals radiate outward from the planet, and could theoretically be detected by other civilizations. Given the enormous size of the spectrum that radio waves cover, scientists have suggested a number of preferred frequencies to hunt for extraterrestrial communication. [The Serious Search for Intelligent Life: 4 Key Questions (Video)]
As technology has improved on Earth, however, humanity has begun to reduce the radio-wave leakage into space. This could suggest that the window for observing accidentally broadcast signals is brief — perhaps only a century or so. While scientists still hope to detect such signals, they also aim to find deliberately transmitted radio waves, which have been designed to travel through space.
The SKA concentrates on a frequency region known as the “terrestrial microwave window,” the spectral region of low natural noise between the galactic background and the emission and absorption of water and oxygen in Earth’s atmosphere. These frequencies can travel through the space between stars and through the water-laden atmosphere of Earth or any other planet with ease, leading scientists to suspect that distant civilizations might use them to communicate
SETI scientists aren’t just searching for signals broadcast at random. They also hope to eavesdrop on interplanetary communications.
If alien technology spreads to multiple planets within a single system, it is feasible to expect these various outposts to communicate with one another. If those planets lie along Earth’s line of sight, and observations are made when the planets are communicating with each other, it is possible that the SKA could pick up those broadcasts, researchers said.
In addition to the recent spate of planets unearthed by NASA’s Keplermission, the European Space Agency’s Gaia spacecrat and future missions such as NASA’s Transiting Exoplanet Survey Satellite(TESS) could produce a catalog of properly aligned planetary systems to watch. Life-hunting researchers have already begun eavesdropping on some of Kepler’s discoveries, for example.
“We’re going to have all kinds of data to figure out how to build these databases in coming years,” Siemion said.
Although the terrestrial microwave window will be the primary focus of the SETI search with the SKA, Siemion cautions that it is not the only potential signal for communication.
“We don’t know exactly what E.T. is going to do,” he said.
Stephen Hawking may have just solved one of the most vexing mysteries in physics — the “information paradox.”
Einstein’s theory of general relativity predicts that the physical information about material gobbled up by a black hole is destroyed, but the laws of quantum mechanics stipulate that information is eternal. Therein lies the paradox.
Hawking — working with Malcolm Perry, of the University of Cambridge in England, and Harvard University’s Andrew Stromberg — has come up with a possible solution: The quantum-mechanical information about infalling particles doesn’t actually make it inside the black hole.
“I propose that the information is stored not in the interior of the black hole, as one might expect, but on its boundary, the event horizon,” Stephen Hawking said during a talk today (Aug. 25) at the Hawking Radiation conference, which is being held at the KTH Royal Institute of Technology in Stockholm, Sweden.
The information is stored at the boundary as two-dimensional holograms known as “super translations,” he explained. But you wouldn’t want super translations, which were first introduced as a concept in 1962, to back up your hard drive.
“The information about ingoing particles is returned, but in a chaotic and useless form,” Hawking said. “For all practical purposes, the information is lost.”
Hawking also discussed black holes — whose gravitational pull is so intense that nothing, not even light, can escape once it passes the event horizon — during a lecture last night (Aug. 24) in Stockholm.
It’s possible that black holes could actually be portals to other universes, he said.
“The hole would need to be large, and if it was rotating, it might have a passage to another universe. But you couldn’t come back to our universe,” Hawking said at the lecture, according to a KTH Royal Institute of Technology statement. “So, although I’m keen on spaceflight, I’m not going to try that.”
Located at the heart of a dwarf galaxy known as RGG 118, the black hole contains about 50,000 times more mass than the sun. It’s therefore less than half as heavy as the second-smallest known supermassive black hole, researchers said.
“It might sound contradictory, but finding such a small, large black hole is very important,” lead author Vivienne Baldassare, a doctoral student at the University of Michigan (UM) in Ann Arbor, said in a statement. “We can use observations of the lightest supermassive black holes to better understand how black holes of different sizes grow.” [Images: Black Holes of the Universe]
There are two types of black hole — stellar mass and supermassive. Stellar-mass black holes weigh a few times as much as the sun and form after the collapse of huge stars. Supermassive black holes reside at the center of most, if not all, galaxies and are thought to evolve and grow along with the collection of stars they inhabit.
RGG 118 is located about 340 million light-years from Earth; the dwarf galaxy was originally identified by the Sloan Digital Sky Survey. Baldassare and her colleagues were able to determine the mass of RGG 118′s central black hole by studying the motion of gas near the galaxy’s center with the 21-foot (6.5 meters) Clay Telescope in Chile.
At 50,000 solar masses, the black hole is quite a lightweight. For example, the Milky Way galaxy’s central supermassive black hole is about 100 times more massive. The heaviest known black holes weigh about 200,000 times as much as the one in RGG 118.
“In a sense, it’s a teeny supermassive black hole,” said co-author Elena Gallo of UM in another statement.
The team also used NASA’s Chandra X-ray Observatory to measure the X-ray brightness of RGG 118′s hot gas, which allowed them to calculate how quickly the black hole is gobbling up material. The scientists found that RGG 118 is consuming material at about 1 percent the maximum rate — similar to that of other, larger supermassive black holes.
“This little supermassive black hole behaves very much like its bigger, and in some cases much bigger, cousins,” said study co-author Amy Reines, also of UM. “This tells us black holes grow in a similar way, no matter what their size.”
Scientists still aren’t sure exactly how supermassive black holesare born and grow. One idea posits that huge clouds of gas collapse into “seed” black holes, which merge over time to form the larger, supermassive black holes. Other researchers think they form when a giant star, approximately 100 times the mass of the sun, runs out of fuel and collapses into a black hole.
“This black hole in RGG 118 is serving as a proxy for those in the very early universe, and ultimately may help us decide which of the two [ideas] is right,” Gallo said.
Active black holeshelp shape how their galaxies grow and evolve, regulating temperature and the movement of the gas and dust that grow into stars. The small size of RGG 118′s black hole indicates that the dwarf galaxy has likely never endured a mergerwith a neighbor — the process by which larger galaxies are thought to grow, researchers said.
“These little galaxies can serve as analogs to galaxies in the earlier universe,” Baldassare said. “By studying how galaxies like this one are growing and feeding their black holes and how the two are influencing each other, we could gain a better understanding of how galaxies were forming in the early universe.”
The research, which included a fourth author, Jenny Greene of Princeton University, is available online in the Astrophysical Journal Letters.
Planetary Resources deployed its first spacecraft from the International Space Station last month, and the Washington-based asteroid-mining company aims to launch a series of increasingly ambitious and capable probes over the next few years.
The goal is to begin transforming asteroid water into rocket fuel within a decade, and eventually to harvest valuable and useful platinum-group metals from space rocks.
“We have every expectation that delivering water from asteroids and creating an in-space refueling economy is something that we’ll see in the next 10 years — even in the first half of the 2020s,” said Chris Lewicki, Planetary Resources president and chief engineer Chris Lewicki.
“After that, I think it’s going to be how the market develops,” Lewicki told Space.com, referring to the timeline for going after asteroid metals.
“If there’s one thing that we’ve seen repeat throughout history, it’s, you tend to overpredict what’ll happen in the next year, but you tend to vastly underpredict what will happen in the next 10 years,” he added. “We’re moving very fast, and the world is changing very quickly around us, so I think those things will come to us sooner than we might think.”
Planetary Resources and another company, Deep Space Industries, aim to help humanity extend its footprint out into the solar system by tapping asteroid resources. (Both outfits also hope to make a tidy profit along the way, of course.)
This ambitious plan begins with water, which is plentiful in a type of space rock known as carbonaceous chondrites. Asteroid-derived water could do far more than simply slake astronauts’ thirst, mining advocates say; it could also help shield them from dangerous radiation and, when split into its constituent hydrogen and oxygen, allow voyaging spaceships to fill up their fuel tanks on the go.
The technology to detect and extract asteroid water is not particularly challenging or expensive to implement, Lewicki said. Scientific spacecraft routinely identify the substance on celestial bodies, and getting water out of an asteroid could simply involve bagging up the space rock and letting the sun heat it up.
Carbonaceous chondrites also commonly contain metals such as iron, nickel and cobalt, so targeting these asteroids could allow miners to start building things off Earth as well. That’s the logical next step beyond exploiting water, Lewicki said.
The “gold at the end of the rainbow,” he added, is the extraction and exploitation of platinum-group metals, which are rare here on Earth but are extremely important in the manufacture of electronics and other high-tech goods.
“Ultimately, what we want to do is create a space-based business that is an economic engine that really opens up space to the rest of the economy,” Lewicki said.
Developing off-Earth resources should have the effect of opening up the final frontier, he added.
“Every frontier that we’ve opened up on planet Earth has either been in the pursuit of resources, or we’ve been able to stay in that frontier because of the local resources that were available to us,” Lewicki said. “There’s no reason to think that space will be any different.”
Planetary Resources isn’t mining asteroids yet, but it does have some hardware in space. The company’s Arkyd-3R cubesat deployed into Earth orbit from the International Space Station last month, embarking on a 90-day mission to test avionics, software and other key technology.
Incidentally, the “R” in “Arkyd-3R” stands for “reflight.” The first version of the probe was destroyed when Orbital ATK’s Antares rocket exploded in October 2014; the 3R made it to the space station aboard SpaceX’s robotic Dragon cargo capsule in April. [Antares Rocket Explosion in Pictures]
Planetary Resources is now working on its next spacecraft, which is a 6U cubesat called Arkyd-6. (One “U,” or “unit,” is the basic cubesat building block — a cube measuring 4 inches, or 10 centimeters, on a side. The Arkyd-3R is a 3U cubesat.)
The Arkyd-6, which is scheduled to launch to orbit in December aboard SpaceX’s Falcon 9 rocket, features advanced avionics and electronics, as well as a “selfie cam” that was funded by a wildly successful Kickstarter project several years ago. The cubesat will also carry an instrument designed to detect water and water-bearing minerals, Lewicki said.
The next step is the Arkyd 100, which is twice as big as the Arkyd-6 and will hunt for potential mining targets from low-Earth orbit. Planetary Resources aims to launch the Arkyd-100 in late 2016, Lewicki said.
After the Arkyd 100 will come the Arkyd 200 and Arkyd 300 probes. These latter two spacecraft, also known as “interceptors” and “rendezvous prospectors,” respectively, will be capable of performing up-close inspections of promising near-Earth asteroids in deep space.
If all goes according to plan, the first Arkyd 200 will launch to Earth orbit for testing in 2017 or 2018, and an Arkyd 300 will launch toward a target asteroid — which has yet to be selected — by late 2018 or early 2019, Lewicki said.
“It is an ambitious schedule,” he said. But such rapid progress is feasible, he added, because each new entrant in the Arkyd series builds off technology that has already been demonstrated — and because Planetary Resources is building almost everything in-house.
“When something doesn’t work so well, we don’t have a vendor to blame — we have ourselves,” Lewicki said. “But we also don’t have to work across a contractural interface and NDAs [non-disclosure agreements] and those sorts of things, so that we can really find a problem with a design within a week or two and fix it and move forward.”
For its part, Deep Space Industries is also designing and building spacecraft and aims to launch its first resource-harvesting mission before 2020, company representatives have said.
Extracting and selling asteroid resources is in full compliance with the Outer Space Treaty of 1967, Lewicki said.
But there’s still some confusion in the wider world about the nascent industry and the rights of its players, so he’s happy that the U.S. Congress is taking up the asteroid-mining issue. (The House of Representatives recently passed a bill recognizing asteroid miners’ property rights, and the Senate is currently considering the legislation as well.)
“I think it’s more of a protection issue than it is an actual legal issue,” Lewicki said. “From a lawyer’s interpretation, I think the landscape is clear enough. But from an international aspect, and some investors — I think they would like to see more certainty.”
The most comprehensive assessment of the energy output in the nearby universe reveals that today’s produced energy is only about half of what it was 2 billion years ago. A team of international scientists used several of the world’s most powerful telescopes to study the energy of the universe and concluded that the universe is slowly dying.
“We used as many space- and ground-based telescopes as we could get our hands on to measure the energy output of over 200,000 galaxies across as broad a wavelength range as possible,” Galaxy And Mass Assembly (GAMA) team leader Simon Driver, of the University of Western Australia, said in a statement. The astronomers created a video explaining the slow death of the universe to illustrate the discovery.
When the Big Bang created the energy of the universe about 13.8 billion years ago, some portion of that energy found itself locked up as mass. When stars shine, they are converting that mass back into energy, as described by Albert Einstein’s famous equation E=mc2 (energy = mass x speed of light squared). [From the Big Bang to Now in 10 Easy Steps]
“While most of the energy sloshing around in the universe arose in the aftermath of the Big Bang, additional energy is constantly being generated by stars as they fuse elements like hydrogen and helium together,” Driver said.
“This new energy is either absorbed by dust as it travels through the host galaxy, or escapes into intergalactic space and travels until it hits something, such as another star, a planet, or, very occasionally, a telescope mirror.”
Astronomers have known that the universe is slowly fading out since the late 1990s. Using several telescopes on the ground, as well as NASA’s orbiting GALEX and WISE and the European Space Agency’s Herschel, the team found that the energy output is dropping over 21 different wavelengths, making their results the most comprehensive assessment to date of the energy output of the nearby universe.
“The universe will decline from here on in, sliding gently into old age,” Driver said.
“The universe has basically sat down on the sofa, pulled up a blanket, and is about to nod off for an eternal doze,” he said.
Astronomers are constantly uncovering the “most distant,” “most massive” or “most energetic” objects in our universe, but today, researchers have announced the discovery of a truly monstrous structure consisting of a ring of galaxies around 5 billion light-years across.
The galactic ring, which was revealed by 9 gamma-ray bursts (GRBs), is located 7 billion light-years away and spans an area of the sky more than 70 times the diameter of a full moon.
GRBs are thought to be detonated when a massive star reaches the end of its life. As the star implodes after running out of fuel, a black hole is formed and vast quantities of energy are blasted in collimated beams. Should Earth be aligned with these beams, an incredibly luminous signal can be observed and these beacons can be used to precisely gauge the distance to the GRB and the location of the galaxy that hosts it.
The GRBs are all cataloged in the Gamma Ray Burst Online Index, which precisely records each GRB distance and location, like pins on a cosmic map.
Astronomers believe these GRBs (and therefore the galaxies they inhabit) are somehow associated as all 9 are located at a similar distance from Earth. According to its discoverers, there’s a 1-in-20,000 probability of the GRBs being in this distribution by chance — in other words, they are very likely associated with the same structure, a structure that, according to cosmological models, should not exist.
“If the ring represents a real spatial structure, then it has to be seen nearly face-on because of the small variations of GRB distances around the object’s center,” said Lajos Balazs, of Konkoly Observatory in Budapest, Hungary, and lead author of a paper published in the journal Monthly Notices of the Royal Astronomical Society. “The ring could though instead be a projection of a sphere, where the GRBs all occurred within a 250 million year period, a short timescale compared with the age of the universe.”
But what could possibly be creating a sphere an unprescedented 5 billion light-years across?
According to most cosmological models, the universe should have a roughly uniform distribution of matter over the largest scales. This is known as the “Cosmological Principal” and observations by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and Europe’s Planck space telescope, which both studied the distribution of the universe’s ancient cosmic microwave background (CMB) radiation, seem to agree. However, other results have recently challenged this idea hinting that structures as large as 1.2 billion light-years may exist. But a growing list of discoveries in the cosmic abyss seem to contradict even the 1.2 billion light-year “limit.”
The GRB ring is 5 times larger than the 1.2 billion light-year limit; a pretty huge anomaly by anyone’s standard. And this latest discovery isn’t even the biggest. In 2013, another distribution of GRBs revealed a 10 billion light-year structure. Other large structures also defy this theoretical limit.
So what could be causing this particular ring of GRBs? One idea focuses around the large-scale structure of the universe where clusters of galaxies amass together in a web-like structure, thought to be clumped around concentrations of dark matter. The “holes” in this web are referred to as voids — regions of the cosmos that are conspicuously near-empty of any matter. The largest voids are called, unsurprisingly, “super-voids.”
But this new structure dwarfs all known super-voids.
“If we are right, this structure contradicts the current models of the universe. It was a huge surprise to find something this big — and we still don’t quite understand how it came to exist at all,” added Balazs.
So is the Cosmological Principal flawed? It’s certainly looking that way.
Galaxies are strung together in filaments separated by immense voids. These filaments are connected in a gargantuan tangle known as the cosmic web.
Much remains a mystery about how galaxies form. Researchers suggest that a key player is a kind of current known as a cold accretion flow. These rivers of gas can get as hot as 18,000 degrees Fahrenheit (10,000 degrees Celsius) — they are only “cold” relative to the kinds of extraordinarily hot winds astronomers regularly see in the universe, such as those around black holes.
One model suggests that, at the points where these filaments intersect, cold accretion flows streaming along the cosmic web’s filaments create disklike or ringlike structures, and that these “protogalactic disks” eventually coalesce into galaxies.
To learn more about how galaxies are born, scientists analyzed the first filament that astronomers ever imaged, a giant structure 1.5 million light-years long and 10 billion light-years away from Earth that was discovered in 2010.
This filament is about one-third as bright as the Milky Way, making it 3 billion times more luminous than the sun and more than 10 times brighter than what is expected for a filament. The filament is probably unusually radiant because it is illuminated by a quasar, the brightest type of object in the universe, researchers have said.
Using the Cosmic Web Imager at Palomar Observatory in California, the scientists discovered that the brightest spot in the filament is a spinning protogalactic disk of hydrogen.
“It is rare and surprising to discover a completely new kind of object,” said study lead author Christopher Martin, an astrophysicist at the California Institute of Technology in Pasadena.
The researchers found that this protogalactic disk is more than 407,000 light-years wide, weighs as much as about 100 billion suns, and is surrounded by a “halo” of invisible dark matter weighing as much as 10 trillion suns. For comparison, the Milky Way may be 160,000 light-years in diameter, and it weighs perhaps 1 trillion suns.
These findings reveal how cold accretion flows might help build protogalaxies — clouds of gas that give birth to galaxies, Martin said.
“It is extremely rare in astrophysics to be able to uncover the physical processes behind an observed phenomenon,” he told Space.com. “In this case, we will be able to study the processes that form the basic constituent of the universe, galaxies.”
In the future, Martin and his colleagues plan to find more protogalactic disks and study them with a larger telescope and better instruments.
“We are about to commission the perfect instrument for this — the Keck Cosmic Web Imager, which will be mounted at the Nasmyth focus of the W. M. Keck Observatory Keck II telescope [in Hawaii],” Martin said. “We plan to start observing at the beginning of 2016 with the Keck Cosmic Web Imager.”
The scientists detailed their findings online today (Aug. 5) in the journal Nature.
Talk about a starry night: A pair of university students in San Jose has found what appear to be the densest galaxies ever seen — cosmic realms where the night sky would appear ablaze with stars from the surface of a planet.
The students, Richard Vo and Michael Sandoval, discovered the so-called ultra-compact dwarf galaxies while sifting through open-source archives of astronomy observations by several different observatories as undergraduates at San Jose State University in California. They also created a video simulation depicting how such dense galaxies can form with a supermassive black hole at their core.
Looking up from a planet embedded inside one of the newfound galaxies, an observer would see more than a million stars at once, compared to the few thousand stars visible in Earth’s night sky, researchers explained. But the way these ultradense star clusters form, and whether they are actually galaxies at all, is still unknown.
“People have written sci-fi stories about things like this; it’s nice to see one that actually exists,” said Aaron Romanowsky, an astronomer at San Jose State University who served as the students’ adviser and co-author of the new study.
The first known ultracompact dwarf galaxy was found in 2013, surprising astronomers by having a supermassive black hole at its heart despite its small size. But the two newly discovered objects are even more tightly packed with stars. The first new object is about twice as dense as the original find, and the second object is a whopping 200 times denser than the original.
“This class of object was overlooked for a hundred years,” Romanowsky told Space.com. “It’s such a bright object, easy to see, but people didn’t know to look at it.” Romanowsky was also part of the team that found the first ultracompact dwarf galaxy two years ago. [A Tiny Dwarf Galaxy and Its Giant Black Hole (Video)]
In the past, such star clusters would have been mistaken for foreground stars because of their brightness. But when these clusters are examined more closely, the single point of light resolves into a fuzzy cluster, and spectrum data reveal it’s much farther away.
The width of one of the ultracompact dwarf galaxies, called M59-UCD3, is 200 times smaller than that of the Milky Way galaxy, but its star density is about 10,000 times higher. The other newfound galaxy, called M85-HCC1, has even more stars — its stellar density is 1 million times that of the Milky Way, and even led researchers to coin a new phrase for it: hypercompact cluster.
The students investigated data from the Sloan Digital Sky Survey, the Subaru Telescope in Hawaii, the Hubble Space Telescope, and the Southern Astrophysical Research Telescope in Chile. Although they intended to survey about one-third of the sky, each of them happened to discover an ultradense object not long after they began searching.
“It was a training procedure, actually,” said Vo, who is now a graduate student at San Francisco University in California. “He [Romanowsky] said, ‘There’s an ultracompact dwarf here; I want you to find it for yourself,’” Vo told Space.com.
But, in addition to the dwarf, he noticed another mysterious cluster. “And it ends up being one of the densest objects in the sky we have discovered so far,” Vo said.
The research is detailed in the July 20 edition of The Astrophysical Journal Letters.
Ultracompact dwarf galaxies have perplexed astronomers because they seem to defy classification. They’re too tiny to clearly be galaxies, but far too dense to be ordinary clusters of stars. [A Zoo of Galaxies in Infrared (Images)]
“For decades, a hundred years, there was a pretty clear distinction — how do you know the difference between a human and an elephant?” Romanowsky said. “Now, we’re finding things that are halfway in between, and we don’t know what to call them … The word we use is ‘ultracompact dwarf,’ but it’s an intentionally ambiguous word.”
The first ultracompact dwarf — which previously held the title of densest galaxy — puzzled astronomers until they spotted a supermassive black hole at its core. That detail suggested that it might have been a large galaxy at some point, before losing most of its stars. Researchers suspect that close interaction with another galaxy, whose gravity stripped off stars as they passed one another, might have transformed a normal dwarf galaxy into a dense ultracompact dwarf.
Sandoval, now a graduate student at the University of Tennessee in Knoxville, put together the above video simulation to demonstrate that process.
“We all know, from a mechanics/theory perspective, how things interact in space, [but] it is still hard to visualize how it actually looks in physical space,” Sandoval told Space.com in an email. “My goal was to see how the theory of tidal stripping would look in physical space, to accurately represent it, and to hopefully start up a method of analyzing phenomena that we can’t actually ‘see’ happening with our own eyes.”
The simulation was about as accurate as Sandoval could get without a supercomputer, and it incorporated imagery others had created showing what it would be like to look around inside the system, he said.
Going forward, the researchers will be searching for telltale signs of this process happening in the newly discovered objects; they’ll look for a supermassive black hole in the center and further analyze disturbances in the “host” galaxies near the objects. Those disturbances suggest that the large galaxies recently consumed stars from the ultracompact dwarfs; heavy metals in the dwarfs also suggest their previous size, as heavy metals are often synthesized by larger galaxies.
Romanowsky said that understanding how these objects form will teach astronomers about the formation of modern galaxies and what happens when they go head-to-head.
“In astronomy, there’s so many discoveries still to be made,” he added. “We’re still in the exploration phase, and even undergraduates can still make discoveries.”
Planets can exist in multiple-star systems. Astronomers have even observed them. Take Kepler-47c, a planet five times the mass of the Earth, in a very Earth-like orbit. The only difference is instead of one star in the center of the system, it has two. So contact your local travel agent and you can recreate that iconic film moment — just don’t forget a space suit: Kepler-47c isn’t exactly capable of supporting life, since it’s most likely a gas giant.
Astronomers don’t know for sure just how common planets are around multiple-star systems. To be fair, we don’t know for sure just how common planets are anywhere, but they appear to be just this side of quite numerous: a hundred billion planets, with a few billion of them life-friendly, in the Milky Way alone.
But you just can’t plop planets down wherever you feel like it, especially when it comes to multiple-star systems. The problem, as usual, is gravity.
Drawn into gravity
We usually think of gravity as easy. Two things attract each other. Done. Drop something, it falls. Launch a rocket, it doesn’t. Sure there are tides, and don’t get near black holes, but this is the kind of stuff that dead folks with interesting wigs figured out a long time ago.
Gravity is indeed pretty easy, when it’s just two things interacting. One planet plus one star? You’re golden. It’s so easy you can even write down the mathematical solutions of the possible orbits. All sorts of stable configurations. But put in another star? Or a third? The situation gets…tricky. Orbital stability isn’t a given. And the math? Just look up a picture of Henri Poincare, one of the first people to try to tackle the problem of multiple objects orbiting together. Look into his eyes, and tell me that isn’t the face of a man who has stared into the depths of mathematical hell and barely survived with his sanity intact.
I’m not saying that it’s impossible: You may have noticed, if you are observant enough, that our own solar system contains more than two objects. Our system didn’t fall apart billions of years ago because there’s a hierarchy. In other words, each planet or moon or asteroid or whatever is dominated by one and only one other player.
For example, the Earth cares a lot about the gravitational pull of the sun, but not of Jupiter, and Jupiter feels likewise. The moon cares a lot about the Earth, but not the sun or Ceres. And so on. Every interaction is essentially one-to-one. Thus, all the planets get nice stable little orbits that can last for billions of years. If you broke this hierarchy, say, by shoving Jupiter into the inner system, or inflating it to be 10 times more massive, its gravity would start to compete with the sun’s, the hierarchy would be broken, and so would the solar system.
All this gravity business means that planets around multiple star systems have only a few orbital options if they intend to stick around. Most potential orbits are unstable: even the faintest stellar breeze could potentially knock them either out of the system altogether or crashing into another body. To make a system a long-term home, a planet has two choices: either ensure that the gravitational pull of one star completely dominates the other, or that their gravitational effects are equal.
And that’s just for a binary star. Don’t get me started on multiples.
When two stars dance
Take Kepler-47c: the two stars orbit each other very closely and tightly , and the planet itself is rather far out. Far enough, in fact, that gravitywise the planet doesn’t even care that there’s two stars — to the planet, the center of the system just looks like a single star with the combined mass of the two suns. Stability achieved.
Another possible configuration is for a planet to only orbit a single star, with the other star far enough away and/or small enough to not matter. Figure-eight patterns around both stars are technically possible, but come on, don’t hold your breath looking for one. Truly chaotic orbits — stable, but never repeating the same pattern twice — would be extremely rare, too, as fun as they might be.
So we can get planets in a binary system, although they might be more rare than planets around solitary stars. But there are heaps of binary stars out there, so even if a tiny percentage of them host planets, that still leaves heaps of planets.
Life on around a binary-star system
What does this mean for such a planet’s weather and the prospects for life? That’s a little more difficult to say, since it’s hard to make general, broad-brush statements about the possibility of life anywhere, let alone in these kinds of binary systems. Instead, it’s best to examine each system (real or imagined) in detail.
While binary systems certainly have a habitable zone, where liquid water could potentially exist on the surface of a planet, life might find it difficult to gain a foothold. Orbiting two stars at once, as our friend Kepler-47c does, makes life very elliptical, occasionally bringing the planet out of the zone. Life doesn’t take too kindly to frequently freezing over.
Orbiting just one star in a binary system? Well, sometimes you’ll have two stars in your sky at once, which can be a tad toasty. And sometimes you’ll have a star on each face of the planet, ruining the night. And don’t forget the double-doses of UV radiation and solar flares.
With that kind of instability, erraticism and irradiation, it’s hard to imagine complex life evolving with the kind of regularity it needs. But thankfully, Mother Nature isn’t limited by our lack of imagination, so who knows what’s out there!
Learn more by listening to the episode “Is Life Possible Around a Binary Star?” on the Ask A Spaceman podcast, available on iTunes and on the Web at http://www.askaspaceman.com. Thanks to Adam Diener for the great question! Ask yours on Twitter using #AskASpaceman or by following @PaulMattSutter.
In the new image, researchers were able to make out the glow of ionized carbon (shown in red) in the process of assembling into a galaxy — called BDF 3299 — around 800 million years after the Big Bang. The carbon cloud is overlaid on another picture of the galaxy’s neighborhood, where you can tell the galaxy itself is off to the right. Researchers think that carbon’s glow is obscured by the supernova blasts and chaos of galactic formation there, but the cold store of carbon nearby still shines as the galaxy draws from it.
The image was captured by the Atacama Large Millimeter/submillimeter Array (ALMA), a giant radio telescope in Chile consisting of 66 radio antennas, most 40 feet (12 meters) in diameter.
“This is the most distant detection ever of this kind of emission from a ‘normal’ galaxy, seen less than one billion years after the Big Bang,” Andrea Ferrara, a cosmologist and co-author of the study from Scuola Normale Superiore, a part of the Pisa University System in Italy, said in a statement. “It gives us the opportunity to watch the build-up of the first galaxies. For the first time we are seeing early galaxies not merely as tiny blobs, but as objects with internal structure!”
BDF 3299 was among the first galaxies to condense out of cold matter during the galaxy’s reionization phase. Seeing the crooked galaxy’s formation offers a chance to refine models of the very early universe.
“We have been trying to understand the interstellar medium and the formation of the reionisation sources for many years,” Ferrara said. “Finally, to be able to test predictions and hypotheses on real data from ALMA is an exciting moment and opens up a new set of questions. This type of observation will clarify many of the thorny problems we have with the formation of the first stars and galaxies in the Universe.”
The black hole orbits in tandem with a sunlike star at the heart of the system V404 Cygni, which lies about 8,000 light-years from Earth. Swift spotted an outburst of activity from the black hole on June 15, and the spacecraft’s X-ray Telescope detected the expanding rings during observations made in late June and early July, NASA officials said.
The black hole is easy to see in the new images without the rings pointing the way; it appears as a bluish-white dot. But the bull’s-eye really marks the spot of the invisible interstellar dust between Earth and the system.
The various layers of dust, which are found between 4,000 and 7,000 light-years from Earth, reflect some of the X-rays over toward us as they fan out in all directions from the black hole.
“The flexible planning of Swift observations has given us the best dust-scattered X-ray ring images ever seen,” Andrew Beardmore, an astronomer at the University of Leicester in England and leader of the investigating team, said in a statement. “With these observations, we can make a detailed study of the normally invisible interstellar dust in the direction of the black hole.”
V404 Cygni’s arousal on June 15 was likely caused by material falling into the black hole, part of a cycle that repeats every few decades, researchers said. The companion star is about 10 percent as massive as the black hole, and the behemoth pulls a stream of gas away from it over time. The cool gas can resist the black hole’s pull, but when enough gas builds up and heats up, it’s suddenly pulled into the center of the black hole, triggering a sudden outburst of X-rays. Astronomers caught its most recent eruption before this one in 1989.
The outburst offers a rare opportunity to gather data about the nearby binary system, the black hole within it and the normally undetectable interstellar dust clouds that stand in its way, NASA officials said.
A newfound giant black hole nearly as massive as 7 billion suns is dozens of times larger than astronomers expected given its host galaxy’s size, researchers say.
This finding may call most current models of galaxy formation into question, scientists added.
Astronomers investigated a supermassive black hole known as CID-947 using the W.M. Keck Observatory in Hawaii, NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton spacecraft.
This black hole, one of the largest ever seen, formed in the early universe about 11.7 billion years ago — 2 billion years after the Big Bang. The very fast motion of gas near the black hole suggests that it has a very high mass — the equivalent of about 7 billion suns.
The discovery was unexpected. “Our survey was designed to observe the average objects, not the exotic ones,” study co-author C. Megan Urry, of Yale University, said in a statement. “This project specifically targeted moderate black holes that inhabit typical galaxies today. It was quite a shock to see such a ginormous black hole.”
However, it was the mass of the galaxy surrounding this black hole that most surprised the research team.
“The measurements correspond to the mass of a typical galaxy,” study lead author Benny Trakhtenbrot, an astrophysicist at the Swiss Federal Institute of Technology in Zurich, said in a statement. “We therefore have a gigantic black hole within a normal-size galaxy.”
Most galaxies, including the Milky Way, possess at their hearts a supermassive black hole with a mass ranging from millions to billions of times the mass of the sun. The supermassive black holes seen up to now usually make up only 0.2 to 0.5 percent of the mass of their galaxies — far less than CID-947 does.
“The black hole has roughly one-tenth of the mass of the host,” Trakhtenbrot told Space.com. “The black hole is massive compared with the normal host galaxy.” The result was so surprising that the astronomers had outside experts verify their results independently.
Current models of galaxy formation suggest that galaxies and their supermassive black holes evolve in sync, growing at the same rate. However, CID-947 defies this rule, precociously growing much faster than researchers would have predicted.
“The black hole and the galaxy were not growing in parallel, as many models would suggest,” Trakhtenbrot said.
In addition, the scientists found that, although the black hole had reached the end of its growth, stars were still forming in its galaxy. Prior research suggested that radiation and flowing gas from around the black hole would stifle the birth of stars.
“The black hole didn’t affect the growth of the galaxy — again, contrary to many common models and ideas in the field,” Trakhtenbrot said. “The black hole has done most of its growth and is shutting down. The galaxy is still growing.”
This finding supports previous research suggesting that black holes may have grown incredibly rapidly in the newborn universe, Trakhtenbrot said. For instance, the early universe was much smaller, and thus denser, on average than it is today, which could have helped black holes back then gorge on “an almost continuous inflow of gas without ‘burping’ too much of it back into the galaxy,” Trakhtenbrot said.
Trakhtenbrot and his colleagues now want to analyze more similarly ancient supermassive black holes to learn more about their interplay with their galaxies.
After taking a 26-year nap, a waking black hole released a burst of X-rays that lit up astronomical observatories on June 15 — and it’s still making a ruckus today.
Astronomers identified the revived black hole as an “X-ray nova” — a sudden increase in star luminosity — coming from a binary system in the constellation Cygnus. The outburst may have been caused by material falling into a black hole.
The burst was first caught by NASA’s Swift satellite, and then by a Japanese experiment on the International Space Station, called Monitor of All-sky X-ray Image (MAXI). [Black Hole Wakes Up With A Bang (Video)]
“Relative to the lifetime of space observatories, these black-hole eruptions are quite rare,” Neil Gehrels, Swift’s principal investigator at NASA’s Goddard Space Flight Center, said in a statement. “So, when we see one of them flare up, we try to throw everything we have at it, monitoring across the spectrum, from radio waves to gamma-rays.”
The binary system responsible for the eruption is called V404 Cygni, according to the statement from NASA. It’s made up of a star slightly smaller than the sun that orbits a black hole 10 times its mass. The orbital period is just 6.5 days, which makes it more than 10 times faster than Mercury orbits our own sun, the statement said.
Because the star orbits so closely to the black hole, the massive body pulls a stream of gas away from the star. Over time, the gas forms into a disc around the black hole.
When the gas is cooler, it’s able to resist the black hole’s pull. But as more gas gathers and it warms, eventually, the dam bursts, and gas is pulled toward the black hole. The rapidly moving, hot gas radiates an outburst of X-rays as it falls toward the gaping black maw, according to NASA.
This stellar duo has been active before, but only sporadically. The system was caught fluctuating in visible light in 1938 and 1956, and then in X-rays in 1989. The latter outburst was observed by instruments aboard Russia’s Mir space station and a Japanese X-ray satellite called Ginga.
Since this most recent outburst began, V404 Cygni has fluctuated several times in brightness — sometimes up to 50 times brighter than the Crab Nebula, a very bright source in X-rays, said Erik Kuulkers, a project scientist for the European Space Agency’s INTEGRAL satellite, one of the satellites that is studying V4040 Cygni. It also has caused more than 70 “triggers” of the burst monitor on NASA’s Fermi Gamma-ray Space Telescope in a single week. Usually, in the same time period, the telescope sees five times fewer triggers from all objects across the sky.
These triggers send email alerts to professional astronomers in the field, which led to a unique problem: “Achievement unlocked: Mailbox spammed by a black hole,” David Yu, a scientist at the Max Planck Institute of Extraterrestrial Physics in Germany, who works on the Fermi gamma-ray burst monitor, joked on social media.
The flares are ongoing. Many observatories around the world — including Swift, Fermi, MAXI, INTEGRAL and the Italian Space Agency’s AGILE — will continue to follow the bursts.
Ground-based professional observatories following the activity include the Gran Telescopio Canarias (Spain), the University of Leicester’s 0.5-meter telescope in Oadby (United Kingdom) and Waseda University’s Nasu radio telescope (Japan).
Astronomers may have discovered an exoplanet that has found the elixir to planetary youth, knocking billions of years off its age.
Until now, stellar rejuvenation has been pure conjecture, but after studying a white dwarf star called PG 0010+280, it turns out that one very interesting explanation for an excess in detected infrared radiation may be down to the presence of an exoplanet that was given a facelift.
White dwarf stars are the remnant husks of stars that have died. Eventually, when a star like our sun runs out of fuel, puffing up into a red giant star, its layers of plasma will be blasted into space by powerful, suicidal stellar winds. This will create a beautiful planetary nebula with a small, dense white dwarf in the core. [The Strangest Alien Planets (Gallery)]
But what happens to all this material that has been jetted into space? Well, as the theory goes, some of it may fall onto massive gaseous exoplanets orbiting far away from the star. Before their star ran out of hydrogen and puffed up into a red giant, that exoplanet was aging gracefully, cooling down billions of years after formation.
The situation changed, however, when its atmosphere became bulked up with stellar plasma, re-heating the massive world and making it appear much younger than it really is.
“When planets are young, they still glow with infrared light from their formation,” Michael Jura of the University of California, Los Angeles, co-author of the study published in The Astrophysical Journal, said in a statement. “But as they get older and cooler, you can’t see them anymore. Rejuvenated planets would be visible again
White dwarf studies have gone into overdrive in recent years after astronomers realized they could study white dwarf atmospheres to find the pulverized remains of asteroids and planetary bodies. When passing into the white dwarf phase, the planets and asteroids that are in orbit may drift too close to the powerful tidal forces near that star, and become shredded.
During a survey of white dwarfs for the chemical signatures of these pulverized planetary remains, undergraduate student Blake Pantoja, who was studying at UCLA at the time, came across something weird in data from NASA’s Wide-field Infrared Survey Explorer, and follow-up study by NASA’s Spitzer Space Telescope confirmed the strange excess in infrared light coming from PG 0010+280. At first the team assumed the excess was radiating from a disk of the pulverized remains of asteroids that may have been present — but the data didn’t fit with this explanation.
So two possible explanations remain: perhaps the excess is being generated by a companion brown dwarf (a failed star) or, potentially, a rejuvenated planet, heated up by an influx of stellar matter.
“I find the most exciting part of this research is that this infrared excess could potentially come from a giant planet, though we need more work to prove it,” said Siyi Xu of UCLA and the European Southern Observatory in Germany. “If confirmed, it would directly tell us that some planets can survive the red giant stage of stars and be present around white dwarfs.”
To confirm if this infrared excess is indeed a rejuvenated planet, astronomers are looking to NASA’s James Webb Space Telescope (that is planned for a 2018 launch) for help. Although tantalizing, we’ll have to wait for confirmation as to what this signal is.
The bizarre find is the first of its kind ever discovered by astronomers. The strange, cometlike planet, known as GJ 436b, is orbiting a red dwarf star and is about 22 times as massive as Earth. Astronomers detected the giant gas cloud around the planet using NASA’s Hubble Space Telescope and Chandra X-ray Observatory.
“I was astonished by the mere size of the cloud of gas escaping from the planet,” said study lead author David Ehrenreich, an astronomer at the observatory of the University of Geneva in Switzerland.
GJ 436b, located about 33 light-years from Earth in the constellation Leo, is a kind of world known as a warm Neptune. Such planets, at about 10 to 20 times the mass of Earth, are about the mass of “cold Neptunes” such as Uranus — and, naturally, Neptune — but they are as close, or closer, to their stars than Mercury is to our sun. With an orbit of only about 3 million miles (4.8 million kilometers), “GJ 436b is 33 times closer to its star than Earth is to the sun, and 13 times closer than Mercury,” Ehrenreich told Space.com.
The cloud of gas around GJ 436b, made up mostly of hydrogen, has a circular head that surrounds GJ 436b, and a tail trailing behind the planet. The diameter of the head is about 1.8 million miles (3 million km), or five times the width of the host star, which is about half that of the sun, Ehrenreich said. The length of the tail is uncertain, because the research team’s observations do not cover it entirely, but their computer models suggest it could be about 9.3 million miles (15 million km) long.
Although prior research has predicted that other gas giants should be blowing off cometlike tails, based on how hot they must be due to their proximity to their stars, “GJ 436b is the first planet for which a cometlike tail is confidently detected,” Ehrenreich said. (A previous study revealed indirect evidence of a rocky world that appears to be disintegrating around its host star, creating a cometlike tail of material behind the planet. That study used data from NASA’s Kepler space telescope, which observed scattering of the light from the planet’s host star.)
The scientists estimated that GJ 436b is currently blowing off up to 1,000 tons of gas per second. This means that GJ 436b is currently losing about 0.1 percent of its atmosphere every billion years, which is far too slow a rate to deplete its atmosphere in the lifetime of its parent red dwarf star. However, when the star was more active in its infancy, the researchers estimated that GJ 436b could have lost 10 percent or more of its atmosphere during its first billion years.
Recently, another team of researchers suggested that GJ 436b might possess a helium-rich sky depleted of hydrogen. “However, in order to be really hydrogen-poor and helium-rich, the atmosphere of GJ 436b should have represented a very small fraction of the planet['s] initial mass, around one-thousandth,” Ehrenreich said. “In such a case, the whole atmosphere would have been gone today, which as we measure is not the case.”
Ehrenreich noted that the Kepler spacecraft, as well as NASA’s upcoming TESS space mission and the European Space Agency’s future CHEOPS and PLATO spacecraft “are poised to find thousands of system like GJ 436 in the coming years.” This suggests that many other planets with cometlike tails could soon be discovered.
The scientists now plan to investigate less massive planets, such as “super-Earths” and “mini-Neptunes” to see if they might also have puffy atmospheres and cometlike tails.
“We’re going to study one such object in the course of next year with Hubble, and have proposed to observe several more,” Ehrenreich said.
The scientists detailed their findings online today (June 24) in the journal Nature.