Scientists have spotted a kind of young birthplace for stars in telescope observations for the first time. The newborn star-forming clump in deep space is a giant cloud of gas that may have given birth to dozens of stars a year, researchers say.
The discovery could shed light on galaxy formation in the early universe, when star formation was at its peak, scientists added.
Stars formed at the greatest speed when the universe was between 3 billion and 4 billion years old, a time when galaxies possessed massive star-forming clumps. It was a mystery as to how these clumps arose, since astronomers have not yet seen them form. Now scientists have uncovered a young star-forming clump, one less than 10 million years old, which could help solve that mystery.
“Clumps have been extensively studied so far, but for the first time, we have observed a newly born one,” study lead author Anita Zanella, an astronomer at the French Alternative Energies and Atomic Energy Commission, told Space.com.
Until now, studied clumps usually contained stars more than 100 million years in age, meaning the clumps were correspondingly old, Zanella said. She and her colleagues instead looked for relatively young stars, which in turn could reveal the presence of relatively young clumps.
The astronomers used NASA’s Hubble Space Telescope to discover the clump, which is located in a galaxy nearly 10.4 billion light-years away, dating back to when the universe was only about 3.3 billion years old. The scientists calculated that the clump was about 3,000 light-years wide and more than 1 billion times the mass of the sun.
Based on the light detected from the clump, the researchers estimated that the gas cloud produced “the equivalent of 32 stars with the mass of the sun every year,” Zanella said. This accounted for nearly 40 percent of the stars produced in the galaxy hosting the clump. All in all, “the clump formed stars 10 times more efficiently than normal galaxies,” Zanella said.
By analyzing the initial phase of clump formation, this research favors a theory that suggests star-forming clumps begin as giant, dense pockets in highly turbulent, gas-rich matter in young galaxies. The researchers’ preliminary estimates suggest that giant clumps such as the one they discovered live about 500 million years.
This research suggests that giant clumps are not rapidly destroyed by the energetic winds from the stars they created as some had previously argued. Instead, the clumps could live long enough to migrate toward the centers of galaxies. “Clump migration could thus explain why and how galaxy bulges form,” Zanella said.
Future research with other telescopes could help discover additional young star-forming clumps, yielding insights on galaxy formation, Zanella said. That research could possibly involve the Atacama Large Millimeter Array in northern Chile and the James Webb Space Telescope, whose launch is planned for the end of 2018.
The results, outlined in a new study, show that the disk is about 60 percent larger than previously thought. Not only do the results extend the size of the Milky Way, they also reveal a rippling pattern, which raises intriguing questions about what sent wavelike fluctuations rippling through the disk.
The researchers said the likely culprit was a dwarf galaxy. It might have plunged through the Milky Way’s center long ago, sparking the rippling patterns astronomers have now detected for the first time.
Roughly 15 years ago, Heidi Newberg, an astronomer at the Rensselaer Polytechnic Institute in New York, and her colleagues found a group of stars beyond the disk’s outermost edge. The so-called Monoceros Ring is about 60,000 light-years from the galactic center (just beyond where the disk was thought to end at 50,000 light-years).
Over the years, astronomers were divided into two camps regarding the origins of the ring. Some argued that it was simply a tidal stream: The debris of a dwarf galaxy that fell into the Milky Way and was stretched in the process. Others argued that the ring is a part of the disk. The issue, however, is that the ring is slightly above the plane of the disk. So astronomers in the latter camp attributed that to the fact that the disk flares up toward the edge.
Enter Yan Xu, an astronomer at the National Astronomical Observatories of China. Xu, Newberg and colleagues took a second look at the problem using data from the Sloan Digital Sky Survey. With improved data compared to previous studies, they found four total structures in and just outside what is currently considered the Milky Way’s outer disk. The third structure was the highly debated Monoceros ring, and the fourth structure was the Triangulum Andromeda Stream, located 70,000 light-years from the galactic center.
All four structures alternated with respect to the disk. They went from above it, to below it, to above it, to below it. Newberg, who was in the tidal stream camp, was surprised that the ring and three other structures were actually a part of an oscillating disk.
“We didn’t know how a disk could go up and down,” said Newberg. Luckily, computer simulations by various teams showed that a dwarf galaxy falling into the Milky Way might create a similar pattern. “When it goes through, it can disturb the disk just like a pebble disturbs water in a puddle,” said Newberg. “And that wave can propagate through the disk from that event.”
This new picture makes sense, said Newberg. It even matches observations of the gases in the disk, which have long been observed as rippled. But the implications extend far beyond a corrugated disk.
“If it’s true that the Monoceros Ring and the Triangulum Andromeda structure are part of this oscillatory pattern, then the stellar disk goes out way further than the textbook tells us it ought to be,” said Newberg. Instead of extending nearly 100,000 light-years from one side to the other, it would be more like 160,000 light-years wide.
This brings the Milky Way’s size up to that of Andromeda. The Milky Way’s small radius in comparison to Andromeda’s larger radius has always puzzled astronomers, because the two galaxies have roughly the same mass.
The team plans to further map the rippled disk of Earth’s galaxy and better match their results to models.
The study was detailed in the March 10 edition of the Astrophysical Journal.
The remains of thousands of stars might exist in a vast graveyard near the giant black hole at the heart of our Milky Way galaxy, a region where dead stars feed on companions like zombies and unleash X-ray “howls,” researchers say.
Scientists have long thought that a monster black hole with the mass of 4.3 million suns, named Sagittarius A* (pronounced Sagittarius A star), lurks at the heart of the Milky Way. Recently, astronomers discovered that a surprising number of young, massive stars exist within a few dozen light-years of this black hole.
“These young, massive stars are puzzling because when we think about how stars form from clouds of gas that gravitationally collapse in on themselves, it’s hard to figure how these clouds could have survived long enough to form stars, given the intense gravitational pull of the supermassive black hole that’s so close to them,” lead study author Kerstin Perez, an astrophysicist now at Columbia University in New York, told Space.com.
To learn more about the mysterious center of the galaxy, scientists have focused on X-rays, whose the wavelengths and energies of can shed light on the kinds of activities take place at the galactic center. Previous research has suggested that relatively weak, “soft” X-rays from the galactic core mostly came from white dwarfs — the dim, fading remnants of stars much like the sun — that are accumulating or accreting matter onto themselves.
Now, using NASA’s NuSTAR X-ray space telescope, astronomers have the best pictures yet of the sources of stronger, “hard” X-rays from the area 100 or so light-years away from the Milky Way’s central black hole. However, the nature of these X-ray sources remains a mystery. In a statement, NASA described the signals as possible “screams” from zombie stars.
“As of right now, we haven’t solved any mysteries about the galactic center — we just launched a new, big mystery,” Perez said, who conducted this research while at Columbia University in New York.
Mystery in the Milky Way
The researchers currently have four possible explanations for these hard X-rays; three of those theories involve different kinds of stellar remnants. However, each of these options presents difficulties, Perez said.
One possible explanation points to what is known as an intermediate polar, which is a binary system made up of a white dwarf with a powerful magnetic field that is accreting matter onto itself from a companion star. Intermediate polars are cataclysmic variables, meaning they can brighten in sharp outbursts. [Latest Black Hole Images from NuSTAR Telescope]
If these powerful X-ray sources are intermediate polars, their presence would be puzzling. For example, if intermediate polars are the source of all this radiation, the researchers estimate that 1,000 to 10,000 intermediate polars might exist in the galactic center — about 1,000 times more than observers might have expected.
In addition, the energy of these X-rays suggests that each of the white dwarfs in these intermediate polars has a mass almost as heavy as the sun’s. That is substantially heavier than any intermediate polars that have previously been seen in the galactic center, which have masses that are about half that of the sun’s. “If these are intermediate polars, why are they so heavy?” Perez said. “Did they form from denser clouds of gas, or did they accrete more matter?
Alternatively, these hard X-ray sources might be millisecond pulsars, which are highly magnetic neutron stars that spin about 1,000 times per second. A neutron star is a dense, city-sized stellar remnant born from the explosive death of a larger star. However, when astronomers look at the galactic center in other wavelengths of light besides X-rays, “we don’t see as many millisecond pulsars as we would need to explain these hard X-rays,” Perez said. “Still, prior research has suggested there may be millisecond pulsars hiding in the galactic center.”
In a third theory, these hard X-rays might come from low-mass X-ray binaries. In this scenario, one of the pair of binary stars is either a black hole or a neutron star, while its companion is either a regular star like the sun, an old star such as a red giant or a stellar remnant such as a white dwarf.
However, “low-mass X-ray binaries are inherently unstable, mostly lasting on time scales of 10 years or so,” Perez said. “Maybe there’s something wacky about the environment of the galactic center that makes them more stable.”
One more scenario
The last possibility is that these powerful X-rays do not come from stellar remnants at all, but rather are the results of outbursts of high-energy particles known as cosmic rays, which are coming from the Milky Way’s supermassive black hole and slamming into dense clouds of gas and dust.
“Prior research has postulated that large flares happening on the order of 100 years could travel from the Milky Way’s supermassive black hole and travel through clouds, lighting them up in X-rays,” Perez said. “The difficulty with that idea is that the X-rays don’t match where material is known to be around the galactic center and models that exist right now of how cosmic rays propagate.”
To help solve the mystery behind these powerful X-rays, Perez and her colleagues hope to use NuSTAR to look at the galactic center within the coming year. “Maybe we’ll be able to narrow down these four possibilities,” Perez said.
The eruption was first recognized in 2014, when astronomer Emily Safron, who had just graduated from the University of Toledo in Ohio with her bachelor’s degree, noticed an object in her data that was brightening dramatically over time.
The finding not only marks the earliest eruption ever recorded but also sheds light on how stars grow to be so massive so quickly, researchers reported in a new study.
Stars are born within the clouds of dust and gas scattered throughout most galaxies. Turbulence within the clouds gives rise to knots that begin to collapse under their own weight. The knot quickly becomes a protostar, and continues to grow denser and hotter. Eventually, the central protostar becomes surrounded by a dusty disk roughly equal to it in mass. Astronomers call this a “Class 0″ protostar.
Although a Class 0 protostar has yet to generate energy by fusing hydrogen into helium deep in its core, it still shines, albeit faintly. As the protostar collapses further and accumulates more material from the disk of gas and dust surrounding it, it releases energy in the form of visible light. But this light is often blocked by the surrounding gas and dust.
Studies have shown, however, that the light heats up the dust around the protostar, causing it to give off a faint glow that can then be detected by infrared observatories, like the Spitzer Space Telescope. In this way, astronomers can detect a protostar’s presence via the faint glow of its surrounding dust clouds.
But in 2006, a Class 0 protostar in the constellation Orion, dubbed HOPS 383, acted out of the norm and brightened dramatically. Over two years, it became 35 times brighter. In addition, the most recent data available, from 2012, show that the eruption isn’t fading.
“HOPS 383 is the first outburst we’ve ever seen from a Class 0 object, and it appears to be the youngest protostellar eruption ever recorded,” William Fischer, a postdoctoral researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement from NASA.
The new study of HOPS 383 was completed using data from the Spitzer telescope in conjunction with the European Space Agency’s Herschel Space Observatory, as part of a project called the Herschel Orion Protostar Survey (HOPS).
Scientists were also surprised by the length of the eruption, thus making HOPS 383 even more intriguing.
“An outburst lasting this long rules out many possibilities, and we think HOPS 383 is best explained by a sudden increase in the amount of gas the protostar is accreting from the disk around it,” Fischer said.
It’s likely that instabilities in the disk lead to episodes in which large quantities of material flow onto the protostar, Fischer said. This causes the star to develop a hotspot on its surface, which, in turn, heats up the disk and brightens it dramatically.
Such episodes have been observed in older protostars and have been theorized to occur in younger protostars. These episodes could help explain why protostars are dimmer than scientists think they should be, according to the study.
To build up the bulk of a typical star over a short time period, protostars should be brighter, as they should accumulate more material from the surrounding disk faster. Because these protostars are so faint, some astronomers suspect that they could also build up the bulk of a typical star by randomly munching on a lot of material from the surrounding disk, as noted in the study. If that were the case, then astronomers should regularly observe these flashes.
The team will continue to monitor HOPS 383 and has submitted a proposal to use NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), the world’s largest flying telescope.
The study was published in the Feb. 10 edition of the Astrophysical Journal.
Supermassive black holes loom in the centers of the majority of massive galaxies. Some of these black holes, like the one in the Milky Way’s center, lie dormant. Others (so-called quasars) actively chow down on gas, causing them to radiate like brilliant beacons of light. They can therefore be seen from across the universe.
Although these monsters clearly accrete huge amounts of matter, some material escapes. It’s flung out into space at close to the speed of light in a jet of plasma. Astronomers don’t understand the physical mechanism at play here, but think it has to do with a strong magnetic field close to the black hole itself.
Luckily, magnetic field lines leave an imprint on any light that passes through them. The magnetic field will twist light so that it is circularly polarized, meaning the electric and magnetic fields rotate continuously as the wave moves, in a corkscrew motion. The stronger the magnetic field, the stronger this imprint.
Until now, only weak magnetic fields located several light-years from the black hole have been caught on camera via this twisting of light. But by looking at higher energies, like the ones visible with ALMA, astronomers can probe more powerful magnetic fields, which lie closer to their black hole counterparts.
“These results, and future studies, will help us understand what is really going on in the immediate vicinity of supermassive black holes,” Muller said in the statement.
Despite the harsh environment created by the monster black hole lurking in the center of the Milky Way galaxy, new observations show that stars — and, potentially, planets — are forming just two light-years away from the colossal giant.
Bright and massive stars were spotted circling the 4-million-solar-mass behemoth more than a decade ago, sparking a debate within the astronomy community. Did they migrate inward after they formed? Or did they somehow manage to form in their original positions?
Most astronomers had said the latter idea seemed far-fetched, given that the black hole wreaks havoc on its surroundings, often stretching any nearby gas into taffylike streamers before it has a chance to collapse into stars. But the new study details observations of low-mass stars forming within reach of the galactic center. The findings lend support to the argument that “adult” stars observed in this region formed near the black hole.
The new evidence for ongoing star formation near the black hole is “a nail in the coffin” for the theory that the stars form in situ, said lead author Farhad Yusef-Zadeh, of Northwestern University. The observations, if accurate, make it unlikely that the stars migrated from elsewhere, the researchers said.
Birth near a black hole
Stars are born within clouds of dust and gas. Turbulence within these clouds give rise to knots that begin to collapse under their own weight. The knots grows hotter and denser, rapidly becoming protostars, which are so-named because they have yet to start fusing hydrogen into helium.
But a protostar can rarely be seen. It has yet to generate energy via nuclear fusion, and any faint light it does produce is often blocked by the disk of gas and dust still surrounding it.
So, when Yusef-Zadeh and his colleagues used the Very Large Array in New Mexico to scan the skies near the central supermassive black hole, they didn’t spot the protostars but rather the disks of gas and dust surrounding them.
“You could see these beautiful cometary-shaped structures,” Yusef-Zadeh told Space.com. Intense starlight and stellar winds from previously discovered high-mass stars had shaped these disks into cometlike structures with bright heads and tails. Similar structures (called bow shocks) can be seen anywhere young stars are being born, including the famous Orion Nebula.
There is, of course, one big catch here — and that is that the tidal force on the black hole is so strong that it’s hard to see how these stars would form,” Yusef-Zadeh said. “Many people think that star formation is forbidden near a supermassive black hole. But nature finds a way.”
Astronomers have managed to find a way as well. Over the last decade, they’ve come up with two scenarios, both of which use the nearby black hole to simulate star formation.
In the first scenario, a cloud might break apart in the strong gravitational field and reassemble into a disk that surrounds the black hole. This disk would then form stars in the same way that the disks surrounding young stars form planets. Although this scenario was first proposed in 2005 by Sergei Nayakshin, an astronomer at the University of Leicester in the United Kingdom, it predicts the formation of low-mass stars. Until now, such stars hadn’t been discovered in the galactic center.
In the second scenario, a cloud gets stretched into a taffylike streamer. But as this happens, the gravitational tide from the nearby black hole does two different things. “It disrupts in one direction, but it squeezes in another direction,” Yusef-Zadeh said. It’s this squeezing, or compressing, that would trigger star formation within the long streamer, Yusef-Zadeh added.
Both scenarios explain why stars encircling the monster black hole, called Sagittarius A*, are found in two rings, or disks, as opposed to random placements.
But some astronomers remain cautious.
“The center of our galaxy is a unique and extreme environment very different from our local solar neighborhood and the rest of the Milky Way,” said Jessica Lu, an astronomer at the University of Hawaii’s Institute for Astronomy. It’s therefore crucial that astronomers don’t jump to any conclusions.
“While these bow shocks have similar shapes to protostars seen in the nearby Orion cluster, there are other ways to produce these bow shocks around small clumps of gas,” Lu told Space.com in an email. [The Strangest Black Holes in the Universe]
Some scientists who do think that stars — even low-mass stars — are forming within a few light-years of supermassive black holes are now starting to wonder if planets are forming there, too.
Typically, a disk circling a protostar will break up into clumps of gas and dust that later become full-fledged planets. But in such an extreme environment, the wind from nearby stars (the same winds that are responsible for the cometlike shapes of the disks seen by Yusef-Zadeh and his colleagues), may also steal mass from these disks. Yusef-Zadeh and his colleagues estimate that there could be enough material left in those disks to form planets.
The team plans to use the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile to better probe the disks where the planets may form. ALMA’s high sensitivity will reveal the disks’ masses and maybe even any gaps in the disks, which likely result from forming planets.
“We’re just beginning to really learn about this environment,” Yusef-Zadeh said, adding that he’s excited to start picking away at all of the questions the new study has opened.
The new Milky Way galaxy maps are based on observations by the European Space Agency’s prolific Planck space observatory. They show the Milky Way in four distinct color signals that, when combined into a single mosaic, create a hypnotic view of our home galaxy.The Planck satellite observed the oldest light in the universe during its mission. In the new Milky Way maps, red colors indicate dust, yellow is gas, green is high energy particles, and blue is the magnetic field.
“Planck can see the old light from our universe’s birth, gas and dust in our own galaxy, and pretty much everything in between, either directly or by its effect on the old light,” Charles Lawrence, the U.S. project scientist for the mission at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement.
The Planck satellite was built to detect microwave light, which made it sensitive to something called the cosmic microwave background, or light left over from the big bang. Planck’s study of the cosmic microwave background is helping scientists answer questions about the very early days of the universe, such as when the first stars were born.
With its microwave vision, Planck can detect more than just the cosmic microwave background.
One of the new Milky Way images released by the Planck collaboration is an overview that shows four separate galaxy views, as well as the final view of them combined. The red version (upper left) show the heat coming from dust throughout the Milky Way galaxy. Planck can capture this thermal light even though the dust is extremely cold — about minus 420 Fahrenheit (minus 251 Celsius).
The yellow version (upper right) shows carbon monoxide gas, which is concentrated in areas where new stars are being born. Meanwhile, the blue image (lower right) shows light created when charged particles get caught up in the Milky Way’s magnetic field, and are pulled along like a swimmer in a current. The particles accelerate to nearly the speed of light and begin to radiate. The green image (lower left) shows light that is created by free particles that zip past one another without quite colliding. This kind of light is often associated with hot, ionized gas near massive stars.
The $795 million Planck satellite launched in 2009 and collected data for just over four years before being decommissioned in 2013. Last week, the collaboration released the results of a much-anticipated joint study with the BICEP2 collaboration. In March 2014, BICEP2 announced what some scientists took as evidence of inflation in the early universe and evidence of gravitational waves. But the results of the join analysis showed that BICEP2′s measurements were contaminated by space dust.
The white spot on Ceres in a series of new photos taken on Jan. 13 by NASA’s Dawn spacecraft, which is rapidly approaching the round dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. But when the initial photo release on Monday (Jan. 19), the Dawn scientists gave no indication of what the white dot might be.
“Yes, we can confirm that it is something on Ceres that reflects more sunlight, but what that is remains a mystery,” Marc Rayman, mission director and chief engineer for the Dawn mission, told Space.com in an email.
The new images show areas of light and dark on the face of Ceres, which indicate surface features like craters. But at the moment, none of the specific features can be resolved, including the white spot.
“We do not know what the white spot is, but it’s certainly intriguing,” Rayman said. “In fact, it makes you want to send a spacecraft there to find out, and of course that is exactly what we are doing! So as Dawn brings Ceres into sharper focus, we will be able to see with exquisite detail what [the white spot] is.”
Ceres is a unique object in our solar system. It is the largest object in the asteroid belt and is classified as an asteroid. It is simultaneously classified as a dwarf planet, and at 590 miles across (950 kilometers, or about the size of Texas), Ceres is the smallest known dwarf planet in the solar system.
The $466 million Dawn spacecraft is set to enter into orbit around Ceres on March 6. Dawn left Earth in 2007 and in the summer of 2011, it made a year-long pit stop at the asteroid Vesta, the second largest object in the asteroid belt.
While Vesta shared many properties with our solar system’s inner planets, scientists with the Dawn mission suspect that Ceres has more in common with the outer most planets. 25 percent of Ceres’ mass is thought to be composed of water, which would mean the space rock contains even more fresh water than Earth. Scientists have observed water vapor plumes erupting off the surface of Ceres, which may erupt from volcano-like ice geysers.
The mysterious white spot captured by the Dawn probe is one more curious feature of this already intriguing object.
Scientists are finding more evidence of a galactic “skeleton” lurking inside the appendages of the Milky Way, and studying these massive “bones” could help researchers get a better idea of what our galaxy looks like from the outside.
In 2013, researchers first suggested that long, thin, dense clouds of gas may form inside the spiral arms of the Milky Way, creating a sort of galactic skeleton that traces the shape of these massive structures. At the time, only one such “bone” — known as Nessie — had been identified.
Now, new research presented at the 225th meeting of the American Astronomical Society shows that Nessie is not alone. Catherine Zucker, an undergraduate physics student at the University of Virginia, has dug up six strong candidates for additional galactic bones.
Living inside the Milky Way comes with a disadvantage: Astronomers cannot see what this galactic house looks like from the outside. The Milky Way is a spiral galaxy, meaning multiple “arms” sprout from a central region and then swirl around it, like streams of water spiraling down a drain. These arms coil around each other in a flat plane, so the galaxy is like a pancake: When it’s viewed face-on, it is circular, but when it’s viewed edge-on, it’s a straight line. The Earth is nestled inside this pancake, toward the outside of the disc. As a result, the Milky Way appears as a ribbon running down the middle of the night sky.
The sun and the Earth are elevated just slightly above the galactic plane, giving scientists a small boost when they’re trying to look at the larger galactic structure (like a kid on an adult’s shoulders, trying to see over a crowd). Scientists have identified the large spiral arms that make up the galaxy, but there is still debate about the exact location of those arms, as well as the location of smaller spirals that branch off of the larger ones.
But the “bones” that scientists have now identified — long, thin, highly dense clouds of gas that can also be identified by the light they absorb — would be significantly easier to spot, and could help scientists create a more precise sketch of what the Milky Way looks like from the outside.
“It’s a really new field of study,” Zucker told Space.com at the AAS meeting in Seattle, where she presented a poster featuring her work on the galactic skeleton. When Zucker started her work, the gas cloud known as “Nessie” was the only object of its kind that had been identified, and the only candidate for a bone. “What I was trying to do was basically prove that the Nessie filament wasn’t some curiosity, wasn’t a fluke — that there are other filaments out there similar to Nessie that can trace galactic structure.”
Zucker started looking through images of the galaxy taken by various telescopes, including the Spitzer Space Telescope. She found 15 long, thin gas clouds that looked like they could be galactic bones.
There were six initial criteria for a galactic bone. For example, it must lie mostly parallel to the plane of the galaxy and be associated with a known spiral arm — Nessie appears to trace the spine of the Scutum-Centaurus Arm, one of the largest arms in the Milky Way. A bone must also be more than 50 times longer than it is wide — Nessie is more than 300 times longer. Zucker also had to make sure she was seeing a single cloud and not multiple clouds in the same line of sight.
With her list of criteria, Zucker identified 10 candidate bones, six of which met the entire list of requirements. She spelled out her conclusion on her poster: “Nessie is not a ‘curiosity’ – other bones exist.”
Zucker is focusing on something called “Filament 5,” which could be a bone that lies in the Scutum-Centaurus Arm, just like Nessie, but on the opposite side of the galaxy. There is still some debate about the exact location of the Scutum-Centaurus arm. Different measurements put it within a few degrees of the center of the galactic plane. Zucker said bones like Nessie could “potentially resolve a lot of those issues.”
Ultimately, these bones could serve as a guide for creating a sketch of the Milky Way’ major structural elements, and give scientists an outside view of our galaxy, without requiring them to leave home.
The giant black hole at the center of the Milky Way galaxy recently spit out the largest X-ray flare ever seen in that region, astronomers say.
The enormous eruption from the Milky Way’s core was detected on Sept. 14, 2013, very close to the supermassive black hole known as Sagittarius A*. Pronounced “Sagittarius A star” and abbreviated as Sgr A*, the Milky Way’s monster black hole has a mass that is about 4.5 million times that of the sun. Scientists unveiled the discovery of the record-breaking flare this month at the 225th meeting of the American Astronomical Society.
The so-called “megaflare” flare was spotted by NASA’s Chandra X-ray Observatory, which can peer through dust and starlight to the center of the Milky Way. The event was 400 times brighter than the normal level of radiation from this region and nearly three times brighter than the previous record-holding flare, recorded in 2012. A second X-ray flare, with a flash 200 times brighter than normal levels, was then seen on Oct. 22, 2014.
Daryl Haggard, of Amherst College in Massachusetts, presented the findings at a news conference here at the AAS meeting on Jan. 5. Haggard and her colleagues have two possible explanations for what might have caused the flare. First, the black hole may be behaving like our own sun, which also emits bright X-ray flares. In the sun, these flares occur when magnetic-field lines become very tightly packed together or twisted, and the researchers said it’s possible something similar took place near the black hole.
It’s also plausible that the flare was the product of Sgr A* having a snack. An asteroid or other object may have come too close to the black hole, ripping it apart. The debris would have accelerated rapidly and potentially radiated a bright burst of X-rays.
“If an asteroid was torn apart, it would go around the black hole for a couple of hours — like water circling an open drain — before falling in,” Fred Baganoff, of the Massachusetts Institute of Technology and a member of the research team, said in a statement. “That’s just how long we saw the brightest X-ray flare last, so that is an intriguing clue for us to consider.”
Researchers saw the flare by chance while watching Sgr A* in anticipation of a different event: A gas cloud called G2 was set to make a close pass by Sgr A*, and some scientists hypothesized that material from G2 would fall into the black hole, generating a bright display of X-rays, NASA officials said in a statement. But no X-ray signal was detected as G2 made its closest approach to Sgr A*. The new flares do not appear to be part of the missing light show, according to Haggard.
We do not think flares are connected to the G2 object,” Haggard said. “And the reason for that is that the time scales don’t quite match. The time scale for these flares is fairly rapid — thousands of seconds,” or an hour or two, she said.
This time scale is characteristic of an object roughly one astronomical unit (the distance from the Earth to the sun) from Sgr A*, Haggard added. G2′s closest approach to Sgr A* was 150 astronomical units, “so the time scale doesn’t quite match up,” she added.
Haggard and her colleagues are hoping for flares from Sgr A*. With more detailed observations, she said, it might be possible to discern whether Sgr A* is rotating or stationary — a feature that can change aspects of a black hole’s physiology.
A NASA probe is about to get the first up-close look at a potentially habitable alien world.
In March 2015, NASA’s Dawn spacecraft will arrive in orbit around the dwarf planet Ceres, the largest object in the main asteroid belt between Mars and Jupiter. Ceres is a relatively warm and wet body that deserves to be mentioned in the same breath as the Jovian moon Europa and the Saturn satellite Enceladus, both of which may be capable of supporting life as we know it, some researchers say.
“I don’t think Ceres is less interesting in terms of astrobiology than other potentially habitable worlds,” Jian-Yang Li, of the Planetary Science Institute in Tucson, Arizona, said Thursday (Dec. 18) during a talk here at the annual fall meeting of the American Geophysical Union.
Life as we know it requires three main ingredients, Li said: liquid water, an energy source and certain chemical building blocks (namely, carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur).
The dwarf planet Ceres — which is about 590 miles (950 kilometers) wide — is thought to have a lot of water, based on its low overall density (2.09 grams per cubic centimeter; compared to 5.5 g/cubic cm for Earth). Ceres is likely a differentiated body with a rocky core and a mantle comprised of water ice, researchers say, and water-bearing minerals have been detected on its surface.
Indeed, water appears to make up about 40 percent of Ceres’ volume, Li said.
“Ceres is actually the largest water reservoir in the inner solar system other than the Earth,” he said. However, it’s unclear at the moment how much, if any, of this water is liquid, he added.
As far as energy goes, Ceres has access to a decent amount via solar heating, since the dwarf planet lies just 2.8 astronomical units (AU) from the sun, Li said. (One AU is the distance between Earth and the sun — about 93 million miles, or 150 million km). Europa and Enceladus are much farther away from our star — 5.2 and 9 AU, respectively.
Both Europa and Enceladus possess stores of internal heat, which is generated by tidal forces. This heat keeps the ice-covered moons’ subsurface oceans of liquid water from freezing up, and also drives the eruption of water-vapor plumes on Enceladus (and probably Europa as well; researchers announced last year that NASA’s Hubble Space Telescope spotted water vapor erupting from the Jupiter moon in December 2012).
Intriguingly, scientists announced the discovery of water-vapor emission from Ceres — which may also possess a subsurface ocean — earlier this year.
Ceres’ plumes may or may not be evidence of internal heat, Li said. For example, they may result when water ice near Ceres’ surface is heated by sunlight and warms enough to sublimate into space.
“Right now, we just don’t know much about the outgassing on Ceres,” Li said.
Dawn should help bring Ceres into much clearer focus when it reaches the dwarf planet this spring. The spacecraft, which orbited the huge asteroid Vesta from July 2011 through September 2012, will map Ceres’ surface in detail and beam home a great deal of information about the body’s geology and thermal conditions before the scheduled end of its prime mission in July 2015.
Ground-based instruments should also play a role in unveiling Ceres. For example, the Atacama Large Millimeter/submillimeter Array, or ALMA — a huge system of radio dishes in Chile — has the ability to probe deeper than Dawn, going into Ceres’ subsurface and shedding more light on the dwarf planet’s composition and thermal properties, Li said.
“This is highly complementary to the Dawn mission,” he said.
Ceres’ relative proximity to Earth also makes it an attractive target for future space missions, Li added.
For years, mysterious dark matter has eluded scientists, and now, a new study shows there may be less of it to find.
Using a century-old equation, scientists have found that the Milky Way galaxy holds half as much dark matter — the invisible stuff believed to make up a sizable chunk of the universe — as scientists had previously thought.
By calculating the speed of stars throughout the galaxy and conducting a detailed study of the Milky Way’s outer edges, a team of astronomers in Australia determined that the amount of the unseen dark matter in the galaxy is just 80 billion times the mass of the sun — half the mass of recent estimates.
In the 1950s, scientists determined that galaxies contain more matter than the human eye can see. The everyday material humans can see is made of baryonic matter, and it contains protons, neutrons and electrons. Scientists think dark matter may be composed of baryonic matter, nonbaryonic matter or a mixture of the two. Several possibilities for the material have been raised in recent years.
“Stars, dust, you and me — all the things that we see — only make up about 4 percent of the entire universe,” study lead author Prajwal Kafle, from the University of Western Australia, said in a statement. “About 25 percent is dark matter, and the rest is dark energy.”
Kafle and his team utilized the most up-to-date measurements of the galaxy. The measurements of the outer edges of the galaxy included more detailed studies than previous observations had. Then, the team used a technique developed by British astronomer James Jeans in 1915, long before researchers had envisioned dark matter.
In determining that the Milky Way contains less dark matter than previously thought, Kafle and his fellow researchers gained insight into a problem that theorists have been struggling with for almost 20 years.
“The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter Theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don’t see that,” Kafle said. “When you use our measurement of the mass of the dark matter, the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see — the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf [Spheroidal] galaxy.”
The oceans soured into a deadly sulfuric-acid stew after the huge asteroid impact that wiped out the dinosaurs, a new study suggests.
Eighty percent of the planet’s species died off at the end of the Cretaceous Period 65.5 million years ago, including most marine life in the upper ocean, as well as swimmers and drifters in lakes and rivers. Scientists blame this mass extinction on the asteroid or comet impact that created the Chicxulub crater in the Gulf of Mexico.
A new model of the disaster finds that the impact would have inundated Earth’s atmosphere with sulfur trioxide, from sulfate-rich marine rocks called anhydrite vaporized by the blast. Once in the air, the sulfur would have rapidly transformed into sulfuric acid, generating massive amounts of acid rain within a few days of the impact, according to the study, published today (March 9) in the journal Nature Geoscience.
The model helps explain why most deep-sea marine life survived the mass extinction while surface dwellers disappeared from the fossil record, the researchers said. The intense acid rainfall only spiked the upper surface of the ocean with sulfuric acid, leaving the deeper waters as a refuge. The model could also account for another extinction mystery: the so-called fern spike, revealed by a massive increase in fossil fern pollen just after the impact. Ferns are one of the few plants that tolerate ground saturated in acidic water, the researchers said.
The Chicxulub impact devastated the Earth with more than just acid rain. Other killer effects included tsunamis, a global firestorm and soot from burning plants. [The 10 Best Ways to Destroy Earth]
The ocean-acidification theory has been put forth before, but some scientists questioned whether the impact would have produced enough global acid rain to account for the worldwide extinction of marine life. For example, the ejected sulfur could have been sulfur dioxide, which tends to hang out in the atmosphere instead of forming aerosols that become acid rain.
Lead author Sohsuke Ohno, of the Chiba Institute of Technology in Japan, and his co-authors simulated the Chicxulub impact conditions in a lab, zapping sulfur-rich anhydrite rocks with a laser to mimic the forces of an asteroid colliding with Earth. The resulting vapor was mostly sulfur trioxide, rather than sulfur dioxide, the researchers found. In Earth’s atmosphere, the sulfur trioxide would have quickly combined with water to form sulfuric acid aerosols. These aerosols played a key role in quickly getting sulfur out of the sky and into the ocean, the researchers said. The tiny droplets likely stuck to pulverized silicate rock debris raining down on the planet, thus removing sulfuric acid from the atmosphere in just a matter of days.
“Our experimental results indicate that sulfur trioxide is expected to be the major sulfide component in the sulfur oxide gas released during the impact,” Ohno told Live Science in an email interview. “In addition to that, by the scavenging or sweeping out of acid aerosols by coexisting silicate particles, sulfuric acid would have settled to the ground surface within a very short time,” Ohno said.
After decades of wondering why young massive stars don’t blow away the gas surrounding them, astronomers have finally found a process that explains how these stellar youngsters hang on to their gassy envelopes.
This star type — more than 10 times the mass of the sun and most active in ultraviolet light — begins shining as a gigantic gas cloud collapses, fusing hydrogen into helium and igniting the star’s nuclear engine. The new research shows that this gas accretion continues even as the star shines, counteracting the stellar radiation that “pushes” against the gas.
A new model reveals that the gas falls unevenly onto the star and also clumps into spiral “filamentary concentrations” because there is so much gas in a small area. When the star moves through the spirals, these filaments absorb the ultraviolet radiation the star emits, protecting the surrounding gas. Once the absorption stops, the gas nebulas shrink. [Top 10 Star Mysteries]
“These transitions from rarefied to dense gas and back again occur quickly compared to most astronomical events,” Mac Low, a curator in the American Museum of Natural History’s Department of Astrophysics and co-author of the paper, said in a statement. “We predicted that measurable changes could occur over times as short as a few decades.”
Massive stars only influential not only when they are alive but also when they die. When a star of this size finishes burning the elements inside it, this triggers a massive collapse and explosion known as a supernova. These explosions created all elements in the universe that are heavier than iron, making Earth and other rocky planets possible.
Young massive stars have been closely studied for decades. Nobody could figure out why the gas around them didn’t blow away, however, as simpler models used previously implied that the gas would expand and dissipate.
The new models, based on observations from the Karl G. Jansky Very Large Array (VLA) in New Mexico, suggest that there are many small ionized hydrogen regions around these stars. The accretion process on the star kept going even after the hydrogen hotspots had formed, which was the opposite of what astronomers expected. Using models, astronomers then supposed that the gas falls unevenly on the star, creating the filaments.
Researchers came to this conclusion after using VLA observations of Sagittarius B2, a huge gas and dust cloud almost 400 light-years away from the center of the Milky Way galaxy. Between observations made in 1989 and 2012, researchers spotted four ionized hydrogen or HII regions getting brighter.
“The long-term trend is still the same, that HII regions expand with time,” said study leader Christopher De Pree, an astronomer at Agnes Scott College. “But in detail, they get brighter or get fainter and then recover. Careful measurements over time can observe this more detailed process.”
The research was recently published in Astrophysical Journal Letters and is also available in preprint form on Arxiv.
Astronomers have found what appears to be one of the oldest known stars in the universe.
The ancient star formed not long after the Big Bang 13.8 billion years ago, according to Australia National University scientists. The star (called SMSS J031300.362670839.3) is located 6,000 light-years from Earth and formed from the remains of a primordial star that was 60 times more massive than the sun.
“This is the first time that we’ve been able to unambiguously say that we’ve found the chemical fingerprint of a first star,” lead scientist Stefan Keller, of the ANU Research School of Astronomy and Astrophysics, said in a statement. “This is one of the first steps in understanding what those first stars were like. What this star has enabled us to do is record the fingerprint of those first stars.” [See amazing photos of supernova explosions]
Scientists think SMSS J031300.362670839.3 is probably at least 13 billion years old, though they do not know its exact age, Anna Frebel, an MIT astronomer associated with the research, said
Keller and his team found that the star actually has an unexpected composition. Astronomers thought that primordial stars — like the one that SMSS J031300.362670839.3 formed from — died in huge supernova explosions that spread large amounts of iron throughout space.
However, the new observations have shown that SMSS J031300.362670839.3′s composition harbors no iron pollution. Instead, the star is mostly polluted by lighter elements like carbon, ANU officials said.
“This indicates the primordial star’s supernova explosion was of surprisingly low energy,” Keller said. “Although sufficient to disintegrate the primordial star, almost all of the heavy elements such as iron, were consumed by a black hole that formed at the heart of the explosion.”
The scientists also found that the early star’s composition is very different from the sun.
“To make a star like our sun, you take the basic ingredients of hydrogen and helium from the Big Bang and add an enormous amount of iron — the equivalent of about 1,000 times the Earth’s mass,” Keller said. “To make this ancient star, you need no more than an Australia-sized asteroid of iron and lots of carbon. It’s a very different recipe that tells us a lot about the nature of the first stars and how they died.”
Because of its low mass, the star, located in the Milky Way, has a long lifetime, Anna Frebel, an MIT astronomer associated with the research, told Space.com via email.
Keller and his team found SMSS J031300.362670839.3 by using the ANU SkyMapper telescope. SkyMapper is surveying the sky at the Siding Spring Observatory in Australia to produce the first-ever digital map of the sky in the Southern Hemisphere. They confirmed their observations using the Magellan telescope in Chile.