An artist’s impression of Athena, and the latest map of the X-ray sky (containing 375000 X-ray sources)
At its meeting in Paris today, the Science Program Committee of the European Space Agency (ESA) selected the "The Hot and Energetic Universe" as the science theme for its next Large (L-class) mission.
The mission is expected to be launched in 2028, with the power to address some of the most fundamental questions in modern astrophysics.
Hot gas in the universe is the dominant form of ordinary matter, the same material that everything we see around us is made from. The hot gas forms the largest structures in the visible universe, aggregated around clusters of galaxies. With temperatures of more than a million degrees, the gas emits copiously at X-ray wavelengths.
With the new mission, astronomers will measure the properties of galaxy clusters in the distant universe, and map the physical characteristics of the largest structures known—information dramatically advancing our understanding of how these structures first assembled when the universe was just two billion years old.
Mapping the motion, temperature and chemical composition of the hot gas and tracking it through cosmic time are crucial to understanding the evolution of the galaxies and stars we see today.
With the powerful new X-ray Observatory, astronomers will be able to look still further back, to observe the first supermassive black holes, and to a time when the first galaxies were forming, less than one billion years after the Big Bang.
It will take another 10 years or so to build the Observatory. In 2028, Athena should begin to reveal the hot and energetic universe in unprecedented detail, and provide an answer to that most basic question—why does the universe look like it does today.
In the 1999 sci-fi film classic The Matrix, the protagonist, Neo, is stunned to see people defying the laws of physics, running up walls and vanishing suddenly. These superhuman violations of the rules of the universe are possible because, unbeknownst to him, Neo’s consciousness is embedded in the Matrix, a virtual-reality simulation created by sentient machines.
The action really begins when Neo is given a fateful choice: Take the blue pill and return to his oblivious, virtual existence, or take the red pill to learn the truth about the Matrix and find out “how deep the rabbit hole goes.”
Physicists can now offer us the same choice, the ability to test whether we live in our own virtual Matrix, by studying radiation from space. As fanciful as it sounds, some philosophers have long argued that we’re actually more likely to be artificial intelligences trapped in a fake universe than we are organic minds in the “real” one.
But if that were true, the very laws of physics that allow us to devise such reality-checking technology may have little to do with the fundamental rules that govern the meta-universe inhabited by our simulators. To us, these programmers would be gods, able to twist reality on a whim.
When the universe was young, galaxies were much smaller amorphous blobs of stars and gases. It was only over time that they merged to form bigger and shapelier blobs, gradually acquiring the contours that have become familiar. Now a team of observers, using several of the world’s most powerful telescopes, reports that they’ve seen this process in its earliest stages, as light from ancient stars has reached us after thirteen billion years. They’ve captured images of three small galaxies in the act of merging only nine hundred million years after the Big Bang, when the universe was only about seven per cent of its present age.
The first stars, and the galaxies that harbored them, were the earliest steps in the process of cosmic evolution that led to the modern universe. For astronomers, finding the first stars would be the equivalent of biologists finding the first organisms that arose on Earth.
According to the standard model of cosmology, the universe faded from the incandescent brilliance of the Big Bang into utter blackness about four hundred thousand years after the cosmos burst into existence. It was a nearly uniform sea of cold hydrogen and helium gas. Over the course of several hundred million years, some of that gas collapsed into distinct clumps. Inside those clumps, the very first stars flared into existence in what astronomers call the Cosmic Dawn.
Theorists believe that those early stars were huge, up to a hundred times the mass of the Sun, and that they lived only a few million years before exploding. (The sun is now four and a half billion years old, and will live for another few billion years.) The debris from those explosions then formed into the second generation of stars, most of them more modest in size, many of which are still burning today.
The first stars were made only of hydrogen and helium, since those were the only elements produced by the Big Bang, along with a tiny bit of lithium. But as they burned, the thermonuclear reactions in their cores created heavier elements, including oxygen, nitrogen, and carbon. Any stars that came after the first generation, including the sun, have detectable traces of those heavier elements.
Once ALMA is complete, he said, “we should be able to find many more of these first-generation star systems.” And with those in hand, astronomers might finally be able understand exactly how the universe went from darkness into light.
Stars in a little explored region of the Large Magellanic Cloud — one of the closest galaxies to the Milky Way — shine in an amazing new photo taken by a telescope in Chile.
The photo, released by the European Southern Observatory today (Nov. 27) and taken by the Very large Telescope, shows new, intensely hot stars molding their surrounding dust and gas into a nebula known as NGC 2035, or the Dragon's Head Nebula, about 160,000 light-years from Earth. You can watch a video flythrough of the cosmic image provided by ESO.
While the baby stars are on prominent display, the left side of the image also reveals the remnants of a supernova — an explosion that marks the death of some stars, ESO officials wrote in a release.
The huge pink, purple and blue cloud of dust on the right side of the photo is an emission nebula. Young stars emit radiation, causing the gas surrounding them to glow, but lurking within that gas are dark spots that create the "weaving lanes and dark shapes across the nebula," ESO officials wrote in a release.
A new class of telescopes could be based on neutrino detection, which would allow scientists to observe and measure cosmic phenomena that are difficult to detect with conventional telescopes (Getty)
"The era of neutrino astronomy has begun. The sources of neutrinos, and the question of what could accelerate these particles, have been a mystery for more than 100 years," said Professor Gregory Sullivan of the University of Maryland.
"Now we have an instrument that can detect astrophysical neutrinos. It's working beautifully, and we expect it to run for another 20 years," said Professor Sullivan, one of the 260 scientists from 11 countries who are participating in the IceCube project.
"This is the first indication of very high-energy neutrinos coming from outside our solar system. It is gratifying to finally see what we have been looking for. This is the dawn of a new age of astronomy," said Professor Francis Halzen, the principal investigator of IceCube.
This composite image reveals the structure of Himiko, an object representing the merger of three young, bright galaxies as seen in the early Universe. The left panel shows the section of the sky containing Himiko (identified in box) and other distant galaxies, as imaged by Hubble's Wide Field Camera 3 (WFC3). Credit: NASA/Hubble. The image in the upper right is a close-up of Himiko with Hubble. The three infant galaxies are clearly resolved where only one was known to exist before. These objects are extremely energetic, suggesting they are undergoing a period of intense star formation. CREDIT: NASA/Hubble. The image in the lower right is the same object with additional data from the Spitzer Space Telescope and Subaru Telescope on Mauna Kea in Hawaii. The halo of ionized hydrogen gas is clearly seen surrounding Himiko. Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope did not detect any telltale signature from carbon, suggesting that these three objects may be very primitive and have not had enough time to seed the intergalactic medium with heavy elements. Credit: NASA/Hubble; NASA/Spitzer; NAOJ/Subaru
"This exceedingly rare triple system, seen when the universe was only 800 million years old, provides important insights into the earliest stages of galaxy formation during a period known as 'cosmic dawn,' when the universe was first bathed in starlight," said Richard Ellis of the California Institute of Technology, Pasadena, a member of the research team.
New data from ALMA, Hubble and Spitzer also led astronomers to speculate that Himiko could be made up almost entirely of primordial gas, a mixture of the light elements hydrogen and helium, which were created in the Big Bang event that gave birth to our universe. If correct, this would be a landmark discovery signaling the detection of a primordial galaxy seen during its formation.
NASA's Hubble Space Telescope has revealed the first visual evidence of how
our home galaxy, the Milky Way, assembled itself into the majestic pinwheel of
stars we see today.
Astronomers used Hubble's deep-sky surveys to study the evolution of 400
galaxies similar to the Milky Way and noted their appearance at various stages
of development over a time span of 11 billion years. Judging from images of
these far-flung galaxies, they found the Milky Way likely began as faint, blue,
low-mass object containing lots of gas. Gas is the fuel for star birth and the
blue color is an indicator of rapid star formation.
They also found the Milky Way probably was a flat disk with a bulge in the
middle, both of which grew simultaneously into the majestic spiral seen today.
The sun and Earth reside in the disk and the bulge is both full of older stars
and home to a supermassive black hole that probably grew along with the
galaxy.
"For the first time, we have direct images of what the Milky Way looked like
in the past," said study co-leader Pieter G. van Dokkum of Yale University in
New Haven, Conn. "Of course, we can't see the Milky Way itself in the past. We
selected galaxies billions of light-years away that will evolve into galaxies
like the Milky Way. By tracing the Milky Way's siblings, we find that our galaxy
built up 90 percent of its stars between 11 billion and 7 billion years ago,
which is something that has not been measured directly before."
The Hubble telescope's superior resolving power, with which it can see
extremely fine details, allowed the researchers to study how the structure of
the Milky Way changed over time. At the peak of star formation, when the
universe was about 4 billion years old, the Milky Way-like galaxies were pumping
out about 15 stars a year. By comparison, the Milky Way today is creating only
one star a year.
(Photo : NASA/ISAS/DSS/O. Urban et al., MNRAS) Suzaku explored faint X-ray emission along eight different directions in the Perseus Galaxy Cluster, shown here in false color. Bluer colors indicate fainter X-ray emission. The dashed circle marks the cluster's effective boundary, where new gas is now entering, and is 2.7 degrees wide.
Most of the universe's heavy elements, including the iron central to life itself, formed surprisingly early in cosmic history and somehow spread evenly throughout the universe, according to a new study of the Perseus Galaxy Cluster using Japan's Suzaku satellite.
Between 2009 and 2011, researchers from the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), jointly run by Stanford University and the Department of Energy's SLAC National Accelerator Laboratory in California, used Suzaku's unique capabilities to map the distribution of iron throughout the Perseus Galaxy Cluster.
What they found is remarkable: Across the cluster, which spans more than 11 million light-years of space, the concentration of X-ray-emitting iron is essentially uniform in all directions.
"This tells us that the iron -- and by extension other heavy elements -- already was widely dispersed throughout the universe when the cluster began to form," said KIPAC astrophysicist Norbert Werner, the study's lead researcher. "We conclude that any explanation of how this happened demands lead roles for supernova explosions and active black holes."
The most profligate iron producers are type Ia supernovae, which occur either when white dwarf stars merge or otherwise acquire so much mass that they become unstable and explode. According to the Suzaku observations, the total amount of iron contained in the gas filling the cluster amounts to 50 billion times the mass of our sun, with about 60 percent of that found in the cluster's outer half.
The team estimates that at least 40 billion type Ia supernovae contributed to the chemical "seeding" of the space that later became the Perseus Galaxy Cluster.
Making the iron is one thing, while distributing it evenly throughout the region where the cluster formed is quite another. The researchers suggest that everything came together during one specific period of cosmic history.
Between about 10 and 12 billion years ago, the universe was forming stars as fast as it ever has. Abundant supernovae accompany periods of intense star formation, and the rapid-fire explosions drove galaxy-scale outflows. At the same time, supermassive black holes at the centers of galaxies were at their most active, rapidly accreting gas and releasing large amounts of energy, some of which drove powerful jets. Together, these galactic "winds" blew the chemical products of supernovae out of their host galaxies and into the wider cosmos.
Folk tales evolve much like species do, a researcher found after studying the evolutionary history of the tale "Little Red Riding Hood." (Photo : Carl Larsson/Wikimedia Commons)
Folk tales evolve much like species do, a researcher found after studying the evolutionary history of the tale "Little Red Riding Hood."
In the study published in the journal PLOS ONE, Durham University anthropologist Jamie Tehrani demonstrates that the story shares a common ancient root with the tale "The Wolf and the Kids," though the two have since evolved into different stories.
"This is rather like a biologist showing that humans and other apes share a common ancestor but have evolved into distinct species," Tehrani said.
Based on his research, "The Wolf and the Kids" likely originated in the 1st century, with "Little Red Riding Hood" branching off roughly 1,000 years later.
In older story, still popular in Europe and the Middle East, a wolf impersonates a nanny goat and eats her kids, whereas a wolf eats a young girl by impersonating her grandmother in "Little Red Riding Hood." Other variations, such as "The Tiger Grandmother," found in Japan, China and Korea, have all evolved.
Tehrani used a phylogenetic model analysis, used by biologists to group closely-related organisms, in order to map out the stories many evolutions based on 72 plot variables.
"My research cracks a long-standing mystery. The African tales turn out to be descended from 'The Wolf and the Kids' but over time, they have evolved to become like 'Little Red Riding Hood,' which is also likely to be descended from 'The Wolf and the Kids,'" he explained.
Going forward, Tehrani says he that in applying the same method to other folk tales, to be able offer new insight into human migration patterns by identifying where they started and where they ended up.
Scientists have spotted a black hole throwing out streams of iron and nickel, seeding the universe with heavy atoms that are part of the building blocks of planets and stars.
Black holes typically put out jets of charged particles, thousands of light-years long, which disperse into surrounding galaxies. However, this is the first time a typical black hole has been spotted pumping out heavier atoms, such as iron, which are 100,000 times more massive, and shooting them out at two thirds the speed of light.
The European Space Agency's XMM-Newton space telescope snapped the black hole, dubbed 4U1630-47, spewing out jets of the material, and the findings are backed up by Compact Array radio telescope in eastern Australia run by the Commonwealth Scientific and Industrial Research Organisation (CSIRO).
"Heavy atoms have been seen in jets from one other system, SS433, but that's a very unusual system, an oddball, whereas this system is quite typical, much more likely to represent black holes in general," CSIRO's Dr Tasso Tzioumis, a member of the research team.
The black hole is a dainty little thing, only a few times the mass of our Sun, but of a common type typically seen in the universe. Scientists are now looking at how these jet streams could affect galactic system development.
"Jets from supermassive black holes help determine a galaxy's fate - how it evolves," said Tzioumis. "So we want to understand better the impact jets have on their environment."
“The Pilbara region of Western Australia is one of the rare geological regions that provides insight into the early evolution of life on Earth,” explained Prof David Wacey from the University of Western Australia, who is a co-author of the paper published in the journal Astrobiology.
The paleontologists discovered the various microbially induced sedimentary structures in the early Archean coastal flats preserved in the Dresser Formation and found close similarities in both form and preservation style to sedimentary structures in younger rocks.
“The research extended the geological record of microbially induced sedimentary structures by almost 300 million years and showed that complex mat-forming microbial communities likely existed almost 3.5 billion years ago,” Dr Noffke concluded.
Harvard Smithsonian Center for Astrophysics, via Associated Press
An artist's impression of the Kepler 62 system, which consists of five worlds circling a yellowish star slightly smaller and dimmer than our sun.
Astronomers reported Monday that there could be as many as 40 billion habitable Earth-size planets in the galaxy, based on a new analysis of data from NASA’s Kepler spacecraft.
One of every five sun-like stars in the galaxy has a planet the size of Earth circling it in the Goldilocks zone — not too hot, not too cold — where surface temperatures should be compatible with liquid water, according to a herculean three-year calculation based on data from the Kepler spacecraft by Erik Petigura, a graduate student at the University of California, Berkeley.
Mr. Petigura’s analysis represents a major step toward the main goal of the Kepler mission, which was to measure what fraction of sun-like stars in the galaxy have Earth-size planets. Sometimes called eta-Earth, it is an important factor in the so-called Drake equation used to estimate the number of intelligent civilizations in the universe. Mr. Petigura’s paper, published Monday in the journal Proceedings of the National Academy of Science, puts another smiley face on a cosmos that has gotten increasingly friendly and fecund-looking over the last 20 years.
Over the last two decades, astronomers have logged more than 1,000 planets around other stars, so-called exoplanets, and Kepler, in its four years of life before being derailed by a mechanical pointing malfunction last May, has compiled a list of some 3,500 more candidates. The new result could steer plans in the next few years and decades to find a twin of the Earth — Earth 2.0, in the argot — that is close enough to here to study.
The nearest such planet might be only 12 light-years away. “Such a star would be visible to the naked eye,” Mr. Petigura said.
His result builds on a report earlier this year by David Charbonneau and Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics, who found that about 15 percent of the smaller and more numerous stars known as red dwarfs have Earth-like planets in their habitable zones. Using slightly less conservative assumptions, Ravi Kopparapu from Pennsylvania State University found that half of all red dwarfs have such planets. Astronomers estimate that there are at least 200 billion stars of all types in the Milky Way galaxy, room for the imagination, and — who knows — perhaps for a few microbes or more complicated creatures to roam.
Geoffrey Marcy of the University of California, Berkeley, who supervised Mr. Petigura’s research and was a co-author of the paper along with Andrew Howard of the University of Hawaii, said: “This is the most important work I’ve ever been involved with. This is it. Are there inhabitable Earths out there?”
“I’m feeling a little tingly,” he said.
At a news conference Friday discussing the results, astronomers erupted in praise of the Kepler mission and its team. Natalie Batalha, a Kepler leader from the NASA Ames Research Center, described the project and its members as “the best of humanity rising to the occasion.”
According to Mr. Petigura’s new calculation, the fraction of stars with Earth-like planets is 22 percent, plus or minus 8 percent, depending on exactly how you define the habitable zone.
There are several caveats. Although these planets are Earth-size, nobody knows what their masses are and thus whether they are rocky like the Earth, or balls of ice or gas, let alone whether anything can, or does — or ever will — live on them.
There is reason to believe, from recent observations of other worlds, however, that at least some Earth-size planets, if not all of them, are indeed rocky. Last week, two groups of astronomers announced that an Earth-size planet named Kepler 78b that orbits its sun in 8.5 hours has the same density as the Earth, though it is too hot to support life.
“Nature,” as Mr. Petigura put it, “knows how to make rocky Earth-size planets.”
Also, the number is more uncertain than it might have been because Kepler’s pointing system failed before it could complete its prime survey. As a result, Mr. Petigura and his colleagues had to extrapolate from planets slightly larger than Earth and with slightly smaller, tighter orbits. For the purposes of his analysis “Earth-size” was anything from one to two times the diameter of the Earth, and Earth-like orbits were between 400 and 200 days.
Dr. Batalha said, “We don’t yet have any planet candidates that are exact analogues of the Earth in terms of size, orbit or star type.”
Dr. Charbonneau said that raised “the terrifying question that haunts us exoplaneteers: Did the Kepler mission get enough data?”
Though Kepler itself is sidelined while astronomers devise a new program it can accomplish with less flexible pointing ability, it has sent back so much data that there is still a whole year’s worth of results left to analyze, Dr. Batalha said, and more improvements to make to the data already obtained. “Scientists,” she said, “are going to work on Kepler data for decades.” She said it would be about three years before they would be able to arrive at a viable rate for the occurrence of habitable Earths.
Kepler was launched in 2009 to perform a kind of cosmic census, monitoring the brightness of 150,000 far-off stars in the Cygnus and Lyra constellations, looking for dips in brightness when planets pass in front of them.
Dr. Petigura and his colleagues restricted themselves to a subset of some 42,000 brighter and well-behaved stars. They found 603 planets, of which 10 were between one Earth and two Earths in diameter, and circled in what Mr. Petigura defined as the habitable zone, where they would receive between a quarter of the light the Earth gets, and four times as much. In the solar system, that zone would spread from inside the orbit of Venus to just outside the orbit of Mars.
Meanwhile, in an innovation borrowed from other data-intensive fields like particle physics, Mr. Petigura designed a computer pipeline so that he could inject fake planets into the data — 40,000 in all — and see how efficiently his program could detect planets of different sizes and orbits.
“It was a ton of work,” he recalled, explaining that he had to try out tens of billions of different periods for each star in order to find planets. “Fortunately, computers are cheap today.”
Sara Seager, an exoplanet astronomer at the Massachusetts Institute of Technology who was not involved in the work, said the pipeline testing had made the results believable. “I would say that small planets are everywhere and very common — no matter how you slice and dice the data. But Kepler is dead and we have no way to get any further data. So we’ll have to be satisfied with this as the final word, for now.”
An artist’s impression of the Smith Cloud approaching our
Milky Way Galaxy. Image credit: Bill Saxton / NRAO / AUI / NSF.
A giant gas cloud is headed straight for the Milky Way Galaxy, but it has a deep-seeded magnetic force field that will likely soften its blow, giving scientists insight to such events.
Astronomers using the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and Robert C. Byrd Green Bank Telescope (GBT) said the force field discovery may explain how a high velocity cloud (HVC) can seamlessly merge with a galaxy.
The Smith Cloud is traveling at a rate of 150 miles per second and will hit out Galaxy disk in 30 million years. The inevitable collision, astronomers believe, will fuel the galaxy and set of a spectacle of star formations.
The gas clouds that slam into galaxy disks may be massive, but their gas makeup is soft and weak and could not survive such an impact on its own. Such clouds seemingly wander aimlessly around space, leading scientists to believe they are leftovers from other galaxy's formations.
"Our Galaxy is in an incredibly dynamic environment," said Hill, "and how it interacts with that environment determines whether stars like the Sun will continue to form."
