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  • richardmitnick 7:59 am on October 4, 2016 Permalink | Reply
    Tags: , , , Do Black Holes Die?, space.com   

    From SPACE.com: “Do Black Holes Die?” 

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    October 3, 2016
    Paul Sutter


    Artist’s illustration of a supermassive black hole emitting a jet of energetic particles. Credit: NASA/JPL-Caltech

    Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center. Sutter is also host of Ask a Spaceman, RealSpace, and COSI Science Now.

    There are some things in the universe that you simply can’t escape. Death. Taxes. Black holes. If you time it right, you can even experience all three at once.

    Black holes are made out to be uncompromising monsters, roaming the galaxies, voraciously consuming anything in their path. And their name is rightly deserved: once you fall in, once you cross the terminator line of the event horizon, you don’t come out. Not even light can escape their clutches.

    But in movies, the scary monster has a weakness, and if black holes are the galactic monsters, then surely they have a vulnerability. Right?

    Hawking to the rescue

    In the 1970s, theoretical physicist Stephen Hawking made a remarkable discovery buried under the complex mathematical intersection of gravity and quantum mechanics: Black holes glow, ever so slightly, and, given enough time, they eventually dissolve.

    Wow! Fantastic news! The monster can be slain! But how? How does this so-called Hawking Radiation work?

    Well, general relativity is a super-complicated mathematical theory. Quantum mechanics is just as complicated. It’s a little unsatisfying to respond to “How?” with “A bunch of math,” so here’s the standard explanation: the vacuum of space is filled with virtual particles, little effervescent pairs of particles that pop into and out of existence, stealing some energy from the vacuum to exist for the briefest of moments, only to collide with each other and return to nothingness.

    Every once in a while, a pair of these particles pops into existence near an event horizon, with one partner falling in and the other free to escape. Unable to collide and evaporate, the escapee goes on its merry way as a normal non-virtual particle.

    Voila: The black hole appears to glow, and in doing so — in doing the work to separate a virtual particle pair and promote one of them into normal status — the black hole gives up some of its own mass. Subtly, slowly, over the eons, black holes dissolve. Not so black anymore, huh?

    Here’s the thing: I don’t find that answer especially satisfying, either. For one, it has absolutely nothing to do with Hawking’s original 1974 paper, and for another, it’s just a bunch of jargon words that fill up a couple of paragraphs but don’t really go a long way to explaining this behavior. It’s not necessarily wrong, just…incomplete.

    Let’s dig into it. It’ll be fun.

    The way of the field

    First things first: “Virtual particles” are neither virtual nor particles. In quantum field theory — our modern conception of the way particles and forces work — every kind of particle is associated with a field that permeates all of space-time. These fields aren’t just simple bookkeeping devices. They are active and alive. In fact, they’re more important than particles themselves. You can think of particles as simply excitations — or “vibrations” or “pinched-off bits,” depending on your mood — of the underlying field.

    Sometimes the fields start wiggling, and those wiggles travel from one place to another. That’s what we call a “particle.” When the electron field wiggles, we get an electron. When the electromagnetic field wiggles, we get a photon. You get the idea.

    Sometimes, however, those wiggles don’t really go anywhere. They fizzle out before they get to do something interesting. Space-time is full of the constantly fizzling fields.

    What does this have to do with black holes? Well, when one forms, some of the fizzling quantum fields can get trapped — some permanently, appearing unfortunately within the newfound event horizon. Fields that fizzled near the event horizon end up surviving and escaping. But due to the intense gravitational time dilation near the black hole, thy appear to come out much, much later in the future.

    In their complex interaction and partial entrapment with the newly forming black hole, the temporary fizzling fields get “promoted” to become normal everyday ripples — in other words, particles.

    So, Hawking Radiation isn’t so much about particles opposing into existence near a present-day black hole, but the result of a complex interaction at the birth of a black hole that persists until today.

    Patience, child

    One way or the other, as far as we can tell, black holes do dissolve. I emphasize the “as far as we can tell” bit because, like I said at the beginning, generality is all sorts of hard, and quantum field theory is a beast. Put the two together and there’s bound to be some mathematical misunderstanding.

    But with that caveat, we can still look at the numbers, and those numbers tell us we don’t have to worry about black holes dying anytime soon. A black hole with the mass of the sun will last a wizened 10^67 years. Considering that the current age of our universe is a paltry 13.8 times 10^9 years, that’s a good amount of time. But if you happened to turn the Eiffel Tower into a black hole, it would evaporate in only about a day. I don’t know why you would, but there you go.

    See the full article here .

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  • richardmitnick 10:11 am on July 28, 2016 Permalink | Reply
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    From SPACE.com- “Asteroid Defense: Scanning the Sky for Threats From Space” 

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    July 28, 2016
    Elizabeth Howell

    This graphic shows all of the potentially hazardous asteroids (and their orbital paths) around Earth (not to scale). As of 2013, scientists had counted over 1,400 of these potentially hazardous asteroids. Credit: NASA/JPL-Caltech

    Earth is hit every day by small bits of space dust. Slightly larger chunks burn up colorfully in the atmosphere, causing the shooting stars you see in the sky. Occasionally even bigger rocks hit our atmosphere; they are known as fireballs, because the light from them burning up is particularly bright. These tend to smack the Earth a few times a year and may produce a few fragments for rock-hunters to find.

    NASA and other organizations do regular scans of the sky to catalog any small bodies that are at risk of crashing into our planet. No imminently threatening bodies have been found yet, but it’s clear that sooner or later Earth will be struck by something big. The organizations are actively researching the best ways to protect Earth from asteroids, meteoroids or comets that may come crashing down.

    Asteroids refer principally to small, rocky bodies. Comets contain more ice and can also pose a threat to Earth. Before fragments enter our atmosphere, they are known as meteroids. During their path in the atmosphere, they are called meteors. If any of these pieces reach the ground, those pieces are called meteorites. The best hunting ground on Earth for meteorites is Antarctica because the ice makes it so easy to see the fragments, and the ground is not disturbed as much as a typical urban area or forest.

    The difference between a meteroid and an asteroid is a little vague. In 1961, The International Astronomical Union (the official body for naming objects in space) said a meteroid is much smaller than an asteroid, but bigger than an atom. A 2010 Meteoritics and Planetary Science paper led by Alan Rubin, a geophysicist at the University of California, Los Angeles, suggested that the limit for meteoroids be about 1 meter in size.

    Characterizing the threat

    It is clear that even small bodies can pose a threat; the asteroid that broke up over Chelyabinsk, Russia, in 2013 was roughly 56 feet (17 meters) across, shattering glass and injuring hundreds of people. In 1908, an estimated 130-foot (40-meter) object exploded over Siberia and flattened trees over 825 square miles (2,137 square kilometers). Around 50,000 years ago, before human civilization began, a rock about 150 feet wide (46 meters) smacked into what is now called Arizona. It left behind Meteor Crater, which is roughly 0.7 miles (1.2 kilometers) wide today.


    Even bigger collisions happened far in the past. The dinosaurs were wiped out 66 million years ago by an object about 6 miles (10 km) wide, which left behind a 110-mile (180 km) crater in Mexico known as Chicxulub. But that’s nothing compared to evidence of another impactor found in 2014. A rock formation in our planet’s crust pointed to a possible impactor 23 to 36 miles (37 to 58 kilometers) across that smacked into Earth 3.26 billion years ago, just a few million years after life evolved.

    NASA began tracking near-Earth objects (NEOs) in the 1970s. Its goal is to find objects that are at least tens of meters in size, “which could cause significant harm to populated areas on the Earth if they were to strike without warning,” NASA stated in 2014.

    Congress directed NASA in 1994 to find at least 90 percent of potentially hazardous NEOs larger than 0.62 miles (1 kilometer) in diameter, which NASA fulfilled in 2010. Congress also asked NASA in 2005 to find at least 90 percent of potentially hazardous NEOs that are 460 feet (140 meters) in size or larger. That’s supposed to be finished by 2020. NASA created a Planetary Defense Coordination Office in 2014 — a year after Chelyabinsk — to better coordinate its efforts, in response to an Office of the Inspector General report. Other space agencies such as the European Space Agency also have their own offices, and the different nations regularly collaborate with each other.

    An artist’s concept for the Asteroid Impact & Deflection Assessment (AIDA) mission led by the European Space Agency to intentionally strike an asteroid and test deflection capabilities that could protect Earth.
    Credit: ESA

    Scanning the sky

    NASA works with several sky surveys to maintain a list of potentially hazardous objects. These include the Catalina Sky Survey (University of Arizona), Pan-STARRS (University of Hawaii), Lincoln Near-Earth Asteroid Research or LINEAR (Massachussetts Institute of Technology) and Spacewatch (University of Arizona). These observatories are constantly upgrading their capabilities to try to catch fainter asteroids.

    Asteroids are also observed from space by several telescopes, but the one most regularly used for NEO searches is called NEOWISE.

    NASA/WISE Telescope
    NASA/WISE Telescope

    It’s the new mission of the Wide-field Infrared Survey Explorer (WISE) telescope, which launched in 2009 and was revived from hibernation in 2013 to search for asteroids. The telescope is expected to keep operating until 2017, when the angle from the sun in its orbit will be too bright to search for asteroids. A follow-up mission called Near Earth Object Camera (NEOCam) has been proposed for 2021, but is competing against five other missions for funding. Mission selection will be announced in September 2016.

    It’s the new mission of the Wide-field Infrared Survey Explorer (WISE) telescope, which launched in 2009 and was revived from hibernation in 2013 to search for asteroids. The telescope is expected to keep operating until 2017, when the angle from the sun in its orbit will be too bright to search for asteroids. A follow-up mission called Near Earth Object Camera (NEOCam) has been proposed for 2021, but is competing against five other missions for funding. Mission selection will be announced in September 2016.

    There are other NASA missions that are looking to get up close to asteroids to better characterize their composition. Some recent examples: The Dawn mission visited asteroid Vesta between 2011 and 2012, and has now been at Ceres (a dwarf planet) since 2015.

    NASA/Dawn Spacescraft
    NASA/Dawn Spacescraft

    OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is expected to depart for asteroid Bennu in 2018 for a sample-return mission, which will come back to Earth in 2023.

    NASA OSIRIS-Rex Spacecraft
    NASA OSIRIS-REx Spacecraft

    Additionally, NASA uses data available from other space agency missions that visited asteroids, such as the Japanese Hayabusa (completed) and Hayabusa 2 (in progress).

    NAOJ Hayabusa 2
    NAOJ Hayabusa 2

    Some planned missions will take even more daring steps at asteroids. NASA has been working on concepts for an Asteroid Redirect Mission (ARM) that would have a robot move a small body into the moon’s orbit, for astronauts to study. Also: NASA, the European Space Agency and other partners are planning a mission called AIDA, or Asteroid Impact and Deflection Assessment. The goal is to change the path of a small moon orbiting the asteroid Didymos using a kinetic impactor.

    A kinetic impactor (perhaps with a nuclear bomb inside) would deflect the orbit, tugging the asteroid slowly using a spacecraft, redirecting it with solar heat, or blasting it with a laser. That is just one idea. There is ongoing research as to what sort of asteroid deflection technique would be best. The best approach depends on many factors, such as cost, the composition of the asteroid, time to impact and technology maturity. Studies are ongoing in these fields; in 2007, NASA said that non-nuclear kinetic impactors had the most mature technology.

    See the full article here .

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  • richardmitnick 6:50 am on July 7, 2016 Permalink | Reply
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    From Stanford: “Stanford researchers help to explain how stars are born, cosmic structures evolve” 

    Stanford University Name
    Stanford University

    July 6, 2016
    Manuel Gnida

    An international team of scientists including Stanford researchers unveiled new findings on understanding the dynamic behavior of galaxy clusters and ties to cosmic evolution.

    Working with information sent from the Japanese Hitomi satellite, an international team of researchers that include Stanford scientists has obtained the first views of a supermassive black hole stirring hot gas at the heart of a galaxy cluster, like a spoon stirring cream into coffee.

    JAXA/Hitomi telescope

    This image created by physicists at Stanford’s SLAC National Accelerator Laboratory illustrates how supermassive black holes at the center of galaxy clusters could heat intergalactic gas, preventing it from cooling and forming stars. (Image credit: SLAC National Accelerator Laboratory)

    These motions could explain why galaxy clusters form far fewer stars than expected – a puzzling property that affects the way cosmic structures evolve.

    The data, published today in Nature, were recorded with the X-ray satellite during its first month in space earlier this year, just before it spun out of control and disintegrated due to a chain of technical malfunctions.

    “Being able to measure gas motions is a major advance in understanding the dynamic behavior of galaxy clusters and its ties to cosmic evolution,” said study co-author Irina Zhuravleva, a postdoctoral researcher at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC). “Although the Hitomi mission ended tragically after a very short period of time, it’s fair to say that it has opened a new chapter in X-ray astronomy.”

    KIPAC is a joint institute of Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory.

    Galaxy clusters, which consist of hundreds to thousands of individual galaxies held together by gravity, also contain large amounts of gas. Over time, the gas should cool down and clump together to form stars. Yet there is very little star formation in galaxy clusters, and until now scientists were not sure why.

    Norbert Werner, a research associate at KIPAC involved in the data analysis, said, “We already knew that supermassive black holes, which are found at the center of all galaxy clusters and are tens of billions of times more massive than the sun, could play a major role in keeping the gas from cooling by somehow injecting energy into it. Now we understand this mechanism better and see that there is just the right amount of stirring motion to produce enough heat.”

    Plasma bubbles stir

    About 15 percent of the mass of galaxy clusters is gas that is so hot – tens of millions of degrees Fahrenheit – that it shines in bright X-rays. In their study, the Hitomi researchers looked at the Perseus cluster, one of the most massive astronomical objects and the brightest in the X-ray sky.

    Other space missions before Hitomi, including NASA’s Chandra X-ray Observatory, had taken precise X-ray images of the Perseus cluster.

    Perseus cluster. Chandra.

    These snapshots revealed how giant bubbles of ultra-hot, ionized gas, or plasma, rise from the central supermassive black hole as it catapults streams of particles tens of thousands of light-years into space.

    Additional images of visible light from the cluster showed streaks of cold gas that appear to get pulled away from the center of the galaxy. However, until now it has been unclear what effect the plasma bubbles have on this intergalactic gas.

    To find out, the researchers pointed one of Hitomi’s instruments – the soft X-ray spectrometer (SXS) – at the center of the Perseus cluster and analyzed its X-ray emissions.

    Perseus cluster. Hitomi Collaboration / JAXA / NASA / ESA / SRON / CSA

    Steve Allen, a co-principal investigator and a professor of physics at Stanford and of particle physics and astrophysics at SLAC, said, “Since the SXS had 30 times better energy resolution than the instruments of previous missions, we were able to resolve details of the X-ray signals that weren’t accessible before. These new details resulted in the very first velocity map of the cluster center, showing the speed and turbulence of the hot gas.”

    By superimposing this map onto the other images, the researchers were able to link the observed motions to the plasma bubbles.

    Zhuravleva said, “From what we’ve seen in our data, the rising bubbles drag gas from the cluster center, which explains the filaments of stretched gas in the optical images. In this process, turbulence develops. In a way, the bubbles are like spoons that stir milk into a cup of coffee and cause eddies. The turbulence, in turn, heats the gas and suppresses star formation in the cluster.”

    Hitomi’s legacy

    Astrophysicists can use the new information to fine-tune models that describe how galaxy clusters change over time.

    One important factor in these models is the mass of galaxy clusters, which researchers typically calculate from the gas pressure in the cluster. However, motions cause additional pressure, and before this study it was unclear if the calculations need to be corrected for turbulent gas.

    “Although the motions heat the gas at the center of the Perseus cluster, their speed is only about 100 miles per second, which is surprisingly slow considering how disturbed the region looks in X-ray images,” said co-principal investigator Roger Blandford, the Luke Blossom Professor of Physics at Stanford and a professor of particle physics and astrophysics at SLAC. “One consequence is that corrections for these motions are only very small and don’t affect our mass calculations much.”

    Although the loss of Hitomi cut most of the planned science program short – it was supposed to run for at least three years – the researchers hope their results will convince the international community to plan another X-ray space mission.

    Werner said, “The data Hitomi sent back to Earth are just beautiful. They demonstrate what’s possible in the field and give us a taste of all the great science that should have come out of the mission over the years.”

    Hitomi is a joint project, with the Japan Aerospace Exploration Agency (JAXA) and NASA as the principal partners. Led by Japan, it is a large-scale international collaboration, boasting the participation of eight countries, including the United States, the Netherlands and Canada, with additional partnership by the European Space Agency (ESA). Other KIPAC researchers involved in the project are Tuneyoshi Kamae, Ashley King, Hirokazu Odaka and co-principal investigator Grzegorz Madejski.

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 9:48 am on June 28, 2016 Permalink | Reply
    Tags: , , space.com, The Universe's First Galaxies May Light Up Its Dark Ages   

    From SPACE.com: “The Universe’s First Galaxies May Light Up Its Dark Ages” 

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    June 28, 2016
    Nola Taylor Redd


    Shown in this artist’s impression, CR7 is one of the bright galaxies of the early universe and may contain some of the first generations of stars.
    Credit: ESO/M. Kornmesser

    A collection of newfound galaxies is illuminating how the early universe broke free from its Dark Ages. The family of galaxies may have played a role in the shift from a time when some light could not penetrate to an era of a transparent universe.

    “Stars and black holes in the earliest, brightest galaxies must have pumped out so much ultraviolet light that they quickly broke up hydrogen atoms in the surrounding universe,” David Sobral, an astrophysicist at Lancaster University in the United Kingdom, said in a statement. Sobral led an international team of scientists aiming to find several of these early galaxies using the Subaru and Keck telescopes in Hawaii and the Very Large Telescope in Chile.

    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA
    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    Keck Observatory, Mauna Kea, Hawaii, USA
    Keck Observatory, Mauna Kea, Hawaii, USA

    ESO/VLT at Cerro Paranal, Chile
    ESO/VLT at Cerro Paranal, Chile

    The results were presented today (Monday, June 27) at the National Astronomy Meeting in Nottingham, England.

    “The fainter galaxies seem to have stayed shrouded for a lot longer,” he said. “Even when they eventually become visible, they show evidence of plenty of opaque material still in place around them.”

    In 2015, Sobral led a team that found the first two members of the collection, galaxies CR7 and MASOSA, which might contain the first generation of stars. Together with a third galaxy known as Himiko, discovered by a Japanese team, the presence of the trio of galaxies hinted that a large population of similar objects might exist.

    The problem, however, is in spotting them. About 150 million years after the Big Bang kicked off the universe’s existence (an event that took place 13.8 billion years ago), the universe was dense with neutral hydrogen that blocked the passage of certain wavelengths of light. As radiation from the earliest stars split apart hydrogen in what scientists call the “epoch of reionization,” light began to slowly pass through the surroundings, bringing the Dark Ages to an end.

    Each of the five newfound galaxies discussed in the presentation contains a large bubble of ionized (charged) gas around them, suggesting that they haven’t managed to completely break free from the Dark Ages.

    This timeline summarizes the evolution of the universe, with the Big Bang at left and about 2 billion years into the universe’s existence at right. As reionization occurred, radiation emitted by the first stars and black holes cleared out the haze of neutral hydrogen.
    Credit: NASA/CXC/M. Weiss

    “Our results highlight how hard it is to study the small, faint sources in the early universe,” said co-author Sergio Santos, a graduate student at Lancaster University.

    “The neutral hydrogen gas blocks out some of their light, and because they are not capable of building their own local bubbles as quickly as the bright galaxies, they are much harder to detect,” he said.

    The fifth of the faraway sources discovered, VR7, is named in tribute to astrophysicist Vera Rubin, who won the Gold Medal of the Royal Astronomical Society in 1996, becoming the first woman to win that award in over 150 years.

    The young galaxies may be just a handful among the hundreds of thousands of ancient galaxies that might be spotted by future instruments.

    “What is really surprising is that the galaxies we find are much more numerous than people assumed, and they have a puzzling diversity,” Sobral said. “When telescopes like the James Webb Space Telescope are up and running, we will be able to take a closer look at these intriguing objects.”

    “We have only scratched the surface, and so the next few years will certainly bring fantastic new discoveries,” he said.

    See the full article here .

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  • richardmitnick 4:15 pm on June 26, 2016 Permalink | Reply
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    From SPACE.com: “New Recipe for Gravitational Waves Calls for Early Double Stars” 

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    June 22, 2016
    Nola Taylor Redd

    Take two massive stars, collapse them into black holes, bake for 10 billion years, and combine. That’s the recipe scientists have cooked up to produce the first detected gravitational waves spotted last September, and one that produces the most recent detection, as well.

    Cornell SXS team. Two merging black holes simulation
    Cornell SXS team. Two merging black holes simulation

    New work shows that that the two stars — the seeds for the first gravitational wave detection — became black holes only a few million years after their birth, then merged more than 10 billion years later. The second pair followed a similar path.

    To figure out the primary ingredients of the gravitational waves detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015 (and reported this year),,,

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    ,,,the team of scientists modeled pairs of stars throughout the lifetime of the universe. They found that most of the black hole mergers LIGO should expect to see would have happened only a few billion years after the Big Bang kicked off the universe 13.82 billion years ago.

    An artist’s schematic impression of the distortion of space-time by a supermassive black hole. Smaller black holes are thought to be responsible for the distortions in space-time (known as gravitational waves) detected by the LIGO experiment. Credit: Felipe Esquivel Reed

    Early universe collisions

    Black hole mergers start with a pair of stars, each ranging from 40 to 100 times the mass of the sun. Binary stars are common; more than half the stars in the universe are part of a stellar couple. The more massive star evolves faster, and begins to transfer material to its companion as it nears the end of its lifetime.

    What happens next is still unknown. Single stars with enough mass often explode as a supernova, blowing off excess material and leaving behind a dense core that collapses inward to form a black hole.

    Supernova in Messier 101, 2011 Image credit: NASA / Swift.
    Supernova in Messier 101, 2011 Image credit: NASA / Swift

    But some studies have suggested that binary stars can jump straight to the black hole stage without the violent supernova stage, and this was incorporated into the models used by the new study’s lead author Krzysztof Belczynski and his team.

    After one star becomes a black hole, the second star can inherited the expelled material from its companion, grow larger and interact with the black hole, shrinking the distance between the pair. Eventually, the second star also dies and forms a black hole.

    The stars that created the ripple spotted by LIGO formed when the universe was about 2 billion years old, Belczynski’s research suggests, making them some of the oldest and brightest stars. It took only about 5 million years for the stellar couple to both become black holes, what Belczynski called “a blink on the universe time scale.” But after the rapid changes came a period of waiting; it took just over 10 billion years for the pair to merge. The collision of the black holes produced waves in the space-time surrounding them, which were ultimately detected on Earth by LIGO.

    One way to determine the age of the original stars comes from understanding their metallicity, the amount of material other than hydrogen and helium the contain. Stars with additional ingredients have stronger winds carrying away their material, reducing their mass. The team found it more likely that stars with little pollution from other elements would interact to form black hole pairs.

    “Binaries at low metallicity survive interactions and form black hole-black hole mergers much more often than in high metallicity environments,” Belczynski, an astronomer at Warsaw University in Poland, told Space.com by email.

    “It is about 50 to 100 times more likely that a massive binary will form a black hole-black hole merger at low metallicities than at high metallicity,” he said.

    The first generations of stars in the universe were made up of hydrogen and helium, and fused other elements within their cores. When they exploded, they scattered the material into space, spreading the gas and dust that would build the next generation of stars. As a result, stars become more polluted with heavier elements over the lifetime of the universe. Therefore, most of the stars likely to produce black hole mergers most likely formed in the first generations, when the stars had lower metallicity.

    While LIGO probably didn’t spot a collision between the very first stars, those first stars may have produced their own black hole mergers and subsequent gravitational waves. No direct observations have been made of the first stars, making them difficult to model.

    “We do not see these first stars, so we have no observational information on how they evolve, so it is hard to predict things for them,” Belczynski said.

    His team focused on subsequent eras of stars, which scientists have observed.

    “For other, later generations of stars, we can see them and we can model them better, and the results are more secure,” he said.

    According to J. J. Eldridge, a physicist at the University of Auckland in New Zealand, these stars would still have appeared relatively early in the unvierse’s history, and could have played a role in lighting up the early universe during its Dark Ages. After the Big Bang, hydrogen created a curtain of darkness that kept certain wavelengths of light from passing through. Only after the first generations of stars heated up the hydrogen did light begin to shine in the early universe.

    The relatively early age of binary pairs that sent out the ripples detected by LIGO suggests that binary stars existed early in the universe, Eldridge said. This confirms work he and Elizabeth Stanway, at the University of Warwick in England, have done studying binary stars.

    “We suggested that binaries have to be common in the early universe,” Eldridge said. “GW 150914 [LIGO’s first detection] possibly coming from such a binary system at this time is a nice bit of extra evidence of how important binaries are to understanding the universe.”

    According to Belczynski, some parts of the today’s universe could still form stellar pairs that could wind up as colliding black holes down the road.

    “The pollution of the universe was not uniform, and even in present times, we have patches of stars and entire galaxies of low metallicity,” Belczynski said.

    “This is why we also predict that some black hole-black hole mergers may form in the present universe.”

    The research was published online in published online in the journal Nature June 22, along with Eldridge’s accompanying perspective article.

    Black hole mosh pit

    The early stars aren’t the only ones capable of producing black hole mergers. Recent evidence also suggests that black holes could have formed in globular clusters, huge collections of stars that travel close together.

    “These are systems that pack stars very tightly,” Frederic Rasio of Northwest University said last week during a news conference at the 228th meeting of the American Astronomical Society.

    The dense cluster pushes stars together. Rasio modeled what happened when two stars and a black hole danced together in a bizarre threesome. He found that, under the right circumstances, the star that started out with the black hole could wind up hurled into space, while the second star formed its own black hole that ultimately collided with its partner. The binary itself would find itself merged out of what he called “the black hole mosh pit.”

    According to Belczynski’s simulations, the rates of black hole mergers produced in the simulations are 40 times smaller than those formed through the combination of early, low-metallicity black holes, making it more likely that LIGO’s observations caught a glimpse of the first combinations. Eldridge agreed that it was more likely, though he noted the formation of the first gravitational waves in a black hole mosh pit could not be ruled out.

    “I suspect that both channels contribute to the merger rate,” Belczynski said.

    “Once we have lots and lots of LIGO detections, we will have mergers coming from both.”

    See the full article here .

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  • richardmitnick 3:44 pm on June 24, 2016 Permalink | Reply
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    From SPACE.com: “SETI Eavesdrops on Nearby Star in Smart Alien Hunt” 

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    June 24, 2016
    Ian O’Neill

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA
    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA

    Astronomers seeking out extraterrestrial intelligence have used a powerful radio telescope to eavesdrop on a star system that is relatively close to Earth in the hope of hearing the faint radio whisper of an alien civilization.

    Using the Allen Telescope Array (ATA) located in California (pictured top), members of the SETI Institute chose Trappist 1 as they know the red dwarf-type star plays host to at least 3 exoplanets.

    SETI Institute

    Trappist 1 system. Credit: ESO/M. Kornmesser

    Traditional SETI searches have looked to random stars in the sky in the hope of detecting an artificial radio signal using luck and some educated guesses. But now we know certain stars play host to exoplanets, alien hunters can be a little more discerning with the selection of stellar targets.

    Known as “targeted SETI”, the ATA has been used to “listen in” on star systems that NASA’s Kepler Space Telescope and other exoplanet-hunting missions have confirmed the presence of exoplanets.

    NASA/Kepler Telescope
    NASA/Kepler Telescope

    Even better than that, as Kepler can identify the physical size and orbit of a given exoplanet, astronomers can deduce whether that planet is located in the star’s “habitable zone.” The habitable zone around any star is the distance at which a hypothetical rocky planet can orbit that is not too hot or too cold for liquid water to exist. As we know from life on our planet, where there’s water, there’s life; could intelligent alien life be living on one of these potentially habitable worlds?

    Earth has been leaking a faint radio signals into space for over 100 years since the advent of commercial radio transmissions around the globe at the beginning of the 20th century. More recently, we’ve been pinging asteroids and the planets with powerful radar. And let’s not forget the controvercial Messaging Extraterrestrial Intelligence, or METI, a practice that has unsettled some scientists. Therefore, in theory, any intelligent aliens living within 100 light-years of Earth — assuming they possess sensitive enough radio receivers — could be aware of our presence.

    And this is what SETI is doing: listening out for alien transmissions that, so far, have proven inconclusive.

    However, last year, Kepler discovered a bizarre transit signal from the star KIC 8462852, otherwise known as Tabby’s Star. Kepler detects exoplanets by detecting their faint shadows cross the faces of their host stars. When Kepler detected Tabby’s Star transit, it was like nothing it had ever recorded; the brightness dip dimmed around 20 percent. Though the generally-accepted hypothesis is that a swarm of comets may have caused this strange transit signal, there’s another idea that it could be evidence of an advanced alien civilization building a “megastructure” around their star.

    Tabby’s Star quickly became a target for SETI, but no transmissions were detected by the ATA.

    According to a SETI Institute news release on Wednesday, even if there were transmitting aliens at Tabby’s Star, the fact it’s nearly 1,500 light-years away would make the detection of alien radio signals extremely unlikely, unless said aliens were deliberately beaming extremely powerful radio waves right at us.

    This is why Trappist 1 was selected for a follow-up SETI investigation. Though there’s no evidence of weird transit signals around this small star, it is an ancient compact planetary system that might, after some assumptions, be considered habitable. What’s more, Trappist 1 is only 40 light-years away — pretty much on our interstellar doorstep. Any signal transmitted from the Trappist 1 system would be athousand times stronger than a signal of identical strength transmitted from Tabby’s Star.

    So, for 2 days in May, the ATA focused on Trappist 1, seeking out an artificial narrowband signal of around 1 Hz or less. As the headline of this article isn’t “Aliens Found!” you can guess what the outcome was: no aliens were detected on this pass. But the ATA did put a valuable upper limit on the strength of a signal if there is a hypothetical alien civilization transmitting a signal at us.

    SETI researchers estimate that if aliens are transmitting from that star system, they’d have to build a 300 meter-wide radio antennae (the approximate size of the Arecibo telescope in Puerto Rico) with a transmitter power of 300 kilowatts. Interestingly, the most powerful radio transmitter on Earthoperates at around 700 kilowatts, so building a transmitter for interstellar messaging purposes is well within the realms of technological possibility.

    So this latest directed SETI campaign drew a blank, but it’s helping us probe regions of the radio frequency spectrum and the expected power output from a hypothetical alien civilization — valuable research if we are to detect and recognize a signal from extraterrestrials in the future.

    See the full article here .



    The science of SETI@home
    SETI (Search for Extraterrestrial Intelligence) is a scientific area whose goal is to detect intelligent life outside Earth. One approach, known as radio SETI, uses radio telescopes to listen for narrow-bandwidth radio signals from space. Such signals are not known to occur naturally, so a detection would provide evidence of extraterrestrial technology.

    Radio telescope signals consist primarily of noise (from celestial sources and the receiver’s electronics) and man-made signals such as TV stations, radar, and satellites. Modern radio SETI projects analyze the data digitally. More computing power enables searches to cover greater frequency ranges with more sensitivity. Radio SETI, therefore, has an insatiable appetite for computing power.

    Previous radio SETI projects have used special-purpose supercomputers, located at the telescope, to do the bulk of the data analysis. In 1995, David Gedye proposed doing radio SETI using a virtual supercomputer composed of large numbers of Internet-connected computers, and he organized the SETI@home project to explore this idea. SETI@home was originally launched in May 1999.

    SETI@home is not a part of the SETI Institute

    The SET@home screensaver image
    SETI@home screensaver

    To participate in this project, download and install the BOINC software on which it runs. Then attach to the project. While you are at BOINC, look at some of the other projects which you might find of interest.


    BOINC WallPaper

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  • richardmitnick 7:54 pm on May 30, 2016 Permalink | Reply
    Tags: , , space.com, Where's the Edge of the Universe?   

    From SPACE.com: “Where’s the Edge of the Universe?” 

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    May 27, 2016
    Paul Sutter

    This Hubble extreme deep field image shows many galaxies outside the Milky Way.
    Credit: NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team

    We all know that the universe is expanding, right? Well, if you weren’t aware, now you are. We live in an expanding universe: Every galaxy is flying away from every other galaxy. This naturally leads to a common question: If the universe is expanding, what’s it expanding into? More universe? Nothing? Something resembling a vague fog? Where’s the edge of our cosmic soap bubble?

    Well, our universe does have an edge — that is, if by “our universe,” you mean the observable universe.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    The speed of light is just that — a speed — and the universe has only been around for so long (about 13.77 billion years), which means only so much of the universe has been revealed to us via the light that has traveled those vast cosmic distances. And what’s outside our observable limit? That one’s easy: It’s just more stuff, like galaxies and black holes and new, fantastic varieties of cheese. It’s forever unreachable by us, sure — but it’s still over there.

    From our perspective, it looks like we’re at the center of everything, and every single galaxy is flying away from us. So that, naturally, leads to the “There’s got to be an edge” line of reasoning. But let’s say you hopped over to Andromeda, our nearest galactic neighbor.

    Andromeda Galaxy NASA/ESA Hubble
    Andromeda Galaxy NASA/ESA Hubble

    From that new vantage point, it still looks like you’re at the center of the universe and everything is flying away from you. Now let’s go really crazy and pretend we can teleport you to the most distant observable galaxy, on the far edge of our observational reach. Guess what? Yup, from your position, it looks like you’re at the center of the universe, and every galaxy — including the distant Milky Way — is racing away from you.

    That’s what we mean when we say “The universe is expanding.” Every galaxy is receding from every other galaxy (with a few minor exceptions from local mergers, but that’s the subject of another article).

    But there’s got to be a limit, right? It’s not like the universe is infinite, right? Right?

    Well, probably not. While it is very, very, very large, the universe is not likely infinitely big.

    But it still doesn’t need an edge.

    Think again about hopping from galaxy to galaxy. From the Milky Way, the universe looks like an enormous soap bubble growing in size, with us at the center.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt
    Milky Way NASA/JPL-Caltech /ESO R. Hurt

    But from another galaxy, this universal bubble looks different, because there’s a different galaxy at the “center” of the bubble.. What we might be tempted to call an “inside” or an “edge” of our universe is meaningless from the new perspective. And that’s true for every single galaxy.

    I’ll say it again: “Expanding universe” just means every galaxy is moving farther apart from every other galaxy. That’s it! No edge. No bubble. Nothing to expand into. The math is simple: The universe gets bigger with time. And that’s it.

    Let’s take a step back. Everyone knows those common analogies used to describe an expanding universe: Galaxies are like ants crawling around on a beach ball. We’re all raisins in a loaf of bread. And — oh! — the beach ball is inflating! Yes! The loaf of bread is rising in the oven! Space is expanding, and the galaxies are carried along with it! See? Easy!

    Those analogies certainly get across an important point: The galaxies aren’t flying or shooting or waltzing away from each other. It’s the space underneath them that’s doing all the work of expanding; the galaxies are just along for the cosmic carpet ride.

    But those analogies also carry a fatal flaw. We can all easily imagine an inflating beach ball or a rising loaf of bread, and we immediately think of them as expanding into something: empty air. The beach ball has a skin. The loaf has a delicious, crunchy crust. They have edges, and they’re moving into something.

    Our minds have played a trick on us, and it’s cheating us from being fully awestruck at what’s going on.

    When we use the ants-on-a-beach-ball analogy, the first thing people say is, “Why ants?” I don’t know; deal with it. And the second thing people say is, “Oh, the center of the universe is right there, in the middle of the ball.” At that point, I have to jump in with the limitations of the analogy:Our entire universe is the surface of the beach ball. And the surface of the ball has no center. Just as the surface of the Earth has no center. We could’ve made the poles anywhere we pleased.

    In the beach ball model, our entire universe is a two-dimensional surface, full of idiot ants trying to crawl toward each other but failing because some jerk keeps inflating it. OK, fine, whatever. That model universe is two-dimensional, but in our mind’s eye, we immediately think of it expanding into a third dimension — a dimension that the ants can’t access, because they can’t jump. But that extra dimension provides a “place” for the surface of the ball to expand into.

    But our real universe is three-dimensional. While string theory suggests there might be extra dimensions, they’re all supertiny, so those don’t count. So is there a fourth extra dimension that provides the “stuff” for our universe to expand into?

    Maybe, maybe not. Here’s the thing: The mathematics could support a fourth dimension for our 3D universe to expand into. And we would definitely have an “edge” in this extra dimension, the same way you can point to the “edge” of a 2D beach ball surface.

    But it doesn’t have to.

    We don’t need a fourth dimension to wrap around our universe. We have a complete and consistent mathematical description of the expansion of the universe using only the normal, workaday three dimensions that we know and love. So that means we can have an expanding universe without needing an edge or a thing for it to expand into.

    I’ll admit I have trouble wrapping my head around this concept. But that’s the beauty of using mathematics to understand the universe: We can create and manipulate concepts that our brains simply couldn’t handle on their own!

    Learn more by listening to the episode What’s the Point in Talking About Science? on the Ask A Spaceman podcast, available on iTunes and on the web at http://www.askaspaceman.com. Ask your own question on Twitter using #AskASpaceman or by following Sutter@PaulMattSutter and facebook.com/PaulMattSutter.

    Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center. Sutter is also host of the podcasts Ask a Spaceman and RealSpace, and the YouTube series Space In Your Face.

    See the full article here .

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  • richardmitnick 2:46 pm on May 7, 2016 Permalink | Reply
    Tags: , , , space.com   

    From SPACE.com- “Parallel Universes: Theories & Evidence” 

    space-dot-com logo


    April 28, 2016
    Elizabeth Howell

    Our universe may live in one bubble that is sitting in a network of bubble universes in space. Credit: Sandy MacKenzie | Shutterstock

    Is our universe unique? From science fiction to science fact, there is a proposal out there that suggests that there could be other universes besides our own, where all the choices you made in this life played out in alternate realities. So, instead of turning down that job offer that took you from the United States to China, the alternate universe would show the outcome if you decided to venture to Asia instead.

    The idea is pervasive in comic books and movies. For example, in the 2009 “Star Trek” reboot, the premise is that the Kirk and Spock portrayed by Chris Pine and Zachary Quinto are in an alternate timeline apart from the William Shatner and Leonard Nimoy versions of the characters.

    The concept is known as a “parallel universe,” and is a facet of the astronomical theory of the multiverse.

    Multiverse. Image credit: public domain, retrieved from https://pixabay.com/
    Image credit: public domain, retrieved from https://pixabay.com/ from Ethan Siegel, “The multiverse and the road not traveled”

    There actually is quite a bit of evidence out there for a multiverse. First, it is useful to understand how our universe is believed to have come to be.

    Arguing for a multiverse

    Around 13.7 billion years ago, simply speaking, everything we know of in the cosmos was an infinitesimal singularity. Then, according to the Big Bang theory, some unknown trigger caused it to expand and inflate in three-dimensional space. As the immense energy of this initial expansion cooled, light began to shine through. Eventually, the small particles began to form into the larger pieces of matter we know today, such as galaxies, stars and planets.

    Inflationary Universe. NASA/WMAP
    Inflationary Universe. NASA/WMAP

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    One big question with this theory is: are we the only universe out there. With our current technology, we are limited to observations within this universe because the universe is curved and we are inside the fishbowl, unable to see the outside of it (if there is an outside.)

    There are at least five theories why a multiverse is possible, as a 2012 Space.com article explained

    1. We don’t know what the shape of space-time is exactly. One prominent theory is that it is flat and goes on forever. This would present the possibility of many universes being out there. But with that topic in mind, it’s possible that universes can start repeating themselves. That’s because particles can only be put together in so many ways. More about that in a moment.

    2. Another theory for multiple universes comes from “eternal inflation.”

    Into what is the universe expanding NASA Goddard, Dana Berry
    Into what is the universe expanding NASA Goddard, Dana Berry

    Based on research from Tufts University cosmologist Alexander Vilenkin, when looking at space-time as a whole, some areas of space stop inflating like the Big Bang inflated our own universe. Others, however, will keep getting larger. So if we picture our own universe as a bubble, it is sitting in a network of bubble universes of space. What’s interesting about this theory is the other universes could have very different laws of physics than our own, since they are not linked.

    3. Or perhaps multiple universes can follow the theory of quantum mechanics (how subatomic particles behave), as part of the “daughter universe” theory. If you follow the laws of probability, it suggests that for every outcome that could come from one of your decisions, there would be a range of universes — each of which saw one outcome come to be. So in one universe, you took that job to China. In another, perhaps you were on your way and your plane landed somewhere different, and you decided to stay. And so on.

    4. Another possible avenue is exploring mathematical universes, which, simply put, explain that the structure of mathematics may change depending in which universe you reside. “A mathematical structure is something that you can describe in a way that’s completely independent of human baggage,” said theory-proposer Max Tegmark of the Massachusetts Institute of Technology, as quoted in the 2012 article. “I really believe that there is this universe out there that can exist independently of me that would continue to exist even if there were no humans.”

    5. And last but not least as the idea of parallel universes. To go back to the idea that space-time is flat, the number of possible particle configurations in multiple universes would be limited to 10^10^122 distinct possibilities, to be exact [Please explain the derivation of this number.]. So, with an infinite number of cosmic patches, the particle arrangements within them must repeat — infinitely many times over. This means there are infinitely many “parallel universes”: cosmic patches exactly the same as ours (containing someone exactly like you), as well as patches that differ by just one particle’s position, patches that differ by two particles’ positions, and so on down to patches that are totally different from ours.

    Arguing against a parallel universe

    Not everyone agrees with the parallel universe theory, however. A 2015 article on Medium by astrophysicist Ethan Siegal agreed that space-time could go on forever in theory, but said that there are some limitations with that idea.

    The key problem is the universe is just under 14 billion years old. So our universe’s age itself is obviously not infinite, but a finite amount. This would (simply put) limit the number of possibilities for particles to rearrange themselves, and sadly make it less possible that your alternate self did get on that plane after all to see China. [Sorry, I do not get this argument at all. Especially the fact that our universe is finite means there could be others.]

    Also, the expansion at the beginning of the universe took place exponentially because there was so much “energy inherent to space itself,” he said. But over time, that inflation obviously slowed — those particles of matter created at the Big Bang are not continuing to expand, he pointed out. Among his conclusions: that means that multiverses would have different rates of inflation and different times (longer or shorter) for inflation. This decreases the possibilities of universes similar to our own [Why do they need to be similar?].

    “Even setting aside issues that there may be an infinite number of possible values for fundamental constants, particles and interactions, and even setting aside interpretation issues such as whether the many-worlds-interpretation actually describes our physical reality,” Siegal said, “the fact of the matter is that the number of possible outcomes rises so quickly — so much faster than merely exponentially — that unless inflation has been occurring for a truly infinite amount of time, there are no parallel universes identical to this one [same question.].”

    But rather than seeing this lack of other universes as a limitation, Siegal instead takes the philosophy that it shows how important it is to celebrate being unique. He advises to make the choices that work for you, which “leave you with no regrets.” That’s because there are no other realities where the choices of your dream self play out; you, therefore, are the only person that can make those choices happen [I really enjoy Ethan Siegel. He is a stellar (no pun intended) science communicator who obviously knows his stuff. But this last point is not Cosmology, Astronomy, or Astrophysics. It is Philososphy. Is Ethan also a philosopher?]

    See the full article here .

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  • richardmitnick 12:33 pm on April 26, 2016 Permalink | Reply
    Tags: , , space.com, Wolf-Rayet stars   

    From SPACE.com: “Wolf-Rayet Stars: Sounds Like Sci-Fi, But Full of Sci-Fact” 

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    April 25, 2016
    Paul Sutter, Astrophysicist
    The Ohio State University, chief scientist at COSI Science Center

    A giant bubble blown by the massive Wolf-Rayet star HD 50896, the pink star in the centre of the image.
    Credit: ESA, J. Toala & M. Guerrero (IAA-CSIC), Y.-H. Chu & R. Gruendl (UIUC), S. Arthur (CRyA–UNAM), R. Smith (NOAO/CTIO), S. Snowden (NASA/GSFC) and G. Ramos-Larios (IAM)

    Sometimes I get a little jealous of pre-20th century astronomers. Nowadays, if you discover something new you get to name it. Back then, if you discovered something new, it got named after you.

    Such was the case when Charles Wolf and Georges Rayet happened upon a strange star one night at the Paris Observatory in 1867. I don’t know what they said to each other after the discovery — even if I could overhear them, my French is a little too rusty — but it probably wasn’t, “Sweet! Our names get to be featured in a skipped-over chapter of every astronomy textbook of the future!”

    You just have that glow

    What cemented their place in trivia lore was the peculiar properties of the light coming from that star they observed. Until then, nobody had seen anything quite like it. And by “it,” I mean emission spectral lines.

    OK, I admit it, that sentence probably doesn’t sound very impressive. Let’s dig ourselves out of the jargon. If you have something hot — a light bulb, say, or maybe a star — it will glow. The light it gives off is a mixture of all sorts of wavelengths. If it’s the right temperature, the wavelengths will be an even mixture of reds, greens and blues, which our brains correctly interpret as “white.” If the object is a little hotter, its light might be a mixture of ultraviolets and blues, without any of the cooler red wavelengths. Once again, our brains identify its color, this time as a “blue” thing.

    You, too, are glowing, and not in the way people like to compliment each other. All the atoms and molecules on the surface of your body are a hoppin’, and a jigglin’, and a dancin’. They give off all sorts of wavelengths of light, but mostly in the infrared part of the spectrum. Slap on some infrared goggles, and people light up like a candle.

    Stars are made of stuff that’s wiggling about like crazy, too, and sure enough, they glow. So when we look in detail at the mixture of light coming from a star, we see all sorts of wavelengths.

    Usually, though, there are some wavelengths missing. This is because the outer layers of a star’s atmosphere have a bunch of atomic junk in them, and those atoms can filter out very specific wavelengths of light. They do this by sucking up those light photons, allowing them to jump to a higher quantum mechanical state, and giving off the energy some other way, usually through vibrations.

    But when Wolf and Rayet looked through their télescope, they instead found extra light at specific wavelengths, not subtracted light. Mon dieu!

    Unsolved mysteries

    It took a while to figure out what was going on, and to be perfectly honest, astronomers still aren’t exactly sure what’s causing it.

    One of the problems is that Wolf-Rayet stars are rare. Just a paltry few hundred in our Milky Way, compared to the hundreds of billions of every other kind of star. So we don’t exactly have a lot of data to go on.

    Wolf-Rayet stars are so rare because they’re massive, meaning a) there’s just fewer of them to start with, because it’s hard to get big balls of gas in the first place, and b) massive stars don’t live long, so if we take a snapshot of the universe, we’re more likely to see the smaller, long-lived stellar denizens than their big-boned cousins.

    That massiveness is a clue to their peculiar light pattern. They appear to be a normal stage in the evolution of a giant star, after the initial hydrogen burn run in the core, and just before the inevitable fireworks show of a supernova — they’re waiting in the galactic green room, just about to burst onto the stage in a grand finale performance.

    And in that warm-up phase, the star throws some serious temper tantrums. Entire layers of the star will peel off like a plasma onion, violently thrown into the surrounding system. The inner regions of the star, naked and exposed to the vacuum of space for the first time, glow much more brightly and intensely than those outer layers. Spewing high-energy radiation, that blinding light impacts the thrown-off gas cloud.

    The ejected gas absorbs high-energy ultraviolet radiation, and spits it back out as lower-energy, safe-for-kids infrared and visible light, creating extra light at very specific wavelengths. At last: emission spectral lines.

    This process is called fluorescence, and you might be more familiar with it in other settings. What do CFL bulbs, deep-sea jellyfish and Wolf-Rayet stars have in common?

    Fluorescence. They have fluorescence in common.

    Honestly, all of this is a guess. A good guess, but a guess nonetheless. Like I said, there aren’t a lot of examples to observe, but we’re making do with what we’ve got.

    Since Wolf-Rayet stars appear to be a warm-up act to a big supernova, by studying them in more detail we can better understand the conditions, warning signs, and circumstances of the Big Blasts themselves. Every little bit helps (with thanks to old-timey French astronomers).

    See the full article here .

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  • richardmitnick 9:51 am on April 21, 2016 Permalink | Reply
    Tags: , , , space.com   

    From SPACE.com: “What Are Cosmic Rays?” 

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    April 21, 2016
    Elizabeth Howell

    Showers of high energy particles occur when energetic cosmic rays strike the top of the Earth’s atmosphere. Most cosmic rays are atomic nuclei: most are hydrogen nuclei, some are helium nuclei, and the rest heavier elements. Although many of the low energy cosmic rays come from our Sun, the origins of the highest energy cosmic rays remains unknown and a topic of much research. This drawing illustrates air showers from very high energy cosmic rays. Credit: Simon Swordy (U. Chicago), NASA

    Cosmic rays are atom fragments that rain down on the Earth from outside of the solar system. They blaze at the speed of light and have been blamed for electronics problems in satellites and other machinery.

    First discovered in 1912, many things about cosmic rays remain a mystery more than a century later. One prime example is exactly where they are coming from. Most scientists suspect their origins are related to supernovas (star explosions), but the challenge is that cosmic ray origins appear uniform when you look across the entire sky.


    While cosmic rays were only discovered in the 1900s, scientists knew something mysterious was going on as early as the 1780s. That’s when French physicist Charles-Augustin de Coulomb — best known for having a unit of electrical charge named after him — observed an electrically charged sphere suddenly and mysteriously not being charged any more.

    At the time, air was thought to be an insulator and not an electric conductor. With more work, however, scientists discovered that air can conduct electricity if its molecules are charged or ionized. This would most commonly happen when the molecules interact with charged particles or X-rays.

    What Are Cosmic Rays?

    Showers of high energy particles occur when energetic cosmic rays strike the top of the Earth’s atmosphere. Most cosmic rays are atomic nuclei: most are hydrogen nuclei, some are helium nuclei, and the rest heavier elements. Although many of the low energy cosmic rays come from our Sun, the origins of the highest energy cosmic rays remains unknown and a topic of much research. This drawing illustrates air showers from very high energy cosmic rays.
    Credit: Simon Swordy (U. Chicago), NASA

    Cosmic rays are atom fragments that rain down on the Earth from outside of the solar system. They blaze at the speed of light and have been blamed for electronics problems in satellites and other machinery.

    First discovered in 1912, many things about cosmic rays remain a mystery more than a century later. One prime example is exactly where they are coming from. Most scientists suspect their origins are related to supernovas (star explosions), but the challenge is that cosmic ray origins appear uniform when you look across the entire sky.


    While cosmic rays were only discovered in the 1900s, scientists knew something mysterious was going on as early as the 1780s. That’s when French physicist Charles-Augustin de Coulomb — best known for having a unit of electrical charge named after him — observed an electrically charged sphere suddenly and mysteriously not being charged any more.

    At the time, air was thought to be an insulator and not an electric conductor. With more work, however, scientists discovered that air can conduct electricity if its molecules are charged or ionized. This would most commonly happen when the molecules interact with charged particles or X-rays.

    But where these charged particles came from was a mystery; even attempts to block the charge with large amounts of lead were coming up empty. On Aug. 7, 1912, physicist Victor Hess flew a high-altitude balloon to 17,400 feet (5,300 meters). He discovered three times more ionizing radiation there than on the ground, which meant the radiation had to be coming from outer space.

    But tracing cosmic ray “origin stories” took more than a century. In 2013, NASA’s Fermi Gamma-ray Space Telescope released results from observing two supernova remnants in the Milky Way: IC 433 and W44.

    NASA/Fermi Telescope
    NASA/Fermi Telescope

    An artist’s illustration of a supernova explosion, which sends off shock waves that accelerate protons to the point that they become cosmic rays, a process called Fermi acceleration. Many details of Fermi acceleration are unknown, but data from NASA’s Fermi Gamma-ray Space Telescope provide overwhelming evidence that Fermi acceleration is responsible for cosmic rays. Image released Feb. 14, 2013.
    Credit: Greg Stewart/SLAC National Accelerator Laboratory

    Among the products of these star explosions are gamma-ray photons, which (unlike cosmic rays) are not affected by magnetic fields. The gamma rays studied had the same energy signature as subatomic particles called neutral pions. Pions are produced when protons get stuck in a magnetic field inside the shockwave of the supernova and crash into each other.

    In other words, the matching energy signatures showed that protons could move at fast enough speeds within supernovas to create cosmic rays.

    Current science

    We know today that galactic cosmic rays are atom fragments such as protons (positively charged particles), electrons (negatively charged particles) and atomic nuclei. While we know now they can be created in supernovas, there may be other sources available for cosmic ray creation. It also isn’t clear exactly how supernovas are able to make these cosmic rays so fast.

    Cosmic rays constantly rain down on Earth, and while the high-energy “primary” rays collide with atoms in the Earth’s upper atmosphere and rarely make it through to the ground, “secondary” particles are ejected from this collision and do reach us on the ground.

    But by the time these cosmic rays get to Earth, it’s impossible to trace where they came from. That’s because their path has been changed as they travelled through multiple magnetic fields (the galaxy’s, the solar system’s and Earth’s itself.)

    According to NASA, cosmic rays therefore come equally from all directions of the sky. So scientists are trying to trace back cosmic ray origins by looking at what the cosmic rays are made of. Scientists can figure this out by looking at the spectroscopic “signature” each nucleus gives off in radiation, and also by weighing the different isotopes (types) of elements that hit cosmic ray detectors.

    The result, NASA adds, shows very common elements in the universe. Roughly 90 percent of cosmic ray nuclei are hydrogen (protons) and 9 percent are helium (alpha particles). Hydrogen and helium are the most abundant elements in the universe and the origin point for stars, galaxies and other large structures. The remaining 1 percent are all elements, and it’s from that 1 percent that scientists can best search for rare elements to make comparisons between different types of cosmic rays.

    Scientists can also date the cosmic rays by looking at radioactive nuclei that decrease over time. Measuring the “half life” of each nuclei gives an estimate of how long the cosmic ray has been out there in space.

    Space radiation concerns

    Earth’s magnetic field and atmosphere shields the planet from 99.9 percent of the radiation from space. However, for people outside the protection of Earth’s magnetic field, space radiation becomes a serious hazard. An instrument aboard the Curiosity Mars rover during its 253-day cruise to Mars revealed that the radiation dose received by an astronaut on even the shortest Earth-Mars round trip would be about 0.66 sievert. This amount is like receiving a whole-body CT scan every five or six days.

    A dose of 1 sievert is associated with a 5.5 percent increase in the risk of fatal cancers. The normal daily radiation dose received by the average person living on Earth is 10 microsieverts (0.00001 sievert).

    The moon has no atmosphere and a very weak magnetic field. Astronauts living there would have to provide their own protection, for example by burying their habitat underground.

    The planet Mars has no global magnetic field. Particles from the sun have stripped away most of Mars’ atmosphere, resulting in very poor protection against radiation at the surface. The highest air pressure on Mars is equal to that at an altitude of 22 miles (35 kilometers) above the Earth’s surface. At low altitudes, Mars’ atmosphere provides slightly better protection from space radiation.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

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