spaceplasma:

The Whirlpool Galaxy Like You’ve Never Seen it Before

Where do we come from? This is the sort of big question that keeps people up at night, and NASA funded. If you are a star, however, the answer is easy: you come from a big cloud of gas. As astronomers, if we want to understand what controls properties of stars — what makes them big, small, clustered, or isolated– we can start by looking at the gas that will make them.

This paper presents a detailed study of the gas in M51, the Whirlpool galaxy. This system is actually two galaxies, but this paper focuses on the larger, main spiral (NGC 5194) in this interacting pair. This galaxy is relatively close by (20 million light years away),  massive (~150 billion solar masses), and quite well-studied: astronomers have looked at it in wavelengths from radio to near-infrared, optical and ultraviolet.  The combined resolution and sensitivity of these new millimeter observations (the J=1-0 rotational transition of the carbon monoxide molecule) allow the authors to detect for the first time individual molecular clouds in this galaxy, the objects from which stars and star clusters are born. Below is an image of M51 from this study showing the gas surface density (the amount of gas along our line of sight) from small amounts (dark blue) to large amounts (bright pink), all representing the fuel required to make the next generation of stars in this galaxy.

So what does it take to make an image like this? ALMA? Not quite. M51, with a declination of +47 degrees, is a galaxy that ALMA (the Atacama Large Millimeter Array, located in Chile at a latitude of 23 degrees South) will find very difficult to observe. Instead, the authors used the Plateau de Bure Interferometer (PdBI) and the IRAM 30m radio telescope to detect gas clouds as small as 40 parsecs across. The image above is a mosaic combining 60 pointings of PdBI with IRAM observations over the same region. But isn’t one telescope enough for the job of observing M51? Why take the time to observe it twice?

The answer is that interferometers (arrays of two or more telescopes which work together to act like a telescope with a diameter equal to the separation between antennas) by themselves have a big problem for big objects like M51. Although interferometers give us the advantage of higher resolution, that is not whole story– not only does the antenna separation determine the resolution, it also sets the size scales that you are sensitive to, acting like a high-pass filter for spatial frequencies. As shown in the figure below, a pair of antennas in an interferometer resolve ‘fringes‘ on the sky representing the resolution of that antenna pair (a function of the frequency of the observations and the spacing of the antennas). Different spacings and orientations from the combinations of many antenna-pair fringes contribute to making your beam– the tiny white dot in the bottom left corner of the above image, and the interferometric equivalent of the point-spread function (PSF). The problem is that flux from structures larger than the largest fringe that goes into making this beam will be lost. Since the shortest antenna spacing yields the largest fringe, and the antenna spacing cannot be smaller than the size of the telescope (get too close and the antennas will start bumping into and blocking each other), there is a maximum size scale that you can detect flux from.

How can we get that flux back? Use a single dish telescope! These telescopes are sensitive to the flux on all size scales larger than the resolution of their dish. By combining the data from an interferometer with single dish data, you can recover all of the flux from an object, and still observe it at high resolution. This synergy is why the most effective radio and millimeter interferometers all have a single-dish buddy: the Very Large Array (VLA) has the Green Bank Telescope (GBT), the PdBI (which took these images) has IRAM, and ALMA will have both a compact array and several ‘total power’ single dishes.

So now that you have a high-resolution picture of almost all of the gas clouds in M51, what do you do with it? This paper focuses on comparing (correlating) the location and amount of this gas with other tracers of galaxy properties. This includes tracers of different phases of the interstellar medium (the ISM, or gas in a galaxy at all temperatures, from plasma to neutral to molecular), tracers of star formation, and tracers of the existing stellar populations.

The PdBI Arcsecond Whirlpool Survey (PAWS). I. A Cloud-Scale/Multi-Wavelength View of the Interstellar Medium in a Grand-Design Spiral Galaxy →

sagansense:

The Curious Channel 37 — Must-see TV For Radio Astronomy

Thanks to Channel 37, radio astronomers keep tabs on everything from the Sun to pulsars to the lonely spaces between the stars. This particular frequency, squarely in the middle of the UHF TV broadcast band, has been reserved for radio astronomy since 1963, when astronomers successfully lobbied the FCC to keep it TV-free.

Back then UHF TV stations were few and far between. Now there are hundreds, and I’m sure a few would love to soak up that last sliver of spectrum. Sorry Charley, the moratorium is still in effect to this day. Not only that, but it’s observed in most countries across the world.

So what’s so important about Channel 37? Well, it’s smack in the middle of two other important bands already allocated to radio astronomy – 410 Megahertz (MHz) and 1.4 Gigahertz (Gz). Without it, radio astronomers would lose a key window in an otherwise continuous radio view of the sky. Imagine a 3-panel bay window with the middle pane painted black. Who wants THAT?

Channel 37 occupies a band spanning from 608-614 MHz. A word about Hertz. Radio waves are a form of light just like the colors we see in the rainbow or the X-rays doctors use to probe our bones. Only difference is, our eyes aren’t sensitive to them. But we can build instruments like X-ray machines and radio telescopes to “see” them for us.

Every color of light has a characteristic wavelength and frequency. Wavelength is the distance between successive crests in a light wave which you can visualize as a wave moving across a pond. Waves of visible light range from one-millionth to one-billionth of a meter, comparable to the size of a virus or DNA molecule.

X-rays crests are jammed together even more tightly – one X-ray is only as big as an small atom. Radio waves fill out the opposite end of the spectrum with wavelengths ranging from baseball-sized to more than 600 miles (1000 km) long.

The frequency of a light wave is measured by how many crests pass a given point over a given time. If only one crest passes that point every second, the light beam has a frequency of 1 cycle per second or 1 Hertz. Blue light has a wavelength of 462 billionths of a meter and frequency of 645 trillion Hertz (645 Terahertz).

The higher the frequency, the greater the energy the light carries. X-rays have frequencies starting around 30 quadrillion Hertz (30 petahertz or 30 PHz), enough juice to damage body cells if you get too much exposure. Even ultraviolet light has power to burn skin as many of us who’ve spent time outdoors in summer without sunscreen are aware.

Radio waves are the gentle giants of the electromagnetic spectrum. Their enormous wavelengths mean low frequencies. Channel 37 radio waves have more modest frequencies of around 600 million Hertz (MHz), while the longest radio waves deliver crests almost twice the width of Lake Superior at a rate of 3 to 300 Hertz.

If Channel 37 were ever lost to TV, the gap would mean a loss of information about the distribution of cosmic rays in the Milky Way galaxy and rapidly rotating stars called pulsars created in the wake of supernovae. Closer to home, observations in the 608-614 MHz band allow astronomers track bursts of radio energy produced by particles blasted out by solar flares traveling through the sun’s outer atmosphere. Some of these can have powerful effects on Earth. No wonder astronomers want to keep this slice of the electromagnetic spectrum quiet. For more details on how useful this sliver is to radio astronomy, click HERE.

Just as optical astronomers seek the darkest sites for their telescopes to probe the most remote corners of the universe, so too does radio astronomy need slices of silence to listen to the faintest whispers of the cosmos.

image 1: The Very Large Array, one of the world’s premier astronomical radio observatories, consists of 27 radio antennas in a Y-shaped configuration 50 miles west of Socorro, New Mexico. Each antenna is 82 feet (25 m) in diameter. The data from the antennas is combined electronically to give the resolution of an antenna 22 miles (36 km) across. credit: NRAO/AUI and NRAO

image 2: Channel 37, a slice of the radio spectrum from 608 and 614 Megahertz (MHz) reserved for radio astronomy, sits in the middle of the UHF TV band. Click to see the full spectrum. credit: US Dept. of Commerce

image 3: The visible colors, infrared, radio, X-rays and gamma rays are all forms of light and comprise the electromagnetic spectrum. Here you can compare their wavelengths with familiar objects and see how their frequencies (bottom numbers) increase with decreasing wavelength. credit: ESA

image 4: Diagram showing what how Earth’s atmosphere allows visible light, a portion of infrared and radio light to reach the ground from outer space but filters shorter-wavelength, more dangerous forms of light like X-rays and gamma rays. To study the cosmos in these varieties of light, orbiting telescopes are required.

image 5: If our eyes could see radio light, this is what the sky would look like. What appear to be stars are actually distant galaxies glowing brightly with energy radiated as matter gets sucked down black holes in the cores. The wispy arcs and shells are the remnants of exploding supernovae. Since air molecules don’t scatter radio waves like they do visible light to create a blue sky, the sky would be dark even on a sunny day. credit: National Science Foundation

image 6: The sun as it would look in the radio portion of the spectrum at a frequency of 1.4 gigahertz (GHz). credit: National Radio Astronomy Observatory (NRAO/AUI)

Stay Curious! Watch: First Contact: Carl Sagan On Radio Astronomy

sagansense:

At the edges of the visible universe, 45 billion light-years away, sit some of the oldest known galaxies. How they formed and developed is a mystery, but a spectrograph installed on Chile’s Very Large Telescope—functional since March—should help astronomers find answers. The six-foot-wide, three-ton instrument contains 24 motorized robotic arms. Each eight-inch arm controls a mirror that focuses on a single galaxy. As a result, the telescope can collect infrared readings for 24 galaxies at the same time—data that show what they looked like when the universe was only a fraction of its current age. With the simultaneous observations, astronomers can perform faster and more precise statistical comparisons between galaxies than with isolated viewings.

photo: Armed Telescope. credit: STFC/UKATC/ESO
source: popsci

sagansense:

Chasing the Edge of the Solar System | Voyager 1 and 2

For most of it’s lifetime, Voyager 1 has been traveling through uncharted territory. Initially launched to study the outer planets, Voyager 1 has soldiered on past Jupiter and Saturn and on to the outer edges of the solar system. It’s currently the farthest human-made object from Earth, but when will it be the first spacecraft to travel between the stars? Well, we won’t know until we answer two more fundamental questions: Where does our solar system end and the rest of the space between the stars begin? And if you were at the “edge” of our solar system, how would you know you had left?

Recent scientific discussions on the Voyager spacecraft missions have captivated many people. And as the scientific debate swirled around the internet in near-real time, it became clear that these questions are not easy to answer.

As the Principal Investigator for NASA’s Interstellar Boundary Explorer, or IBEX, spacecraft, I lead a team that is also studying this last frontier of our solar system. Data from IBEX complements the Voyager spacecraft—both missions are working together to find the very farthest reaches of the solar system. Unlike the Voyager spacecraft, which are careening out into interstellar space, IBEX orbits the Earth, collecting particles that have traveled in from the solar system’s boundary region and beyond. From those particles, we can determine many things, including what the boundary is like and what, exactly, is happening out there.

More Than Planets
Most everyone knows our solar system is composed of small solid objects orbiting the Sun—planets, comets, and asteroids. But there’s more to it than that. Our Sun continuously emits a “wind” of material outward in all directions, typically at speeds of about a million miles per hour (1.6 million kilometers per hour). The solar wind is composed mostly of charged particles, such as electrons and protons. It also carries the Sun’s magnetic field.

As the solar wind streams away from the Sun, it races out past all the planets, past Pluto, and toward the space between the stars more than 10 billion miles away. We tend to think of that space as empty, but it’s not. Rather, it contains cold hydrogen gas, dust, ionized gas, and traces of other material. Called the interstellar medium, it’s a very thin mix that comes from exploded stars and the stellar wind of other stars.

When the magnetic fields of the solar wind hit the magnetic fields of the interstellar medium, they do not intermix. The expanding solar wind pushes against the interstellar medium, clearing out a cavity in interstellar space known as the heliosphere. The boundary of that bubble is where the solar wind’s strength exactly matches the pressure of the interstellar medium. We call it the heliopause, and it’s often considered to be the very outer edge of our solar system.

The Heliopause
A few things about the heliopause: It isn’t an impermeable wall. Instead, it’s more like the edge of a forest clearing—the boundary is well defined, but easily negotiated. It’s also shaped more like a drop of water than a uniform sphere. That’s because our entire heliosphere, which contains our Sun, the planets, and everything else in our solar system, is moving through the interstellar medium at about 50,000 miles per hour (80,000 kilometers per hour). That motion creates a wake in the interstellar medium, much like a boat moving through water. As the solar system travels through the interstellar medium the heliopause is closest at the “front,” or the foremost point in the direction in which our solar system is traveling. At that point, the heliopause is still over 10 billion miles, or 16 billion kilometers, from the Sun.

At least, that’s our best guess. We don’t know exactly where the boundary is or what it’s like. That’s what the IBEX and Voyager missions are trying to find out. IBEX lets us peer into the boundaries of our solar system to get a better idea of what it’s like and what’s happening there. However, because IBEX orbits the Earth, we cannot use it to mark where the boundary is located. That’s where Voyager 1 and 2 come in. Currently, they are directly sampling the boundary region. Several of the instruments on Voyager 1 and 2 are no longer working, including the cameras used to snap the stunning fly-by photos of Jupiter, Saturn, Uranus, and Neptune, but others that detect charged particles and magnetic fields are still gathering data.

Both Voyagers are traveling in roughly the same direction as our solar system through the interstellar medium. We expect Voyager 1, the quicker and farther out of the two, to reach the heliopause first. Currently, it’s just over 11 billion miles, or 18 billion kilometers, from the Sun. This is so distant that radio signals from Voyager 1, which are traveling at the speed of light, take 17 hours to reach Earth.

Three Criteria
Before we can declare that Voyager 1 has crossed the heliopause, we are waiting to observe three main changes:

A decrease in highly energetic charged particles from inside our heliosphere,

An increase in highly energetic charged particles from outside our heliosphere,

And a change in the strength and direction of the magnetic field, matching that outside the heliosphere.

Voyager 1 observed the first two in late 2012, and IBEX has provided what are likely the best observations of the third. By using IBEX to look at particles that have traveled in from outside the heliosphere, we have an idea of the direction of the magnetic field beyond the solar system, and it’s very different from the Sun’s, which is carried out by the solar wind. So far Voyager 1 hasn’t observed this change direction of the magnetic field. That’s why we don’t think that Voyager 1 has crossed the heliopause—yet.

Now, Voyager 1 has clearly passed into a new region of space, one that we have not detected before. Every new bit of data coming from the venerable spacecraft is teaching us more about this uncharted territory. All of this information is new, and we are learning more every day.

So, do we know when Voyager 1 will cross the heliopause? We really have no idea. And that’s part of the fun. But learning about the edge of space is more than just an esoteric pursuit. Our heliosphere is a protective cocoon, a crucial layer of shielding against dangerous charged particles, known as galactic cosmic rays, that are harmful to living things. Understanding it will help us understand how the heliosphere has protected our solar system, enabling life to flourish on this planet we call home. And someday, that knowledge will help us prepare for our first voyage beyond the protective cocoon of the solar system, when we step across the threshold and venture into deep space.

image 1: The identical Voyager 1 and Voyager 2 are currently probing the farthest reaches of the solar system.

image 2: As solar wind pushes out against the interestellar medium, it creates a bubble known as the heliosphere; the boundary between the two is known as the heliopause. The termination shock is where the solar wind slows as it presses against more of the interstellar medium, which also raises the plasma’s temperature. The bow wave is where the interstellar medium material piles up in front of our heliosphere, similar to water in front of a moving boat.

image 3: The IBEX satellite orbits the Earth, capturing particles that have traveled into the solar system from beyond the heliosphere.

via NOVANext, PBS.org

Stay Curious! Watch: And Still They Move: Ann Druyan on Carl, Love, and Voyager

scienceisbeauty:

100,000 Stars (click image to enjoy it) is an interactive visualization of the stellar neighborhood created for the Google Chrome web browser. It shows the location of 119,617 nearby stars derived from multiple sources, including the 1989 Hipparcos mission. Zooming in reveals 87 individually identified stars and our solar system. The galaxy view is an artist’s rendition based on NGC 1232, a spiral galaxy like the Milky Way.

sagansense:

What happened…when the object apparently responsible for the extinction of the dinosaurs hit the Earth 65 million years ago?

“First, there was a gigantic fireball brighter than the Sun as the comet plunged to its death, not with a whimper, but a bang. One casualty was the ozone layer, which temporarily vanished. Seconds after the big comet first encountered Earth’s upper atmosphere, it carved out a crater - now buried - 200 kilometers wide and 25 kilometers deep. All that debris shot up into the sky and came back again, all over the Earth. No place would have been spared a hit of at least a tiny particle.

Reacting to this incredible bombardment, the air temperature rose quickly until, for mor ethan two hours, the worldwide temperature reached that of an oven set to broiling. The sky glowed like an electric heater. Ground fires flared everywhere. Then the temperatures started to drop, and drop, and drop. A thick cloud of dust blackened the world, setting off a several-month period without sunlight. Rains poisoned with sulfuric and nitric acid added to the misery.

With blow after blow to the biosphere…most large land-roving dinosaurs probably died within weeks. Other creatures took longer; those who survived one disaster would perish in the next one. Slowly, the great cloud dissipated, and temperatures began to rise again, this time due to a greenhouse effect that lasted for centuries or millennia. Overall, perhaps 70 percent of all the species of life died during the siege, and in North America at least, about half of the species of flowering plants.

But not everybody. Some of the hardier representatives of many species, including the ones equipped to hibernate, made it through the impact winter. Enough small mammals survived that, when the biosphere finally started to recover, they began to proliferate and flourish.

Impacts clear the decks for new forms of life. The fossil record shows that after major impacts, there is a burst of speciation. New life forms fill the niches that the old ones leave behind. If there were no impacts, the thrust of evolution might have slowed down, and today there would be a different set of species inhabiting the Earth.”

David H. Levy, Gene Shoemaker in an exchange about comets and cosmic collisions| Impact Jupiter: The Crash Of Comet Shoemaker-Levy 9

[image credit]

sagansense:

Neil deGrasse Tyson Explains The Origins Of Atomic Elements In Our Bodies

What’s the human body made of? Ninety-nine percent consists of atoms of just six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus, with the remaining one percent consisting of trace elements like magnesium, sulfur, and iron.

But where did those elements come from? That question long presented a puzzle to scientists. At least it did until the publication of a now-obscure scientific paper in the middle of the twentieth century, as celebrated astrophysicist Neil deGrasse Tyson explains in a new video (above).

“There was a seminal paper — one of the most important research papers ever published — that gave us the description of the origin of the elements,” Tyson says in the video.

The paper is entitled “Synthesis of the Elements in Stars” but is sometimes referred to as the B2FH paper, after the authors’ initials. It was published in Reviews of Modern Physics in 1957. Before its publication, the prevailing theory held that all elements were products of the Big Bang 15 billion years ago. But this theory accounted only for light elements like hydrogen and helium.

So where did the heavy elements found in nature come from?

The B2FH paper argued that all heavy elements were created within stars via nuclear fusion — a process known as stellar nucleosynthesis. As stars cool and “die,” they release the heavy elements into space. Ultimately, some of this material is incorporated into planets and even our bodies.

If the paper was so important, why do so few nonscientists know about it? According to Tyson, it’s because the paper’s origins don’t fit conventional notions of scientific discovery.

“There was no lone scientist burning the midnight oil making the eureka discovery,” Tyson says. “It was a little messier than that. But the consequences of it are profound.”

Stay Curious! Watch The Extended Interview With NDT

scinerds:

Minute Physics - The True Science of Parallel Universes

ikenbot:

Black Hole Firewall: Trouble On The Edge

Ever wondered what happens to things as they are consumed by the black hole, the left over matter of dead stars? For a time, it used to be okay to assume matter was destroyed once it entered into a black hole, spaghettified and all.. but it turned out that this couldn’t be further away from the truth. NewScientists Anil Ananthaswamy has a wonderful 3 page piece getting into full details of this history and what questions scientists are asking now. If you love black holes, this is a definite recommend. Although registration (completely free!) is required to view the whole article. It’s pretty insightful and accurately presents the problems currently being faced with how black holes do what they do:

“Paradoxes are good in physics,” reflects John Preskill. “They help to point the way towards important discoveries.” Quantum mechanics and Einstein’s theories of relativity offer plenty to choose from. There’s the cat that can be dead and alive at the same time. Or the Back to the Future-style time traveller who kills his own grandfather, rendering his own birth impossible. Or the twins who disagree on their age after one returns from a near light-speed trip to a neighbouring star. Each perplexing scenario forces us to examine the fine print of the problem, thereby advancing our understanding of the theory behind it. A case in point is Einstein, whose own theories came from trying to resolve the paradoxes of his time.

Image: Ring of fireSam Chivers

Now Preskill, a theoretical physicist at the California Institute of Technology in Pasadena, is scratching his head over the latest one to surface. Nicknamed the black hole firewall paradox, it comes about when you consider what happens to someone falling into a black hole.

With the nearest black hole more than 1000 light years away, the question is very much a theoretical one. Yet just by studying such a possibility, physicists are hoping to make a breakthrough in their efforts to combine general relativity and quantum mechanics into a theory of quantum gravity – one of the most intractable problems in physics today.

Black holes have long been fertile breeding grounds for paradoxes. Back in 1974, Stephen Hawking, along with Jacob Bekenstein of the Hebrew University in Jerusalem, Israel, famously showed that black holes are not entirely black. Instead, they radiate energy known as Hawking radiation comprising photons and other quantum particles – an agonisingly slow process that eventually causes the black hole to evaporate completely.

Hawking spotted a problem with this picture. The radiation seemed so random that he surmised it couldn’t carry any information about the stuff that had fallen in. So as the black hole evaporates, the information it holds must eventually disappear. Yet this is in direct conflict with a central tenet of quantum physics, which says that information cannot be destroyed. The black hole information paradox was born.

Over the decades, physicists have struggled with this paradox. Hawking thought that black holes destroyed information and the answer was to question quantum mechanics. Others disagreed. After all, Hawking’s idea came from his efforts to meld general relativity and quantum mechanics – a mathematical feat so elusive that he was forced to make approximations. Preskill even made a bet with Hawking that black holes don’t destroy information.

Several arguments suggest that Hawking was wrong. One of the most compelling comes from thinking about what happens as the evaporating black hole gets smaller and smaller. If information can’t escape or be destroyed, then more and more has to be stored in an ever-shrinking volume. But if this is the case, quantum theory says the probability for making a tiny black hole increases from virtually nothing to almost infinity wherever matter collides against matter. “You should have seen it at the Large Hadron Collider, you should have seen it at Fermilab, you should have seen it in tiny room-sized particle accelerators from the 1930s,” says Don Marolf, a theorist at the University of California in Santa Barbara (UCSB). “You should see it when you go and jump up and down on the grass.”

Obviously that hasn’t happened. The other possibility – that matter and the information it carries can leak out from a black hole – is unlikely. Any material that falls in would need to travel faster than light to escape the black hole’s fearsome gravity.

Perhaps, instead, the answer lies with the Hawking radiation itself. Maybe it isn’t so featureless. “A common reaction was that Hawking had simply been careless,” says Joseph Polchinski, also at UCSB. “It wasn’t that information was lost, it was that he hadn’t kept track of it enough.”

Yet all early efforts to do away with the paradox proved unsuccessful. “Hawking had identified a really deep problem,” says Polchinski.

As it happened, Hawking changed his mind in 2004, partly due to work by an Argentinian physicist called Juan Maldacena (see “Hawking’s change of heart”). Black holes don’t destroy information after all, he conceded. He honoured the bet he made with Preskill and presented him with an encyclopaedia of baseball, which Preskill likened to a black hole, because it was heavy and it took effort to get information out of it.

Into The Abyss..

[Full Article]

(via kenobi-wan-obi)

ikenbot:

8 Baffling Astronomy Mysteries

We’ve seen a lot of information explaining the wonders of astronomy and space, but what of the mysteries? The realm scientists have yet to fully understand. SPACE has this awesome article getting into a few, 8 in total, of those very areas in the study of the stars that continue to baffle scientists:

The universe has been around for roughly 13.7 billion years, but it still holds many mysteries that continue to perplex astronomers to this day. Ranging from dark energy to cosmic rays to the uniqueness of our own solar system, there is no shortage of cosmic oddities.

The journal Science summarized some of the most bewildering questions being asked by leading astronomers today. In no particular order, here are eight of the most enduring mysteries in astronomy:

8 What is Dark Energy?

Dark energy is thought to be the enigmatic force that is pulling the cosmos apart at ever-increasing speeds, and is used by astronomers to explain the universe’s accelerated expansion.

This elusive force has yet to be directly detected, but dark energy is thought to make up roughly 73 percent of the universe.

7 How Hot is Dark Matter?

Dark matter is an invisible mass that is thought to make up about 23 percent of the universe. Dark matter has mass but cannot be seen, so scientists infer its presence based on the gravitational pull it exerts on regular matter.

Researchers remain curious about the properties of dark matter, such as whether it is icy cold as many theories predict, or if it is warmer.

6 Where are the Missing Baryons?

Dark energy and dark matter combine to occupy approximately 95 percent of the universe, with regular matter making up the remaining 5 percent. But, researchers have been puzzled to find that more than half of this regular matter is missing.

This missing matter is called baryonic matter, and it is composed of particles such as protons and electrons that make up majority of the mass of the universe’s visible matter.

Some astrophysicists suspect that missing baryonic matter may be found between galaxies, in material known as warm-hot intergalactic medium, but the universe’s missing baryons remain a hotly debated topic.

5 How do Stars Explode?

When massive stars run out of fuel, they end their lives in gigantic explosions called supernovas. These spectacular blasts are so bright they can briefly outshine entire galaxies.

Extensive research and modern technologies have illuminated many details about supernovas, but how these massive explosions occur is still a mystery.

Scientists are keen to understand the mechanics of these stellar blasts, including what happens inside a star before it ignites as a supernova.

4 What Re-ionized the Universe?

The broadly accepted Big Bang model for the origin of the universe states that the cosmos began as a hot, dense point approximately 13.7 billion years ago.

The early universe is thought to have been a dynamic place, and about 13 billion years ago, it underwent a so-called age of re-ionization. During this period, the universe’s fog of hydrogen gas was clearing and becoming translucent to ultraviolet light for the first time.

Scientists have long been puzzled over what caused this re-ionization to occur.

3 What’s the Source of the Most Energetic Cosmic Rays?

Cosmic rays are highly energetic particles that flow into our solar system from deep in outer space, but the actual origin of these charged subatomic particles has perplexed astronomers for about a century.

The most energetic cosmic rays are extraordinarily strong, with energies up to 100 million times greater than particles that have been produced in manmade colliders. Over the years, astronomers have attempted to explain where cosmic rays originate before flowing into the solar system, but their source has proven to be an enduring astronomical mystery.

2 Why is the Solar System so Bizarre?

As alien planets around other stars are discovered, astronomers have tried to tackle and understand how our own solar system came to be.

The differences in the planets within our solar system have no easy explanation, and scientists are studying how planets are formed in hopes of better grasping the unique characteristics of our solar system.

This research could, in fact, get a boost from the hung for alien worlds, some astronomers have said, particularly if patterns arise in their observations of extrasolar planetary systems.

1 Why is the Sun’s Corona so Hot?

The sun’s corona is its ultra-hot outer atmosphere, where temperatures can reach up to a staggering 10.8 million degrees Fahrenheit (6 million degrees Celsius).

Solar physicists have been puzzled by how the sun reheats its corona, but research points to a link between energy beneath the visible surface, and processes in the sun’s magnetic field. But, the detailed mechanics behind coronal heating are still unknown.

(via kenobi-wan-obi)

electricspacekoolaid:

Puzzle of Spiral Galaxies Solved —“Self-perpetuating, Persistent, and Surprisingly Long Lived”

Some 15 percent of all galaxies in the visible Universe are spirals. The great fog-like clouds of stars, the oldest and largest galaxies in the Universe are ellipticals. Becasue ellipticals also include many of the smallest galaxies, they are the most numerous. Our own Milky Way, astronomers believe, is a spiral. Our solar system and Earth reside somewhere near one of its filamentous, swept-back arms. And nearly 70 percent of the galaxies closest to the Milky Way are spirals, suggesting they have taken the most ordinary of galactic forms in a universe with somewhere between 100 billion and 200 billion galaxies.

But a long-standing question has been: how do galaxies like the Milky Way get and maintain their characteristic arms has proved to be an enduring puzzle in astrophysics. How do the arms ofspiral galaxies arise? Do they change or come and go over time?*The answers to these and other questions are now coming into focus as researchers capitalize on powerful new computer simulations to follow the motions of as many as 100 million “stellar particles” as gravity and other astrophysical forces sculpt them into familiar galactic shapes.

Writing April 1 in The Astrophysical Journal, a team of researchers from the University of Wisconsin-Madison and Harvard-Smithsonian Center for Astrophysics report simulations that seem to resolve longstanding questions about the origin and life history of spiral arms in disk galaxies.

“We show for the first time that stellar spiral arms are not transient features, as claimed for several decades,” says UW-Madison astrophysicist Elena D’Onghia, who led the new research along with Harvard-Smithsonian Center for Astrophysics colleagues Mark Vogelsberger and Lars Hernquist. “They are self-perpetuating, persistent and surprisingly long lived.”

The origin and fate of the emblematic spiral arms in disk galaxies have been debated by astrophysicists for decades, with two theories predominating: One holds that the arms come and go over time. A second and widely held theory is that the material that makes up the arms – stars, gas and dust – is affected by differences in gravity and jams up, like cars at rush hour, sustaining the arms for long periods.

The new results fall somewhere in between the two theories and suggest that the arms arise in the first place as a result of the influence of giant molecular clouds, star forming regions or nurseries common in galaxies. Introduced into the simulation, the clouds, says D’Onghia, a UW-Madison professor of astronomy, act as “perturbers” and are enough to not only initiate the formation of spiral arms but to sustain them indefinitely.

“We find they are forming spiral arms,” explains D’Onghia. “Past theory held the arms would go away with the perturbations removed, but we see that (once formed) the arms self-perpetuate, even when the perturbations are removed. It proves that once the arms are generated through these clouds, they can exist on their own through (the influence of) gravity, even in the extreme when the perturbations are no longer there.”

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The Giant Magellan Telescope - GMT

WIth the James Webb telescope launch set for 2015, the GMT, and a lot more telescopes being built, the questions of our universe almost seem to be closer and closer waiting to be solved. I wrote about the GMT almost a year ago and it quickly became one of my favorite telescopes. It will be operational in 10 years the engineers say. I don’t know if that’s too short or too long. Either way let me tell you a little about this amazing telescope. 

The Namesake - Magellan

Ferdinand Magellan, everybody knows the famous explorer, he led an expedition in 1522 which was the first to circumnavigate the earth, an ambitious feat for exploration. Astronomy was the primary tool of navigation of that time and Magellan was a certainly a student of astronomy. The expedition saw in the southern hemisphere obscure clouds in the night sky, later named the Magellanic Clouds. These clouds turned out to be island universes, filled with millions of stars orbiting another island universe, our Milky Way. 

The Giant Magellan Telescope will continue the tradition of exploration that was set forth 500 years ago. The telescope is also peering into the unknown, maybe finding new questions to our Universe and searching for new worlds.

The Telescope - A Giant

The GMT will utilize a new and unique design. There will be seven 27ft segmented mirrors surrounding a central segment forming a single optical surface. This precision will give the telescope a resolving power 10x that of the Hubble Telescope. The light will be concentrated into CCD (Charge Coupled Device) image cameras which will measure the distance of objects and what their composition is.

This is Where is Gets More Interesting

The telescopes segmented mirrors are flexible. Under each mirror there are hundreds of ‘actuators’ that constantly adjust the mirrors to counteract atmospheric turbulence. These actuators will turn flickering stars into sharp points of light.

High and Dry

A huge advantage is the location of the GMT. Located in Chile in the Atacama Desert at an altitude of approximately 8,500 ft it is the highest and driest location on Earth.

Pictures, Website, Info

sagansense:

Mystery of Strange Star Outbursts May Be Solved

Scientists have detected what appears to be a stellar outburst from a pair of stars locked in a cosmic tryst within a shared veil of gas, a find that marks the first discovery of a long-sought type of space eruption.

Most outbursts from stars are lumped into two categories — novas or supernovas. A nova is a thermonuclear explosion from a white dwarfstar driven by fuel piled on from a companion star. Novas do not result in the destruction of their stars, but supernovas do.

Supernovas, which are bright enough to briefly outshine all the stars in their galaxies, happen in two known ways — type Ia supernovas occur after a white dwarf dies from gorging on too much fuel from a companion star, while type II supernovas take place after the core of a star runs out of fuel, collapses into an extraordinarily dense nugget in a fraction of a second, and then bounces and blasts outward.

However, over the years, scientists have recognized another class of outbursts that are brighter than novas but dimmer than supernovas. Investigators called these mysterious events intermediate-luminosity red transients, or ILRTs.

Now, researchers suggest the culprits behind these enigmas may lurk behind shrouds of gas.

“I find it extremely exciting that we have explained a class of events that previously no one knew what they were,” study lead author Natasha Ivanova, an astrophysicist at the University of Alberta in Canada, told SPACE.com. “That does not happen very often in science.”

This image shows the amazing V838 Monocerotis outburst of 2002 in stages. Scientists think it was caused by a “common-envelope event.” Image released Jan. 24, 2013.
CREDIT: NASA, ESA and The Hubble Heritage Team (STScI/AURA)

Two stars in dusty veil
Scientists had long theorized that two stars can temporarily orbit each other with an envelope of gas they share. In these “common-envelope events,” the star with less mass should become engulfed by matter from the larger companion star. The interactions between these stars can explosively hurl this super-hot envelope away from them at speeds of up to 2.2 million mph (3.6 million kph), releasing about as much mass as a supernova and about 10,000 times more than a nova.

However, astronomers did not expect to see these events directly. They are both rarer than novas but not as bright as supernovas, making them difficult to spot.

After developing computer models of the properties of common-envelope events, researchers found the energies, colors, short time scales, ejection velocities of ILRTs, as well as the rates at which they happened, match those of the predicted properties of long-sought common-envelope events.

“The surprise was that the appearance of the events (common-envelope events) is very different to what the original predictions were — the outbursts are much brighter and the durations are much longer than once thought,” Ivanova said.

This image depicts a stellar outburst observed in the simulations of V1309 Sco, which scientists suspect was a binary “common-envelope event.”
CREDIT: James C. Lombardi Jr. using SPLASH (Price 2007)

New star outburst model
This new model applies best to a subset of ILRTs often called luminous red novae. “It may be expected that not all of the ILRTs must necessarily be caused by common-envelope events, and some don’t seem to be easily explained by our model unless it will be extended to take into account further complications,” Ivanova said.

Common-envelope events are thought to create many binary systems, and could potentially help produce the progenitors of type Ia supernovas and gamma-ray bursts, the most powerful explosions in the universe. The scientists estimate about 24 common-envelope events happen every 1,000 years per galaxy like the Milky Way.

“We hope that the whole field of studies of interacting binaries — this includes such binaries as Type Ia progenitors, gamma-ray burst progenitors and merging double-stellar black holes — will receive a strong shake up,” Ivanova said.

Ivanova and her colleagues detailed their findings in the Jan. 25 issue of the journal Science.

main image: This image shows the spectacular stellar outburst of V838 Monocerotis in 2002. Scientists now suspect the outburst was caused by a so-called “common-envelope event,” an outburst from two stars sharing a gas shell. Image released Jan. 24, 2013.
CREDIT: NASA, ESA and The Hubble Heritage Team (STScI/AURA)

electricspacekoolaid:

Ancient DNA Precursors Found in Interstellar Clouds - Predating Formation of Solar System

During the past decade, astrochemists have found that DNA molecules, the fundamental building blocks of life, find their origins not on Earth, but in the Cosmos. They are the languange of the Universe —the information they inherited comes from the stars and the cosmic ecology that formed them. Scientists using the National Science Foundation’s Green Bank Telescope (GBT) in West Virginia to study a giant cloud of gas some 25,000 light-years from Earth, near the center of our Milky Way Galaxy, have discovered a molecule thought to be a precursor to a key component of DNA and another that may have a role in the formation of the amino acid alanine.

 ”Finding these molecules in an interstellar gas cloud means that important building blocks for DNA and amino acids can ‘seed’ newly-formed planets with the chemical precursors for life,” said Anthony Remijan, of the National Radio Astronomy Observatory (NRAO).

One of the newly-discovered molecules, called cyanomethanimine, is one step in the process that chemists believe produces adenine, one of the four nucleobases that form the “rungs” in the ladder-like structure of DNA. The other molecule, called ethanamine, is thought to play a role in forming alanine, one of the twenty amino acids in the genetic code.

In each case, the newly-discovered interstellar molecules are intermediate stages in multi-step chemical processes leading to the final biological molecule. Details of the processes remain unclear, but the discoveries give new insight on where these processes occur.

Previously, scientists thought such processes took place in the very tenuous gas between the stars. The new discoveries, however, suggest that the chemical formation sequences for these molecules occurred not in gas, but on the surfaces of ice grains in interstellar space.

“We need to do further experiments to better understand how these reactions work, but it could be that some of the first key steps toward biological chemicals occurred on tiny ice grains,” Remijan said.

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