Tag Archives: Universe

When will the universe end? Not for at least 2.8 billion years

Cosmic doom

We’re safe for now. The way the universe is expanding, it won’t be tearing itself apart for at least a few billion years.

For those of you only now discovering that such an end was a possibility, here’s a little background. Observations of stars and galaxies indicate that the universe is expanding, and at an increasing rate. Assuming that acceleration stays constant, eventually the stars will die out, everything will drift apart, and the universe will cool into an eternal “heat death”.

But that’s not the only possibility. The acceleration is thought to be due to dark energy, mysterious stuff that permeates the entire universe. If the total amount of dark energy is increasing, the acceleration will also increase, eventually to the point where the very fabric of space-time tears itself apart and the cosmos pops out of existence.

One prediction puts this hypothetical “big rip” scenario 22 billion years in the future. But could it happen sooner? To find out, Diego Sáez-Gómez at the University of Lisbon, Portugal, and his colleagues modelled a variety of scenarios and used the latest expansion data to calculate a likely timeline. The data involved nearby galaxies, supernovae andripples in the density of matter known as baryon acoustic oscillations, all of which are used to measure dark energy.

The team found that the earliest a big rip can occur is at 1.2 times the current age of the universe, which works out to be around 2.8 billion years from now. “We’re safe,” says Sáez-Gómez.

Time equals infinity

And when is the latest it could happen? “The upper bound goes to infinity,” he says. That would mean the rip never comes and we end up with the heat death scenario instead.

Given that the sun isn’t expected to burn out for at least another 5 billion years, it would be surprising if the universe ended so early. But pondering our doom could be a worthwhile exercise anyway, Sáez-Gómez says. Scenarios like the big rip result from a lack of understanding of physics in particular our inability to marry quantum mechanics and general relativity, the theory of gravity. Exploring the possibilities could show us a way forward.

“You learn more about a physical theory by looking at the exotic and extreme cases,” says Robert Caldwell of Dartmouth College in New Hampshire, who helped come up with the big rip idea. He thinks Sáez-Gómez’s lower bound is very conservative, however – the universe is likely to last much longer. Even if it doesn’t, at least we’ve got a good run ahead of us. he says.

Reference: arxiv.org/abs/1602.06211v1

Citizen Scientists Discover Yellow “Space Balls”

Citizen scientists scanning images from NASA’s Spitzer Space Telescope, an orbiting infra-red observatory, recently stumbled upon a new class of curiosities that had gone largely unrecognized before: yellow balls.

“The volunteers started chatting about the yellow balls they kept seeing in the images of our galaxy, and this brought the features to our attention,” said Grace Wolf-Chase of the Adler Planetarium in Chicago.

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A new ScienceCast video examines “yellow balls” and their role in star formation. Play it

The Milky Way Project is one of many “citizen scientist” projects making up the Zooniverse website, which relies on crowdsourcing to help process scientific data.  For years, volunteers have been scanning Spitzer’s images of star-forming regions—places where clouds of gas and dust are collapsing to form clusters of young stars.  Professional astronomers don’t fully understand the process of star formation; much of the underlying physics remains a mystery. Citizen scientists have been helping by looking for clues.

Before the yellow balls popped up, volunteers had already noticed green bubbles with red centers, populating a landscape of swirling gas and dust. These bubbles are the result of massive newborn stars blowing out cavities in their surroundings. When the volunteers started reporting that they were finding objects in the shape of yellow balls, the Spitzer researchers took note.

Auroras Underfoot (signup)

The rounded features captured by the telescope, of course, are not actually yellow, red, or green—they just appear that way in the infrared, color-assigned images that the telescope sends to Earth. The false colors provide a way to humans to talk about infrared wavelengths of light their eyes cannot actually see.

“With prompting by the volunteers, we analyzed the yellow balls and figured out that they are a new way to detect the early stages of massive star formation,” said Charles Kerton of Iowa State University, Ames. “The simple question of ‘Hmm, what’s that?’ led us to this discovery.”

A thorough analysis by the team led to the conclusion that the yellow balls precede the green bubbles, representing a phase of star formation that takes place before the bubbles form.

“Basically, if you wind the clock backwards from the bubbles, you get the yellow balls,” said Kerton.

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An artist’s concept shows how “yellow balls” fit into the process of star formation.

Researchers think the green bubble rims are made largely of organic molecules called polycyclic aromatic hydrocarbons (PAHs). PAHs are abundant in the dense molecular clouds where stars coalesce. Blasts of radiation and winds from newborn stars push these PAHs into a spherical shells that look like green bubbles in Spitzer’s images. The red cores of the green bubbles are made of warm dust that has not yet been pushed away from the windy stars.

How do the yellow balls fit in?

“The yellow balls are a missing link,” says Wolf-Chase. They represent a transition “between very young embryonic stars buried in dense, dusty clouds and slightly older, newborn stars blowing the bubbles.”

Essentially, the yellow balls mark places where the PAHs (green) and the dust (red) have not yet separated. The superposition of green and red makes yellow.

So far, the volunteers have identified more than 900 of these compact, yellow features.  The multitude gives researchers plenty of chances to test their hypotheses and learn more about the way stars form.

Meanwhile, citizen scientists continue to scan Spitzer’s images for new finds. Green bubbles.  Red cores.  Yellow balls.  What’s next?  You could be the one who makes the next big discovery.  To get involved, go to zooniverse.org and click on “The Milky Way Project.”

Discovered: A Cold, Close Neighbor of the Sun

NASA’s Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope have discovered what appears to be the coldest “brown dwarf” known — a dim, star-like body that  surprisingly is as frosty as Earth’s North Pole. Named “WISE J085510.83-071442.5,” the brown dwarf appears to be 7.2 light-years away, earning it the title for fourth closest system to our sun.

“It’s very exciting to discover a new neighbor of our solar system that is so close,” said Kevin Luhman, an astronomer at Pennsylvania State University’s Center for Exoplanets and Habitable Worlds, University Park.

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This animation shows the brown dwarf WISE J085510.83-071442.5 moving across the sky. It was first seen in two infrared images taken six months apart in 2010 by NASA’s Wide-field Infrared Survey Explorer (WISE). Two additional images of the object were taken with NASA’s Spitzer Space Telescope in 2013 and 2014. All four images were used to measure the distance to the object — 7.2 light-years — using the parallax effect.  Movie

Brown dwarfs start their lives like stars, as collapsing balls of gas, but they lack the mass to burn nuclear fuel and radiate starlight. The newfound coldest brown dwarf is named WISE J085510.83-071442.5. It has a chilly temperature between minus 54 and 9 degrees Fahrenheit (minus 48 to minus 13 degrees Celsius). Previous record holders for coldest brown dwarfs, also found by WISE and Spitzer, were about room temperature.

“It is remarkable that even after many decades of studying the sky, we still do not have a complete inventory of the sun’s nearest neighbors,” added Michael Werner, the project scientist for Spitzer at NASA’s Jet Propulsion Laboratory. “This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer.”

WISE was able to spot the rare object because it surveyed the entire sky twice in infrared light, observing some areas up to three times. Cool objects like brown dwarfs can be invisible when viewed by visible-light telescopes, but their thermal glow — even if feeble — stands out in infrared light. In addition, the closer a body, the more it appears to move in images taken months apart. Airplanes are a good example of this effect: a closer, low-flying plane will appear to fly overhead more rapidly than a high-flying one.

“This object appeared to move really fast in the WISE data,” said Luhman. “That told us it was something special.”

After noticing the fast motion of WISE J085510.83-071442.5, Luhman spent time analyzing additional images taken with Spitzer and the Gemini South telescope on Cerro Pachon in Chile. Spitzer’s infrared observations helped determine the frosty temperature of the brown dwarf. Combined detections from WISE and Spitzer, taken from different positions around the sun, revealed the object’s parallax, and thus its distance. The closest system to Earth, a trio of stars, is Alpha Centauri, at about 4 light-years away. WISE J085510.83-071442.5 is only a few light years farther than that.

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This diagram pinpoints star systems closest to the sun. The year when the distance to each system was determined is listed after the system’s name.  More

WISE J085510.83-071442.5 appears to be 3 to 10 times the mass of Jupiter. With such a low mass, it could be a gas giant similar to Jupiter that was ejected from its star system. But scientists estimate it is probably a brown dwarf rather than a planet since brown dwarfs are known to be fairly common. If so, it is one of the least massive brown dwarfs known.

In March of 2013, Luhman’s analysis of the images from WISE uncovered a pair of much warmer brown dwarfs at a distance of 6.5 light years, making that system the third closest to the sun. His search for rapidly moving bodies also demonstrated that the outer solar system probably does not contain a large, undiscovered planet, which has been referred to as “Planet X” or “Nemesis.”

Waves from the birth of time: Scientists find traces of the first growth spurt of the universe

scientists reported finding the earliest echoes of the Big Bang. The long-sought evidence supports the idea that the universe inflated in a flash. A scientific theory, called inflation, held that during the first trillionth of a trillionth of a trillionth of a second after the Big Bang, the universe grew outward faster than the speed of light. It soon stretched out farther than any telescope can see.

Cosmologists are astronomers who study the early universe. They first introduced the theory of inflation more than 30 years ago. Since then, it’s become an important part of the explanation for how the universe began. Inflation helps answer some questions raised by the Big Bang. One is why the universe looks the same in every direction. Another is why it isn’t clumpier in some directions. (Inflation would have smoothed everything out. It’s just like what happens when blowing up a party balloon.)

However, scientists couldn’t be sure inflation happened. They lacked solid evidence. The new discovery provides that evidence. It identified the lingering effects of inflation on the oldest light in the universe.

“We now have a much stronger belief that we understand the early universe than we did yesterday,” Sean Carroll told Science News on the day of the news announcement. An astrophysicist at the California Institute of Technology in Pasadena, he studies the role of energy and other physical phenomena affecting stars and other objects in space. He did not work on the new study.

But dozens of other scientists did. They couldn’t travel back in time to the Big Bang; it was 13.8 billion years ago. But they also didn’t have to. According to that inflation theory, the Big Bang sent waves rippling through the stuff of space. Known as “gravitational waves,” they would alternately squeeze and stretch the fabric of space. So their passage should have left a mark on the farthest reaches of the known universe. Scientists had sought those telltale marks.

For their search, the scientists used a telescope at the South Pole. It’s called BICEP2 (short for the Background Imaging of Cosmological Extragalactic Polarization). By gauging the temperature of deep space, this telescope works almost like a giant thermometer. Scientists built it deep in Antarctica. The region’s cold, dry and stable air is perfect for peering deep into space — and back into time.

For 50 years, scientists have known that energy in the form of microwave radiation lingered long after the Big Bang. BICEP2 studies this type of light. The telescope records the behavior of photons. Those particles transport radiation, like this microwave signal.

John Kovac led the new search for the Big Bang’s echoes. An astronomer, he works at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. His large team has just published a series of papers online. These report finding twists and turns in the patterns of the microwave photons. Kovac’s group now concludes that gravitational waves are the only plausible explanation for that.

These scientists will to continue to go over their data. They want to make sure their results didn’t arise from a problem in the telescope or some error in their analysis. And at least eight other telescopes will continue to look for similar patterns in that early light, called the cosmic microwave background radiation.

For now, many scientists are thrilled by the news. Among them is Scott Dodelson, at the Fermi National Accelerator Laboratory in Batavia, Ill. Confirmation of gravitational waves offers new opportunities for scientists to test more ideas about the nature of the universe, the astrophysicist told Science News.

“This opens up a whole new window,” he explains — “a whole new research area.”

We are stardust

Stars glitter in the Arizona sky like a million winks. Inside the Kitt Peak National Observatory, Catherine Pilachowski zips her coat against the chilly night air. She steps up to the huge telescope and peers into its eyepiece. Suddenly, distant galaxies and stars come into focus. Pilachowski sees dying stars called red giants. She sees supernovas, too — the remains of exploded stars.

An astronomer at Indiana University in Bloomington, she feels a deep connection to these cosmic objects. Maybe that’s because Pilachowski is made of stardust.

So are you.

Every ingredient in the human body is made from elements forged by stars. So are all of the building blocks of your food, your bike and your electronics. Similarly, every rock, plant, animal, scoop of seawater and breath of air owes its existence to distant suns.

All such stars are giant, long-lived furnaces. Their intense heat can cause atoms to collide, creating new elements. Late in life, most stars will explode, shooting the elements they forged out into the far-flung reaches of the universe.

New elements also may develop during stellar smash-ups. Astronomers have just witnessed evidence for the creation of gold and more during the distant collision between two dying stars.

Another team discovered the light from a long-gone “starburst” galaxy. Shortly after the universe formed, this galaxy churned out stars at an amazing speed. Special star factories like this one might help explain how enough elements built up to create the solar system.

Such discoveries are helping scientists better understand where everything in the universe got its start.

This artist’s depiction shows what astronomers think the very early universe might have looked like when it was less than 1 billion years old. The image portrays an intense period of hydrogen coalescing to form many, many stars.

SCIENCE: NASA AND K. LANZETTA (SUNY). ART: ADOLF SCHALLER FOR STSCI

After the Big Bang

Elements are the basic building blocks of our universe. Earth hosts 92 natural elements with names like carbon, oxygen, sodium and gold. Their atoms are the amazingly tiny particles from which all known chemicals are made.

Each atom resembles a solar system. A tiny, but commanding structure sits at its center. This nucleus consists of a mix of bound particles known as protons and neutrons. The more particles in a nucleus, the heavier the element. Chemists have compiled charts that place the elements in order based on structural features, such as how many protons they have.

Topping their charts is hydrogen. Element one, it has a single proton. Helium, with two protons, comes next.

People and other living things are chock full of carbon, element 6. Earthly life also contains plenty of oxygen, element 8. Bones are rich in calcium, element 20.  Number 26, iron, makes our blood run red. At the bottom of the periodic table of natural elements sits uranium, nature’s heavyweight, with 92 protons. Scientists have artificially created heavier elements in their laboratories. But these are extremely rare and short-lived.

The universe didn’t always boast so many elements. Blast back to the Big Bang, about 14 billion years ago. Physicists think that’s when matter, light and everything else exploded out of a fantastically dense, hot mass the size of a pea. This set in motion the expansion of the universe, an outward dispersion of mass that continues to this day.

The Big Bang was over in a flash. But it kick-started the whole universe, explains Steven Desch of Arizona State University in Tempe. An astrophysicist, Desch studies how stars and planets form.

“After the Big Bang,” he explains, “the only elements were hydrogen and helium. That was just about it.” Assembling the next 90 took a lot more time. To build those heavier elements, nuclei of lighter atoms had to fuse together. This nuclear fusion requires serious heat and pressure. Indeed, says Desch, it takes stars.

Star power

For a few hundred million years after the Big Bang, the universe contained only giant gas clouds. These consisted of about 90 percent hydrogen atoms; helium made up the rest. Over time, gravity increasingly pulled the gas molecules toward each other. This increased their density, making the clouds hotter. Like cosmic lint, they began to gather into balls known as protogalaxies. Inside them, material continued to amass into ever-denser clumps. Some of these developed into stars. Stars are still being born this way, even in our Milky Way galaxy.

Elements as massive as gold are not born directly inside stars, but instead through more explosive events — collisions between stars. Shown here is an artist’s rendering of the moment two neutron stars collided. Neutron stars are the immensely dense cores that remain after two stars had exploded as supernovas.

DANA BERRY, SKYWORKS DIGITAL, INC.

Converting lightweight elements into heavier ones is what stars do. The hotter the star, the heavier the elements it can make.

The center of our sun is some 15 million degrees Celsius (about 27 million degrees Fahrenheit). That may sound impressive. Yet as stars go, it’s pretty wimpy. Average-size stars like the sun “don’t get hot enough to produce elements much heavier than nitrogen,” says Pilachowski. In fact, they create mainly helium. 

To forge heavier elements, the furnace must be immensely bigger and hotter than our sun. Stars at least eight times bigger can forge elements up to iron, element 26. To build elements heavier than that, a star must die.

In fact, making some of the heaviest metals, like platinum (element number 78) and gold (number 79), might require even more extreme celestial violence: collisions between stars!

In June 2013, the Hubble Space Telescope detected just such a collision of two ultra-dense bodies known as neutron stars. Astronomers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., measured the light emitted by this collision. That light provides “fingerprints” of the chemicals involved in those fireworks. And they show that gold formed. Lots of it: enough to equal several times the mass of Earth’s moon. Because a similar smash-up probably takes place in a galaxy once every 10,000 or 100,000 years, such crashes could account for all of the gold in the universe, team member Edo Berger toldScience News.

Death of a star

No star lives forever. “Stars have a lifespan of about 10 billion years,” says Pilachowski, an expert in dead and dying suns.

Gravity is always drawing the components of a star closer together. As long as a star still has fuel, pressure from nuclear fusion pushes outward and counter-balances the force of gravity. But once most of that fuel has burned up, so long star. Without fusion to counter it, “gravity forces the core to collapse,” she explains.

 

Mira is an elderly sun in the constellation Cetus. A relatively cool red-giant star, it has an odd football-like shape. The Hubble Space Telescope photo shows Mira to be about 700 times the size of our sun. Mira also has a hot “companion” star (not shown).

MARGARITA KAROVSKA (HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS) AND NASA

The age at which a star dies depends on its size. Small to medium-size stars don’t explode, Pilachowski says. While their core of iron or lighter elements collapses, the rest of the star expands gently, like a cloud. It swells into a huge growing, glowing ball. Along the way, such stars cool and darken. They become what astronomers call red giants. Many atoms in the outer halo surrounding such a star will just drift away into space.

Bigger stars come to a very different end. When they use up their fuel, their cores collapse. This leaves them extremely dense and hot. Instantly, that forges elements heavier than iron. The energy released by this atomic fusion triggers the star to expand yet again. At once, the star finds itself without enough fuel to sustain fusion. So the star collapses once again. Its massive density causes it to heat up again —after which it now fuses its atoms, creating heavier ones.

“Pulse after pulse, it steadily builds up heavier and heavier elements,” Desch says of the star. Amazingly, this all happens within a few seconds. Then, faster than you can say supernova, the star self-destructs in one ginormous explosion. The force of that supernova explosion is what forges elements heavier than iron.

“Atoms go blasting out into space,” says Pilachowski. “They go a long way.”

Some atoms drift gently from a red giant. Others rocket at warp speed from a supernova. Either way, when a star dies, many of its atoms spew into space. Eventually they become recycled by the processes that form new stars and even planets. All of this element-building “takes time,” says Pilachowski. Perhaps billions of years. But the universe is in no rush. It does suggest, however, that the longer a galaxy has been around, the more heavy elements it will contain.

When a star — W44 — exploded as a supernova, it scattered debris over a broad area, shown here. This image was produced by combining data collected by the European Space Agency’s Hershel and XMM-Newton space observatories. W44 is the purple sphere dominating the left side of this image. It spans about 100 light-years across.

HERSCHEL: QUANG NGUYEN LUONG & F. MOTTE, HOBYS KEY PROGRAM CONSORTIUM, HERSCHEL SPIRE/PACS/ESA CONSORTIA. XMM-NEWTON: ESA/XMM-NEWTON

Blast from the past

Consider the Milky Way. When our galaxy was young, 4.6 billion years ago, elements heavier than helium made up just 1.5 percent of the Milky Way. “Today it’s up to 2 percent,” Desch notes.

Last year, astronomers at the California Institute of Technology, or Caltech, discovered a very faint red dot in the night sky. They named this galaxy HFLS3. Hundreds of stars were forming inside it. Astronomers refer to such celestial bodies, with so many stars springing to life, as starburst galaxies. “HFLS3 was forming stars 2,000 times more rapidly than the Milky Way,” notes Caltech astronomer Jamie Bock.

To study distant stars, astronomers like Bock essentially become time travelers. They must look deep into the past. They can’t see what’s happening now because the light they study must first cross a vast expanse of the universe. And that can take months to years —sometimes thousands of millennia. So when describing star births and deaths, astronomers must use the past-tense.

A light-year is the distance light travels over a span of 365 days — 9.46 trillion kilometers (or some 6 trillion miles). HFLS3 was more than 13 billion light-years from Earth when it died. Its faint glow is just now reaching Earth. So what has happened in its vicinity during the past 12-billion-plus years won’t be known for eons.

But the just-arriving old news on HFLS3 did offer two surprises. First: It turns out to be the oldest starburst galaxy known. In fact, it is almost as old as the universe itself. “We found HFLS3 when the universe was a mere 880 million years old,” says Bock. At that point, the universe was a virtual baby.

Second, HFLS3 didn’t contain just hydrogen and helium, as astronomers might have expected for such an early galaxy. While studying its chemistry, Bock says his team discovered “it had heavy elements and dust that must have come from an earlier generation of stars.” He likens this to “finding a fully developed city early in human history where you were expecting to find villages.”

This distant galaxy, known as HFLS3, is a star-building factory. New analyses indicate it is furiously transforming gas and dust into new stars more than 2,000 times faster than occurs in our own Milky Way. Its starburst rate is one of the fastest ever seen.

ESA–C.CARREAU

Lucky us

Steve Desch thinks HFLS3 might help answer some important questions. The Milky Way galaxy is some 12 billion years old. But it doesn’t make stars fast enough to have created all of the 92 elements present on Earth. “It’s always been a bit of a mystery how so many heavy elements built up so fast,” says Desch. Maybe, he now suggests, starburst galaxies are not all that rare. If so, such high-speed star factories might have given the creation of heavy elements an early boost.

By about 5 billion years ago, stars in the Milky Way had generated all 92 elements now present on Earth. Indeed, gravity pulled them together, packing them into a hot cosmic stew that together would eventually coalesce to form our solar system. A few hundred million years later, Earth was born.

Within the next billion years, the first signs of life on Earth appeared. No one is exactly sure how life here got its start. But one thing is clear: Elements that formed Earth and all life upon it came from outer space. “Every atom in your body was forged in the center of a star,” observes Desch, or from collisions between stars.

 

If the elements responsible for life on Earth started off in space, might they also have triggered life somewhere else?

No one knows. But that’s not for lack of trying. Whole organizations, like an institute focused on the Search for Extraterrestial Intelligence, or SETI, have been scouting for life beyond our solar system.

Desch, for one, doesn’t think they’ll find anyone else out there. He mentions a famous graph. It shows that planets can’t form until there are enough heavy elements. “I saw that graph, and in an instant I understood that we really may be alone in the galaxy, because before the sun there weren’t that many planets,” Desch says.

He therefore suspects that “Earth may be the first civilization in the galaxy. But not the last.”