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Update November 2017


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Update by Natrakorn Paewsoongnern
 
 
 
Science & Nature
 

Update Saturday, Nov. 25 - Dec. 1, 2017

Stellar encore: Dying star keeps coming back big time

This illustration made available by the European Southern Observatory in 2014 shows dust surrounding a supernova explosion. On Wednesday, Nov. 8, 2017, astronomers reported that a star 500 million light-years away exploded in 1954 and apparently again in 2014. The research confounds scientists who thought they knew how dying stars ticked. (M. Kornmesser/ESO via AP)

Marcia Dunn

Cape Canaveral, Fla. (AP) - Death definitely becomes this star.

Astronomers reported Wednesday on a massive, distant star that exploded in 2014 - and also, apparently back in 1954. This is one supernova that refuses to bite the cosmic dust, confounding scientists who thought they knew how dying stars ticked.

The oft-erupting star is 500 million lightyears away - one lightyear is equal to 5.9 trillion miles (9.5 trillion kilometers) - in the direction of the Big Bear constellation. It was discovered in 2014 and, at the time, resembled your basic supernova that was getting fainter.

But a few months later, astronomers at the California-based Las Cumbres Observatory saw it getting brighter. They’ve seen it grow faint, then bright, then faint again five times. They’ve even found past evidence of an explosion 60 years earlier at the same spot.

Supernovas typically fade over 100 days. This one is still going strong after 1,000 days, although it’s gradually fading.

“It’s very surprising and very exciting,” said astrophysicist Iair Arcavi of the University of California, Santa Barbara who led the study. “We thought we’ve seen everything there is to see in supernovae after seeing so many of them, but you always get surprised by the universe. This one just really blew away everything we thought we understood about them.”

The supernova - officially known as iPTF14hls - is believed to have once been a star up to 100 times more massive than our sun. It could well be the biggest stellar explosion ever observed, which might explain its death-defying peculiarity.

It could be multiple explosions occurring so frequently that they run into one another or perhaps a single explosion that repeatedly gets brighter and fainter, though scientists don’t know exactly how this happens.

One possibility is that this star was so massive, and its core so hot, that an explosion blew away the outer layers and left the center intact enough to repeat the entire process. But this pulsating star theory still doesn’t explain everything about this supernova, Arcavi said.

Harvard University’s astronomy chairman, Avi Loeb, who was not involved in the study, speculates a black hole or magnetar - a neutron star with a strong magnetic field - might be at the center of this never-before-seen behavior. Further monitoring may better explain what’s going on, he said.

Las Cumbres, a global network of robotic telescopes, continues to keep watch.

Scientists do not know whether this particular supernova is unique; it appears rare since no others have been detected.

“We could actually have missed plenty of them because it kind of masquerades as a normal supernova if you only look at it once,” Arcavi said.

Nothing lasts forever - not even this super supernova.

“Eventually, this star will go out at some point,” Arcavi said. “I mean, energy has to run out eventually.”


Study: Great white sharks are swimming farther and deeper

In this Sept. 13, 2012 file photo, Captain Brett McBride places his hand on the snout of the crew’s first specimen while scientists collect blood, tissue samples and attach tracking devices on the research vessel Ocearch off the coast of Chatham, Mass. Before release, the nearly 15-foot, 2,292-pound great white shark was named Genie for famed shark researcher Eugenie Clark. (AP Photo/Stephan Savoia, File)

Philip Marcelo

Boston (AP) - The movements of great white sharks in the Pacific and Indian oceans have long been the subject of academic study, but new research is just starting to shed light on the behavior of their Atlantic Ocean counterparts.

Researchers in Massachusetts say white sharks appear to venture offshore farther, with more frequency and at greater depths than previously known in the Atlantic.

Some of the 32 sharks tracked between 2009 and 2014 ended up as far east as the Azores, the Portuguese island chain located more than 2,300 miles (3,701 kilometers) from Cape Cod, where most of the animals were initially outfitted with satellite tags.

They also were found to make frequent deep dives - as far down as 3,700 feet (1,127 meters) - and spend more time at those dark depths than previous studies in the Atlantic suggest.

The team, which included scientists from the state Division of Marine Fisheries, the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, had its findings published last week in Marine Ecology Progress Series, a prominent scientific journal.

“Everything we knew previously indicated that the white shark in the Atlantic is more coastally-oriented, moving north-to-south and remaining on the continental shelf,” explained Gregory Skomal, the study’s lead author. “So what we’re now describing is this other component, this offshore movement into open ocean.”

Skomal says the work has implications for shark conservation efforts since it extends the known habitat for these ancient predators. White sharks are not considered endangered or threatened, but it’s illegal to hunt them in U.S. waters.

“You’ve got U.S. protection within 200 miles of shore, but you have sharks clearly leaving that protection that are vulnerable to harvest,” Skomal said. “We need to engage other countries fishing in these waters to talk about putting similar protections in place.”

The research is exciting because it represents the “first real insights into the movement patterns of white sharks” in the northern part of the Atlantic, says Tobey Curtis, a Massachusetts-based shark researcher for the National Marine Fisheries Service who was not involved with the study.

“Prior to this, we were only able to piece together information about their distribution from widely scattered reports from fishermen, scientists and the public,” he said. “Having tracks of individual sharks really helps fill in the gaps, and provides a more complete picture of white shark movements and migrations.”

The study seems to hew closely to what’s been observed of white sharks in other oceans - that juveniles tend to stay in the relatively shallower waters of the continental shelf where food sources abound, while adults are more apt to venture into open ocean, observes Christopher Lowe, a shark researcher at California State University in Long Beach also not involved with the research.

Indeed, most of the tagged sharks in the Atlantic study generally followed a north-south migration along the Eastern Seaboard.

They headed to Newfoundland and New England waters in the summer, then down south to the Carolinas and even the Bahamas for the winter.

Lowe says it remains to be seen what impact continued growth of white shark populations in the Atlantic has on these habits, or whether climate change is playing a role.

Another key question is finding out what these sharks are actually doing so far offshore.

Researchers in northern California suggest offshore movements are for mating, a ritual that has never been observed among white sharks. But Skomal and his team believe the animals are more likely foraging - it’s just not immediately obvious what they’re feeding on.

“That’s the great mystery right now,” he said.

 


Update Saturday, Nov. 18 - Nov. 24, 2017

Pence pledges that US will go to the moon, Mars and beyond

Vice President Mike Pence speaks in front of NASA’s Space Shuttle Discovery at the National Space Council first meeting at the Steven F. Udvar-Hazy Center, Thursday, Oct. 5, 2017 in Chantilly, Va. (AP Photo/Andrew Harnik)

Washington (AP) - Seated before the grounded space shuttle Discovery, a constellation of Trump administration officials used soaring rhetoric to vow to send Americans back to the moon and then on to Mars.

After voicing celestial aspirations, top officials moved to what National Intelligence Director Dan Coats called “a dark side” to space policy. Coats, Vice President Mike Pence, other top officials and outside space experts said the United States has to counter and perhaps match potential enemies’ ability to target U.S. satellites.

Pence, several cabinet secretaries and White House advisers gathered in the shadow of the shuttle at the Smithsonian Institution’s Steven F. Udvar-Hazy Center to chart a new path in space - government, commercial and military - for the country. It was the first meeting of the National Space Council, revived after it was disbanded in 1993.

But details, such as how much the new ideas will cost, were scant and outside experts said they’ve heard grandiose plans before only to see them fizzle instead of launch.

“We will return American astronauts to the moon, not only to leave behind footprints and flags, but to build the foundation we need to send Americans to Mars and beyond,” Pence said.

Space industry leaders say they and NASA are building the spaceships to get there. And they’re promising that in five years, astronauts could be working around the moon.

David Thompson, president of the space company Orbital ATK, said NASA’s Orion capsule and super-sized Space Launch System rocket should be ready in a couple years, so flying around the moon and even making a lunar orbiting outpost is within reach. But he said a lunar landing would take longer. Blue Origin rocket company chief executive officer Bob Smith said his firm could have a lunar lander program ready within five years.

No humans have been on the moon since Apollo 17 in December 1972. Only 12 men have set foot on the moon, all have been Americans.

Past presidents George H.W. Bush and George W. Bush proposed returns to the moon and then going on to Mars. Barack Obama rerouted the moon plan to an asteroid as a first-stop with Mars as the goal. All plans had lack of money keep them from coming true, said space expert Brian Weeden of the Secure World Foundation. He wasn’t part of the council meeting.

“Is it going to happen? Who knows? I feel like I’ve been disappointed so many times I refuse to get excited,” said Roger Launius, a longtime space historian.

And Gwynn Shotwell, president of SpaceX, said her company next year will launch astronauts to the International Space Station, the first American launch of people since 2011. After the 2003 space shuttle Columbia broke apart on descent, then-president George W. Bush announced the phasing out of the space shuttle program. Eventually, NASA started building new multibillion dollar ships, the Orion capsule and the SLS mega-rocket.

Pence several times bemoaned a U.S. space program that had fallen behind, asking space executives what they thought.

“America is out-innovating the world in space launch,” Shotwell said, noting that her company had launched 13 rockets this year, more than any other nation.

After talking about how “we will blaze new trails into that great frontier” Pence turned the discussion to the dangers of space and how much of the U.S. intelligence system and day-to-day life are dependent on commercial satellites operating safely. And he and others outlined threats to those satellites from potential enemies that could cripple American security and daily life.

Experts worried that satellites could be destroyed and debris in orbit could ruin others.

Pence asked if the U.S. should “weaponize” space.

“The choice whether or not to weaponize space is not one that we can make. We can only decide to match and raise our adversaries who are already weaponizing space,” former NASA chief Michael Griffin said. “That horse is already out of the barn.”

White House National Security Adviser H.R. McMaster said the country needs to “deter and when necessary defeat adversaries’ counter-space efforts...  We may not start it but we will finish it.”


Update Saturday, Nov. 11 - Nov. 17, 2017

What cosmic crash confirmed: Einstein was as good as gold

Julie McEnery, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md., speaks at the National Press Club in Washington, Monday, Oct. 16, 2017, during an announcement about one of the most violent events in the cosmos that was witnessed completely for the first time in August and tells scientists where gold and other heavy elements come from. (AP Photo/Susan Walsh)

Seth Borenstein

Washington (AP) - When two extremely dense neutron stars crashed together in a distant galaxy, astronomers struck scientific gold, confirming previously unproven theories, including some from Albert Einstein.

Scientists announced that after picking up two faint signals in mid-August, they were able to find the location of the long-ago crash and see the end of it play out. Measurements of the light and other energy that the crash produced helped them answer some cosmic questions.

Gravitational Waves

Scientists, starting with Einstein, figured that when two neutron stars collide they would produce a gravitational wave, a ripple in the universe-wide fabric of space-time. Four other times that these waves were detected they were the result of merging black holes. This is the first time scientists observed one caused by a neutron star crash.

Where gold comes from

The Big Bang created light elements like hydrogen and helium. Supernovas created medium elements, up to iron. But what about the heavier ones like gold, platinum and uranium? Astronomers thought they came from two neutron stars colliding, and when they saw this crash they confirmed it. One astronomer described as a “giant train wreck that creates gold.” They estimate that this one event generated an amount of gold and platinum that outweighs the entire Earth by a factor of 10.

Gamma Rays

Gamma ray bursts are some of the most energetic and deadly pulses of radiation in the universe. Astronomers weren’t quite sure where short gamma ray bursts came from, but figured that a crash of neutron stars was a good bet. Watching this event confirmed the theory.

Expanding Universe

Astronomers know the universe is expanding, and they use a figure called the Hubble Constant to describe how fast. Two different ways scientists have of measuring this speed of expansion yields two numbers that are somewhat close to each other, but not quite the same. By measuring how far the gravitational wave had to travel, astronomers came up with another estimate that was between the earlier two, but it also comes with a large margin of error.

How fast do rays and waves go?

The crash showed that gravitational waves and gamma rays travel at nearly the speed of light - which is what Einstein’s General Relativity theory says. NASA astrophysicist Julie McEnery said: “Yet again, Einstein passes another test.”


Update Saturday, Nov. 4 - Nov. 10, 2017

Scientists witness huge cosmic crash, find origins of gold

This illustration provided by the Carnegie Institution for Science depicts the collision of two neutron stars detected on Aug. 17, 2017. The explosion threw matter, light, radiation and gravitational waves into space. The discovery was reported on Monday, Oct. 16, 2017. (Robin Dienel/Carnegie Institution for Science via AP)

Seth Borenstein

Washington (AP) - It was a faint signal, but it told of one of the most violent acts in the universe, and it would soon reveal secrets of the cosmos, including how gold was created.

Astronomers around the world reacted to the signal quickly, focusing telescopes located on every continent and even in orbit to a distant spot in the sky.

What they witnessed in mid-August and revealed Monday, Oct. 16, was the long-ago collision of two neutron stars - a phenomenon California Institute of Technology’s David H. Reitze called “the most spectacular fireworks in the universe.”

“When these things collide, all hell breaks loose,” he said.

Measurements of the light and other energy emanating from the crash have helped scientists explain how planet-killing gamma ray bursts are born, how fast the universe is expanding, and where heavy elements like platinum and gold come from.

“This is getting everything you wish for,” said Syracuse University physics professor Duncan Brown, one of more than 4,000 scientists involved in the blitz of science that the crash kicked off. “This is our fantasy observation.”

It started in a galaxy called NGC 4993, seen from Earth in the Hydra constellation. Two neutron stars, collapsed cores of stars so dense that a teaspoon of their matter would weigh 1 billion tons, danced ever faster and closer together until they collided, said Carnegie Institution astronomer Maria Drout.

The crash, called a kilonova, generated a fierce burst of gamma rays and a gravitational wave, a faint ripple in the fabric of space and time, first theorized by Albert Einstein.

“This is like a cosmic atom smasher at a scale far beyond humans would be capable of building,” said Andy Howell, a staff scientist at the Las Cumbres Observatory. “We finally now know what happens when an unstoppable force meets an immovable object and it’s a kilonova.”

The crash happened 130 million years ago, while dinosaurs still roamed on Earth, but the signal didn’t arrive on Earth until Aug. 17 after traveling 130 million light-years. A light-year is 5.88 trillion miles.

Signals were picked up within 1.7 seconds of each other, by NASA’s Fermi telescope, which detects gamma rays, and gravity wave detectors in Louisiana and Washington State that are a part of the LIGO Laboratory, whose founders won a Nobel Prize earlier this month. A worldwide alert went out to focus telescopes on what became the most well-observed astronomical event in history.

Before August, the only other gravity waves detected by LIGO were generated by colliding black holes. But black holes let no light escape, so astronomers could see nothing.

This time there was plenty to see, measure and analyze: matter, light, and other radiation. The Hubble Space Telescope even got a snapshot of the afterglow.

Finding where the crash happened wasn’t easy. Eventually scientists narrowed the location down to 100 galaxies, began a closer search of those, and found it in the ninth galaxy they looked at.

It is like “the classic challenge of finding a needle in the haystack with the added challenge that the needle is fading away and the haystack is moving,” said Marcelle Soares-Santos, an astrophysicist at Brandeis University.

“The completeness of this picture from the beginning to the end is unprecedented,” said Columbia University physics professor Szabolcs Marka. “There are many, many extraordinary discoveries within the discovery.”

The colliding stars spewed bright blue, super-hot debris that was dense and unstable. Some of it coalesced into heavy elements, like gold, platinum and uranium. Scientists had suspected neutron star collisions had enough power to create heavier elements, but weren’t certain until they witnessed it.

“We see the gold being formed,” said Syracuse’s Brown.

Calculations from a telescope measuring ultraviolet light showed that the combined mass of the heavy elements from this explosion is 1,300 times the mass of Earth. And all that stuff - including lighter elements - was thrown out in all different directions and is now speeding across the universe.

Perhaps one day the material will clump together into planets the way ours was formed, Reitze said - maybe ones with rich veins of precious metals.

“We already knew that iron came from a stellar explosion, the calcium in your bones came from stars and now we know the gold in your wedding ring came from merging neutron stars,” said University of California Santa Cruz’s Ryan Foley.

The crash also helped explain the origins of one of the most dangerous forces of the cosmos - short gamma ray bursts, focused beams of radiation that could erase life on any planet that happened to get in the way. These bursts shoot out in two different directions perpendicular to where the two neutron stars first crash, Reitze said.

Luckily for us, the beams of gamma rays were not focused on Earth and were generated too far away to be a threat, he said.

Scientists knew that the universe has been expanding since the Big Bang. By using LIGO to measure gravitational waves while watching this event unfold, researchers came up with a new estimate for how fast that is happening, the so-called Hubble Constant. Before this, scientists came up with two slightly different answers using different techniques. The rough figure that came out of this event is between the original two, Reitze said.

The first optical images showed a bright blue dot that was very hot, which was likely the start of the heavy element creation process amid the neutron star debris, Drout said. After a day or two that blue faded, becoming much fainter and redder. And after three weeks it was completely gone, she said.

This almost didn’t happen. Eight days after the signal came through, the LIGO gravitational waves were shut down for a year’s worth of planned upgrades. A month later the whole area where the crash happened would have been blocked from astronomers’ prying eyes by the sun.

Scientists involved with the search for gravitational waves said this was the event they had prepared for over more than 20 years.

The findings are “of spectacular importance,” said Penn State physicist Abhay Ashtekar, who wasn’t part of the research. “This is really brand new.”

Almost all of the discoveries confirmed existing theories, but had not been proven - an encouraging result for theorists who have been trying to explain what is happening in the cosmos, said France Cordova, an astrophysicist who directs the National Science Foundation.

“We so far have been unable to prove Einstein wrong,” said Georgia Tech physics professor Laura Cadonati. “But we’re going to keep trying.”
 


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HEADLINES [click on headline to view story]

Stellar encore: Dying star keeps coming back big time

Study: Great white sharks are swimming farther and deeper


Pence pledges that US will go to the moon, Mars and beyond


What cosmic crash confirmed: Einstein was as good as gold


Scientists witness huge cosmic crash, find origins of gold

 



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