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NASA, ESA, and G. Bacon (STScI)
NASA, ESA, and G. Bacon (STScI)

What Two Dead Stars Reveal About Earth's Origins

NASA, ESA, and G. Bacon (STScI)
NASA, ESA, and G. Bacon (STScI)

By Chris Gayomali

Sitting on the nose of the constellation Taurus, about 150 light-years away from Earth in the star cluster Hyades, are the dulling embers of two white dwarf stars.

Under normal circumstances, the stars' burnt-out cores would be unremarkable. But scientists from Cambridge University peering through NASA's Hubble telescope noticed something peculiar.

Instead of being surrounded by mostly empty space, the stars' remnants were swimming in a dusty cloud of asteroid debris, likely smashed to bits by the dwarves themselves

Surprisingly, the matter in this instance was mostly composed of heavy elements like silicon and carbon — the chemical building blocks of planets like Earth. 

[The] research suggests asteroids less than 100 miles (160 kilometers) wide probably were torn apart by the white dwarfs' strong gravitational forces. Asteroids are thought to consist of the same materials that form terrestrial planets, and seeing evidence of asteroids points to the possibility of Earth-sized planets in the same system.

The pulverized material may have been pulled into a ring around the stars and eventually funneled onto the dead stars. The silicon may have come from asteroids that were shredded by the white dwarfs' gravity when they veered too close to the dead stars. [NASA]

"When these stars were born, they built planets, and there's a good chance they currently retain some of them. The material we are seeing is evidence of this," says Jay Farihi, an astronomer at Cambridge and lead author of the study. "The debris is at least as rocky as the most primitive terrestrial bodies in our solar system."

The discovery could shed light on how so-called "cosmic nurseries"—which produce stars and planets much like our humble blue marble—gather materials to create new worlds. 

"If you have giant rocks that are many kilometers in size flying about, it is almost certain that planet formation has happened," Farihi told the Los Angeles Times. "It's like seeing a bunch of Lego blocks strewn around a kid's room. You know they were building something, but you don't know exactly what they are building."

It should also give astronomers a clearer indication of what happens when our own sun eventually runs out of fuel.

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How Often Is 'Once in a Blue Moon'? Let Neil deGrasse Tyson Explain
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From “lit” to “I can’t even,” lots of colloquialisms make no sense. But not all confusing phrases stem from Millennial mouths. Take, for example, “once in a blue moon”—an expression you’ve likely heard uttered by teachers, parents, newscasters, and even scientists. This term is often used to describe a rare phenomenon—but why?

Even StarTalk Radio host Neil deGrasse Tyson doesn’t know for sure. “I have no idea why a blue moon is called a blue moon,” he tells Mashable. “There is nothing blue about it at all.”

A blue moon is the second full moon to appear in a single calendar month. Astronomy dictates that two full moons can technically occur in one month, so long as the first moon rises early in the month and the second appears around the 30th or 31st. This type of phenomenon occurs every couple years or so. So taken literally, “Once in a blue moon” must mean "every few years"—even if the term itself is often used to describe something that’s even more rare.

[h/t Mashable]

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Space
Neutron Star Collision Sheds Light on the Strange Matter That Weighs a Billion Tons Per Teaspoon
Two neutron stars collide.
Two neutron stars collide.

Neutron stars are among the many mysteries of the universe scientists are working to unravel. The celestial bodies are incredibly dense, and their dramatic deaths are one of the main sources of the universe’s gold. But beyond that, not much is known about neutron stars, not even their size or what they’re made of. A new stellar collision reported earlier this year may shed light on the physics of these unusual objects.

As Science News reports, the collision of two neutron stars—the remaining cores of massive stars that have collapsed—were observed via light from gravitational waves. When the two small stars crossed paths, they merged to create one large object. The new star collapsed shortly after it formed, but exactly how long it took to perish reveals keys details of its size and makeup.

One thing scientists know about neutron stars is that they’re really, really dense. When stars become too big to support their own mass, they collapse, compressing their electrons and protons together into neutrons. The resulting neutron star fits all that matter into a tight space—scientists estimate that one teaspoon of the stuff inside a neutron star would weigh a billion tons.

This type of matter is impossible to recreate and study on Earth, but scientists have come up with a few theories as to its specific properties. One is that neutron stars are soft and yielding like stellar Play-Doh. Another school of thought posits that the stars are rigid and equipped to stand up to extreme pressure.

According to simulations, a soft neutron star would take less time to collapse than a hard star because they’re smaller. During the recently recorded event, astronomers observed a brief flash of light between the neutron stars’ collision and collapse. This indicates that a new spinning star, held together by the speed of its rotation, existed for a few milliseconds rather than collapsing immediately and vanishing into a black hole. This supports the hard neutron star theory.

Armed with a clearer idea of the star’s composition, scientists can now put constraints on their size range. One group of researchers pegged the smallest possible size for a neutron star with 60 percent more mass than our sun at 13.3 miles across. At the other end of the spectrum, scientists are determining that the biggest neutron stars become smaller rather than larger. In the collision, a larger star would have survived hours or potentially days, supported by its own heft, before collapsing. Its short existence suggests it wasn’t so huge.

Astronomers now know more about neutron stars than ever before, but their mysterious nature is still far from being fully understood. The matter at their core, whether free-floating quarks or subatomic particles made from heavier quarks, could change all of the equations that have been written up to this point. Astronomers will continue to search the skies for clues that demystify the strange objects.

[h/t Science News]

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