Archive for the ‘astronomy’ Category

Conditions like those inside Neptune cause diamond formation

August 27th, 2017

Enlarge / That lovely blue exterior could be hiding a heart of diamond. (credit: NASA)

Carbon, oxygen, and nitrogen are some of the easiest heavier elements to form through fusion. As a result, they’re common in our Solar System, typically found combined with hydrogen to make ammonia, water, and methane. In the gas and ice giants of the outer Solar System, however, these chemicals are placed under extreme pressures, where chemistry starts to get a bit weird. Do these chemicals survive the crushing interiors of these planets?

One intriguing idea is that methane doesn’t survive. As pressure and temperature increase, methane should start condensing into more complex hydrocarbons. Then, as pressures increase further, calculations indicate the hydrogen and carbon should separate out, leaving pure carbon to sink to the depths of these planets. As a result, it’s been hypothesized that, close to their core, planets like Neptune and Uranus have a layer of pure diamond.

While some evidence supporting this theory has surfaced over the years, it’s been hard to precisely replicate the temperatures and pressures found inside the planets. Now, new work done at the SLAC X-ray laser facility supports the idea that these planets are full of diamonds. But the work indicates the diamonds only form at greater depths than we’d previously thought.

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Total eclipse of the Ars

August 21st, 2017

Enlarge (credit: John Timmer)

Our staff is sharing its eclipse stories and photos from today. The post will be updated as more come in.

OAKLAND, Calif.—Oakland  and the surrounding Bay Area are well-known for morning fog, particularly in the summertime. So despite having two telescopes and the helpful staff at the Chabot Space & Science Center, the clouds unfortunately didn’t cooperate. Nevertheless, that didn’t stop hundreds of people from gathering along the observation deck, near the historic telescopes named Leah and Rachel. Most people had brought protective eyewear or had made pinhole boxes, but with the cloud cover blocking the Sun anyway, they quickly figured out that they wouldn’t be able to see the Sun with them on. Attendees squealed and yelped with joy as they attempted to view what was left of the Sun peeking out from behind the Moon and the thick white cloud cover. Your correspondent caught a few glimpses of the partially-eclipsed and cloud-covered Sun for just a few moments.

Meanwhile, my sister-in-law, Kelly Guyon, 28, who traveled north from Oakland, California, to Madras, Oregon, to observe totality, has declared herself an “eclipse chaser” now.

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Get out of the office, see the eclipse

August 20th, 2017

Enlarge (credit: NASA)

Unless you’ve been living under a rock, you know that August 21 will treat much of the United States to a partial or total solar eclipse. The total eclipse will be visible along a path that stretches from the Oregon-Washington border to South Carolina.

But even if you’re not on the path of totality, you’d have to be in northern Maine to see more than half the Sun during the eclipse. New York City is over 1,000 kilometers from South Carolina, but we’re still going to have over 70 percent of the Sun hidden.

Rather than rehash all the details—or warning you again not to look at the Sun without protection—we here at Ars are simply going to urge you to stop what you’re doing and step outside if you’re anywhere in North America. Even if it’s cloudy. Even if you haven’t gotten organized enough to obtain eclipse glasses.

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We may have caught supernova debris slamming into neighboring stars

August 17th, 2017

Enlarge / When the smaller star finally explodes, its companion will obviously get hit by the debris. (credit: Fermilab)

Supernovae are some of the most energetic events in the Universe, sending massive shock waves out into the interstellar medium. And there’s every reason to think those shock waves run into things before they’ve had much of a chance to dissipate. Many stars have companions, either planets or other stars that orbit in reasonable proximity. In fact, there’s an entire subtype of supernova that appears to require a nearby companion.

So what happens to these objects when the shock wave hits? With our improved ability to rapidly identify supernovae, we may be on the cusp of finding out. Several times recently, researchers have spotted an extra blue glow to the burst of light from a supernova. And, in the most detailed observations yet, they make the case this glow comes from the supernova debris slamming into a companion star.

A supernova explosion that envelopes a nearby star is an inevitability. Eta Carinae, for example, is a system with two stars that are at least 30 times the Sun’s mass, meaning they’ll both eventually explode as a type-II supernova. Whichever goes first will undoubtedly send debris into the second. But there’s a different class of supernova, type-Ia, which requires the presence of a nearby star.

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Hypothetical black holes could be eating neutron stars

August 10th, 2017

Enlarge (credit: NASA’s Goddard Space Flight Center)

Immediately after the Big Bang, the Universe’s matter was incredibly dense and rippled with random fluctuations. Is it possible that some portions of it reached densities high enough to collapse into black holes?

The idea of primordial black holes has been kicking around in theoretical circles for a while, in part because they could provide much of the dark matter that seems to dominate the Universe’s large-scale structures. But testing for their existence requires some sort of consequence that we could detect, and the theorists have largely come up short there. But now, a team of three physicists writing in Physical Review Letters has come up with a rather intriguing consequence: these black holes could swallow a neutron star that, under the right conditions, would spit out heavy elements.

Truth or consequences

Two things could distinguish primordial black holes from those formed in the collapse of a massive star. One is that they could be nearly any mass, from less than the mass of a star up to thousands of times heavier than anything formed during a supernova. The heavier end of the spectrum is appealing, since it could explain how supermassive black holes appeared so quickly (in astronomical terms) after the Universe’s birth.

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Europa’s future: A runaway greenhouse

August 1st, 2017

Enlarge (credit: NASA)

Stars like the Sun brighten over the course of their history, a trend that has significant consequences for the habitability of Earth and other bodies both in our Solar System and beyond. An icy world on the far edge of the habitable zone may turn into a temperate paradise given enough time.

Or, it could go straight to being a Venus-style hell if a new study turns out to be right. The study’s authors tuned a full-planet climate model loose on a planet covered in ice. The find that, under a level of incoming light that’s sufficient to melt the ice, the planet reaches a greenhouse state that would cause it to lose all its water to space and possibly head straight into a runaway greenhouse.

The only thing that saved Earth from a runaway greenhouse is, ironically, the presence of greenhouse gasses in its atmosphere.

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Kepler data may hold a Neptune-sized surprise, our first exomoon

July 31st, 2017

Enlarge (credit: NASA/JPL-Caltech)

One of the most important things we’ve learned from the Kepler mission is that, in many ways, our Solar System isn’t unique. Lots of stars have planets, many have multiple planets, and the list of planets includes many with sizes and densities similar to our eight planets. But there are lots of details of our own planets, like the composition and presence of atmospheres, that are much harder to examine at these distances.

One of the features we haven’t gotten a grip on is the presence of moons. Most of our Solar System’s planets have them, and they seem to form by a variety of mechanisms. We’d expect them to be common in exosolar systems, too, but so far we haven’t yet spotted any.

A new paper, which goes into extensive detail about the calculations needed to look for an exomoon, makes it clear why: we simply don’t have enough observation time to pick one up in most cases. But the paper also suggests there may be an exception, as the data hints at a Neptune-sized exomoon, though the statistics aren’t yet conclusive.

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