A white dwarf murder mystery

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What killed the white dwarfs? (Aside from the giant explosion)

Merger or extra matter? Two papers come to opposite conclusions

For Ars Technica:

Type Ia supernovae are explosions that occur when white dwarfs strip matter off a companion star, exceed their maximum possible mass, and blow up.

No, wait: type Ia supernovae are the explosions caused when two white dwarfs collide.

While it’s reasonably certain that white dwarfs—the Earth-size remnant of stars similar to the Sun—are involved, the observational evidence for how these supernovae actually explode is messy. This week’s issue of Nature is a prime example: two back-to-back papers provide evidence for a white dwarf-companion star explosion and a two-white-dwarf collision scenario, respectively. Ultimately, these apparently contradictory results could mean there are two distinct types of white dwarf supernovae… or that we still don’t understand what’s going on.

The stakes are high. Unlike other supernovae, which involve the death of a star much more massive than the Sun, type Ia supernovae all explode in very similar ways. The pattern of light they emit during and after the explosion provides a reliable measurement of how far away they are. Since supernovae are bright enough to be visible from billions of light-years away, astronomers use them to measure the expansion and acceleration rate of the Universe, as recognized in the 2011 Nobel Prize in physics. Because they are so important to cosmology, researchers want to understand what objects are involved in the explosion and exactly how they blow up. [Read the rest at Ars Technica…]

Looking to the heavens for neutrino masses

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Looking to the heavens for neutrino masses

From Symmetry Magazine:

Neutrinos may be the lightest of all the particles with mass, weighing in at a tiny fraction of the mass of an electron. And yet, because they are so abundant, they played a significant role in the evolution and growth of the biggest things in the universe: galaxy clusters, made up of hundreds or thousands of galaxies bound together by mutual gravity.

Thanks to this deep connection, scientists are using these giants to study the tiny particles that helped form them. In doing so, they may find out more about the fundamental forces that govern the universe. [Read the rest at Symmetry]

A possible ocean like ours on the moon Europa

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Europa’s Salty Sea

My first contribution to the brand-new magazine Hakai:

You can find bits and pieces of Earth seemingly scattered around the solar system. The surface of Mars looks a lot like Earth’s deserts; Titan’s atmosphere isn’t far off (minus a lack of oxygen); and the moon shares Earth’s basic geology. If you want to see oceans like ours, new research suggests your best bet is Jupiter’s moon Europa.

“Oceans like ours” in a chemical sense, that is. There are no fish or whales or coral on Europa. But Europa’s massive ocean is a salty one—and according to planetary geologist Kevin P. Hand and geochemist Richard W. Carlson, the specific salt that fills its sea, sodium chloride (or table salt), is the same salt that is crucial to life on Earth. [Read the read at Hakai…]

Hakai is focused on coastal ecosystems, which is a little off the beaten path for me, but they indulged me in writing about oceans on another world. And of course there’s physics hiding in a lot of areas, so I’ll hopefully be writing more for them in the future. In the meantime, check out the magazine: it looks really great!

Bathing asteroids with nuclear weapons

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A gentle nudge with a nuke: deflecting Earth-bound asteroids

From Ars Technica:

In 2013, a small asteroid exploded in the atmosphere over Chelyabinsk, Russia. The sonic boom from the event sent more than a thousand people to the hospital, mostly from flying glass from shattered windows. The Chelyabinsk meteor was a relatively small chunk of space rock—asteroid researchers think it was probably about 20 meters (66 feet) across—but exploding over a city made it a noteworthy event. It’s probable many similar asteroids hit Earth on a regular basis, but most don’t happen to fly over metropolitan areas; they fall into the ocean or over lightly populated regions.

However, Earth has played target in the cosmic darts tournament before. Meteor Crater in Arizona, the Tunguska impact in Siberia in 1908, and most famously the Chicxulub asteroid in Mexico (which played a part in the extinction of the dinosaurs) are just three of many known examples. That’s why many people are looking at viable options for planetary defense: destroying or turning asteroids aside before they can hit Earth. And planetary defense is one reason the United States’ National Nuclear Safety Administration (NNSA) has given for not destroying some of its surplus nuclear warheads. [Read the rest at Ars Technica…]

If we could only build one huge observatory….

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Q: Suppose we can only build one big telescope. Should we look for life among the stars or the origins of the universe?

I participated in an experts’ roundtable for Aeon Magazine, in which we were asked (more or less facetiously) what single project we would support to settle either questions about the very early universe or the existence of life elsewhere in the cosmos. Of course my real answer is that we should support all the science, because discovery isn’t about looking for one thing, but seeing what new things we can find. Throwing all our money at one big project might accomplish something, but it’s a bad way to do science. But anyway, taking the question for what it is — a fun exercise in wishing — here’s my answer, along with thoughts from Ross Andersen and Caleb Scharf.

Unless you’re a werewolf, the full Moon isn’t to blame for your problems

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Get Over Your Full Moon Fears

From The Daily Beast:

The full Moon is making everyone crazy. More people get arrested when the Moon is full.
The new Moon is making everyone depressed.

Maybe you’ve heard things like that. Maybe you’ve said them yourself. It seems plausible that the second-brightest thing in the sky, the closest astronomical body to Earth, and the object largely responsible for the tides, could cause measurable changes in human behavior. After all, some animals coordinate their behaviors with the phase of the Moon.

As a result of this style of thinking, hospital workers will sometimes claim more births or injuries happen, police will notice more arrests, mental health professionals will feel their clients change behaviors, and so forth, depending on the Moon’s phase. Despite that, repeated studies have shown no strikingly different behavior: there aren’t big differences in car wreck frequency, births, murders, or depression incidents between the new Moon and full Moon. [Read the rest at The Daily Beast…]

The dinosaur-killing dark matter of DOOM!

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A few weeks ago, several news outlets ran stories based on a press release, in which a researcher claimed that dense clumps of dark matter could be responsible for the extinction of dinosaurs. I found this claim dubious, based on what we know about dark matter. Here’s my response.

Did Dark Matter Doom the Dinosaurs?

From Slate:

he history of life on Earth is marked by occasional mass extinctions, events wiping out huge numbers of species. The most famous of these killed off all the dinosaurs (or at least those that hadn’t evolved into birds) 65 million years ago. But the mass extinction that ended the Permian period 250 million years ago was even more dramatic, killing off 90 percent of all species in an astonishingly short amount of time. As yet, the cause of this devastation is unexplained.

Mass extinctions have happened at least five times. (A sixth great extinction currently in progress, but that’s an anomaly because humans are responsible.) Some researchers have tried to figure out whether they’re periodic, recurring after specific time intervals. If they truly do repeat regularly, maybe there’s a common cause for them. [read more on Slate.com]