Ivan Semeniuk’s Embedded Universe

Too strange by half? The neutron star at the heart of Cas A has always been an odd ball. (NASA/CXC/M.Weiss/Southampton/W.Ho)

Call it the story of the young and the quarkless:  Astronomers have a surprising new take on the youngest supernova remnant in our corner of the Milky Way, and it may solve a long standing mystery.

The object in questions is Cas A (rhymes with passé) a glowing wreath of energized gas that was discovered years ago in the constellation Cassiopeia.  Cas A was created when a massive star reached the end of its nuclear rope about three centuries ago and proceeded to blow itself to smithereens.  What’s left at the centre is a tiny nugget of superdense matter called a neutron star, the youngest example of one we know.

So far, so good.  But there’s always been something weird about the neutron star in Cas A since it was first spotted by the Chandra X-ray Observatory in 1999. Now it looks like there’s an explanation.

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Fermi: sneaking a peak at the dark side. (NASA/GSFC)

A team of Harvard and NYU researchers has upped the ante in the race to discover the true nature of dark matter. 

In a new paper posted online this week, the team says NASA’s Fermi satellite has confirmed the existence of a vast cloud of energetic electrons surrounding the centre of our galaxy—electrons, they suggest, which could be subatomic shrapnel from dark matter particles colliding with one another.

If correct, their interpretation of the Fermi data would tie together a number of hints and puzzling observations that suggest dark matter is making itself visible through a process of annihilation.  It also implies the existence of a new force to which only dark matter particles are attuned.

 “It’s very easy to produce this kind of a signal with dark matter,” says Doug Finkbeiner of the Harvard-Smithsonian Center for Astrophysics, who is a co-author of the paper. “It’s not so easy to do it with other things.” Continue reading →

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A simulated image of the disk of gas surrounding the supermassive black hole at the centre of the Milky Way as it might appear with new methods designed to reveal the black hole's dark edge. The light-bending effects of the black hole's strong gravitational field as well as the disk's rapid rotation would produce a crescent shaped image wrapped around the event horizon. (Credit: Avery Broderick)

A black hole is like a scary monster from children’s literature.  It’s vividly imagined but never actually seen in real life. This is true even for the largest black holes we know—the ones that reside at the centres of galaxies. The nearest of these lies some 30,000 light years away, in the core of the Milky Way. If you placed it in our solar system it would probably span the orbit of Mercury. Yet, because of its great distance, it’s a mere speck against the sky, about 36 million times smaller than the full moon. How could anyone see any detail when looking at something with an apparent size THAT small?

Amazingly, there is a way.  And now it’s promising not only to reveal the giant black hole in our own galaxy, but also a much larger and more active one in the galaxy known as M87 in Virgo.

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Smoke billows from backfires set to deplete fuel around the Mt. Wilson observatory. (LA Times)

What do you do when a raging wildfire threatens to engulf your observatory? You light backfires, spray fire retardant and water bomb the slopes… but mostly you just hope for good luck.

Last month, the Mt. Wilson Observatory got a welcome dose of good luck when it escaped destruction by the notorious Station Fire, which burned out of control for weeks in the mountainous woodlands north of Los Angeles.

Mt. Wilson is home to the 100-inch Hooker telescope, one of the most storied instruments in the history of astronomy. It’s here that Edwin Hubble gathered the crucial evidence that allowed him to demonstrate, in 1925, that the universe is much, much bigger than previously thought. 

In this episode of The Universe in Mind podcast, Harold McAllister, director of the Mt. Wison Instiute, talks about the observatory’s brush with oblivion.  Marcia Bartusiak, author of The Day We Found the Universe explains how Hubble’s work on Mt. Wilson was the culmination of an amazing epoch of discovery that saw the cutting edge of observational astronomy migrate from Europe to the New World.  

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Throw in a magnetic field and the fate of the "evaporating" planet HD209458b gets foggy. Illustration: European Space Agency, Alfred Vidal-Madjar (Institut d'Astrophysique de Paris, CNRS, France) and NASA

Do planets around other stars have magnetic fields? It may seem an esoteric question, but life as we know it—at least terrestrial life—could not survive on Earth without the magnetic umbrella that protects us from an onslaught of hard solar radiation.

Now it appears a planet that is light years from our own may be depending on a magnetic field for its continued existence.

The planet in question is HD209458b. Admittedly, it’s more of a serial number than a name, but to astronomers it’s one of the most infamous handles in the galaxy. 

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Shuffling into oblivion: Did a comet wipe out the great mammals of North America? (Source: PLoS Biology)

At the end of the last ice age North America was in the midst of an epic thaw. The giant glaciers that had covered nearly all of Canada and the northern United State for millennia were receding fast.  Spring was in the air.

This was, presumably, good news for all the exotic creatures that populated North America at the time, including the mammoths, mastadons, giant sloths, sabre tooth cats, dire wolves and several other large species, collectively known as the Pleistocene megafauna. It was also good news for the Clovis people, a population of Paleolithic hunters that found their way into North America from Siberia, via an ice free corridor that ran just east of the rockies.  They had plenty of big game to live on, as their kill sites demonstrate.

So what happened?

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Good vibrations. Gravity waves offer a entirely new way to perceive events such as the collisions of black holes. (Illustration: W. Benger, Zuse Institute Berlin/Max-Planck Institute for Gravitational Physics)

Astronomy is the ultimate “seeing” science.  Unlike our experience of everyday reality, there’s no sound out in the cosmos, so the processes and events that we observe in the universe unfold before us like a silent movie.

Now some researchers are trying to add a soundtrack to that movie. They are the ones searching for gravitational waves—ripples in spacetime caused by the rapid motion of massive objects. If detected these waves will offer an entirely new way to perceive the universe—one that has more in common with hearing than seeing.

In Episode #11 of The Universe in Mind podcast we hear from Neil Cornish (Montana State University, Bozeman) about recent progress in the hunt for gravitational waves, and we get a bold prediction for how soon these elusive but revealing signals will be detected.

Jacqueline Radigan of the University of Toronto also drops by to explain how brown dwarfs—objects that are midway between stars and planets—can have their own weather patterns

Enjoy the program!

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Even this artist's impression of TMT is too big to fit into our imaginary camera.

There are only so many mountains where you can put a telescope on this Earth and when you’re trying to build the biggest telescope ever you want to choose a good one.  That much is obvious, but the selection of a site for a major observatory is no simple matter. Rather, it is the result of a complex interplay of astronomy, geography and economics. If you want to see where the pristine but unfeeling grandeur of the cosmos comes cheek to jowl with the messy subjectivity of human affairs then eavesdrop on a telescope site selection meeting.

Last week, the Thirty Meter Telescope (TMT) consortium announced the result of a long deliberation over where to park their 1430-ton spyglass, to be built over the next 10 years. This may not seem like a big surprise—after all Mauna Kea is already home to the largest concentration of major telescopes in the world.  But there is a strong contender in Chile named Cerro Armazones that could have come out ahead.

I’m interested in understanding why Hawaii prevailed. Sure enough, there’s a politics-behind-the-science story here.  But there’s an even more fascinating science-behind-the-politics story too.

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A picture perfect Whirlpool bodes well for Herschel's scientific promise

Sometimes, seeing is not just believing, seeing is celebrating. 

Astronomers working with the Herschel mission are in good spirits this week after capturing a stunning new image of M51, the Whirlpool galaxy.  The galaxy’s elegant spiral arms can easily be discerned in the infrared image, which is far sharper at long wavelengths than images by Herschel’s predecessor, NASA’s Spitzer Space Telescope.

“It’s very exciting to see the first images from Herschel,” says Christine Wilson of McMaster University in Hamilton, Ontario. Wilson leads the Herschel Key Project, which will characterize interstellar dust in nearby galaxies.

“M51 is one of our targets,” says Wilson.  “The picture is really spectacular and I have been thinking today about what it means.”

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If you don't like the weather, just wait 2.4 hours. (Illustration: Douglas Pierce-Price, Joint Astronomy Centre)

Space artists have had fun lately trying to picture what a brown dwarf might look like up close. Is it like Jupiter on steroids? Does it wear stripes, spots or perhaps something in a paisley?

It’s all guesswork because we have so little to go on. Thanks to the Sun we know what an average star looks like and we can extrapolate how smaller and cooler stars should appear.  But once we get to objects that are only seven percent the Sun’s mass we’re into new territory–brown dwarf territory.

Working from the other direction, Jupiter is our guide when it comes to visualizing what giant planets look like. But Jupiter’s appearance is influenced by the energy its atmosphere receives from the Sun.  In contrast, brown dwarfs can exist on their own, away from other stars and they start off with far more internal heat than Jupiter ever had. 

So what does something that’s midway between a planet and a star look like? Like women’s fashions of yesteryear, the question leaves a lot to the imagination.

Fortunately for astronomers, at least one brown dwarf has decided to be a bit more revealing, It goes by the name SIMP0136, and it offers the strongest evidence yet that brown dwarfs can display vivid weather patterns.

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