The scale of things

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Betelgeuse Blows Out a Monstrous Arc of Gas Nearly As Big As Our Solar System | Phil Plait
Bad Astronomy | Thursday, April 25, 2013, at 8:00 AM


^ Betelgeuse! Betelgeuse! Betelgeuse! Photo: University of Manchester

The famous star, marking the shoulder of Orion, is a red supergiant, a massive and massively swollen star. It’s ridiculously huge; if you replaced the Sun with Betelgeuse it would stretch out nearly to the orbit of Jupiter.

It’s also near the end of its life. Someday, probably within the next million years or so, it’ll explode, becoming a supernova, and shining about as bright as the moon in our sky. Mind you, it’s 640 light years—6.4 quadrillion kilometers—away. So yeah, it’s quite the behemoth. It’s so big that sophisticated techniques can resolve details on Betelgeuse, even from that mind-crushing distance.

And new observations of it show that it’s weirder than previously thought. Using the new e-MERLIN radio telescope array in England, astronomers have zoomed way in on the star, showing some details on and around Betelgeuse. The image above is the result, and several things leap to the eye.


^ Not a brain slug. Photo:
University of ManchesterFor one, the outer atmosphere (which is where the radio waves from the star originate) stretches out a full five times larger than the star’s surface in visible light. The image inset here shows the visible disk of Betelgeuse outlined compared to the star’s outer atmosphere (red supergiants don’t have a surface per se, they just kinda peter out with distance, like the Earth’s atmosphere). For another, there are two hot spots of unknown origin in the atmosphere. They may be regions where convection has brought up hotter material from deep within the star, or it could be they’re where the outer atmosphere is thinner, allowing us to peer deeper inside, where it’s hotter.

But it’s that arc of material to the lower right that makes the hair on the back of my neck stand up. Seriously, that looping bridge is huge, vast, monstrous. It’s an enormous arch of gas, erupted from the star itself, and it contains 2/3 as much mass as the Earth. And the size: It towers 7 billion kilometers (4 billion miles) over the star!

That’s almost the size of Neptune’s orbit. Not Neptune itself, its orbit. That arc of gas casually tossed out by Betelgeuse is on the same size scale as our solar system.

< Driving the point home: Betelgeuse with the orbits of the outer planets on it (from the inside out): Jupiter, Saturn, Uranus, and Neptune. Photo: University of Manchester

On top of all that, we’re not really sure how it formed. Clearly, Betelgeuse is blowing off its outer layers, and there are structures in that wind that may form as it interacts with previously ejected material, or the material that floats between the stars. This arc may be something like that (though at 150K, or -120°C, that seems unlikely to me; the gas would be warmer if it were slamming into other material and getting compressed), or it may be a single structure like a gigantic solar prominence.

Taking images on this sort of scale is relatively new; the technology needed is fierce. The data feeds from several telescopes have to be combined in exquisite detail and with incredible accuracy for this to work. This technique is called interferometry, and it’s been used on Betelgeuse before. e-MERLIN is a big upgrade to the previously existing system, and along with other interferometers around the world, is helping us understand Betelgeuse better. Stars like it are critical to the galactic ecosystem; they blast out winds of material before exploding, and then upon their deaths seed the space around them for many light years with heavier elements; the basic constituents of planets, moons, you, and me.

Knowing them is literally knowing ourselves. Not a bad target for our attention.

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Scientists in Antarctica Find Invading Neutrinos from Another Galaxy! | Phil Plait
Bad Astronomy | Thursday, April 25, 2013, at 11:37 AM


^ Schematic of one of the two ultra-high-energy neutrino events detected by IceCube in Antarctica. Diagram by IceCube Collaboration/M.G. Aartsen et al.

I don’t get to write hyperbolic science fiction titles very often, but I couldn’t resist this one. Even if it’s not entirely accurate; in reality the experiment only most likely saw invading neutrinos from another galaxy. But it seems like they probably did. And they used faster-than-light travel to find them!

Well, kinda. OK, let me explain.

Neutrinos are subatomic particles, and they’re weird. They don’t interact with matter very much, so to them most of the Universe is transparent. They can pass right through the Earth without even noticing.

Really, though, to them the Universe is only mostly transparent. There’s a teeny tiny chance they’ll interact with matter. If you have enough neutrinos, a small number of them can ping off an atomic nucleus and create an effect we can measure. The good news is there are a lot of neutrinos flying around all the time. Billions of them are passing through you right now!

That makes them possible to detect if you are patient and careful. Happily, scientists are both. Neutrino detectors have been assembled in various parts of the world and have been pretty successful in finding the little suckers. They use various methods to see them; for example, some use the fact that when a neutrino slams into a chlorine nucleus, it can change it into an argon nucleus. Those detectors need huge amounts of chlorine for this, so they use tetrachloroethylene: dry cleaning fluid!

But the news today comes from a different kind of detector. This one relies on the idea that a neutrino passing through ice can create a shower of subatomic particles, like shrapnel. These particles scream out from the collision and can actually travel faster than light through the ice. I know, this sounds impossible, but light speed is the Universal limit when it’s traveling through a vacuum. Light slows down when passing through air, or liquid, or matter. So a subatomic particle can travel faster than light through matter, while still traveling slower than light does in a vacuum.

[Note: This is all very, very different than the claim of faster-than-light neutrinos from 2011. That turned out to be due to an equipment malfunction.]

< Detectors designed to see the faint flashes of light when neutrinos interact with ice. Click to enzeframcochrenate. Photo by: DESY

When this happens, the particle creates a shock wave, just like a sonic boom is created when something travels faster than sound. In this case, though, it’s not a sonic boom, but a photonic boom, a shock wave of light. This creates a faint blue flash called Cherenkov radiation, and that can be seen using very sensitive detectors.

Scientists have built just such a device in Antarctica. It’s called (get this) IceCube, and it consists of a string of detectors lowered 1,500 to 2,000 meters (1 to 1.5 miles) beneath the very clear ice. At that depth the ice is very smooth and dark, making it easier to see the flash of light from a neutrino reaction.

Neutrinos come from lots of different sources. Nuclear reactions in the Sun produce prodigious numbers of them, as do nuclear reactors on Earth, natural radiation from uranium decay inside the Earth, and even more exotic phenomena like exploding stars. These neutrinos all have different energies, so it’s possible in principle to categorize the source by looking at how energetic the detected neutrino is.

And that’s where IceCube has come through. Out of the countless detections it’s seen, two of them—nicknamed, seriously, Bert and Ernie—were phenomenally, unbelievably energetic: Each had an energy over one thousand trillion times the energy of a visible light photon. That’s huge, far larger energies than even the Large Hadron Collider can create. It’s very roughly equivalent to the energy of a raindrop hitting you on the head… which may not sound like much, but remember we’re talking about a single subatomic particle with that much energy. That’s phenomenal!


^ A detector being lowered into a hole drilled into the ice. Click to enthingenate. Photo by IceCube Collaboration/NSF

Not very many things in the Universe can make neutrinos with that much energy. Supermassive black holes in the centers of galaxies are one possible candidate; they are sloppy eaters, gobbling down and spewing out fantastically high-energy beams of matter and energy. Another possible source are gamma-ray bursts; explosions of stars so violent they are second only to the Big Bang itself. These typically occur in the very distant Universe, so statistically speaking if these are the engines making these super-high-energy neutrinos, then those little particles have traveled a long, long way before hitting the ice in Antarctica.

The scientists who made this detection note that they can’t completely rule out less exotic sources; there’s a 99 percent or so certainty that these neutrinos are not from some background source. That’s not quite enough to pass the rigorous standards of particle physicists (they prefer a minimum of 99.7 percent certainty to make a claim, and really a 99.9999 percent certainty to claim discovery, like with the Higgs particle last year).

Still, it’s provocative. And what a claim! Using faster than light particles to detect ghostly but super-high-energy intergalactic particles that have traveled tens or hundreds of millions of light years, only to get trapped beneath the Antarctic ice…

Hey, wait a second. I’ve seen that movie. I hope those scientists have flame throwers.

[smoking since 1879]

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Thirty Meter Telescope, To Be World’s Biggest, Approved By Hawaii Land Board
Huffington Post, AUDREY McAVOY | 04/13/13 12:08 AM ET EDT AP

HONOLULU -- A plan by California and Canadian universities to build the world’s largest telescope at the summit of Hawaii’s Mauna Kea volcano won approval from the state Board of Land and Natural Resources on Friday.

The decision clears the way for the group managing the Thirty Meter Telescope project to negotiate a sublease for land with the University of Hawaii.

The telescope would be able to observe planets that orbit stars other than the sun and enable astronomers to watch new planets and stars being formed. It should also help scientists see some 13 billion light years away for a glimpse into the early years of the universe.

Construction costs are expected to top $1 billion.

The telescope’s segmented primary mirror, which is nearly 100 feet (30 meters) long, will give it nine times the collecting area of the largest optical telescopes in use today. Its images will also be three times sharper.

But the telescope may not hold the world’s largest title for long. A group of European countries plans to build the European Extremely Large Telescope, which will have a 138-foot (42-meter)-long mirror.

Some Native Hawaiian groups had petitioned against the project, arguing it would defile the mountain’s sacred summit.

Resume.

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Astrophotographers Capture “Mini” Lunar Eclipse
Universe Today, Nancy Atkinson | April 25, 2013


^ The brief partial lunar eclipse on April 25, 2013 captured over Israel. Credit and copyright: Gadi Eidelheit.

The lunar eclipse on April 25 was described by astrophotographer Gadi Eidelheit as “the greatest, slightest eclipse I ever saw!” The brief and small eclipse saw just 1.47% of the lunar limb nicked by the dark umbra or shadow from the Earth. It was visible from eastern Europe and Africa across the Middle East eastward to southeast Asia and western Australia. Here are a few more shots, including a serendipitous shot of an airplane flying through the eclipse!


^ Airliner flies through partial eclipse! On April 25, 2013, around 10:10 PM local time, the partial Lunar eclipse was at its maximum. The Moon only traveled 1,3% into the central Earth shadow (umbra). The event was visible from Europe, Asia and Australia. Canon EOS 600D on 130 mm (f/7,1) triplet Apo-refractor settings: 1/200 exposure at ISO 100. Credit and copyright: Philip Corneille – FRAS (Belgium).


^ The small, shallow eclipse on April 25, 2013. Credit and copyright: Andrei Juravle.


^ Partially eclipsed Moon rising over Brixton in the UK on April 25, 2013. Credit and copyright: Owen Llewellyn.


^ Eclipsed Moon on April 25, 2013 over the UK. Credit and copyright: Sculptor Lil on Flickr.


^ The eclipsed Moon, with Saturn showing as a bright point of light on the left, as seen over Königswinter, Germany. Credit and copyright: Daniel Fischer.


^ The mini lunar eclipse on April 25, 2013 as seen from Bruges, Belgium. Credit and copyright: Cochuyt Joeri.


^ A ‘before’ and ‘during’ comparison picture of the partial lunar eclipse on the 25th of April 2013. The photo on the left (‘before’) was taken at about 20h00 CAT and the photo on the right (‘during’) was taken around 22h06 CAT. Credit and copyright: Hein Oosthuyzen, Johannesburg, South Africa.


^ Partial Lunar Eclipse on April 25, 2013. Credit and copyright: Henna Khan.

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Saturn-lit Moon | Phil Plait
Bad Astronomy | Friday, April 26, 2013, at 1:17 PM

There are days when I’m a little overtaxed, overwrought, overworked, and I need a break, something to help me get perspective. Not much, just something to let me sit back and go, “Ahhhhhh, niiiiiiice.”

I found that something for today. Here is Enceladus, a moon of Saturn, as seen by the Cassini spacecraft in January 2011 and put together by Gordan Ugarković, a Croatian software developer and accomplished amateur image artist processor:



Ahhhhhh, niiiiiiice.

Enceladus is small, about 500 kilometers (300 miles) in diameter, about the size of my home state of Colorado. It’s mostly ice, and we know it has liquid water under its surface; there are geysers of water erupting from its south polar region.

I love the contrast of harsh and soft light in the image. On the right, the crescent is brilliantly lit by the Sun, but the rest of the moon was actually being lit by the yellowish glow from Saturn itself! Light from the Sun illuminated Saturn, was reflected onto the “dark side” of Enceladus, filling in the shadow, and that light was reflected back into space where it was seen by Cassini. A similar thing happens with the Earth and the Moon, when the dark part of the new Moon is softly visible. We call that Earthshine, or even more poetically “the old Moon in the new Moons arms”.

The Saturn-lit half is bright enough to see the terrain, and you may notice that there are craters in the northern part of the moon (top) in the picture, but very few in the south. That tells you right away the ice near the top is older; the old craters in the south have been eradicated in some more recent resurfacing event, possibly due to stress and strain from Saturn’s immense gravity (which is also responsible for the intricate pattern of ridges and cracks on the surface, too).

Even though we have spectacular high-resolution images of the moon (see this one and be amazed), there’s a lot to learn about Enceladus still. It’s one of only two worlds in the solar system where we have direct evidence of liquid water (the other is Earth, of course, though with Jupiter’s moon Europa we have very strong indirect evidence), and there could be an entire ocean flowing under that shell of rock-hard ice.

Imagine! All that, hidden under that gorgeous face. One of my very favorite things about astronomy is how the surface beauty couples with the science and mystery lying within. Which, come to think of it, is true for a great many things.

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Cosmic C.S.I.: Searching for the Origins of the Solar System in Two Grains of Sand
Universe Today, Jason Major | April 24, 2013


^ Composite Spitzer, Hubble, and Chandra image of supernova remnant Cassiopeia A, a star that exploded over 300 years ago. Silica was identified within this cloud of cast-off star-stuff. (NASA/JPL-Caltech/STScI/CXC/SAO)

“The total number of stars in the Universe is larger than all the grains of sand on all the beaches of the planet Earth,” Carl Sagan famously said in his iconic TV series Cosmos. But when two of those grains are made of a silicon-and-oxygen compound called silica, and they were found hiding deep inside ancient meteorites recovered from Antarctica, they very well may be from a star… possibly even the one whose explosive collapse sparked the formation of the Solar System itself.

Researchers from Washington University in St. Louis with support from the McDonnell Center for the Space Sciences have announced the discovery of two microscopic grains of silica in primitive meteorites originating from two different sources. This discovery is surprising because silica — one of the main components of sand on Earth today — is not one of the minerals thought to have formed within the Sun’s early circumstellar disk of material.

Instead, it’s thought that the two silica grains were created by a single supernova that seeded the early solar system with its cast-off material and helped set into motion the eventual formation of the planets.

According to a news release by Washington University, “it’s a bit like learning the secrets of the family that lived in your house in the 1800s by examining dust particles they left behind in cracks in the floorboards.”

< A 3.5-cm chondrite meteorite found in Antarctica in Nov. 1998. Dark meteorites show up well against the icy terrain of Antarctica. (Carnegie Mellon University)

Until the 1960s most scientists believed the early Solar System got so hot that presolar material could not have survived. But in 1987 scientists at the University of Chicago discovered miniscule diamonds in a primitive meteorite (ones that had not been heated and reworked). Since then they’ve found grains of more than ten other minerals in primitive meteorites.

The scientists can tell these grains came from ancient stars because they have highly unusual isotopic signatures, and different stars produce different proportions of isotopes.

But the material from which our Solar System was fashioned was mixed and homogenized before the planets formed. So all of the planets and the Sun have the pretty much the same “solar” isotopic composition.

Meteorites, most of which are pieces of asteroids, have the solar composition as well, but trapped deep within the primitive ones are pure samples of stars, and the isotopic compositions of these presolar grains can provide clues to their complex nuclear and convective processes.

< The layered structure of a star about to go supernova; different layers contain different elements (Wikimedia)

Some models of stellar evolution predict that silica could condense in the cooler outer atmospheres of stars, but others say silicon would be completely consumed by the formation of magnesium- or iron-rich silicates, leaving none to form silica.

“We didn’t know which model was right and which was not, because the models had so many parameters,” said Pierre Haenecour, a graduate student in Earth and Planetary Sciences at Washington University and the first author on a paper to be published in the May 1 issue of Astrophysical Journal Letters.

Under the guidance of physics professor Dr. Christine Floss, who found some of the first silica grains in a meteorite in 2009, Haenecour investigated slices of a primitive meteorite brought back from Antarctica and located a single grain of silica out of 138 presolar grains. The grain he found was rich in oxygen-18, signifying its source as from a core-collapse supernova.

Finding that along with another oxygen-18-enriched silica grain identified within another meteorite by graduate student Xuchao Zhao, Haenecour and his team set about figuring out how such silica grains could form within the collapsing layers of a dying star. They found they could reproduce the oxygen-18 enrichment of the two grains through the mixing of small amounts of material from a star’s oxygen-rich inner zones and the oxygen-18-rich helium/carbon zone with large amounts of material from the outer hydrogen envelope of the supernova.

In fact, Haenecour said, the mixing that produced the composition of the two grains was so similar, the grains might well have come from the same supernova — possibly the very same one that sparked the collapse of the molecular cloud that formed our Solar System.


“It’s a bit like learning the secrets of the family that lived in your house in the 1800s by examining dust particles they left behind in cracks in the floorboards.”

Ancient meteorites, a few microscopic grains of stellar sand, and a lot of lab work… it’s an example of cosmic forensics at its best!

Source: Washington University in St. Louis

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Entire Galaxies Feel The Heat Of Newborn Stars
Universe Today, Tammy Plotner | April 25, 2013


^ This illustration shows a messy, chaotic galaxy undergoing bursts of star formation. This star formation is intense; it was known that it affects its host galaxy, but this new research shows it has an even greater effect than first thought. The winds created by these star formation processes stream out of the galaxy, ionising gas at distances of up to 650 000 light-years from the galactic centre. Credit: ESA, NASA, L. Calçada

If you think that star-formation only has an impact within the confines of a host galaxy, then think again. Thanks to the magic of the NASA/ESA Hubble Space Telescope, astronomers are now realizing starburst activity can change the properties of galactic gases at distances almost twenty times larger than a galaxy’s visible boundaries. Not only does this affect galactic evolution, but it has ramifications on how matter and energy ripple across the cosmos.

What’s going on here? Once upon a time in the early Universe, galaxies would form new stars in huge blasts of activity known as starbursts. While it happened frequently long ago, it’s much less common now. During these starburst episodes, hundreds of millions of stars spring to light and their combined energy sets off massive stellar winds that push outward into space. While these winds were known to have effects on the parent galaxy, new research shows they have an even greater effect than anyone knew.

Recently a team of international astronomers took on twenty galaxies which are known to be hosting starburst activity. What they found was the starburst stellar winds were able to ionize gas at huge distances – up to 650,000 light years from the galaxy’s nucleus – and around twenty times beyond the galaxy’s visible perimeter. For the first time, researchers were able to verify that starburst activity could impact the gas around the parent galaxy. This new observational evidence shows just how important each phase a galaxy goes through can impact the way it forms stars and how it evolves.

“The extended material around galaxies is hard to study, as it’s so faint,” says team member Vivienne Wild of the University of St. Andrews. “But it’s important — these envelopes of cool gas hold vital clues about how galaxies grow, process mass and energy, and finally die. We’re exploring a new frontier in galaxy evolution!”


^ This animation shows the method used to probe the gas around distant galaxies. Astronomers can use tools such as Hubble’s Cosmic Origins Spectrograph (COS) to probe faint galactic envelopes by exploiting even more distant objects — quasars, the intensely luminous centres of distant galaxies powered by huge black holes. As the light from the distant quasar passes through the galaxy’s halo, the gas absorbs certain frequencies – making it possible to study the region around the galaxy in detail. This new research utilised Hubble’s COS to peer through the very thin outskirts of galactic halos, much further out than shown in this representation, to explore galactic gas at distances of up to twenty times greater than the visible size of the galaxy itself. Credit: ESA, NASA, L. Calçada

So how did they do it? According to the news release, the researchers employed the Cosmic Origins Spectrograph (COS) instrument located on the NASA/ESA Hubble Space telescope. By examining the spectral signature of a variety of starbirth and control galaxies, the team was able to carefully examine the regions of gas surrounding the galaxies. However, they had a little boost, too… quasars. By adding the light of the intensely luminous galactic cores to the mix, they were able to further refine their observations by watching the quasar’s light as it passed through foreground galaxies. This method allowed them to even more closely examine their targets.

“Hubble is the only observatory that can carry out the observations necessary for a study like this,” says lead author Sanchayeeta Borthakur, of Johns Hopkins University. “We needed a space-based telescope to probe the hot gas, and the only instrument capable of measuring the extended envelopes of galaxies is COS.”

The eureka moment came when the astronomers found the starburst galaxies in their samples showed abnormal amounts of highly ionized gases in their halos. By comparison, the control galaxies – those known to have no starburst activity – did not. Now they knew… the ionization had to be the product of the energetic winds which accompanied the birth of new stars. Armed with this information, researchers can now confidently say that galaxies which host starburst activity has taken on new parameters. Since galaxies enlarge by feeding on gas from the space around them and convert this into new stars, we realize that the ionization process will regulate future star formation.

“Starbursts are important phenomena — they not only dictate the future evolution of a single galaxy, but also influence the cycle of matter and energy in the Universe as a whole,” says team member Timothy Heckman, of Johns Hopkins University. “The envelopes of galaxies are the interface between galaxies and the rest of the Universe — and we’re just beginning to fully explore the processes at work within them.”

Burn, baby, burn…

Original Story Source: NASA/ESA Hubble Space Telescope News Release. Further reading: The Impact of Starbursts on the Circumgalactic Medium.

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The Sun Blasts Out Two CME’s Towards Mercury
Universe Today, Nancy Atkinson | April 25, 2013


^ The Solar Heliospheric Observatory (SOHO) captured this series of four images of a coronal mass ejection (CME) escaping the sun on the morning of April 25, 2013. The images show the CME from 5:24 a.m. to 6:48 a.m. EDT. This was the second of two CMEs in the space of 12 hours. Both are headed away from Earth toward Mercury. Credit: ESA&NASA/SOHO.

Over the past 24 hours, the Sun has erupted with two coronal mass ejections (CMEs), sending billions of tons of solar particles into space. While these CMEs are not directed at Earth, they are heading towards Mercury and may affect the Messenger spacecraft, as well as the Sun-watching STEREO-A satellites. One CME may send a glancing blow of particles to Mars, possibly affecting spacecraft at the Red Planet.

This solar radiation can affect electronic systems on spacecraft, and the various missions have been put on alert. When warranted, NASA operators can put spacecraft into safe mode to protect the instruments from the solar material.

The first CME began at 01:30 UTC on April 25 (9:30 p.m. EDT on April 24), and the second erupted at 09:24 UTC (5:24 a.m. EDT) on April 25. Both left the sun traveling at about 800 kilometers (500 miles per second).

See this animation from the STEREO-B spacecraft:


^ Animations of CMEs on April 25, 2013 from the STEREO-B spacecraft. Credit: NASA/Goddard Space Flight Center.

Source: NASA

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Saturn Reaches Opposition on April 28
Universe Today, Nancy Atkinson | April 28, 2013

Saturn is one of the most striking objects to see through a telescope, and it is now at its brightest in the night sky as it reaches opposition from the Sun. This is when Earth stands mostly perfectly in line between Saturn and the Sun. It is when Saturn is brightest (at magnitude +0.3), closely approximating famous “first magnitude” stars like Betelgeuse. Also, it is when Saturn is out all night long.

Slooh Space Camera will broadcast a free, real-time feed of Saturn at opposition, with the giant planet’s rings impressively angled — its best in six years. Slooh’s coverage will begin on Sunday, April 28th, starting at 6:30 p.m. PDT / 9:30 p.m. EDT / 01:30 UTC (April 29th), with observatory feeds from their world-class observatory site in the Canary Islands off the coast of Africa. Viewers can watch live on their PC/Mac at Slooh.com, or by downloading the free Slooh iPad app in the iTunes store and touching the broadcast icon.