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The post Weekly Science Picks appeared first on Australian Science.
]]>Also, between talks, twitter is where I heard most of this week’s worldwide science happenings. So here are a few of the things which caught my eye…
Firstly, Katie Mack (a long term inspiration to me) wrote an article for The Research Whisperer on the perils of the academic lifestyle and being a science nomad – and how that affects your personal life. Being still very recently relocated to Japan myself, this strikes something of a chord with me. It’s worth reading for anyone considering a science career themselves. while I personally rather enjoy the nomadic nature of this job, it’s certainly not for everyone. And I have yet to see how I feel about it a couple more years down the line…
As for me, I confess I haven’t figured it out. I have two years left on my contract in Australia and no idea whatsoever which country I’ll end up in next. I’m applying broadly, and there’s no guarantee I’ll have a choice about location if I want to stay on the path toward becoming tenure-track faculty at a major research institution. When it’s not unusual for a single postdoc job to have 300 applicants, and faculty jobs are even more selective, getting even one offer is considered a huge win.
Moving on to life of a different kind, a brand new species has been discovered in the waters off the coast of California. And anyone who’s been reading my articles awhile will know how exciting I find the discovery of new species! This time around, it’s a somewhat scary looking new species of crustacean. Don’t worry though. It only eats copepods.
The frail crustacean, which is only a few millimeters in length, was discovered by scientists from the University of Seville in Spain and the Museum of Natural History in Canada, who had published a taxonomic description of the new species in the journal Zootaxa.
Meanwhile in space… When people talk of space stations and lasers, a lot of us will immediately think of Star Wars. Or whatever other sci fi we might prefer. However, up in orbit around Earth, our own space station is preparing to use lasers for a rather less destructive purpose – to transmit video back to use down here on the ground.
“Optical communications (also referred to as ‘lasercomm’) is an emerging technology wherein data is modulated onto laser beams, which offers the promise of much higher data rates than what is achievable with radio-frequency (RF) transmissions.
Cite this article:
Hammonds M (2013-11-24 12:42:52). Weekly Science Picks. Australian Science. Retrieved: Apr 28, 2024, from http://australianscience.com.au/news/weekly-science-picks-55/test
The post Weekly Science Picks appeared first on Australian Science.
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The post Weekly Science Picks appeared first on Australian Science.
]]>And speaking of those leaps and bounds…
Astronomers have managed to determine the colour an exoplanet would appear if were able to see it with our own eyes. Planet HD 189733b, one of the most well studied worlds out there in our galaxy, is a beautiful azure blue planet. But don’t let the similarity to our own planet’s colour fool you. The blue colour of HD 189733b is because it’s a hot jupiter, orbiting scorchingly close to its parent star, and that colour is because the rain on this world is made of glass!
“This planet has been studied well in the past, both by ourselves and other teams,
Cite this article:
Hammonds M (2013-07-21 07:56:55). Weekly Science Picks. Australian Science. Retrieved: Apr 28, 2024, from http://australianscience.com.au/news/weekly-science-picks-38/test
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The post Explosions visible from across the Universe appeared first on Australian Science.
]]>December 9th, 2011. NASA’s Swift telescope detected a sudden spike of gamma rays from somewhere within the constellation of Phoenix, visible in the Southern hemisphere. Gamma ray bursts (GRBs for short) like these are normally subdivided into two types, short bursts and long bursts, which have different causes. Short bursts last for just a couple of seconds, while long bursts can last for several minutes. But this particular burst, dubbed GRB 111209A (pictured above), was very different. One of a unique, rare breed of extra long lived GRBs, and by far the longest ever observed – lasting an unprecedented 7 hours!
Ever since then, astronomers have been picking at the data which were recorded, trying to work out exactly what kind of unusual circumstances would cause such a goliath GRB. One team, a collaboration between Bruce Gendre now at the French National Center for Scientific Research, and David Coward and Eric Howell at the University of Western Australia, managed to get to what may be the bottom of the puzzle. In short, these extra long GRBs are caused by the deaths of the Universe’s most massive stars.
It’s a sobering fact that all stars die. Some burn slowly for billions of years. The very smallest may burn for trillions. But the most massive stars burn out rapidly before dying in titanic explosions which we know as supernovae. It seems that the most massive of the massive, exceptionally rare, die in a unique type of GRB.
So far, only three of these ultra-long GRBs have been found, appearing so bright that some astronomers initially believed that they came from inside our own galaxy. As it happens, this wasn’t the case. Analysing GRB 111209A, Gendre and his colleagues hypothesised the source of it to be an extremely hot, massive star.
A furiously burning blue supergiant (possibly a hypergiant), hundreds of times the diameter of the Sun. When a star like this dies, its core collapses into a black hole, which then proceeds to start devouring the star from the inside out. As that black hole hungrily eats, its mammoth gravitational forces brutally tearing matter apart at the subatomic level, it generates an immense amount of energy which causes two jets of material to shoot out from its north and south poles. These are blasted outwards out with such ferocity that they actually punch two holes in the doomed star.
Read that again. A star which is hundred of times as massive as the sun, and these jets are powerful enough to blast two holes in it! The amount of energy required to accomplish that is truly difficult to comprehend.
The stars which die in these titanic events still require a specific set of circumstances. These stars are apparently enriched in elements heavier than helium (astronomers refer to these as “metals”, even though chemists would disagree on a few counts). More of these heavier elements cause a star’s stellar wind to increase, causing its rotation speed to slow as it loses material. But faster spinning stars seem to be more likely to cause these long bursts, which led some to wonder if the massive star behind GRB 111209A was also cannibalising another nearby star – a process which could possibly cause its rotation to speed up.
The exact cause is still a matter of puzzles and hypotheses. We won’t know more until we observe more of these ultra-long GRBs, and seeing as we’ve only ever spotted 3 of them, it may remain a puzzle for a while yet. But a tantalising glimpse like this of one of the Universe’s most extreme events gives us a good reason to keep watching and waiting. When we do finally understand, it will almost certainly have been worth waiting for.
Image credits:
Top – NASA/Swift/B. Gendre (ASDC/INAF-OAR/ARTEMIS)
Bottom – CNRS/ARTEMIS – Céline Lavalade
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]]>Interface Region Imaging Spectrograph (IRIS) to launch!
At the end of this month, NASA will launch IRIS. IRIS will watch the Sun and provide NASA with information on the Sun’s atmosphere and the interface region. This will give scientists a better understanding of how the Sun’s energy powers the solar wind!
NASA and the Italian Space Agency (ASI) to explore Mercury
NASA Administrator Charles Bolden and Italian Space Agency (ASI) President Enrico Saggese signed a Memorandum of Understanding for cooperation on the European Space Agency (ESA) led BepiColombo mission to Mercury
Earth’s plant life shown in Hi Res imaging
NASA’s Suomi NPP Satellite shows Earth’s vegetation mapped at a higher resolution than ever before.
A new three-dimensional map, aptly called BigBrain is the most detailed ever constructed! Scientists hope it will lead to a more accurate picture of how the brain’s different regions function.
Can high energy y-ray astronomy be done from Earth?
Traditionally astronomers have relied on space telescopes to conduct high-energy y ray astronomy because Earth’s atmosphere is a very efficient shield for y rays. However, in early July at the International Cosmic Ray Conference in Rio de Janeiro, Brazil, indicate that γ-ray astronomers are betting their future on an ambitious ground-based telescope.
What drives mammals to extinction?
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The post Neutron star glitch needs new theories to explain it appeared first on Australian Science.
]]>These sudden changes in rotation are known as glitches, and they happen to a particular, rare type of neutron star, known as a magnetar – a neutron star with an exceptionally strong magnetic field, which occasionally undergoes violent outbursts known as starquakes. These starquakes have been known to cause the rotation speed of a neutron star to suddenly increase. But one of these oddities is an oddity among oddities. A magnetar known as 1E 2259+586 was recently observed not to speed up, but to slow down. The reason? No one knows.
The team in charge of this work, led by Victoria Kaspi at McGill University, Montreal, summed up their observation in a press release by saying that it “constitute[s] a new theoretical challenge.” Now, to someone like me, this is very exciting. Specifically because this means that, working with existing theories, they don’t know what’s going on. It’s currently unexplainable. And when this sort of thing happens, it means we’ve discovered something which we didn’t know before.
Any good scientist should be thrilled when they don’t understand something, because this means that there’s something new to understand. In this particular case, the fact that this magnetar seems to have done the opposite of what it should has managed to throw a spanner in the works**.
“Astronomers have witnessed hundreds of events, called glitches, associated with sudden increases in the spin of neutron stars, but this sudden spin-down caught us off guard,” Kaspi explained. Indeed, the regular type of glitch is, we think, quite well understood.
What precisely might be found beneath the ultra hard crust of a neutron star is a mystery. We might perhaps never be able to directly observe it and find out (neutron stars aren’t fond of guests, and have a tendency to turn anything which lands on them into a large thermonuclear explosion). But what we can deduce is that the interior of a neutron star is a kind of superfluid, composed mostly of neutrons. At the surface of a neutron star, high energy particles are accelerated outwards. This is known as a pulsar wind, and it’s the main mechanism through which neutron stars cool.
As this pulsar wind carries away energy, it gradually grains energy and momentum from the surface of the neutron star. But this causes stress to build up under the surface. After enough stress builds up, the crust ruptures with an almighty crack. This causes the star to emit a huge burst of x-rays. It also allows the crust to catch up with the rotation speed of the interior. Neutron stars slow down when they’re ready to and not a moment sooner.
The neutron star in question, 2259+586, lies around 10,000 light years away in the constellation of Cassiopaeia and rotates once every 7 seconds or so. In the x-ray image shown above, it’s quite obvious in high energy x-rays (coloured blue in the image). The lower energy x-rays show a pulsar wind nebula as those high energy particles streaming away from it crash headlong into the surrounding interstellar medium.
Crust fractures in neutron stars sometimes go by the name of starquakes, and they can be caused by tangled up magnetic field lines too. But it’s this particular mechanism which causes these stars to glitch. 2259+586, however, is going against the grain. Because it’s been observed to do the opposite of what it should, this previously unknown phenomenon has been dubbed an ‘anti-glitch’. What’s more, not content with its abrupt slowdown, 2259+586 is also slowing its speed faster than it was previously observed to (an effect known as “spinning down”).
Sometime in late April, before the anti-glitch was discovered, the Fermi space telescope picked up a powerful x-ray burst. Lasting just 36 milliseconds, the researchers believe that it was this burst which signalled the magnetar’s unprecedented drop in rotational speed. Robert Archibald, the lead author on the paper published on this work, explained, “What is really remarkable about this event is the combination of the magnetar’s abrupt slowdown, the X-ray outburst, and the fact we now observe the star spinning down at a faster rate than before.”
As for why this has happened? Well, now we need to wait for the theoreticians to solve the puzzle. And, at least for some of us, that’s the fun part!
* As one tumblr user so wonderfully described it, “an average printed period, if it were as dense as a neutron star, would weigh about as much as a train car FILLED WITH BRICKS.”
** A star mangled spanner, perhaps?
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The post An Animated Visualization of Every Meteorite Since 861 AD appeared first on Australian Science.
]]>Data from the Meteoritical Society.
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First up this week, sad news. After exemplary service ever since its launch in 2009 and a mission extension last year, the Kepler telescope has finally broken down. Kepler spots transiting exoplanets by staring unblinkingly at the same patch of sky, and in order to do that it needs to keep very still. Sadly, two of its four gyroscopes are out of action, meaning that Kepler may be shutting down for good.
“Frankly, I’m absolutely delighted that we’ve got all this data, that we have been so successful, that we have found so many thousands of planetary candidates,
Cite this article:
Hammonds M (2013-05-19 07:45:28). Weekly Science Picks. Australian Science. Retrieved: Apr 28, 2024, from http://australianscience.com.au/news/weekly-science-picks-31/test
The post Weekly Science Picks appeared first on Australian Science.
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NASA’s Kepler mission has found a star system which has not one, but two possibly terrestrial planets in its habitable zone.
Whether either or both of Kepler-62’s optimally positioned planets actually has water is beyond the technical capabilities of the Kepler and other telescopes. Kepler works by detecting the very slight dips in light coming from a star caused by a planet passing by, relative to the telescope’s line of sight.
Sometimes the best way to learn more about nature is to try and recreate it. That happens to be exactly what happened when a group of roboticists were looking at insects…
They found that the moth moved its abdomen in direct response to its shifting visual environment. “If the pattern is rotating up (clockwise), the moth would raise its abdomen up (counterclockwise),” says study co-author Jonathan Dyhr, a University of Washington biologist. “The moth was raising or lowering its abdomen to counteract the movement.”
To celebrate the 23rd anniversary of the Hubble Space Telescope’s launch into orbit, NASA have released a brand new and frankly beautiful image of the iconic Horsehead Nebula. Phil Plait explains more…
The Horsehead itself is the site of ongoing star formation. The dense gas and dust inside the nebula is collapsing to form stars, and, at the same time, the edges are being eroded away by the fierce ultraviolet light of Sigma Orionis. The top of the Horsehead is acting a bit like a shield, protecting the material beneath it, which is why it’s taken on that umbrella-like shape. You can see more sculpted pillars of material around the sides, too, like sandbars in a stream.
Ants are fascinating little creatures, and a team of Swiss researchers have been studying the goings on inside a colony of them – by tracking them with barcodes!
Analyzing the color codes, they found that younger ants were more likely to work nursing the young, and older ants were more likely to be foragers. In general, they watched ants transition from nursing to cleaning to foraging as they age, but there’s a lot of individual variation in how quickly these transitions took place.
Finally, everyone’s favourite astronaut, Commander Chris Hadfield aboard the ISS answers an interesting question. What happens if you wring out a wet cloth in zero gravity? Click the link to watch the video!
Two Nova Scotia high school students, Kendra Lemke and Meredith Faulkner, submitted this experiment to Canadian Space Agency and got to see astronaut Chris Hadfield actually test it out on the ISS. The results are seriously extraordinary and you need to see them.
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The post A Supernova Post-Mortem in Radio Waves appeared first on Australian Science.
]]>Named SN 1987A, this was the death of a massive star in the Tarantula nebula. Distant enough to not even be in our own galaxy, but in the Large Magellanic Cloud – one of the Milky Way’s smaller satellite galaxies, the discovery was reported independently by Albert Jones in New Zealand. This began decades of fascinating observations for astronomers, as many began to watch this supernova expand over the years, in real time.
Supernova which are close enough to see with the naked eye are rare beasts. This was, and still is, the only one close enough and visible enough to see properly with modern telescopes, giving us some of the best information we’ve ever had about how an exploding supernova interacts with the dusty interstellar clouds which surround it.
The latest observations of this literally awesome event come courtesy of a team of astronomers working in Australia and Hong Kong, led by Giovanna Zanardo at the International Centre for Radio Astronomy Research (ICRAR). Using CSIRO’s Australia Telescope Compact Array in New South Wales, the researchers have published the highest resolution images of the stellar explosion’s aftermath ever taken.
High resolution images are wonderful in astronomy. The higher the resolution, the more you can learn about what you’re seeing. Zanardo and her colleages compared their observations with other images and data taken at optical and x-ray wavelengths. On doing so, they gained some fresh insight into exactly what happens shortly after a star explodes.
In the centre of the explosion, stellar ground zero, they discovered a pulsar wind nebula. This is a pocket of intensely hot material emitted by a neutron star*, the last remains of the exploding star’s core, proving that SN 1987A did not create a black hole.
Referred to in technical jargon as a “compact source”, a neutron star is a tiny ball of incredibly dense material. With a mass up to over 3 times the mass of the Sun, these bizarre little objects truly are compact. An average neutron star has a radius of just 12 km, which is comparable with the size of Sydney. Yes, you read that correctly. The mass of a star compressed into something with a size similar to a large city.
This discovery actually answers a long standing puzzle about SN 1987 A. Supernovae like SN 1987A are normally expected to form neutron stars, because of the near-unimaginable pressures which occur inside an exploding star. But for several years, despite looking carefully, no astronomers could find any trace of a neutron star amid the stellar debris. But the star which caused this supernova would not have been massive enough to collapse into a black hole, leading theoreticians to try and devise explanations for why there was no neutron star to be seen.
If Zanardo’s team are right, and they have indeed found a pulsar wind nebula inside the shattered remnants of this dead star, then it has to be generated by something. Unless I’m mistaken, this may be some of the most convincing evidence yet for the missing neutron star!
Discovering all of this, however, was far from easy. Radio images at centimetre wavelengths are difficult to capture with detail. Exceptionally good weather conditions are needed. Zanardo explains, “For this telescope, these [observations] are usually only possible during cooler winter conditions, but even then the humidity and low elevation of the site makes things very challenging.
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The post It’s a small world after all appeared first on Australian Science.
]]>Kepler-37b really is tiny. In fact, the whole Kepler-37 system is tiny – the entire system discovered so far can fit inside the orbit of Mercury! The innermost little world is under 100th the mass of Earth, it’s expected to have a radius of around 3867 km (assuming the same average density as the planets in our own solar system) making it smaller than Earth’s moon. One can only apprehensively wonder if this will spark yet another debate over how large an object has to be before it’s considered a planet. With such a tiny orbit, it also has a year lasting just 13 Earth days. Even though the star Kepler-37 is slightly smaller and cooler than the Sun, it’s still enough to heat the surface of tiny 37b to a roasting 700 Kelvin (nearly 430°C). Needless to say, while we all like stories which talk about potential alien life, this is unlikely to be a home for any lifeforms we might recognise.
Kepler-37b is very definitely the runt of the litter. Its sibling worlds, denoted by the letters c and d, are respectively slightly smaller than Earth and about twice the size of Earth. Of course, these planets are also very close to their parent star. The interesting thing is that we’re discovering more and more small worlds around other stars. More and more exoplanet astronomers are warming to the idea that small rocky planets are likely to be the most common in our galaxy. Our current technology might have trouble spotting them further than a certain distance from their parent stars, but they’re likely to be out there waiting to be found.
Even detecting Kepler-37b was quite a notable feat. It was only possible, in fact, because of a set of rather special circumstances. The star Kepler-37 is particularly quiet, lacking the noisy sunspots and features which cause brightness variation in most stars, making it a particularly clear target. It’s also relatively bright in Kepler’s field of view.
To learn more about this star, and hence get greater accuracy on the measurement of the planets it carries in tow, NASA astronomers used a technique known as asteroseismology. Not dissimilar to the way geologists measure earthquakes, asteroseismology is the study of vibrations within a star, measured by accurately observing pulsations in the star’s surface. All stars are constantly bubbling and boiling, and this causes the whole star to vibrate at a number of resonant frequencies – soundwaves – in exactly the same way a bell vibrates when it rings. By measuring the precise frequencies of those soundwaves, a lot can be determined about the interior of a star. Incidentally, this same technique can be used to effectively “listen” to the Sun.
Interestingly, because Kepler-37 has such an eerily peaceful surface for a star, it was very easy to measure those vibrations, making Kepler-37 the smallest star ever to be studied this way. Normally, only large stars are observed using asteroseismology because the measurements need to be very precise. Conveniently though, the Kepler telescope was built for breathtaking precision.
A tiny planet discovered orbiting a singing star 215 light years away. How poetic!
Image credits:
Top – NASA/Ames/JPL-Caltech
Middle – Karl Tate/ © space.com
Bottom – NASA/Ames/JPL-Caltech
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