A supernova that was observed in 1680 by Britain’s first Astronomer Royal, John Flamsteed, has been revealed to have produced a strange little neutron star that will give astronomers insight into how such stars are born and mature. The remains of the supernova, known as Cassiopeia A, have been something of a mystery to astronomers. Supernovae usually leave behind an extremely dense object such as a black hole or neutron star. But for decades no such object was seen at the centre of Cassiopeia A [Nature News]. Now new observations suggest that the 330-year-old neutron star escaped detection because of its odd atmosphere.
Instead of resembling more mature neutron stars, which are surrounded by hydrogen, this baby star is blanketed in carbon gas – a discovery that could provide important new insights into the evolution of neutron stars [Physics World]. The new study, published in Nature, suggests that the star is still extremely hot in the aftermath of the supernova–about 2 billion degrees Fahrenheit. This overheated condition caused a nuclear fusion reaction on the star’s surface that converts all the hydrogen and helium into carbon gas, researchers say. As time goes on, and as the star cools, the researchers think the surface fusion reaction will stop and the star will develop a more traditional hydrogen atmosphere.
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Image: NASA / CXC / Southampton / W. Ho / M. Weiss
The quest to find a second Earth–a potentially habitable planet that’s about the size of our home, but that lies in a distant solar system–has hit a snag. The Kepler space telescope was expected to be well on its way to detecting Earth-sized exoplanets by now, but an electronic glitch is slowing it down. The delays are caused by noisy amplifiers in the telescope’s electronics. The team is racing to fix the issue by changing the way data from the telescope is processed, but the delay could mean that ground-based observers now have the upper hand in the race to be the first to spot an Earth twin [Nature News].
Kepler, which was launched in March, uses the transit method to detect exoplanets; it’s watching a patch of 100,000 stars in hopes of detecting the brief dimming of a star’s light, which indicates that a planet has passed in front of the star. Kepler focuses light onto 42 light-detecting chips, called CCDs, each of which monitors stars in a different part of the telescope’s field of view. Each CCD is split into two for the purposes of sending data back to Earth, for a total of 84 data channels. Three of these channels are plagued by electronic noise that makes stars in their field of view appear to flicker – “like it’s changing its brightness at a rapid rate”, says Kepler chief scientist William Borucki [New Scientist]. That’s awkward, since the artificial flickers could obscure the real dimming that occurs during a planet’s transit.
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Talk about a long trip. An exploding star’s burst of light traveled 13 billion years, from the early days of the universe to the present day, before being detected by astronomers here on Earth. Researchers say this exploding star is the most distant blast ever seen.
The light from the distant explosion, called a gamma-ray burst, first reached Earth on April 23 and was detected by NASA’s Swift satellite. Gamma-ray bursts are thought to be associated with the formation of star-sized black holes as massive stars collapse. Within hours, telescopes around the world were turned on the burst — the most violent explosions in the universe — observing its fading afterglow to glean clues about its source and location [SPACE.com].
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Planets, planets, everywhere! Astronomers have announced the discovery of 32 new planets orbiting distant stars, bringing the list of known exoplanets up to more than 400. The batch of freshly discovered worlds include four that are only five or six times the mass of Earth, an encouraging sign in the quest for a truly Earth-like world that could support life. Researcher Stephane Udry says the discovery is exciting because it suggests that low-mass planets could be numerous in our galaxy. “From [our] results, we know now that at least 40% of solar-type stars have low-mass planets. This is really important because it means that low-mass planets are everywhere, basically” [BBC News].
The discovery was made with the HARPS telescope at the European Southern Observatory’s facility in Chile. HARPS uses the so-called wobble method to detect planets, in which researchers look for the slight quiver in a star’s regular movements that indicates the gravitational tug of an orbiting planet.
Planets were found around a surprising variety of star types. Gas giant planets were found orbiting “metal-poor” stars — those lacking in elements other than hydrogen and helium — which until now had been considered unlikely places for planets to form [Washington Post]. Researchers also located four exoplanets around relatively cool, small stars known as M-class red dwarfs, and will continue to examine such stars for signs of Earth-like planets. The team expects to keep spotting planets by the dozen, says Udry: “Nature doesn’t like a vacuum so if there is space to put a planet it will put a planet there” [Reuters].
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Image: European Southern Observatory. Artist’s impression of a newly discovered planet orbiting the star Gliese 667 C, which is part of a triple star system.
The Mount Wilson Observatory has allowed astronomers to gaze at the heavens for more than a century from a peak in the San Gabriel Mountains, just northeast of Los Angeles, but the devastating conflagration known as the Station Fire that ripped through the Angeles National Forest over the past week had stargazers wondering if the historic facility was about to go up in smoke. The flames got so close at one point that firefighters abandoned the facility, but now L.A. County Deputy Fire Chief Jim Powers has assured astronomers that he foresees “another hundred years for Mount Wilson Observatory.” This is the story of how firefighters saved the birthplace of modern astronomy as well as a virtual forest of communication towers that serve the region [AP].
On Monday night, the scene was grim. The observatory had been hastily evacuated that day, and only two-dozen firefighters stood overnight sentry, positioned along the gloomy perimeters of the observatory and towers. A greater number might have been deployed, but there were more pressing priorities in the urban elevations — the protection of hillside homes [Los Angeles Times]. By daybreak, fire chiefs made the call to retreat from the mountaintop, where firefighters could easily be trapped by the oncoming flames. “It’s not worth dying for,” said Los Angeles County Fire Department Battalion Chief Steve Martin [Los Angeles Times].
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It’s a galaxy-eat-galaxy world out there. A new study of the Andromeda galaxy, the closest neighbor to our own Milky Way at 2.5 million light years away, has mapped Andromeda in unprecedented detail and found evidence that it grew through devouring smaller galaxies. Stars and dwarf galaxies that got too close to Andromeda were ripped from their usual surroundings. “What we’re seeing right now are the signs of cannibalism,” said study lead author Alan McConnachie…. “We’re finding things that have been destroyed … partly digested remains” [AP].
Astronomers had already posited the “hierarchical model” in which small galaxies combine to form large ones, but the new study shows the model in action. The map shows stars in bright streams and clumps that were also likely ripped from dwarf galaxies that once orbited Andromeda [New Scientist]. Researchers say the clumps of stars around the edge of Andromeda couldn’t have formed there, because there wouldn’t have been enough gas to give birth to them.
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Looking for the best place on Earth to gaze at the stars? Scientists have identified the exact spot on the planet that provides the greatest view of the heavens. The location, called Ridge A, is deep in the Antarctic interior, according to a study published in the Publications of the Astronomical Society.
You’ll want to bundle up, though, because the 13,297-foot-high location has an average winter temperature of about -94 degrees Fahrenheit. It’s so inhospitable that researchers say that no human has ever set foot on Ridge A.
To search for the perfect site to take pictures of the heavens, a U.S.-Australian research team combined data from satellites, ground stations and climate models in a study to assess the many factors that affect astronomy — cloud cover, temperature, sky-brightness, water vapor, wind speeds and atmospheric turbulence [LiveScience]. Scientists believe that a telescope set in place on Ridge A could take pictures as well as the Hubble Space Telescope, which is orbiting the Earth, thanks to the area’s lack of wind and weather.
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Image: flickr / es0teric
In a star system 330 light years away from Earth, astronomers have spotted a giant planet that booms around its parent star in tight, fast circles, completing an orbit (the planet’s “year”) in less than one Earth day. The exoplanet, known as Wasp-18b, is so close to its star that researchers say it appears to be spiraling inwards to its fiery doom. But the odds of seeing a planet in its death throes are so low that researchers are searching for alternate explanations, and say the planet could force scientists to rethink established ideas about planetary forces known as tidal interactions [National Geographic News].
The planet is known as a “hot Jupiter,” meaning that it’s a massive gas giant like our own solar system’s Jupiter, but it orbits in close proximity to its star. Current theories say that such a massive planet so close to its star should be pulling on the host star, creating a tidal effect similar to the moon’s pull on Earth. At that range the planet’s pull would be so strong that it would drain energy from its orbit, causing the planet to rapidly fall into the star [National Geographic News]. But if that’s the case, the planet would meet its death in less than a million years. Since the star system is thought to be about 1 billion years old, the odds of catching the planet in its last stages are one in a thousand.
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Volunteers helping astronomers classify galaxies in an online project have identified an entirely new type of galaxy, which they dubbed “green pea” galaxies due to their resemblance to little green legumes floating in space. The citizen scientists who had noticed the oddities, and who came to call themselves the “Pea Corps” and the “Peas Brigade,” began to discuss the phenomena on an online forum, and soon enough professional astronomers with links to the project confirmed that the volunteers had found a never-before-seen type of galaxy.
Says astronomer Carolin Cardamone: “No one person could have done this on their own…. Even if we had managed to look through 10,000 of these images, we would have only come across a few Green Peas and wouldn’t have recognized them as a unique class of galaxies.” Of the one million galaxies that make up the image bank, the researchers found only 250 Green Peas [SPACE.com]. Cardamone and her colleagues wrote up the results, which will be published in the Monthly Notices of the Royal Astronomical Society.
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The dormant Hawaiian volcano Mauna Kea has been selected as the site of the world’s largest telescope, the much-anticipated Thirty Meter Telescope. Its enormous mirror will have nine times the light-gathering capacity as the biggest telescopes operating today, and will be able to look back to the beginnings of the universe. “It will really provide the baby pictures of the universe” [Honolulu Advertiser], says Charles Blue, a spokesman for the Thirty Meter Telescope Observatory Corporation.
The telescope’s mirror, stretching 30 meters (almost 100 feet) in diameter, will be so large that it should be able to gather light that will have spent 13 billion years traveling to earth. This means astronomers looking into the telescope will be able to see images of the first stars and galaxies forming — some 400 million years after the Big Bang [AP]. The telescope is expected to be completed by 2018, but it may not be the world’s largest for long–the European Extremely Large Telescope is scheduled for completion around the same time, and will boast a 138-foot mirror.
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Astronomers believe they’ve found something never before detected in the universe: a black hole of intermediate size. And while that may not sound thrilling to the layman, researchers are thrilled by the discovery of the so-called “Hyper-Luminous X-ray Source 1,” which is poised at the edge of galaxy ESO 243-49. Astronomers are excited because they’ve seen plenty of small black holes and large black holes, but experts had questioned whether a medium-sized variety could exist. These middleweights, at about 500 times the mass of the sun, could represent a missing link between common stellar black holes, created by the death of a single star, and the supermassive variety that can pack the mass of millions or even billions of suns [SPACE.com].
Astronomers explain that small black holes, between three and 20 times the mass of the sun, are created when big stars collapse and leave behind a gravitational pull strong enough to block nearby light rays. Researchers have speculated that super-massive black holes result from the successive fusion of many smaller black holes. But without finding evidence of a medium-size hole, it was a tough theory to prove [Wired.com]. Supermassive black holes are of particular interest because they lurk at the hearts of most galaxies, and may play an important role in galaxy formation.
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Only 20 years ago, astronomers were arguing over whether a colleague had discovered the first exoplanet–a planet beyond our solar system that is in orbit around an alien sun. Fast forward to the present day, and researchers have now spotted more than 300 exoplanets in our Milky Way galaxy, and the new topic of discussion is whether a group of astronomers has detected the first extragalactic planet in the Andromeda galaxy.
A new study to be published in the Monthly Notices of the Royal Astronomical Society explains that it should be possible to identify extragalactic planets with the technique of gravitational microlensing, in which a distant source star is briefly magnified by the gravity of an object passing in front of it. This technique has already found several planets in our galaxy, out to distances of thousands of light years. Extending the method from thousands to millions of light years won’t be easy, says [study coauthor] Philippe Jetzer, … but it should be possible [New Scientist]. In fact, it may have already been accomplished.
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By pretending to observe the sunlight shining through the Earth’s atmosphere from the vantage point of the moon, astronomers have gained a clue that may help them in the search for Earth-like exoplanets that could be harboring life.
The astronomers made their observations on 16 August 2008 during a lunar eclipse — in which the Moon moves into Earth’s shadow. Even when the Moon is totally eclipsed by Earth, it is still bathed in a dim red light — from sunlight that has been bent as it passes through the edge of Earth’s atmosphere. Using Earth-based telescopes, the astronomers detected some of this light after it bounced back from the Moon [Nature News].
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Researchers have recalculated the mass of a gigantic black hole at the core of the M87 galaxy, and found that it’s about two times as massive as previously estimated: The new study says that M87’s black hole weighs the same as 6.4 billion suns. Researchers say the findings may indicate that many black holes have been underestimated, and also say that the results from this “local” galaxy only 50 million light-years away may solve a mystery regarding the extremely distant black holes known as quasars.
Astronomers had previously estimated M87’s total mass, calculating how much of that mass came from both the galaxy’s stars and its central black hole. But previous models didn’t have the supercomputing power to estimate the mass contributed by the galaxy’s “dark halo.” The dark halo is a spherical region surrounding the galaxy that extends beyond its main visible structure. It contains “dark matter”, an as yet unidentified material that cannot be directly detected by telescopes but which astronomers know is there from its gravitational interaction with everything else that can be seen [BBC News].
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