The first ever picture of an exoplanet was taken 11 years ago–but no one noticed. Now, in a new study, astronomers have subtracted the starlight from an image taken by the Hubble in 1998, and found the exoplanet by its dim infrared glow. While some exoplanets were detected before 1998, they were discovered indirectly by observing their influence on their parent stars; this was was seen directly.
The new technique has excited researchers wondering how many more new planets can be found in old, archived data. “They’ve dug up old Hubble images and found a planet! Crazy!” Geoff Marcy, an astronomer at the University of California, Berkeley, commented by email. “This will spawn a wild race by astronomers everywhere in the world to dig out their old Hubble images to hunt for planets lost in the rubble of the Hubble” [National Geographic News].
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On Friday night, a Delta 2 rocket blasted off from the Kennedy Space Center and roared into space carrying a satellite that will search the heavens for Earth-like planets. The craft, Kepler, named after the German astronomer Johannes Kepler, who discovered the planetary laws of motion, is to spend the next three and a half years in an orbit around the Sun, where it will count planets by looking for the tiny blips in starlight caused by planets eclipsing their suns [The New York Times].
The $600 million satellite will stare into a region of the Milky Way that’s thick with stars, in the direction of the constellations Cygnus and Lyra. While Kepler is expected to identify many new planets beyond our solar system, known as exoplanets, the real prize would be to find rocky planets in the “habitable zone” around a star, where conditions might be right for life as we know it. “The habitable zone is where we think water will be,” Bill Borucki, Kepler principal investigator at NASA Ames, says in a video on the space agency’s Kepler site. “If you can find liquid water on the surface we think we may very well find life there. So that zone is not too close to the star, because it’s too hot and water boils, and not too far away where the water is condensed…a planet covered with glaciers. It’s the Goldilocks zone–not too hot, not too cold, just right for life” [CNET].
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While astronomers have found more than 300 planets beyond our solar system in the last 15 years, none of those “exoplanets” has been a likely candidate for extraterrestrial life. The exoplanets discovered thus far are all either too close to the hot sun or too far away and therefore too frigid to host life as we know it. But Alan Boss says it’s just a matter of time before we find Earth-like planets in the “Goldilocks zone”: he calculates that 100 billion of them may exist within our own Milky Way galaxy. And NASA’s Kepler satellite, which is expected to launch on March 5, may be the key to finding them, he says.
Boss, an astrophysicist and author of the new book “The Crowded Universe: The Search for Living Planets,” says that if any of the billions of Earth-like worlds he believes exist in the Milky Way have liquid water, they are likely to be home to some type of life. “Now that’s not saying that they’re all going to be crawling with intelligent human beings or even dinosaurs,” he said. “But I would suspect that the great majority of them at least will have some sort of primitive life, like bacteria or some of the multicellular creatures that populated our Earth for the first 3 billion years of its existence” [CNN].
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A rocky world about twice the size of Earth has been detected orbiting a sun-like star 390 light years away from our solar system. While the “super-Earth” is hot and inhospitable to life as we know it, its discovery puts researchers firmly on the path towards finding other habitable planets. “For the first time, we have unambiguously detected a planet that is ‘rocky’ in the same sense as our own Earth” [Wired News], said project scientist Malcolm Fridlund. The exciting find was made by the CoRoT satellite, which was launched by the French space agency to scan the skies for exoplanets (planets outside our solar system). The results were announced at a CoRoT symposium in Paris.
CoRoT team member Suzanne Aigrain explains that the planet is so close to its parent star that it orbits around it once every 20 hours, and is subject to inferno-like conditions. “It’s likely that there is a solid surface somewhere,” says Aigrain. But the extreme surface temperatures of around 1000°C [around 1800 degrees Fahrenheit] could mean that the planet is host to vast lava fields and boiling oceans. It also may be ‘tidally locked’ to its parent star, leaving one face bathed in constant, searing sunlight while the other is shrouded in continuous night. “It would be a very odd place to set foot on,” she says [Nature News].
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For the first time, researchers have watched weather conditions shift on a planet outside our solar system, and say the temperature spikes are out of this world. Normally, the planet is a toasty 980 degrees [Fahrenheit] or so. But in the few hours it whips around its sun the planet gets zapped with mega-heat, pushing the thermometer closer to 2,240 degrees…. When it comes closest to its star, it becomes one giant “brewing storm” [AP].
The gas giant, known as HD 80606b, lies about 190 light-years away in the constellation Ursa Major, and has an extremely elliptical orbit. When it’s closest to its sun, it is barely more than 300,000 miles away – not much more distant than our cold moon is from us. But when the planet is farthest away from its sun and coolest, it’s nearly 70 million miles away. That would be like some object flying somewhere far out between the orbits of Earth and Venus [San Francisco Chronicle]. One complete orbit around its sun takes 111 days.
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Astronomers know that at the heart of every supermassive galaxy is a giant black hole. But new data suggests that the two did not necessarily form in tandem. Instead, black holes may have formed earlier, or at least much more quickly, than their surrounding galaxies. Previous studies had revealed a striking link between black holes and the amount of gas and stars contained in [their] galaxies’ bulges — the regions that lie within a few thousand light-years of the galaxies’ cores. Regardless of their size, the bulges always turned out to be 700 times as massive as the giant black holes at the galaxies’ hubs [Science News]. New measurements of much more distant galaxies, which appear much younger, defy the expected mass ratio. In these younger pairings, the relative mass of the black holes is much greater, hinting that the black holes came first.
Researchers used the Very Large Array radio telescope in New Mexico and the Plateau de Bure Interferometer in France to measure the mass of four distant galaxies as they appeared less than two billions years after the Big Bang. From the motions of the molecular gas, which concentrates in the central part of the galaxies, the team calculated the total amount of mass in the bulges and compared that number to the mass of the central black holes [Science News]. The galactic bulges were only about 30 times more massive than their central black holes. At the American Astronomical Society‘s meeting, where the work was presented, astronomer Chris Carilli said, “The simplest conclusion is that the black holes come first and they somehow grow the galaxy around them” [Wired News].
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In the violent heart of our Milky Way galaxy lies a supermassive black hole with a mass equivalent to four million suns. But although the gravitational maw gobbles up anything that gets too close, it can also set up conditions that allow for the birth of new stars just a few light years away, according to a new study. Lead researcher Elizabeth Humphreys says the results, which uncovered what appear to be two young stars as close as seven light-years from the galactic center, were surprising, as that is “one of the last places … you would expect to find stars forming” [Scientific American].
Gas clouds that approach a black hole are usually ripped apart by the intense gravitational forces, but the new finding suggests that the molecular gas at the center of the Milky Way from which the stars form is denser than previously thought. The higher density gas makes it easier for the self-gravity of the condensing cloud to overcome the strong pull of the black hole and to collapse to form new stars [SPACE.com].
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Dead stars surrounded by fields of dust from pulverized asteroids may seem to make up a forbidding and ominous picture, but researchers who studied six such star systems say the dust should actually fuel the optimism of people who dream of finding extraterrestrial life. The dust’s composition suggests that rocky planets like our own Earth may be common in the universe, researchers say, which ups the chance that life as we know it has evolved somewhere out there.
The dust in question was found surrounding small, dense white dwarf stars. As stars like our own sun near the end of their life, they puff up into red giants that consume their innermost planets and jostle the orbits of outer planets and asteroids. Eventually the stars blow off their outer layers and shrink down into white dwarfs. Occasionally, a perturbed asteroid will wander too close to the white dwarf, whose gravity rips the rocky body to shreds, forming debris [SPACE.com].
That debris is what researchers studied with NASA’s Spitzer Space Telescope. By viewing the stars through a spectrograph, which separates out light from different wavelengths, the scientists were able to observe the telltale signatures of certain chemicals in the light. Since that starlight is passing through the film of the asteroid debris, the light picked up signatures of the asteroids’ composition, too [Wired News]. Lead researcher Michael Jura announced at the ongoing American Astronomical Society meeting that the composition of the asteroid dust was remarkably similar to that of the rocky planets in our solar system.
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We residents of the Milky Way can puff ourselves up with pride: A new study has discovered that our galaxy is more of a force to be reckoned with than previously realized. Astronomers said Monday that the Milky Way is more massive than earlier known, given new measurements showing that the Sun is moving at 600,000 miles per hour around the center of the galaxy, or 100,000 m.p.h. faster than past calculations suggested. The higher speed of the Sun means the galaxy must have more mass — about 50 percent more — so as to generate a stronger gravitational pull to keep hold of the Sun, as well as all its other stars [The New York Times].
The new calculation puts our galaxy’s mass about equal to that of the nearby Andromeda galaxy, which was previously thought to be bigger than the Milky Way, says lead researcher Mark Reid. “Previously we thought Andromeda was dominant, and that we were the little sister of Andromeda,” Reid said. “But now it’s more like we’re fraternal twins” [AP]. But although the estimate gives our galaxy some new bragging rights, it’s not all good news. Being bigger means the gravity between the Milky Way and Andromeda is stronger. So the long-forecast collision between the neighboring galaxies is likely to happen sooner and less likely to be a glancing blow, Reid said [AP]. Luckily, that collision still isn’t expected for 2 to 3 billion years.
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A supernova first observed in the 16th century by Danish astronomer Tycho Brahe has been sighted again, astronomers report. Brahe observed its direct light but “light echoes” from the supernova that took a long detour around the universe have finally made it to Earth and have been captured by the Subaru Telescope in Hawaii. The new observations confirm that the supernova was the explosion of a white dwarf star. “Using light echoes in supernova remnants is time-traveling in a way, in that it allows us to go back hundreds of years to observe the first light from a supernova event,” said Tomonori Usuda, lead project astronomer at Subaru [Space.com].
In November 1572, Brahe noted a new shimmer in the night sky and thought it was the birth of a new star. But the shimmer disappeared 16 months later and some claimed it was a comet. Only in the early 20th century did astronomers understand that the fleeting brightness was a supernova and represented not the birth but the death throes of a star. The direct light from the supernova swept past Earth long ago. But some of it struck dust clouds in deep space, causing them to brighten [AP]. These light echoes are what astronomers have now captured and reported in Nature [subscription required]. “What we have essentially done here is to use interstellar dust as a kind of a mirror,” says [co-author] Oliver Krause [Nature News].
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For the first time, carbon dioxide has been detected in the atmosphere of an exoplanet, astronomers working with the Hubble Space Telescope report. Although the Jupiter-sized planet, which closely orbits the star HD 189733 about 63 light-years from Earth, is much too hot to support life, scientists are hailing the discovery as an exciting technical achievement. “In that context, the carbon dioxide measurement constitutes a dress rehearsal …for our long-term goal of trying to detect signs of life or signs of habitability on terrestrial-mass planets or super Earths in the habitable zone,” [Science News] says Mark Swain of NASA’s Jet Propulsion Laboratory.
Researchers deduced the presence of carbon dioxide by measuring the planet’s light spectrum with the Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS). To isolate the light spectrum coming from the planet, researchers used a method known as “secondary transit.” This involves recording the light spectrum of the planet and its star, and then measuring the spectrum of the star alone while the planet is hidden behind it. The difference of the two spectra is the spectrum of the light coming directly from the planet [Nature News]. Unlike previous measurements that focused on the mid-infrared range, NICMOS took measurements in the near-infrared range, enabling detection of the carbon dioxide signature.
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In news that has thrown astronomers and space enthusiasts into a tizzy of excitement, two separate research teams announced today that they have taken the first pictures of exoplanets, planets orbiting stars beyond the edge of our solar system. It’s an achievement that has long been considered vital in the search for planets like our own [Physics World].
One team spotted a single planet circling a bright star only 25 light-years away in the constellation Piscis Austrinus, while the other detected three giant planets orbiting a star 130 light-years away in the Pegasus constellation.
More than 300 so-called extrasolar planets have been found circling distant stars, making their discovery the hottest and fastest growing field in astronomy. But the observations have been made mostly indirectly, by dips in starlight as planets cross in front of their home star or by wobbles they induce going by it. Astronomers being astronomers, they want to actually see these worlds, but a few recent claims of direct observations have been clouded by debates about whether the bodies were really planets or failed stars [The New York Times]. But these newly discovered celestial objects are the right size for planets, and were observed moving around their parent stars.
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The Fermi Gamma-ray Space Telescope may have just gotten a hint in its hunt for the mysterious dark matter that is thought to make up the bulk of the universe’s mass. A group of astrophysicists has run a simulation of the distribution of dark matter in a galaxy like our Milky Way, and say that if the telescope scans the right region of space it may be able to detect gamma rays given off by collisions between the particles that are thought to make up dark matter (which have never been directly detected, and are still speculative).
Previously, some cosmologists have proposed that the best chance of a detection lies in nearby dwarf galaxies, since they should contain dense nuggets of dark matter that could be relatively easy to pinpoint. But a new study argues that a diffuse dark matter ‘halo’ surrounding the Milky Way offers an even better shot at glimpsing the mysterious stuff. “I would bet on it,” says lead author Volker Springel…. “And I’d be willing to risk a bit of money as well” [New Scientist].
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After several weeks of remote-control repair work, the Hubble Space Telescope is back in action, and is once again taking breathtaking images of distant galaxies. Today, NASA released an image which it called a “perfect 10″ because the paired galaxies resemble the number 10. The picture was released this morning by NASA to demonstrate that the observatory’s workhorse Wide Field Planetary Camera 2 is on the job again [Baltimore Sun], and a happy NASA press release added that the camera scored a perfect 10 for both its performance and the beautiful results.
The image shows a pair of galaxies, known as Arp 147, which are about 400 million light years away from Earth. The two galaxies are thought to have collided, and the image shows that aftermath. The blue ring was formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, or ripples, an outwardly propagating ring of higher density was generated at the point of impact of the two galaxies, astronomers explained. As this excess density collided with outer material that was moving inwards due to the gravitational pull of the two galaxies, shocks and dense gas were produced, stimulating star formation [SPACE.com].
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The nearest planetary system to our own has two asteroid belts in addition to a previously known ice belt, according to the latest observations by NASA’s Spitzer Space Telescope. The location and structure of the asteroid belts relative to the system’s central star, Epsilon Eridani, suggests the existence of earth-like planets. “We certainly haven’t seen it yet, but if its solar system is anything like ours, then there should be planets like ours,” says astronomer Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics [USA Today].
The Epsilon Edidani system has long been of interest to astronomers and science fiction fans alike because of its proximity (10.5 light-years) and resemblance to our solar system. The newly discovered asteroid belts give the system an appearance even more like our own. The inner asteroid belt looks identical to ours in terms of material, and it orbits at 3 astronomical units (AU) from Epsilon Eridani — the same distance between the sun and the rocky asteroid belt between Mars and Jupiter. (An astronomical unit equals the average Earth-sun distance of 93 million miles, or about 150 million km.) Epsilon Eridani’s second asteroid belt is 20 AU from the star, or about where Uranus is in relation to our sun, and it is crowded with as much mass as Earth’s moon [Science News]. The outer asteroid belt was captured directly by Spitzer’s infrared cameras and the inner asteriod belt, though too far from the cameras, was indicated by the thermal energy from its infrared emissions.
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