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Dec 15, 2005 - Astronomers have discovered a dusty disk around a young star that could be in the process of forming new planets. The star, which is approximately the size of our own Sun, was observed using NASA's Spitzer Space Telescope. The star, known as HD 12039, is about 30 million years old; the age at which astronomers believe the terrestrial planets in our solar system had nearly formed. Based on Spitzer's analysis to date, it looks like only 1-3% of young Suns have a disk like this surrounding them.
Sep 8, 2005 - Researchers at the Washington University in St. Louis have developed a "field guide" for planet hunters searching for other Earths. They modeled the chemistry of silicate vapour and steam rich environments, similar to the early stages when an Earthlike planet is forming. During this stage, the planet is covered with a magma ocean which vapourises. This is a very distinct moment in the lifetime of a planet, and should be detectable because silicon monoxide gas is easy to see in infrared and radio wavelengths.
Jul 19, 2005 - Astronomers from the Harvard-Smithsonian Center for Astrophysics have found a dusty disk around a star which is 25 million years old. Planetary disks like this have been seen before, but never around a star which is so old; it's possible it'll never form planets. Most planetary disks make the transition within just a few million years, and the previous record was 10 million years. The disk still has a lot of gas in it, so researchers think it's still possible that it could form gas giants.
Jul 14, 2005 - A backdrop in many science fiction stories is to have multiple suns in the sky. Astronomers have now found such a world, called HD 188753 Ab. Our heroes couldn't set foot on this planet, though, since it's a "hot jupiter"; roughly the mass of Jupiter, but orbiting its parent star every 3.3 days. The other two stars in the system take 25.7 years to orbit the main star (about the distance from the Sun to Saturn), and spin around each other every 156 days,
Jul 13, 2005 - As techniques and equipment for finding extrasolar planets improve, astronomers are finding planets with smaller masses. First it was Jupiter-sized planets and larger, then Saturn-sized planets, and now Neptunians. But could these Neptune-mass planets actually be terrestrial planets, made of rock instead of gas and ice? Unlike Neptune and Uranus, these planets orbit very close to their host star. Astronomers will need to find one that transits in front of its host star to they can determine its density, to know if it's rock, ice or gas.
Jul 11, 2005 - Of the 130 extrasolar planets discovered to date, most have been found using the radial velocity method, where a planet causes tiny changes to a star's velocity compared to the Earth. This back and forth motion changes the wavelength of the light from our perspective. Another method, the transit method, has turned up 6 planets so far, and should find many more in the coming years. It works by watching for a star to dim slightly on a regular basis as a planet passes in between us and the star.
Jul 2, 2005 - Astronomers have found an extrasolar planet that contains the largest core ever seen in a planet. This planet orbits the Sun-like star HD 149026, is roughly the size of Saturn, and takes only 2.87 days to complete its year. The planet was first discovered by the effect of its gravity around its parent star. Astronomers were then fortunate to detect how much it dims the light from the star as it passes in front. From this information, they were able to measure the planet's size, and calculate the size of its core. This discovery adds evidence to the "core accretion" theory of planetary formation, where planets start as balls of rock and ice, and collect a gas envelope around themselves.
Jun 22, 2005 - The Hubble Space Telescope has taken a detailed image of a narrow, dusty ring around nearby star Fomalhaut. Although they can't see it directly, astronomers think a planet has been tugging at the ring with its gravity. According to researchers, the shape and position of the ring couldn't exist without a planet. This is similar to the twists and knots that NASA's Cassini spacecraft has photographed in Saturn's rings, which are caused by its shepherd moons.
Jun 15, 2005 - When the recent discovery of a planet orbiting Gliese 876 was announced by astronomers, much of the interest focused on how "Earthlike" it is. So, just how like our home planet is it? Well... not very. For starters, the planet orbits only.021 the distance from the Earth to the Sun, and whips around its star once every 2 days. It has 6-8 times the mass of the Earth, so the gravity would be crushing for any potential life, not to mention the terrible radiation exposure from being so close to its parent star.
Jun 13, 2005 - Astronomers have found the most Earthlike extrasolar planet discovered so far. This new planet is about 7.5 times the mass of the Earth, and has twice the radius of our own planet. It whips every two days around a nearby star called Gliese 876, which is only 15 light years away - this star also possesses two additional giant, Jupiter-class planets. This is the first time that a rocky (or terrestrial) planet has been discovered around another star.
May 23, 2005 - Two amateur astronomers from New Zealand, working with a team of astronomers from around the world have helped to discover an extrasolar planet 15,000 light years from Earth. They used a technique known as gravitational microlensing, which occurs when a massive object (like a star or even a black hole) passes in front of a more distant star; its gravity bends and focuses light like a lens. The team noticed that the closer star had a strange pattern of distortion to its light that indicated a planet. This method could be used to find much smaller, even Earth-sized, planets.
May 18, 2005 - Canadian astronomers using the MOST (Microvariability & Oscillations of STars) Space Telescope have detected that a giant extrasolar planet has forced its parent star into a lock-step orbit. This interaction is between the star tau Bootis and its "hot Jupiter" planet discovered in 1997. MOST was able to detect subtle variations in the star's brightness that correspond with the planet's orbit. It's likely that the planet has forced the outer layer of tau Bootis' atmosphere so that it rotates to keep the same side facing.
May 16, 2005 - Astronomers working with the Canadian Microvariability & Oscillations of STars (MOST) space telescope have been able to indirectly probe the atmosphere of a planet orbiting another star. The planet, HD209458b, was imaged earlier this year by NASA's Spitzer space telescope; it's a "hot jupiter", orbiting very close to its parent star. MOST will watch how its parent star changes in brightness as the planet passes in front and behind, and should be able to provide details about its temperature, pressure, and even cloud cover.
May 2, 2005 - Astronomers working with the European Southern Observatory have confirmed the first direct photograph of a planet orbiting another star. The team originally announced their discovery in September 2004, but they confirmed their findings this year using the powerful new NACO instrument on ESO's Very Large Telescope in northern Chile. The planet is approximately five times the size of Jupiter, and orbits its brown dwarf star at about the distance that Neptune travels around the Sun.
Apr 14, 2005 - When astronomers discovered that the planets around Upsilon Andromedae had very strange orbits, they weren't sure what could have caused it. Researchers from Berkeley and Northwestern have developed a simulation that shows how an additional planet could have given the other planets the orbital kick they needed to explain their current eccentricities. If a similar planet had passed through our own solar system early on, all our planets could be in wildly different orbits around the Sun.
Apr 11, 2005 - Since the beginning of astronomical observation, science has been viewing light on a curve. In a galaxy filled with thousands of eclipsing binary stars, we've refined our skills by measuring the brightness or intensity of so-called variable star as a function of time. The result is known as a "light curve". Through this type of study, we've discovered size, distance and orbital speed of stellar bodies and refined our ability to detect planetary bodies orbiting distant suns. Here on Earth, most of the time it's impossible for us to resolve such small objects even with the most powerful of telescopes, because their size is less than one pixel in the detector. But new research should let us determine the shape of an object... like a ringed planet, or an orbiting alien space station.
Apr 8, 2005 - Astronomers have discovered more than 150 planets orbiting distant stars, but only indirectly. Now an international team of researchers think they might have the first direct photograph of a planet orbiting another star. The image is of GQ Lupi, a young star located 400-500 light-years away. A dimmer object, potentially a planet, is located to the right of the star separated by 100 astronomical units (2.5 times the distance of the Sun to Pluto). Unfortunately, the astronomers haven't been able to determine the mass of the object, so they can't rule out that it might be a brown dwarf.
Apr 5, 2005 - The chances of finding life somewhere else in the Universe depends on how many planets are capable of supporting life. Well, according to new calculations by astronomers at Open University, as many as half of all star systems could contain habitable planets. The team created mathematical models of known exoplanetary systems, and then added Earth-sized planets into the mix. They found that in half of all planetary systems they simulated, the gravity of the gas giants won't catastrophically affect the orbits of these smaller planets, giving life a chance to evolve.
Mar 22, 2005 - NASA's Spitzer telescope has detected the light from distant planets for the first time. Until now, extrasolar planets have only been discovered indirectly, by the effect of their gravity on their parent star. Astronomers first detected two planets using indirect methods, and then used Spitzer to perform followup observation with its infrared instruments. They detected the difference in star brightness when the planet was in front and behind the star, and were able to calculate how much of this light was supplied by the planet.
Feb 18, 2005 - In the last month planet hunters have uncovered 12 new worlds orbiting other stars, bringing the total planet count to 145. Two European planet hunting teams have discovered 6 gas giants as part of the High Accuracy Radial velocity Planet Search (HARPS), and an American team uncovered 5 more using the W.M. Keck observatory in Hawaii. And a single, Pluto-sized planet was discovered orbiting a pulsar by Penn State's Alex Wolszczan and Caltech's Maciej Konacki.
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