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Earth to Earth... do we have a twin? |
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Physicists Drs John Green and Stefan Dieters are planet searchers.
(photo courtesy of the University of Tasmania) |
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The planet system
(photo courtesy of the University of Tasmania) |
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If there is another planet like Earth spinning out in space and quite possibly supporting life, astronomers from the University of Tasmania are determined to be among the first to find it. And it looks like they are on their way.
Planet hunters Dr John Greenhill and Dr Stefan Dieters from the University of Tasmania School of Mathematics and Physics were recently part of an international breakthrough in man's knowledge of space when they were part of the team that discovered the first planetary system with similarities to our own solar system.
These men were the only Australian contributors to a global collaboration, led by Dr Scott Gaudi of Ohio State University, which uncovered the system and recently reported its results in the prestigious journal, Science.
The newly discovered system - codenamed OGLE-2006-BLG-109L - contains two planets orbiting a cooler star half the mass of our Sun and situated about 5000 light years from Earth, give or take a light year.
"While 250 planets have so far been discovered outside our solar system, there have been no similarities so this is the first planetary system like this to be discovered. It is extremely exciting," said John.
The collaboration used a technique known as gravitational micro-lensing with photometric data (or brightness measurements) from telescopes in Chile, the United States, New Zealand, Israel, The Canary Islands and the University of Tasmania Mt Canopus one-metre telescope that is based near Hobart.
John explained that the use of gravitational micro-lensing is different from the conventional Doppler mechanism most astronomers use to search for exoplanets - or planets beyond our solar system.
"The Doppler effect is used to determine how fast stars and galaxies move towards or away from us on Earth and can be used to identify new planets and solar systems," he said. "In fact, the belief that the universe is expanding is based on measurements using the Doppler Effect showing stars and galaxies to be constantly moving away from the Earth and away from each other.
"In contrast, gravitational micro-lensing gives us a single snapshot of the universe and the ability to detect and study objects that emit little or no light, such as this solar system which has a star that is smaller and cooler than our own sun."
In gravitational micro-lensing, the light of a background star is magnified by the effect of gravity from a foreground star as it passes. This causes the background star to brighten and fade smoothly as the alignment between the two stars changes as each move through space. If the foreground star has a planet, it can cause distortions to this smooth process, which appear as very short brightening and fading. It is the analysis of these changes that can lead to the discovery of new planets.
While pinpointing a new planet may seem thrilling in itself, what really excites astronomers about this discovery is the similarity of the planetary system to our own solar system.
"It resembles a scaled-down version of our solar system with the two planets having mass ratios – as compared with their star – orbital separations and surface temperatures similar to those of Jupiter and Saturn," Stefan, the University of Tasmania's other researcher, explained.
"The discovery is particularly significant because it demonstrates that, using micro-lensing, scientists could estimate how many planetary systems similar to ours there are in the galaxy," he said.
"However, the technique does not necessarily detect all planets in the system, so it's possible that OGLE-2006-BLG-109L may contain other planets – even ones like Earth but any Earth-like planet that exists within this solar system would have to be located a lot closer to its central star, in order to maintain temperatures suitable to support life," Stefan concluded.
So although the search for life on other planets may be a little way off, for astronomers, a life spent hunting planets and watching bright stars is, quite literally, never dull.
This article is based on an article recently published in The University of Tasmania's UniTas magazine. The original article can be found at here. |
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Our Sun has a name. It is known as ‘Sol' which is Latin for 'Sun'.
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Our Sun's core has a temperature of over 13 million degrees.
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Pluto is not a planet. Instead it is considered one of our own solar system's three dwarf planets; including Pluto, Ceres and Eris. These dwarf planets are part of an asteroid belt surrounding our solar system.
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Dwarf planets are usually large parts of an asteroid belt. They differ from asteroids as they exhibit their own types of gravity.
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In the future, other asteroids may be discovered as dwarf planets. There are currently 42 objects in our solar system that might be considered dwarf planets.
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