Thursday, July 30, 2009

The Planet Hunters - 47 Ursae Majoris b

The astronomers knew that an earth like planet could only survive if the gas giants were like our own in circular orbit hundreds of millions of miles away from their stars. Our fondest goals are to find planets in circular orbits with orbital periods of about ten or twenty years similar to Jupiter and Saturn in our own system. If we saw such planets in circular orbit that would be a fabulous discovery. Because it would be a sign that this is the sort of solar system that might have other better planets.

The search was slow and frustrating. After more than fifteen years of planet hunting there was no sign of a planetary system like our own. But the planet hunters never gave up hope. In the late summer of 2001 their luck was about to change. Three years after finding their first planetary system the planet hunters stood at the brink of another groundbreaking discovery. At the University of California at Berkley Deborah Fisher remained convinced that she could find a planetary system that could harbour an earth like planet.

Near the familiar star pattern of the big dipper lies 47 Ursae Majoris, one of the stars that Fisher had been tracking for many years. She already had evidence that two planets orbited the star but she had also discovered something far more promising, both were following circular orbits far from the star. TopPlanets from Hell / Peg51Planets from Hell /Upsilon AndromedaeThe Planet Hunters 47 Ursae Majoris bPlanet OGLE-2005-BLG-390LbA Planet with Planets?The Planet Hunters Extreme LifeThe Planet Hunters Extreme Life - Eating RocksThe Planet Hunters Extreme Life - The DebateName a PlanetSearching for Life around a Red DwarfPartial Ingredients for DNA and Protein Found Around StarLife’s Building Blocks are Common in Space

“Now for the first time;” says Fisher, “we have a star with two gas giant planets that are well outside like in our solar system that appear not to have migrated in, not in eccentric orbit and going fairly in a circular orbit.” Here was the perfect configuration. The two planets are very similar to our own gas giant Saturn and Jupiter. Perhaps here was a system of planets with a pattern like our own. Most important was the absence of gas giants near the star.

“From our detection technique we have a big empty gap that’s between the star and the inner planets, so is there something there that could be a terrestrial type planet?” Said Fisher. For Fisher 47 Ursae Majoris offered the most promising condition she had found so far. For the first time in almost two decades the planet hunters had discovered a place that could be hiding another earth. If there is an earth like planet orbiting 47 Ursae Majoris, how could the planet hunters detect it? Any wobble it would produce in the star would be too slight for astronomers to pick up with their current technology. At the Keck Telescopes in Hawaii scientists are paving the way now for the next era of planet hunting. Here an ambitious plan is underway. To combine the light of the two Kecks and create a virtual super telescope. If he can make this happen, optical engineer Mark Swain will give the planet hunters a telescope powerful enough to detect planets as small as earth.

Beneath the Keck Domes lies a series of super clean tunnels. It’s here that starlight from one telescope is delayed and combined with the light of the second telescope. In March 2001 Swain managed to combine the light from the two Kecks for the very first time. He has created a telescope with a virtual mirror the size of a football field. It may be only a few years before this technology reveals to them the first small rocky planet. Even more ambitious planet hunting projects are planned for space. The first is scheduled for launch this year, 2006. A three hundred million dollar Keppler telescope will continuously monitor a hundred thousand stars scanning for any brief dip in light whenever planets pass in front of its star. During its four year vigil Keppler should pick out even the tiniest star indicating a planet as small as the earth. “The detection of an earth like planet is going to be very difficult” says Fisher; ”It is very challenging and the technical hurdles to overcome. But I believe that in the next decade we have a good chance of actually getting an image of an earth like planet orbiting a near by star.” “To find a smaller object you find a bigger mirror.” Says Swain. “You simply can’t build an enormous mirror so if you hook two small mirrors together in the right way you can simulate a much larger mirror so you can see a smaller object.” Swain has to make sure that light waves arriving at a millionth of a second apart that the two telescopes can be recorded at exactly the same moment.

Type of Star: Yellow Dwarf
Spectral Class: G1V
Distance: 46 Lightyears
Luminosity: 1,82 L
Mass: 1,03 Solar Masses
Surface Temperature: 5800 K

But what if the planet hunters do realize their dreams and find an earth like planet orbiting a star? What would our space faring descendants find once they would arrive there?

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