Morgan BellAmateur astronomers discover extra-solar planet
May 22nd 2006 07:31
Artist's impression of a planet in transit
The team was led by Peter McCullough of the Space Telescope Science Institute in Baltimore, who said on a HubbleSite media release: "This discovery suggests that a fleet of modest telescopes and the help of amateur astronomers can search for transiting extrasolar planets many times faster than we are now." The team used what they call an “XO telescope”, which, McCullough estimates, costed $60,000 to build, and much more for software.
The planet was discovered by the relatively new transit method of detecting extrasolar planets. The method is explained on NASA’s Kepler Mission website as follows:
“When a planet crosses in front of its star as viewed by an observer, the event is call a transit. Transits by terrestrial planets produce a small change in a star's brightness of about 1/10,000 (100 parts per million, ppm), lasting for 2 to 16 hours. This change must be absolutely periodic if it is caused by a planet. In addition, all transits produced by the same planet must be of the same change in brightness and last the same amount of time, thus providing a highly repeatable signal and robust detection method.
Once detected, the planet's orbital size can be calculated from the period (how long it takes the planet to orbit once around the star) and the mass of the star using Kepler's Third Law of planetary motion. The size of the planet is found from the depth of the transit (how much the brightness of the star drops) and the size of the star. From the orbital size and the temperature of the star, the planet's characteristic temperature can be calculated. From this the question of whether or not the planet is habitable (not necessarily inhabited) can be answered.”
(image from Hubblesite)
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