387 Detected as of November 2009 281 single planets around single normal stars 98 multiple-system planets around single normal stars 1 around red dwarf / white dwarf binary 1 around subdwarf B star / red dwarf binary 1 around pulsar / white dwarf binary 3 orbit single pulsars 1 orbits single subdwarf B star 1 orbits single brown dwarf Exoplanets
Pulsar Planets Two planets discovered in 1992 around the millisecond pulsar PSR These were the first two extrasolar planets discovered, and the first multi-planet extrasolar planetary system discovered, and the first pulsar planets discovered. (b) had period of 66 days and mass of 4.3 Earths. (c) had period of 98 days and mass of 3.9 Earths. Two additional planets of lower mass were later discovered by the same technique
51 Pegasi First exoplanet around a main-sequence star (1995) 50 light-years away Mass: > 1 Jupiter Period: 4 days “ Hot Jupiter”: surface temperature 1000 ° C (1800 ° F)
HD b The planet orbiting this G3 star has one of the most eccentric planet orbits known to date. The 572- day orbit takes it from 0.39 AU to 2.31 AU from its star. It is located in the constellation Aquarius, 137 light-years distant. The water on this world's satellite, if one exists, goes through seasonal periods of melting and refreezing.
HD b HD b is a 1.52 Jupiter mass planet orbiting the K0 star HD177830, located 192 light-years away in the constellation Vulpecula. This planet is likely to be within its habitable zone. A moon found here could have liquid water and look similar to our own home world.
Upsilon Andromedae The first planetary system ever found around a normal star consists of three planets in orbit around Upsilon Andromedae. The innermost (and first known) of the three planets, Upsilon Andromedae b, contains at least three-quarters of the mass of Jupiter and orbits only 0.06 AU from the star. It traverses a circular orbit every 4.61 days. The middle planet contains at least twice the mass of Jupiter and it takes 242 days to orbit the star once. It resides approximately 0.83 AU from the star, similar to the orbital distance of Venus. The outermost planet has a mass of at least four Jupiters and completes one orbit every 3.5 to 4 years, placing it 2.5 AU from the star.
55 Cancri Five confirmed planets (most in any system) The innermost planet (e): 2.8 day orbit, discovered in Mass: 11 Earth masses. The next planet (a), discovered in 1996; 14.7-day orbit. Mass:.824 Jupiters. Planet ( c ), with an orbit of 44.3 days. Mass: 56 Earth masses. The fourth world (f) is the newest discovery, having 45 Earth masses and an orbit of 260 days. It is near the star’s “habitable zone”! The farthest world out (d)has an orbit comparable to Jupiter's. Period: 14.6 years.
Gliese 581 At least four planets are believed to be orbiting Gliese 581. A fourth planet, Gliese 581 e, was discovered in This planet, at an estimated minimum mass of 1.9 Earths, is currently the lowest mass exoplanet identified around a normal star. It takes 3.15 days to orbit Gliese 581- but it’s too hot! Gliese 581 b is at least 16 times as massive as Earth (similar to Neptune's mass) and completes a full orbit of Gliese 581 in only 5.4 days. Gliese 581 c is probably a rocky planet with a radius 1.5 times that of Earth and a mass of roughly five times Earth— or one third that of Neptune. Gliese 581 c orbits just inside of the habitable zone of its parent star. It is notable as it is the planet with lowest minimum mass yet discovered in the habitable zone of another star, making it the most earthlike exoplanet found to date. [ The mean blackbody surface temperature has been estimated to lie between -3 °C (for a Venus-like albedo) and 40 °C (for an Earth-like albedo), however, the temperatures could be much higher (about 500 degrees Celsius) due to a runaway greenhouse effect akin to that of Venus. Gliese 581 c completes a full orbit in just under 13 days. Observations of the star also revealed a third planet, Gliese 581 d, with a mass of roughly 7 Earths, or half a Uranus, and an orbit of 66.8 Earth days. It orbits just inside of the habitable zone of its star, which makes it a potential candidate for being able to support life. “Water world?”
Kepler Mission Launched : March 6, 2009 First Light: April 16, 2009 Checkout Ended: May 13, 2009 Data Collection: 3.5 years Will monitor field of 223,000 stars Should find: ~ 30 outer-orbit giant planets ~ 135 inner-orbit giant planets ~ 640 Super-Earths ~ 50 Earth-mass planets
A New Earth? Within the next 5 years, we will probably find another Earth-like planet – an Earth- sized world in a stable orbit in a HZ of a Sun-like star