An artist's concept of a planetary system

A planetary system consists of the various non-stellar objects orbiting a star such as planets, moons, asteroids, meteoroids, comets, and cosmic dust.^[1][2] The Sun together with its planetary system, which includes Earth, is known as the Solar System.^[3][4]

Origin and Evolution

An artist's concept of a protoplanetary disk

Some planetary systems may form differently, however. Planets orbiting pulsars—stars which emit periodic bursts of electromagnetic radiation—have been discovered by the slight variations they cause in the timing of these bursts. Pulsars are formed in violent supernova explosions, and a normal planetary system could not possibly survive such a blast—planets would either evaporate, or the sudden loss of most of the mass of the central star would see them escape the gravitational hold of the star. One theory is that existing stellar companions were almost entirely evaporated by the supernova blast, leaving behind planet-sized bodies. Alternatively, planets may somehow form in the accretion disk surrounding pulsars.^[6]

List of planetary systems

Artist's concept of a distant planetary system

Our solar system compared with the planetary system of 55 Cancri

• Solar System ? The Sun and its planetary system, the first such system discovered
• PSR B1257+12 ? the first extrasolar planetary system discovered, the first pulsar planetary system discovered, the first multi exoplanet system discovered
• Upsilon Andromedae ? the first multiplanet extrasolar planetary system discovered around a main sequence star, found to be so in April 1999
• PSR B1620-26 ? the first multistar planetary system discovered.
• 55 Cancri ? the largest extrasolar planetary system discovered (5 known planets as of November 6, 2007, along with a distant stellar companion.)^[7]
• Gliese 876 ? the first system around a red dwarf star and the first discovered to be in an orbital resonance
• HD 69830 ? found to have three Neptune-mass planets and an asteroid belt, all within 1 AU ^{[8] [9]}
• 2M1207 ? the first imaged system and the first brown dwarf system with a planet discovered ^[10]
• Gliese 581 - first extrasolar system discovered with a planet located within the habitable zone (Gliese 581 c)^[11]
• Mu Arae - The system's innermost planet was the first "hot Neptune" to be discovered
• HD 188753 - The first triple star planetary system discovered
• HD 37124
• HD 12661
• HD 73526
• 47 Ursae Majoris
• Epsilon Eridani
• 14 Herculis
• UX Tau A

See also

• Extrasolar planet
• List of stars with confirmed extrasolar planets
• Stellar nursery
• Stars and planetary systems in fiction

References

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