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Extrasolar Planets We ride across the universe on a ball of rock tethered to a star The Extra Solar Enclopaedia: http://exoplanet.eu/ GC Lupi with 2.5 MJupiter planet at distance of Neptune Planet Transits Algol Lambda Tau More than half of the known stars actually consist of 2 or more stars in orbit about each other, and in our own case Jupiter might be considered a failed solar companion. There are presently 13 known multiplanet systems. Correlation with Metallicity of Star Mstar = Fe/Hstar / Fe/Hsun Approximately 210 planets have now been discovered in orbit about 10 different nearby stars, whose light spectrum are relatively rich in metals (metallicity ~ MSol). Extra Solar Planets by Mass and Distance Because of the limits of detection, most of these new planets are relatively large (similar to Jupiter in size), but there is a rapid drop off in examples with masses greater than ~ 10Jupiter (the critical mass for deuterium fusion and the formation of so called brown dwarf stars is ~ 13Jupiter), despite the greater ease of detecting larger. Habitable Extra Solar Planets ? Approximately 1/4 of the new planets that have been discovered fall within the water window in terms of distance form their suns, and thus temperature, and they or their satellites may well be capable of supporting life as we know it. water window water window water window water window Brown Dwarf 50 light years away 55 AU First Planet ? Mantle Xenoliths Chondritic Meteorites lherzolite chondrite P P Classification of Stony Meteorites EL (0.8%) Enstatite (1.6%) H (30%) - opx, no oliv - 18% Feo - opx, no oliv - 25% Feo - 15% Feo L (40%) - 6% Feo LL (7%) - 3% Feo EH (0.8%) Ordinary (78%) Chondrites (85-87%) - chondrules - oliv, opx, Feo CV (1%) CO (1%) STONES < 30% Feo (94-97%) Carbonaceous (4.8%) CM (2%) CI (0.8%) Achondrites (10-12%) - volatile depleted - refractory lithophile enriched - refractory inclusions - volatile depleted - matrix < 30% - slight volatile depletion - matrix > 30% - volatile-rich - hydrated silicates - no oliv or chondrules Aubrites - enstatite & Fe alloy Ureilites (0.4%) - shock-melted carbonaceous chondrites? - olivine + Fe alloy, diamonds Lunar - feldspar breccia SNC (1%) - basaltic to ultramafic composition - shocked, young (1.4 bys) - Martian rare-gas isotopic ratios Eucrites (2.8%) - basaltic composition - largely of opx & felds - assoc: diogenites (opx) & howardites (breccias) - old (4.5 bys) MgO Al2O3 SiO2 CaO FeO Total = = = = = = 37.8 4.4 45.0 3.5 8.1 98.8 SiO2 + MgO + FeO ~ 91.1% Mars Moon Venus