Astro 101 12-1 - Astro 101 12-1 Life elsewhere in the...

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Astro 101 12-1 Life elsewhere in the universe Habitable Planets A habitable world contains the basic necessities for life as we know it, including liquid water. It does not necessarily have life. We know that about 10% of stars have planets, but so far we would not have been able to detect a terrestrial planet We can infer from theoretical understanding of planet formation that two likely go together Constraints on star systems: 1) Old enough to allow time for evolution (rules out high-mass stars – 1%) 2) Need to have stable orbits (might rule out binary/multiple star systems – 50% or even some stars with known planets) 3) Size of habitable zone region in which a planet of the right size could have liquid water on its surface Even so billions of stars in the MW seem at least to offer the possibility of habitable worlds The more massive the star, the larger the habitable zone – higher probability of a planet in this zone Kepler (2009 launch) will monitor 100000 stars for transit events for 4 years
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Astro 101 12-1 - Astro 101 12-1 Life elsewhere in the...

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