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Discovering exoplanets in the habitable zone via gravitational attraction and observational methods like Kepler mission. Learn about the scale of our solar system, planet detectability, and the influence of supermassive black holes.
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Exoplanet detection (500+) Gravitational attraction between a stellar mass (sun) and planets (bigger the better, why?) makes sun’s position wobble about barycenter. Big question is: How many planets are in life-zone where liquid water is stable? Life zone is where a sun’s luminosity and a planet’s orbital radius are correct: the green zone below. The red zone is too hot (Mercury-like) and the blue zone is to cold and makes gaseous planets (Jupiter-like) 2 detected exoplanets to scale for planet orbital radius (planets not to scale!) Our solar system to scale for Jupiter and Saturn orbital radius
Exoplanet detection methods Direct observation infrared Transit method: light dims Radial velocity wobble (Doppler shift)
Kepler mission (launched 2009): watching 100,000 nearby stars. We will know statistical probability of earth-like planets (liquid water) in 4 years The Kepler-scope: measure 100,000 stars brightness (photometry) at same time (wide view field) to find planets The local structure of our Galaxy, the Milky Way. The stars sampled are similar to the immediate solar neighborhood. Young stellar clusters, ionized hydrogen (HII) regions and the neutral hydrogen (HI) distribution define the arms of the Galaxy.
Predicted Exoplanet detectability Stellar mass (our sun masses) Planet orbit (earth-sun distance (AU)) • Kepler’s third law: T2 ~ R3 • Giant planets based on transits • 135 inner-orbit planets • Densities for 35 of the inner-orbit planets, and 30 outer-orbit planets. • Terrestrial inner-orbit planets • 50 planets if most have R ~ 1.0 Re • 185 planets if most have R ~ 1.3 Re • 640 planets if most have R ~ 2.2 Re • Giant inner planets based on reflected light • About 870 planets with periods less than one week
Suns orbits around 4 million solar mass black hole at galactic center of milky way galaxy A black hole has the biggest gravitational pull of any object. The gravity is so strong that the mass-energy of light is frozen in time on the event horizon so that no radiation is emitted. Gravity makes time run slow. At the black hole event horizon time stops and all energy-matter dissapears into the singularity.
Galactic core black-hole sun motion for 8 yrs Gravity is a busy force moving stuff around rapidly
Supermassive black holes at center of most all galaxies Andromeda central SM blackhole Milky way galaxy center