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Proper motion using transverse line and distance from

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Proper motion – Using transverse line and distance from sun to star (triangulationmethod as well) to find proper motionTemperature:oWein’s law (color temp relationship)oSpectral class ( O hot – M cool) classification of stars
Luminosity:oMeasure’s stars apparent brightness & distanceoCalculate by inverse square lawSurface/Atmosphere Composition:oSpectral lines/absorption lines observed in starNebulae:Def: Clouds of gas & dust between starsoGas: individual atoms such as hydrogen (71%) & helium (27%)oDust: larger molecules, such as silicates, carbon compounds, ash and they absorboptical lightoTemp = Aroun 10 K (-441 F)Birth of a star/formation:1.Low temperature of gases in nebulae lead to low pressure to supportagainst gravitational collapse2.Gravity causes swirls and ripples to form leading in clumpy, non-uniform, smaller, warmer & denser clumps (cloud fragments)3.These clumps then form intoprotostars& remaining gas & dustsurrounding star formsproto planetary disk4.These gas & dust particles due to twisting magnetic field can alsocreate ‘jets5.Gravity continues to pull material in due to dense core6.Heats to 7 mill K & eventually hydrogen fusion begins7.Protostar continues to increase in size by collecting material (accrete) from disk for106years8.Wind blows away additional/surrounding dust to stop accumulation of additionalmaterialoOther plants can eventually form from the proto-planetary diskBipolar outflow/JetsoJets create bipolar outflow around proto staroSeen @ radio wavelengthoCan be 1 light year longWeek 5, Lecture 2Protoplanetary diskoPlanets form out of this material due to collisionoSmall rocks bump into each other & stick to one anothereventually reachingplanet sizeExoplanetsoPlanets around other stars
oFind exoplanets using three methods:1.Doppler shift-Planets cause stars to wobble & create small doppler shifts2.Shadow-Planets create a shadow when they pass Infront of star-Small decrease in brightness of star3.Taking a pictureoSome planets live around binary stars (two stars can be seen),can have ‘double sunsets’Proxima CentaurioRed dwarf star (M type- smaller & cooler than earth)o4.25 light years awayoFound using Doppler shiftPlanet BoExoplanet orbiting within habitable zone of closest start (Proxima Centauri) to suno4.2 light years away (1.3 parsec, 40 trill km or 25 trill miles)Life of a StaroHydrostatic equilibrium (forces of outer gravity cancels internal gas pressure)oInternal gas pressure produced by nuclear fusion (converting hydrogen to helium) visproton proton chainoOnce hydrogen runs out the star dies, either1.Quietly into a white dwarf2.Violently into neutron star or black holeDeath of a staroOnce hydrogen runs out, core heats up to 100 mill degreesoDue to heat & pressure three helium nuclei fuse to form carbonprocess calledTriple Alpha processMass & deathoLifetime of a star heavily depends on its massoAlso helps to determining what material a star will burn (Helium, Carbon…)oTwo different types of deaths based on mass:1.Low mass stars2.

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Term
Spring
Professor
GraemeSmith

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