STARS,GALAXIES&COSM ASTRO 150
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This 3 page Class Notes was uploaded by Solon Leuschke on Sunday September 27, 2015. The Class Notes belongs to ASTRO 150 at Iowa State University taught by Staff in Fall. Since its upload, it has received 11 views. For similar materials see /class/214518/astro-150-iowa-state-university in Astronomy and Astrophysics at Iowa State University.
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Date Created: 09/27/15
As1iu15EI Fail 2mm Lecluie 17 new Reading Chapter 18 Sect 181 71 83 Homework handed out In recitation due In Lecture Tuesday October 26 Exam 2 Thursday October 28 essay next Tuesday Brief review of last time Stellar Evolution 0 White Dwarf Stars 0 hot but faint gt very small Sirius B 0 supported by electron degeneracy pressure 0 evolution through cooling 0 Final evolution 8MSLlrl lt M lt 25M 0 burns C etc but with diminising efficiency 0 onionskin structure 0 iron burning eats energy 0 Supernova 0 iron core collapse rebound in seconds 0 synthesis of all heavy elements 0 expanding supernova remnant 0 Neutron Stars 0 supported by neutron degeneracy o M 2Msun R 20 km density 1014 gcc 0 small and very faint sun Discoverv of Neutron Stars Pulsarwsmni i i g 0 1967S Jocelyn Bell discovers a radio sig 0 regularly pulsing 0 rapid once every 133 seconds PSR 0229 0 extraterrestrial 0125 0 aliens LGM ILGM2 0 Neutron stars 0 1968 Tommv Gold and Franco Pacini 0 pulsars are rapidly rotating neutron stars 0 beaming by e in magnetic field 0 NS rotation sweeps beams 0 confirmed by measures change in spin rate 1974 Nobel Prize to Tony Hewish i iig i Bell39s advisor 39 34w neumm SIB quot mimicn axla Asimianraiiznm Lecimenpage 6 Pulsars a new tool for astronomv and DhVSics Crab Pulsar 0033 s 0 Binary Pulsars precise tests of general relativity 1993 Nobel Hulse ampTayor PSR 1937 0 Millsecond Pulsars 0001675 recycled pulsars spun up by companion Don Backer 0 Black Widow Pulsars pulsar blasts away its companion Dan Stinebring 0 Pulsars with Planets timing jitter gt planet sized companions AlexWolsczan As17u 15 Fall 2mm Lecluve 17 page 5 M gt 25 Msun 39 iron core gt 5 M 39 even neutron degeneracy can39t stop collapse 0 complete gravitational collapse to 0 Why black 0 Escape velocity u from Earth 113 kms 25400 mph I from Sun 600 kms 1350000 mph from a WD 5000 kms from a NS 200000 kms 23 the speed of light 0 1783 John Mitchell escape velocity gt speed of light when R lt Rsch 3 km x MMsun As17u 15 Fall 2mm Lecluve 17 page a 1905 Albert Einstein 0 NOTHING can travel faster than light 0 the ultimate speed limit is 300000 kms 0 near Black Holes light cannot escape 0 no light 2 no information 0 EVENT HORIZON point of no return 0 Within Event Horizon central singularity 0 Anything that enters the Event Horizon loses contact with the rest of the Universe forever 0 Life near a Black Hole 0 far outside d gtgt Rsch feel gravity as elsewhere 0 just outside tidal forces 0 inside d lt Rsch cut off from Universe As17u 15 Fall 2mm Lecluve 17 page 7 The Black Hole Environment 0 Dangerous tidal forces are enormous D As17u 15 Fall 2mm Lecluve 17 page a The Black Hole Environment 0 Dangerous tidal forces are enormous The Black Hole Environment 0 Dangerous 7 tidal fomes are enormous 0 strange views 7 graintauonal bending of light 0 warped time 7 grainty near a black hole slows down me with respect to ouiside observers Black holes and time machines Monster Black Holes in Galaxy Cores How can we find a black hole39r 0 They exert a gravitational force find a binary siar With an unseen companion M gt 5 MSW 0 They suck sortof o surrounding matter may iaii Into UK 0 gas iaiiing in 9eu squeezed 39P eaLs L o glows as XrRays 0 Best candidate Cygnus X i o Vlslble star 09 20 Mm spectroscopic binarycompanion 10 Msun o copious eray emission Speciium oi Gas Disk in Active Galaxy M87