Midterm 2 Study Guide
Midterm 2 Study Guide Astr 1010-100
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This 4 page Study Guide was uploaded by Alyssa Karounos on Sunday February 15, 2015. The Study Guide belongs to Astr 1010-100 at University of Washington taught by Dr. Oliver Fraser in Winter2015. Since its upload, it has received 152 views. For similar materials see Introductory Astronomy 1 in Astronomy at University of Washington.
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Date Created: 02/15/15
Exam Two Study Guide 0 Describe the meaning of the individual stellar classi cations 0 What causes this lines is that atoms have particular energy spectrums for their electrons By looking at spectrum lines we deduced that the sun and the universe are made of the same things we are Williamina Fleming devised a system of classi cation of stars based on the strength of the hydrogen lines on a spectra From AO A having the strongest and 0 having the least OBAFGKM letters were chosen because they are most easily distinguished based on hydrogen lines out of all Annie Jane Camp redevised a system of classi cation based on temperature using Fleming s hydrogen line classi cations This gave us 0 stars as the hottest down to M being the coolest OBAFGKM 0 Describe the meaning of the order of star classi cation OBAFGKM O The individual letters tells you temperature of star and strength of hydrogen lines on the spectra The order is from hottest to coolest 0 Explain how we measure stellar temperatures brightness distance luminosities sizes and masses 0 Brightness I Hipparchus s Magnitude scale from 16 If past 6 you cannot see it with the naked eye One is the brightest The scale has extended onward 0 Temperature I Color is a quick measure of temperature using Wien s Law Red is cool yellow is medium and blue is hot The cooler the star the shorter the wavelength 0 Distance I Use the parallaX geometric system to measure distance Extremely hard to do Compare stars with stars that have a distance that doesn t change in the sky 0 Luminosity I With both brightness and distance you can nd luminosity Luminosity is the measure of energy per second Luminosity depends on size and temperature but temperature is more important than size L 0t R2T4 0 Sizes and Mass I Find something falling around a star and use the gravity equation to determine mass This is called the Doppler effect Look at the spectra of a star Also an HR diagram 0 Identify the major steps of stellar evolution in name and on the HR diagram 0 Stars fall on the Main Sequence of the HR diagram following the Turn Off Those with a large mass have a larger luminosity and a shorter life span they will be found on the top left of the diagram A turn off of the Main Sequence begins to happen as the most massive stars begin to evolve first They have more fuel to burn and are burning it at a faster rate Once they begin to run out of fuel they move to the right of the spectra still very luminous but now cooler When the star runs out of hydrogen to burn in its core the burning turns off and the pressure settles down The core is now made up of the helium ash that the hydrogen has burned With a new helium core and hydrogen shell the core begins to burn again Once it burns out all hydrogen core and moves to helium core it goes off the main sequence and become a red giant A star will run out of the hydrogen shell because the helium got so big that the hydrogen cooled off It will now burn all of the helium By burning helium it uses up energy must faster and runs out of helium faster During the burning of helium it rains down carbon gass Now the star has a double shelled core with one shell of carbon and one shell of helium The double shell puffs out all of the molecules and the rest of its atmosphere into the universe This is called Planetary Nebula Once it has puffed out its entire atmosphere and has nothing left it becomes a white dwarf SPECTRAL CLASSES o B A F G K M I I I I I I I 10000 RED GIANT 1000 39 GASEOUS 100 CLOUD 474W PROTOSTAR LUMINOSITY The sun1 being taken as the standard of comparison ES 1 6 6 84 110 100 WHITE DWARF I l I 40000 1 300009 20000 15000 10000 5030quot 4000 3000 SURFACE TEMPERATURE In degrees Kelvin O 0 Rank the ages of clusters based on their colormagnitude diagram 0 All stars in a cluster have the same distance and the same age and therefore we can measure their relative luminosity using the colormagnitude diagram Because all stars in the cluster are the same age and we know that more massive stars have a short life span you can find how old a cluster is by how many red giants and white dwarfs it has 0 Read HR diagrams for Stellar temperature radii and luminosities O Luminosity is on the yaXis temperature is on the XaXis and radius is found on diagonal lines going from the bottom right to the top left a lm giants IIEIEJ e 1i 39l 39 quot j ELI pa gima 3411 1IZI 4 1 r 1 quot V El EHEVEDH I an h duff 39 quotTE ram ImE n R I I i J I4 1151 F J 5 I a iantr 1 tri ing I I 39 D r a 21 n p 41 JD F P mi sultan 5 Iruj E V a Hutu axtznjh aquot J IE E gtEquotkunq inngnu H a sin l Hilda 3 m nth i I 1 LEI27 7 r 77 w iii37712711331 j a E Wlmtzi ija FEE quot33 hzah V a I39Dquot a H d DU QUEEN l E 33m 0 TempErltiu m H O Relate the three main types of spectra to the physical situations that form spectra 0 starlight prism spectrum continuum spectrum 0 starlight then cloud of cool gas cooler than the sun prism absorption light 0 starlight gas from the side prism emission spectrum EH CEIl39Itil39ILlLHTI SDEEU39LHT39I at 39 tr I g ElT39I iSSiEll39l Lil39lE S JEEU39LHTI eg CUM GEE ADSUI DHDH Li B Sectrum nlllllf f a O 0 Absorption lines are light that is absorbed and emission lines are light that is emitted O Relate spectral lines and atomic structure 0 Electrons prefer the ground state of an atom Without added energy If given energy in the form of a photon they can only raise to another energy state or get rid of the energy through light Red holds less energy than blue 0 Explain What makes a star 0 Stars have hydrostatic equilibrium where the balance of weight of gas alone and pressure support the gas in the star It gets hotter the farther you go in Using Emc2 we concluded that the sun must be using Nuclear Fusion not nuclear ssion to produce the energy it has been Bare protons in the star are moving very quickly with positive charges The difference in mass of 4 Hydrogen nuclei turning Helium into energy releases a by product of Helium and lost of energy minus a small fraction of mass After discovering the Neutrino which is the small particles lost in the equation we prove the eXistence of nuclear fusion in a star In the sun the gas is boiling The sun has strong magnetic fields and is made mostly of plasma Sun spots happen because the equator rotates faster than poles which stretches the field lines to become tighter Solar ares are a magnetic field that stretches off of the sun and pushes material into space
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