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Spectra and Stars How do colors in a spectrum help us understand stars? Image from http://upload.wikimedia.org/wikipedia/commons/c/cd/Embryonic_Stars_in_the_Rosette_Nebul a.jpg (C) Copyright 2014 - all rights reserved www.cpalms.org We can’t go to stars and planets to see what they are like. Deep space image from http://upload.wikimedia.org/wikipedia/commons/2/21/Hubble_Ultra_Deep_Field_NICMOS.jpg So we learn about them by studying the light that they emit or reflect. (C) Copyright 2014 - all rights reserved www.cpalms.org Thinking about the spectra activity, what evidence do you have that we can learn something about stars from their light? 1. From Activity 1 about adding light……. 2. From Activity 2 about using c-spectra and colored . filters……. 3. From Activity 3 about light from a hot gas……… (C) Copyright 2014 - all rights reserved www.cpalms.org NASA: Spectroscopy in Action PLAY VIDEO (C) Copyright 2014 - all rights reserved www.cpalms.org https://www.youtube.com/watch?v=oRm0z8ggJSk The color of light is the wavelength. Visible light ranges in wavelength from ~400 to ~700 nanometers. But visible light is only a small part of the electromagnetic spectrum. (C) Copyright 2014 - all rights reserved Image from http://science.hq.nasa.gov/kids/imagers/ems/visible.html www.cpalms.org Light is energy …….. energy travels in waves........ waves have properties! Waves only transfer energy without the physical movement of material from one location to another. Light travels through space at 300,000,000 m/s. One property of a wave is the wavelength – the distance between successive wave peaks. Electromagnetic waves are transverse waves. (C) Copyright 2014 - all rights reserved Image from www.cpalms.org Light travels as a wave in an infinite spectrum of electromagnetic radiation. The range of all possible frequencies of electromagnetic radiation is called the electromagnetic spectrum. The wavelength of an EM wave is inversely proportional to its frequency and also to it’s energy. The shorter the wavelength, the higher the frequency and the more energy the wave has. Image from http://en.wikipedia.org/wiki/Microwave#mediaviewer/File:EM_spectrum.svg (C) Copyright 2014 - all rights reserved www.cpalms.org CONTINUOUS SPECTRUM Light is separated into its various wavelengths using a piece of glass called a prism. A rainbow is an example of continuous spectrum. Image from http://commons.wikimedia.org/wiki/File:Spectral_lines_continous.png Another Image that shows the experiment can be viewed at http://astronomy.nju.edu.cn/~lixd/GA/AT4/AT404/HTML/AT40401.htm (C) Copyright 2014 - all rights reserved www.cpalms.org EMISSION & ABSORPTION SPECTRUM Occur when the light coming from a gas is passed through the surfaces of a prism or c-spectra. Depending on whether or not the gas cloud is in front of a blackbody object, the spectrum will either be an emission line spectrum or an absorption line spectrum. Image from http://commons.wikimedia.org/wiki/File:Visible_spectrum_of_hydrogen.j pg Another Image that shows the experiment can be viewed at Image from http://astronomy.nju.edu.cn/~lixd/GA/AT4/AT404/HTML/AT40401.htm (C) Copyright 2014 - all rights reserved www.cpalms.org Different Types of Spectra Each element has different emission lines which show the same colors that are missing in the absorption line. Image from http://commons.wikimedia.org/wiki/File:Visible_spectrum_of_hydrogen.jpg and Image from http://commons.wikimedia.org/wiki/File:Spectral_lines_continous.png Another Image that shows a comparison can be viewed at (C) Copyright 2014 - all rights reserved http://www.extremetech.com/extreme/167878-every-color-of-the-suns-rainbow-why-arewww.cpalms.org there-so-many-missing Each atom of a given element is unique and has unique properties, including what kind of color is emitted when it’s heated. Images from http://commons.wikimedia.org/wiki/File:Periodic_table_large.png (C) Copyright 2014 - all rights reserved www.cpalms.org Hydrogen Emission Spectrum Absorption Spectrum Image from http://commons.wikimedia.org/wiki/File:Visible_spectrum_of_hydrogen.jpg What is the difference between Emission and Absorption Spectra? The emission lines emit the color / wavelength. Absorption lines absorb the same color / wavelength. (C) Copyright 2014 - all rights reserved www.cpalms.org Identifying Absorption Lines of a Star Image from http://upload.wikimedia.org/wikipedia/commons/d/d7/Cumulative-absorption(C) Copyright 2014 - all rights reserved spectrum-hubble-telescope.jpg www.cpalms.org Sun’s Absorption Spectrum Black lines are caused by gases on, or above, the Sun’s surface that absorb some of the emitted light. Image from http://www.extremetech.com/extreme/167878-every-color-of-the-suns-rainbow-why-are-there-so-many-missing The Mystery???? Some lines are not identified. Are they produced by elements that don’t exist on Earth? (C) Copyright 2014 - all rights reserved www.cpalms.org Ultraviolet Image of the Sun Ultraviolet (UV) light waves are invisible to the human eye. Image from http://missionscience.nasa.gov/ems/10_ultravioletwaves.html (C) Copyright 2014 - all rights reserved www.cpalms.org If we change the detector, we can ‘see’ these shorter wavelengths. X-ray Image of the Sun X-ray detectors are used by scientists to see and record the energy within the corona. Data was collected by x-ray detectors on satellites in orbit around the Earth by the Japan's Hinode spacecraft. Image from http://missionscience.nasa.gov/images/ems/emsXRays_mainContent_xraysun.png (C) Copyright 2014 - all rights reserved www.cpalms.org Different Types of Telescopes and Detectors Used to study the light from planetary images and satellite imagery. First telescope - Galileo in 1609. The eye detects visible light only. Radio telescopes - detects the very longest wavelength of light. Space Telescopes - detects different wavelengths, like X-ray, ultraviolet and infrared. Space Telescopes - operate in space to avoid the obscuring effects of our atmosphere. Hubble Space Telescope - Optical Spitzer Infrared Observatory (C) Copyright 2014 - all rights reserved www.cpalms.org Chandra X-ray Observatory Images from http://www.nasa.gov/mission_pages/