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The Sun, our favorite star!

The Sun, our favorite star!. WE CAN SEE IT REALLY WELL. The Sun is the basis for all of our knowledge of stars. Why?. Kelvin Temperature Scale. Today we will take a journey from the center of the Sun, starting just outside the core…. …and ending up deep in the corona.

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The Sun, our favorite star!

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  1. The Sun, our favorite star! WE CAN SEE IT REALLY WELL. The Sun is the basis for all of our knowledge of stars. Why?

  2. Kelvin Temperature Scale

  3. Today we will take a journey from the center of the Sun, starting just outside the core… …and ending up deep in the corona.

  4. Overview of Solar Structure(aka, our Sun as a jawbreaker) The Sun is made of mostly HYDROGEN and HELIUM • Main Parts: • Corona • Chromosphere • Photosphere • Convection Zone • Radiative Zone • Core

  5. Rotation 25 Days at the Equator 35 Days at the Poles

  6. This twisting leads to the loopy structures we see!

  7. p p p n n p p p The Core Fusion takes place here. + Energy 4H 1He http://astro.unl.edu/classaction/animations/sunsolarenergy/fusion01.html Fusion Animation

  8. The interior of the Sun… • Energy is generated in the core, but how does it get out and end up as sunshine? The next two layers of the Sun are all about getting the energy being made in the core out into space!

  9. How does energy get from one place to another? 1. Convection 2. Conduction 3. Radiative Diffusion Convection and Radiative Diffusion are most important for the Sun!

  10. Radiative Diffusion The photons “diffuse” outwards, heating the gas as they go. Ionized gas • Photons can “scatter” off of unbound electrons • When they scatter, the photons share their energy with the electrons • The electrons get hotter

  11. Ionized gas The Radiative Zone Here, photons bounce around in a “random walk” Eventually they make it out of the radiative zone, but it takes a long, long time!

  12. Convection Hot stuff rises… Cool stuff sinks! Hot water goes up to the surface while cool water sinks down -- cool water then gets heated and rises a.k.a: BOILING

  13. The Convective Zone Photosphere The Convective Zone is the layer just under the photosphere Convective “cells”: As seen from the top, these are the granules we see in the photosphere

  14. Conduction Metal of the pan heats by conduction… …heat travels through the atoms of the pan Not very important for stars!

  15. PHOTOSPHERE • Characteristics • the part of the sun we see • one of the coolest parts at 6000K • densest part of solar atmosphere • contains sun spots, granules (ation)

  16. Photosphere temperature is about 5800 K… • Remember how the temperature and color of stars are related? The temperature of our Sun gives it its yellowish color! Our Sun is really yellowish green, but our atmosphere absorbs and scatters some of the blue light.

  17. The photosphere has some interesting features too… Sunspots: Regions where magnetic field pokes through the photosphere. Sunspots are cooler than surrounding stuff, so they look dark! Granules: Where the roiling, boiling convection zone underneath bubbles up.

  18. Sunspots • dark cooler (4000K vs. 5800K) regions on the sun • last several days to several weeks • caused by the sun’s magnetic field upwelling to the • photosphere • occur in cycles • contribute to solar storms such as flares and coronal • mass ejections

  19. Sunspot pairs Describe what you see in this image to someone in class

  20. Explain what you see in this picture to someone else in class.

  21. Granulation • Cover the sun’s surface • approx. 1000km across • (Texas sized) • tops of convection cells • white centers are hotter • than dark edges • flow can be up to • 15000 mph • individual cells last • 20 min

  22. http://www.youtube.com/watch?v=zxzhfijFML8&feature=related

  23. CHROMOSPHERE • Characteristics • red color due to hydrogen emission lines • temperature 4500K to 10000K • prominences form here • 2500 km thick • spicules (jets of plasma) form here

  24. Spicules • small jet like eruptions that last a few minutes • send material out into corona at 20-30 km/s

  25. TRANSITION REGION • Region of rapid temperature change between • chromosphere and corona

  26. THE CORONA • temperature 1-3 million K • very irregularly shaped • strong x-ray emitter • uncertain as to why it is so hot • coronal holes are the origin of the • solar wind • produces an absorption and • continuous spectrum • http://www.nasa.gov/mission_pages/sunearth/news/colorful-science_prt.htm

  27. Coronal Mass Ejections • Huge bubbles of gas ejected • from the sun • Can cause problems with • communications • Often occur with flares

  28. SOLAR WIND • low density gases (ionized hydrogen) • travels 300 to 1000km/s • sun loses 10,000,000 tons of mass per year Current Solar Wind Data can be found at www.spaceweather.com

  29. A short Video Earth to scale. Yes, really.

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