Our Star, the Sun and The Nature of the Stars Chapter 18 & 19 Sun Energy source Interior structure and helio-seismology Surface features Atmosphere of the sun Nature of the stars Distance – parallax Motion of the stars – proper and radial motion Spectral types H-R diagram Binary systems By the way, how is your research going?

16-1 The source of the Sun’s heat and light 16-2 How scientists model the Sun’s internal structure 16-3 How the Sun’s vibrations reveal what lies beneath its glowing surface 16-4 How scientists are able to probe the Sun’s energy-generating core 16-5 Why the gaseous Sun appears to have a sharp outer edge 16-6 Why the upper regions of the solar atmosphere have an emission spectrum 16-7 The relationship between the Sun’s corona and the solar wind Chapter 16 By reading this chapter, you will learn 16-8 The nature of sunspots 16-9 The connection between sunspots and the Sun’s magnetic field How magnetic reconnection can power immense solar eruptions

Energy source of the sun Steps to Fuse Hydrogen into Helium Step 1: 2 protons or hydrogen nuclei, combine to form a 2H. also produces a neutrino (n ), a neutral, nearly massless particle, & positron (e+). This positron encounters an electron (e-), annihilates to produce gamma-ray photons ( ). Step 2: 2H combines with a third proton, forming an isotope of helium (3He) and releasing another gamma-ray photon. Step 3: 2-3He nuclei formed 4He and releasing two protons. The gamma- ray & KE, are the source of the Sun's energy.

H fusion PP chain Neutrino detection?

Interior structure

How are you doing? The sun is the largest object in the solar system: the sun’s diameter is about __ than Earth. a) In order of million times larger, b) 1300 times larger, c) 100 times larger, d) 10 times larger The sun generates energy at: a) The surface ( photosphere), b) anywhere in the sun, c) only at the core which takes up about 50% in radius, d) none of the above Sun’s energy source is a) Hydrogen fission, b) hydrogen fusion, c) helium fission, d) helium fusion, e) uranium fission Click “enter” to review your answers C, d,b

Watch the Solar blast video player/science/space-sci/solar- system/solar-blast-sci.htmlhttp://video.nationalgeographic.com/video/ player/science/space-sci/solar- system/solar-blast-sci.html Is the sun a peaceful ball of gas? How hot is the core of the sun? What are / what causes the sun spots? What is a solar blast? Effect on earth?

Photosphere

Zeeman effect Differential rotation and magnetic field line

Go to the SOHO link. Is there any significant sun spot today? s/

Temperature graph (2) Coronal mass ->solar wind Chromosphere

1.The convective current on the sun creates: a) granulations, b)Sunspots, c) solar wind, d) tide on Earth 2.Who was the first person to observe the sunspots? a) Hubble, b) Aristotle, c) Hipparchus, d) Galileo 3.What are sunspots? a) Permanent marking on the sun’s surface. b) higher temperature than surroundings, c) lower temperature than surrounding. d) made of different material than surrounding. (like storms on Jupiter) 4.Zeeman effect measures: a) temperature, b) mass, c) electric field, d) magnetic field Click “enter” to review your answers A,d, c, d