Our Star, the Sun and The Nature of the Stars

Chapter 18 & 19Sun•Energy source•Interior structure and helio-seismology•Surface features•Atmosphere of the sunNature 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 16By reading this chapter, you will learn

16-8 The nature of sunspots16-9 The connection between

sunspots and the Sun’s magnetic field

16-10 How magnetic reconnection can power immense solar eruptions

Energy source of the sunSteps to Fuse Hydrogen into HeliumStep 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 fusionPP 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 isa) Hydrogen fission, b) hydrogen fusion, c) helium

fission, d) helium fusion, e) uranium fissionClick “enter” to review your answers C, d,b

Watch the Solar blast video• http://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

Photosphere

Zeeman effect

Differential rotation and

magnetic field line

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

• http://sohowww.nascom.nasa.gov/sunspots/

Temperature graph (2)Coronal mass ->solar windChromosphere

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