Chapters 12 and 13The Sun & Measuring the Properties of

Stars

“We are star stuff”

- Carl Sagan

Reminder...

• star: A self-luminous, gravitationally bound, ball of gas that shines or has shone because of nuclear reaction in its interior

Brown Dwarfs- Failed Stars

• Mass < 8% the mass of the Sun

• And 10-80 times the mass of Jupiter

• First detected in 1995

The Sun and other stars are huge and massive!!!

Figure 11.1

Our Sun

Sunspots• regions of the photosphere that are dark and relatively cool

• corresponds to regions of intense magnetic fields

• Galileo monitored their movement to determine the rotation period of the Sun=about 1 month

Figure 11.16

Sunspots occur when the magnetic field loops outof the photosphere

Figure 11.18a

Prominences

Filaments

Flares and Coronal Mass Ejections

coronal mass ejections

flares

The Earth’s magnetic field protects us!

Sunspot Cycle

Maximum number

Minimum number

Figure 11.23

Sun’s Rotation

Babcock’s Magnetic Dynamo Theory

Binary Stars

binary stars: multiple systems bound by gravity and orbiting each other around their center of mass (double star)

Contact Binary Stars

Star Clusters

Open Cluster Globular Cluster

Open or Globular Cluster?