Chapters 12 and 13
The 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 out
of the photosphere
Figure 11.18a
Prominences
Filaments
Flares and Coronal Mass Ejections
flares
coronal
mass
ejections
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?