Download Characteristics of Stars

Characteristics of Stars
Star classification
• Stars are classified
based on the
following
characteristics:
Size, Temperature/color
and Brightness
Size (smallest to largest)
Neutron star
White dwarf
Medium (Sun)
Giant
Super giant
Temperature/Color (coolest to
hottest)
• Red (3,200 degrees C)
• Yellow (Our sun 5,500
degrees C)
• White-blue (15,000
degrees C)
Brightness of Stars
• Absolute magnitude – measure of the
amount of light given off by a star
• Apparent magnitude – a measure of the
amount of light received on Earth
(a dim star can appear bright if its close to
Earth; a bright star can appear dim if its far
away)
H-R Diagram
(Hertzbrung and Russell)
Stars with higher temperatures have greater
absolute magnitudes
H-R Diagram con’t
• 90 % of stars are
main sequence stars
• White dwarfs are hot
but not bright
• Giants/super giants
are bright but not hot
Measuring distances to stars
• Measure parallax – the
apparent shift in the
position of an object when
viewed from two different
positions.
• Knowing the angle that
the star’s position
changes and the size of
Earth’s orbit, astronomers
can calculate the distance
of the star from earth.
Light year
• *** is a measure of distance, not time!
• Unit representing the distance light travels
in one year – (300,000 km/sec) or about
9.5 trillion km/year used to record
distances between stars and galaxies
• Proxima Centauri is 4.3 light years away
• Looking back in time
Constellations
• Pattern of stars
• Example: Orion
• Rigel (blue)
• Betelgeuse (red)
Constellations
• Constellations change due to the Earth’s rotation
and revolution
• According to the H-R
diagram, as a star’s
temperature
increases its
brightness ________.