Download Ordinary Stars - Edgewood High School

Ordinary Stars
The Colors of Stars
Color of a star is determined by the
peak wavelength of light emitted
The color of a star depends on its
temperature:
Low temperature: Red
High temperature: Blue
Color & Temperature of Stars
Ordinary Stars
Wien’s Displacement Law
As the temperature of a star increases,
the peak of its radiation is shifted toward
shorter (blue) wavelengths
Stefan-Boltzmann Law
As the temperature of a star increases,
the total energy output increases as the
4th power of the temperature
Ordinary Stars
Example:
If one star has a temperature
of 10,000 K and another a temperature
of 5,000 K, how much more energy
does the hotter star put out?
The
first star is 2x hotter. That star puts
out 24 or 16 times as much energy
Ordinary Stars
Spectral Lines
Emission Spectra: Certain wavelengths
of light appear brighter due to the
presence of certain chemicals that are
excited enough to glow
Absorption Spectra: Certain wavelengths
are missing due to a cool gas absorbing
those wavelengths
Spectral Lines
Ordinary Stars
Spectral Types
Different stars show different spectra
A classification scheme was soon
developed
The different spectral types of stars
are classified as:
O B A F G K M
Ordinary Stars
Spectral Types
Type O Star: 30,000 - 60,000 K
Color = Blue
Very short life Burn out quickly
Type B Star: 10,000 - 30,000 K
Color = Blue
Example: Rigel (Orion)
Ordinary Stars
Spectral Types
Type A Star: 7,500 - 10,000 K
Color = Blue/White Strong H, Ca, Mg
lines
Examples: Sirius (Canis major), Deneb
(Cygnus)
Type F Star: 6,000 - 7,500 K
Color = Yellow
Ordinary Stars
Spectral Types
Type G Star: 5,000 - 6,000 K
Color = yellow Example: The Sun
Type K Star: 3,500 - 5,000 K
Color = Red Example: Aldebaran
Type M Star: < 3,500 K
Color = Red Example: Betelgeuse
Variable Stars
Long
Period Variables
Cepheid
RR
Variables
Lyrae Variables
Binary Stars
Pairs
or groups of stars bound by
gravity
Types of Binaries:
Visual
Spectroscopic
Eclipsing
Astrometric
Star Clusters:Open (Galactic)
Clusters
 Shape:
Irregular, no
specific shape
 Where: Galactic
disk
 Types of Stars:
Population I
 Age of Stars:
Young!
Star Clusters:Open (Galactic)
Clusters
Open clusters contain a few dozen to a
few hundred stars
Star Clusters: Globular
Clusters
 Shape:
Spherical
 Where found:
Galactic Halo
 Types of Stars:
Population II
 Age of Stars:
Old
Star Clusters: Globular
Clusters
Globular clusters contain 50,000 to 1
million stars