Chapter 2 Stars Section 1 Stars
COLORS OF STARS • Which flame is hotter? • How do you know? • Color • Red = Cool • Blue =HOT
Orion Which star is hotter? Rigel or Betelgeuse? • Rigel!! It is Blue hot!! • Betelgeuse is Red cool
Composition of stars • Stars are made of different elements in gaseous form • The inner layers of a star are dense and hot. • The outer atmosphere is made of cooler gases. • Elements in the atmosphere absorb wavelengths of light that are emitted by the inner layers. • How can this help Astronomers? • Astronomers look at the stars spectrum and detect the missing colors to the spectrum and they can tell what elements are in atmosphere absorbing that portion of the spectrum.
The Colors of Light A Prism creates a continuous spectrum
Spectrograph A spectrograph is used to break starlight up into their spectrums. Astronomers can calculate a stars composition and temperature from these spectrum.
Make an ID Emission lines are made when certain wavelengths of light are given off by “hot” gases . Each element has it’s own unique set of emission lines. This is like a finger print for that element.
Absorption Spectrum An absorption spectrum forms when “hot” gases produce a spectrum, then passes through a cooler atmosphere and some of the wavelengths get absorbed. The pattern of lines in the star’s absorption spectrum helps detect the elements that are present in that stars atmosphere.
All stars are different, but how are they classified? • Stars are classified by brightness and temperature. • Stars are classified in order of highest to lowest temperatures.(OBAFGKM) • hottest stars being classified as O • coolest stars being classified as M. • Star’s are also classified according to their brightness.