Chapter 3 Stars and Galaxies

Section 1:Tools of Astronomy Electromagnetic Spectrum Includes radio waves, infrared radiation, visible light, ultraviolet radiation, x-rays, and gamma rays Ranges from long wavelength to short wavelength

Visible light : Complementary Colors Blue and Green lights make the color _________

Visible Light Telescopes Refracting telescope Uses convex lenses to focus on a small area

Reflecting telescope Built by Issac Newton Uses a mirror instead of lenses

Radio Telescopes Used to detect radio waves Let’s review !!

Spectrographs Breaks light from an object into colors and photographs of resulting spectrum Get information about chemical composition and temperatures of stars

Types of visible Spectrum Continuous - Formed by white light Includes all colors of spectrum (ROY G BIV) Dark-line – white light passes through a cool gas Bright-line (emission) – due to a gas that has been heated.

Classifying Stars Stars – sphere of glowing gas due to fusion Classify stars by: size, temperature Brightness (magnitude)

Sizes of Stars Supergiant – Largest – 1000x as big as the sun Giant Medium sized – most stars White dwarf Neutron stars - smallest

Color and Temp of Stars Hottest – Blue (35,000 C) White Yellow Red-orange Coldest – Red (3000 C)

The H-R diagram Shows the relationship between surface temperature of a star and brightness

Lives of Stars Nebula – large amount of gas an dust over a large area Birthplace of stars

Lifetime of Stars How long a stars lives depends on its size. Stars that have more mass than the sun have shorter lives. Stars that have less mass live longer.

Death of Stars Once fuel is gone: White dwarf star (when small or medium stars die) A neutron star (form when giant stars die) Black hole – form when massive stars die)

Black hole

Constellations Not really a group of stars – just looks that way 88 constellations

Circumpolar constellations Seen all night long in the northern hemisphere

Orion

Ursa Major

Ursa Minor (little bear)

Cassiopeia

Cepheus

Draco

Galaxies A giant structure in the universe that contains millions of stars Milky Way the galaxy our sun is in

Three types of galaxies: Spiral galaxies Center of Milky way is about 25,000 light years away.

Elliptical Galaxies “flattened balls” Contains old stars Not a lot of gas and dust

Irregular Galaxies No real shape