GALACTIC UNIVERSE
What is a Galaxy? It is a group of billions and billions of stars held together by gravity.
All existing matter; everything Universe All existing matter; everything
Spiral Galaxy Huge; contains stars, gas, and dust Side View Bulge Disk Top View Huge; contains stars, gas, and dust Held together by gravity Pinwheel shape/looks like a hurricane Bulge and thin disk Halo (glow) is present Rich in gas and dust Young and old stars are present
The “Milky Way” galaxy is a spiral galaxy The “Milky Way” galaxy is a spiral galaxy. The Sun is in a spiral arm half-way out from the center.
Map of Milky Way Our Sun(yellow dot) is in a spiral arm, ½-way out
Spiral Galaxy
Spiral Galaxy
Spiral Galaxy
Spiral Galaxy
Huge; contains stars, gas, and dust Held together by gravity Elliptical Galaxy Huge; contains stars, gas, and dust Held together by gravity Round to oval Bulge but no disk Halo is present Little cool gas and dust Mainly OLD STARS are present
Elliptical Galaxy
Elliptical Galaxy
Elliptical Galaxy
Elliptical Galaxy
Irregular Galaxy Huge; contains stars, gas, and dust Held together by gravity No regular shape May show signs of a disk and/or bulge Halo is present Usually rich in gas and dust Young and old stars are present
Irregular Galaxy
Irregular Galaxy
Irregular Galaxy
Stellar Nebula (where stars are born) Nebulae Stellar Nebula (where stars are born) Planetary Nebula (death of a star) Movie
Stellar Nebula
Stellar Nebula
Stellar Nebula
Stellar Nebula
Planetary Nebula
Planetary Nebula
Planetary Nebula
Planetary Nebula
Colliding Galaxies
Orion Constellation Betelgeuse Rigel Betelgeuse is the brightest star in the Orion Constellation. Discuss Betelgeuse’s and Rigel’s apparent magnitude after comparing their size
Recently Betelgeuse showing bubbles and losing mass Recently Betelgeuse showing bubbles and losing mass. Discuss the possibility that it has already become a supernova but it’s light has not reached us yet.
View of an expanding halo of light around V838-Mon at the outer edge of our Milky Way galaxy. The illumination of interstellar dust comes from the red supergiant star at the middle of the image, which gave off a flashbulb-like pulse of light in 2002, becoming 600,000 times more luminous than our Sun. It was thus one of the most luminous stars in the entire Milky Way. The dust and gas was probably ejected from the star after a previous explosion some tens of thousands of years ago.” It is thought that it is in the process of becoming a supernova.
Supernovae
Stellar Nebula Massive Star Neutron Star Red Supergiant Black Hole White Dwarf Planetary Nebula Red Giant Sun/main sequence star Stellar Nebula Protostar Stars form in a nebula from collapsing clouds of interstellar gas and dust. Massive Star Neutron Star Red Supergiant Supernova Black Hole