Forms a protostar (1 st stage of a star) The first type of nebulae we are going to explore are called Emission Nebulae, because they emit their own light. Red or pink. A blue relfection nebulae is completely different from an emission nebulae. This is because rather than emitting their own light, they are reflecting the light of the stars around them Although this third type of nebulae is called a planetary nebulae, it actually has nothing to do with planets. A planetary nebulae is formed when a dying sun sized star begins to shed its outer layers.
Gravity pulls the dust and gas into a sphere. As it gets hotter and denser the gases change from Hydrogen to helium and called nuclear fusion
A star can change classifications as it gets older
Huge amount of energy in the core and releases lots of energy (hydrogen to fuse the helium atoms) This is the stage our sun is currently in!
Without hydrogen, gravity wins and causes the star to contract. Stars core temp increases and shell temp decreases Hydrogen loss causes the center of the star to shrink and the atmosphere of the star grows very large and cools to form a red giant or a supergiant. Red giants can be 10 times bigger than the sun and supergiants are 100 times bigger.
No hydrogen left and can’t generate energy by fusion. Can shine for billion of years before they cool Leaves a really hot core. Hot in temperature, but not very bright because it is smaller in size now Can die and become a black dwarf or explode into a nova. The whole process then may be repeated! Or it could supernova and become a neutron star which may turn into a black hole
Hertzsprung compared the brightness and temperature of a stars on a graph. Two years later Norris made similar graphs.
Shows how stars are classified and how they change over time
Modern HR diagram. Temperature is on bottom and luminosity (or absolute magnitude) is on the left side. Hot stars are (blue) on the left and do not stay in main sequence very long. Quickly use up they hydrogen in their cores. Cool stars (red) are on the right. Red stars are low mass stars and remain there a long times and are the oldest stars. Bright stars are at the top and dim stars are at the bottom. The brighteset stars on here are 1 million times brighter than the sun. The dimmest are 1/10,000 as bright as the sun. The diagonal pattern you see is the Main Sequence. This is where the star spends the majority of its life. As they age from the main sequence, they move up and to the righ on the Hr diagram to become giants or supergiants and then down to the left to become white dwarfs. Point out the sun. It is an average star and is in the main sequence.
Remember, the lower the magnitude, the brighter the star
Produce hydrogen fasters than the stars like the sun do. Generate more energy which makes them blue. Explosion is so fierce it may light up the entire galaxy for several days.
After a supernova explodes the materials in the center are squeezed together to form a new star. This is two times bigger than the sun. The particles inside lose their charge and become neutrons. If it is spinning it is called a pulsar. Pulsar sends out beams of radiation. Detected by radio telescopes as clicks, or pulses.
Shows you the star during its explosion on the right, and on the left before its explosion. Picture on the right was taken by the Hubble in 1994. the stars remains form a double ring of gas and dust.
This was the first supernova visible to the unaided eye in 400 years.
Doesn’t gobble up stars like shown in the movies. However, they don’t give off light so locating them can be difficult. If a star is nearby, some gas or dust from the star will spiral into the black hole and give off X rays. These x rays are we how detect black holes.