All about Stars Sections 9.2 & 9.4

Star Brightness Stars are giant balls of hot gases that produce and emit energy (much In the form of visible light) The total amount of energy produced by a star per second is called luminosity. Things appear brighter when they are closer.

Star Colour & Temperature The colour gives scientists an indication of the temperature.

The Mass of a Star The sun has a mass of 2.0 x 1030 kg and this is one solar mass Star masses range from approx. 0.1 to 120 solar masses!

Life Cycle of a star

Star beginnings A star has its beginning deep inside a massive cloud of interstellar gases (mainly hydrogen) and dust called a nebula. A star is formed when parts of the nebula collapse on themselves

protostars Massive concentration of gas and dust thought to eventually develop into a star after the nebula collapses. Overtime a protostar becomes a tightly packed sphere of matter which increases its gravity. This allows nuclear fusion to begin.

Nuclear Fusion Occurs at 15 million c Hydrogen atoms “fuse” to make helium atoms

The Death of A star Medium Stars (SUN) red giant  White Dwarf When H runs out the flow of energy slow. The core contracts and gets hotter forming a red giant. When nuclear fusion stops the outer layers of the star drift away and the core is the only part left (white dwarf)

Large Stars  Supernovas When fusion stops the star collapses under its own gravity. The explosion sends out shockwaves when it explodes (supernova) Neutron Star – dense star made of neurons (initial star 10-29 solar masses) Black Hole – dense quantity of matter in space from which no light or matter can escape (initial star greater than 30 solar masses)

A Summary

Today’s Tasks Pg. 373 #1, 3, 7, 9 Pg. 382 #6