Properties of Stars Apparent Magnitude the brightness of
Properties of Stars • Apparent Magnitude: the brightness of a star as it appears from Earth. – Size – Temperature – Distance • Absolute Magnitude: how bright the star actually is. – Two stars with the same apparent magnitude may not have the same absolute magnitude. – Two stars with different apparent magnitude may have different absolute magnitude.
Properties of Stars • Color and Temperature – Stars with the highest temperatures appear blue (53, 500 o. F). – Stars with middle temperatures appear yellow (8, 500 -10, 300 o. F). – The coolest stars appear red.
Properties of Stars • Hertzsprung-Russell Diagram: shows the relationship between the absolute magnitude and the temperature of the stars. – Temperature is also related to size: the bigger the size of the star, the Cooler the temperatures.
Properties of Stars • Binary Stars: pairs of stars that orbit each other. – These stars are used to determine the stars’ masses. – The stars move in a circle around a center of mass. • If the center of mass is directly in the middle between the 2 stars, the masses are the same. • If the center of mass is closer to one of the stars, then that star is larger.
Properties of Stars • Variable Stars: stars that fluctuate in brightness. – Cepheid variable star: brightness alternates at a regular interval called a light period. (Bright dim bright, etc. ) – Nova: sudden brightening of a star usually due to a nova eruption. • The brightest moment is seen within a few days, remains bright for a few weeks, then returns to normal brightness within a year.
Properties of Stars • Nebulae (interstellar matter): clouds of dust and gases. – If this matter gets too close to a hot star, it will glow. – This is known as a bright nebulae. – There are two types of bright nebulae. • Emission Nebulae: turns energy into visible light which fluoresces. • Reflection Nebulae: dense clouds of dust reflect the light from nearby stars
Assignment • The Hertzsprung-Russell Diagram Worksheet
- Slides: 7