30.3 Star Groups
Constellations• Constellations:________________________
_____________________________________.
• Standard set of ____ constellations set by group of astronomers in 1930.– Acts as a road map to locate particular stars.
Naming Constellations• ____________________________________
________________________.
• Names come from…– Real animals e.g. Ursa Major, “The Great Bear”
(The Big Dipper)– Imaginary animals e.g.Draco, “The Dragon”– Ancient Gods– Legendary Heroes
Multiple-Star Systems
• Binary Stars : __________________________
______________________________________.
• Barycenter:____________________________
______________________________________.
• Estimated that more than half of all observed stars are multiple-star systems.
Star Clusters• _________: groups of hundreds or
thousands of stars
• Globular Clusters:_____________________
_____________________________________.
• ____________: loosely shaped and rarely contains more than a few hundred stars.
Galaxies• Galaxy:______________________________
___________________________________________________.
• Major building blocks of universe
• Typical galaxy is 100,000 l.y. in diameter and contains 200 billion stars
• Estimated that universe_________________
__________________.
Types of Galaxies• ______________________: has a nucleus of
bright stars and flattened arms that spiral around the nucleus
• Elliptical Galaxies: vary in shape from nearly spherical to very elongated. Extremely bright in the center and have no spiral arms.
• Irregular Galaxies:______________________
________________________________________________________________. More rare than other galaxies.
The Milky Way• Spiral galaxy in which the sun is one of
hundreds of billions of stars.
• ___________________________________________________________________.
• Takes sun 225 million years to complete one orbit.
• Closest galaxies are _____________away from Earth.
Quasars• Discovered in 1963• ___________: quasi-stellar radio source; a very
luminous object that produces energy at a high rate.
• Not related to star but related to galaxies.• ______________________________________
___________________________________________________________.
• Believed that black holes are present in those galaxies
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