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