Explorations: Introduction to Astronomy (Arny), 6th EditionChapter 15:
Stellar Remnants: White Dwarfs, Neutron Stars, and Black Holes <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0010202009/220722/chapter15.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (213.0K)</a>]]>- We live in the Milky Way galaxy.
- It contains about 100 billion stars (in addition to the Sun), which orbit within it.
- Two main classes of stars occupy the Milky Way:
- Old red stars
- Young, often blue, stars
- The Milky Way is about 100,000 light-years across.
- The Milky Way contains gas and dust clouds in the immense spaces between the stars.
- The Milky Way contains dark matter whose nature is unknown.
- Dark matter exerts a gravitational force on the stars and gas in our galaxy, but it emits no as-yet detectable radiation.
- A black hole of more than a million times the Sun’s mass lies at the center of the Milky Way.
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