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This X-ray image of Tycho’s supernova, first seen as a visible-light object by Tycho Brahe in 1572, was taken in 2003 by the Chandra X-ray Observatory. Gas and dust with temperatures in the millions of kelvins (shown in red and green) are expanding outward at about 10 million km/hr (6.2 million mi/hr), following a shell of high-energy electrons (blue).

The Deaths and Remnants of Stars

WHAT DO YOU THINK?

  • Will the Sun someday cease to shine brightly? If so, how will this occur?

  • What is a nova? How does it differ from a supernova?

  • What are the origins of the carbon, silicon, oxygen, iron, uranium, and other heavy elements on Earth?

  • What are cosmic rays? Where do they come from?

  • What is a pulsar?

  • Are black holes empty holes in space? If not, what are they?

  • Does a black hole have a solid surface? If not, what is at its surface?

  • What power or force enables black holes to draw things into themselves?

  • How close to a black hole do you have to be for its special effects to be apparent?

  • Can you use black holes to travel to different places in the universe?

  • Do black holes last forever? If not, what happens to them?

Answers to these questions appear in the text beside the corresponding numbers in the margins and at the end of the chapter.

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In this chapter we learn how the later stages of stellar evolution are significantly different for stars with different masses. Some of them stop evolving by relatively mild emissions of their outer layers, while others have spectacular finales. Then we will explore the properties of the remnants left over from the stars.

In this chapter you will discover

  • what happens to stars when core helium fusion ceases

  • how heavy elements are created

  • the characteristics of the end of stellar evolution

  • why some stars go out relatively gently and others go out with a bang

  • the incredible density of the matter in neutron stars and how these objects are observed

  • that Einstein’s theory of general relativity predicts the existence of regions of space and time that are severely distorted by the extremely dense matter they contain

  • that space and time are not separate entities

  • how black holes arise

  • the surprisingly simple theoretical properties of black holes

  • that X-rays and jets of gas are created near many black holes

  • the fate of black holes

  • the unsurpassed energy emitted by gamma-ray bursts