1.1. an incredibly dense but incredibly small sphere composed primarily of neutrons
2. Supernovae Remnants
2.1. Outer atmosphere of Star
2.2. Task #3
2.3. "The doomed star’s outer layers were blasted into space with such violence that they are still traveling through the interstellar medium at supersonic speeds 15,000 years later. As this expanding shell of gas plows through space, it collides with atoms in the interstellar medium, exciting the gas and making it glow. We saw in Section 11-1 that the passage of a supernova remnant through the interstellar medium can trigger the formation of new stars, so the death of a single massive star can cause a host of new stars to be born."
3. Pulsars
3.1. A pulsating radio source thought to be associated with a rapidly rotating neutron star.
3.2. Bell detected regular pulses of radio noise from one particular location in the sky. These radio pulses were arriving at regular intervals of 1.3373011 seconds—much more rapid than those of any other astronomical object known at that time. Indeed, they were so rapid and regular that the Cambridge team at first suspected that they might not be of natural origin. Instead, it was proposed that these pulses might be signals from an advanced alien civilization.
3.3. An isolated pulsar slows down as it ages, so its pulse period increases.
4. Black Holes
4.1. An object whose gravity is so strong that the escape speed exceeds the speed of light.
4.2. In a sense, a hole is punched in the fabric of the universe, and the dying star seems to disappears into this cavity (Figure 12-12). None of the star’s mass is lost when it collapses to form a black hole, and a black hole’s gravitational influence can still be felt by other objects.
