Page 21 - Curriculum Visions Dynamic Book

4, 5, 6, 7, 8—Eventually, the hydrogen fuel is used up, and only helium is left to burn. Since helium burns at much higher temperatures than hydrogen, the star gets brighter. At the same time, the outer part of the star begins to expand again, forming a red giant star (page 26).
Eventually, the star literally blows apart and produces the spectacular “fireworks” in space called a supernova (pages 31–33).
A supernova is a red giant that explodes. It suddenly increases in brightness by a factor of many billions, but even within a few weeks it begins to fade. The Crab Nebula (some 7,000 light-years away) consists of material ejected by the supernova of 1054 (for pictures see pages 13 and 32).
A supernova may radiate more energy in a few days than the Sun does in 100 million years. The stellar remnant left behind after the explosion is a star only a few kilometres in diametre but with an enormously high density.
black dWarf A degenerate star that has cooled so that it is now not visible.
chain reaction A sequence of related events with one event triggering the next.
fUsion The joining of atomic nuclei to form heavier nuclei.
nebUla (pl. nebUlae) Clouds of gas and dust that exist in the space between stars.
neUtron star A very dense star that consists only of tightly packed neutrons. It is the result of the collapse of a massive star.
pUlsar A neutron star that is spinning around, releasing electromagnetic radiation, including radio waves.
radiation The transfer of energy in the form of waves (such as light and heat) or particles (such as from radioactive decay of a material).
radio Waves A form of electromagnetic radiation, like light and heat. Radio waves have a longer wavelength than light waves.
red giant A cool, large, bright star at least 25 times the diametre of our Sun.
sUpernova A violently exploding star that becomes millions or even billions of times brighter than when it was younger and stable.
White dWarf Any star originally of low mass that has reached the end of its life.
11 10
Black dwarf
7 Red giant
9 8 Planetary nebula
(see pages 26–28)
9, 10, 11—The remnant star then contracts as a neutron star or
WHite dWarf, spinning quickly and sending out pulses of radio Waves like a galactic beacon. That is why a neutron star is also sometimes called a pulsar (page 34). Eventually, the neutron star dies, its heat is lost, and it ceases to shine. Although it still exists in the galaxy, it can no longer be seen, and it is now called a black dWarf (page 29).
White dwarf (neutron star, pulsar)
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