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1 | |
The Sun’s evolution from youngest to oldest stage is: |
| | A) | white dwarf, red giant, main-sequence, protostar |
| | B) | red giant, main-sequence, white dwarf, protostar |
| | C) | protostar, red giant, main-sequence, white dwarf |
| | D) | protostar, main-sequence, red giant, white dwarf |
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2 | |
Protostars initially do not experience hydrogen fusion. How then do they heat up? |
| | A) | The light from nearby stars. |
| | B) | Gravitational energy from infalling material. |
| | C) | Fusion of hydrogen into helium. |
| | D) | Energy from their magnetic fields. |
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3 | |
Because protostars are at a low temperature (for a star!) and surrounded by dust and gas, astronomers must observe them with |
| | A) | radar. |
| | B) | ultraviolet telescopes. |
| | C) | infrared and radio telescopes. |
| | D) | gamma ray telescopes. |
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4 | |
What is a T Tauri star? |
| | A) | Any variable star. |
| | B) | A red giant with a peculiar spectrum. |
| | C) | Any star found in the constellation of Taurus. |
| | D) | A young star that exhibits variable light and outflowing gas. |
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5 | |
A star enters the main sequence when |
| | A) | nuclear fuel in its core can supply enough energy to stop its collapse. |
| | B) | it collapses, and its envelope becomes degenerate. |
| | C) | it stops fusing nuclear fuel in its core and starts to expand. |
| | D) | it forms planets. |
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6 | |
What determines how long a star stays on the main sequence? |
| | A) | Its temperature and mass. |
| | B) | Its luminosity and radius. |
| | C) | Its mass and luminosity. |
| | D) | Its radius and mass. |
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7 | |
A star leaves the main sequence when |
| | A) | nuclear fuel in its core can supply enough energy to stop its collapse. |
| | B) | it collapses, and its envelope becomes degenerate. |
| | C) | it stops fusing nuclear fuel in its core and starts to expand. |
| | D) | it forms planets. |
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8 | |
When a star like the sun evolves into a red giant, its core |
| | A) | expands and cools. |
| | B) | contracts and heats. |
| | C) | expands and heats. |
| | D) | contracts and cools. |
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9 | |
Why can high-mass stars “burn” helium more easily than low-mass stars? |
| | A) | A high-mass star's core is already very hot, so it only needs to compress its core a little to burn helium. |
| | B) | High-mass stars are already burning helium on the main sequence. |
| | C) | Low-mass stars have proportionately less helium than high-mass stars. |
| | D) | This statement is false. It is much harder for high-mass stars to burn helium. |
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10 | |
What is a “pulsating star”? |
| | A) | A rotating neutron star that emits radio waves in a narrow beam. |
| | B) | A star whose luminosity changes as it swells and shrinks rhythmically. |
| | C) | A planetary nebula. |
| | D) | A star whose mass changes as it comes into contact with another star. |
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11 | |
What is a “planetary nebula”? |
| | A) | It is the disk of gas around a young star. |
| | B) | It is the cloud from which protostars form |
| | C) | It is a shell of gas ejected from a star late in its life. |
| | D) | It is what is left when a white dwarf star explodes as a supernova. |
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12 | |
What is left when a planetary nebula dissipates? |
| | A) | A red giant |
| | B) | A black hole. |
| | C) | A white dwarf. |
| | D) | A neutron star. |
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13 | |
Low-mass stars like the Sun probably do not form iron cores during their evolution because |
| | A) | all the iron is ejected when they become planetary nebulas. |
| | B) | their cores never get hot enough for them to make iron by nucleosynthesis. |
| | C) | the iron they make by nucleosynthesis is all fused into uranium. |
| | D) | their strong magnetic fields keep their iron in their atmospheres. |
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14 | |
What makes a high-mass star's core collapse? |
| | A) | Energy from its outer layers compresses its core. |
| | B) | The only thing that can make a star's core collapse is a collision with another star. |
| | C) | Massive stars develop iron cores that cannot fuse anymore, so the core collapses under gravity. |
| | D) | Massive stars' cores don't collapse. They expand and become planetary nebulas. |
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15 | |
What can be observed from Earth when a supernova explodes? |
| | A) | Light and neutrinos. |
| | B) | Electrons and geraniums. |
| | C) | Photons and neutrons. |
| | D) | Phasers and betazoids. |
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2002 McGraw-Hill Higher Education