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SGBH Test 2
| Question | Answer |
|---|---|
| What does it mean to say that the Sun is in “equilibrium”? | The inward force of gravity is balanced by the outward force of radiation pressure. |
| What two properties of the Sun are responsible for producing Sunspots? | differential rotation and magnetic fields |
| What is the fuel that powers the Sun? | protons and hydrogen |
| The increase and decrease in solar activity that results in more or less sunspots happens roughly every years. | 11 |
| What property of a star determines how quickly it will age? | its Mass |
| White Dwarf stars are composed primarily of . | carbon |
| Why is iron (Fe) the most stable element in the known Universe? (in other words, why does iron not undergo fusion or fission as a nuclear fuel?) | Iron has the least mass per nuclear particle |
| All main-sequence stars that are more luminous than the Sun . | fuse hydrogen into helium more rapidly than the Sun does |
| What event triggers a star to evolve past the main-sequence stage of its life? | The core of the star turns into helium |
| When the Sun became a protostar, during its pre-main-sequence evolution, its size was roughly its current size. | 100 times |
| What is the difference between a protostar and a star? | A star is powered by nuclear fusion in its core. |
| Which of the following is a major difference between a Type I Supernova and a Type II Supernova? | The spectrum of a Type II Supernova shows the presence of a lot of hydrogen, while that of a Type I Supernova does not. |
| Red Supergiant stars are among the stars. | largest and most luminous |
| The Sun's convection zone is responsible for which of the Sun's characteristics? | its granulated surface |
| Consider a star with a luminosity of: L* = 100L. How would its luminosity change if its radius were to double? | L* = 400L |
| Consider a star with a luminosity of: L* = 100L. How would its luminosity change if the distance between Earth and the star were to double? | L* = 100L |
| Our solar system contains some heavy elements, such as iron, because . | earlier generations of stars in our galaxy produced heavy elements while exploding |
| What is the Sun's luminosity? | 4 x 10^26 watts |
| According to the the accepted theoretical models of the Sun, approximately what is the temperature at the core of the Sun? | about 15 million Kelvin (15,000,000 K) |
| How long is the Sun's life? | 8.8 billion years |
| The Sun contains several different elements, but the vast majority of the atoms in the sun (over 90% of them) are . | Hydrogen (H) |
| In order for two identical stars to have the same apparent brightness as seen from Earth, what must be true about the stars? | They must both lie at the same distance from Earth. |
| Therefore, star's apparent magnitude depends on , while its absolute magnitude does not. | the distance from Earth to the star |
| Put the H-R diagram spectral classes in order from hottest to coolest. | O, B, A, F, G, K, M |
| An H-R diagram is a graph of the luminosity of a star versus a star's _______, ______, and _______ | surface temp, spectral classification, color |
| The masses of stars (i.e. how "heavy" they are) are typically measured by studying | binary stars (pairs of stars that orbit each other) |
| A(n) nebula is glowing cloud of hot interstellar matter where new stars are in the process of forming. | emission |
| What is the name of the low density region of space our solar system is in? | "local bubble" |
| As a single cloud collapses, before it becomes a star, the center of the cloud is a dense, opaque region called a(n) . | protostar |
| As a young protostar, the sun was roughly its current size as a star. | 100 times |
| The protostar that eventually became the Sun was significantly than the Sun. | brighter |
| What is the primary difference between a protostar and a true star? | A true star is powered by nuclear fusion, whereas a protostar is not. |
| Protostars sometimes develop bipolar jets that expel material from their poles. (T/F) | T |
| What property of a newborn star determines its location on the main sequence of the H-R diagram? | its mass |
| Objects that are more massive than planets, but are still not massive enough to become stars, are called , and are sometimes referred to as failed stars. | brown dwarfs |
| The end result of the collapse of a large interstellar cloud is a group of stars, all formed from the same large parent cloud at about the same time, and all lying in the same region of space. Such a collection of stars is called a(n)- | star cluster |
| After about 10 billion years of steady core hydrogen burning, the center of a star like the Sun will run out of hydrogen and turn into pure . | helium |
| Rank the following stages of the Sun's future evolution by putting them in chronological order, earliest (1) to last (6) : | 1. main sequence star, 2. subgiant branch, 3. helium flash, 4. horizontal branch, 5. asymptotic-giant branch, 6. planetary nebula and white dwarf |
| When the Sun reaches "stage 9" of its future evolution and undergoes the helium flash, it will have swelled up to times its current size. | 100 |
| The nuclear reaction, called the triple-alpha process, is the fusion of three Helium nuclei into one ______ nucleus. | carbon |
| After the Sun dies (nuclear fusion ceases), its core will turn into a "white dwarf", which will be composed primarily of ____________. | carbon |
| A "Carbon-detonation supernova" occurs when a white dwarf, in a close binary star system with another star, explodes after gaining mass mass from the companion star. This is a supernova. | Type I |
| A "Core-collapse supernova" occurs when a single, high-mass star explodes shortly after iron atoms are generated in its core by nuclear fusion. This is a supernova. | Type II |
| Which element is the most stable? | Iron |
| Which type of supernova has a "plateau" in its observed light curve? | Type II |
Created by:
trinmal