Questions and Answers
The larger the magnitude number, the brighter will be the star.
False
Which main-sequence stars are the least massive?
Which main-sequence stars are the most massive?
Which color stars have the coolest surface temperature?
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When a main-sequence star has exhausted the fuel in the inner region, it becomes a ________.
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The Sun belongs to this class of stars.
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The hottest main-sequence stars are also the most massive.
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Based on the observed red shifts in the spectral lines of distant galaxies, astronomers conclude that ________.
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Stars spend most of their life span as giants.
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The final stage in the evolution of a star like our Sun is a neutron star.
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One of the most common units used to express stellar distance is the ________.
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The measure of a star's brightness is called its magnitude.
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The discovery that the universe appears to be expanding led to a widely accepted theory called ________.
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The most dense stars known to exist are ________.
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Stars with a surface temperature of 3000 K appear red in color.
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These stars are produced during a supernova event.
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Hubble's law states that galaxies are receding from us at a speed that is proportional to their ________.
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The Sun is considered an average star.
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Stars spend most of their life span as main-sequence stars.
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Stars having the same surface temperature radiate the same amount of energy per unit area.
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A star in which light cannot escape because of the immense gravitational pull at its surface is called a ________.
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Which one of the objects listed below has the largest size?
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The Sun belongs to this class of stars.
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Most stars are in this stage of evolution.
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The most dense objects known are black holes.
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The measure of a star's brightness is called its ________.
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The greatest number of galaxies belong to the type known as elliptical galaxies.
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Our galaxy is called the ________.
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The Milky Way is classified as a spiral galaxy.
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Which main-sequence stars are the most massive?
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The least massive main-sequence stars are blue in color.
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The measurement of a star's brightness is __________.
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A galaxy that lacks symmetry is called an __________ galaxy.
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A small dense star that was once a low-mass or medium-mass star whose internal heat energy was able to keep these gaseous bodies from collapsing under their own weight is called a __________.
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A graph showing the relation between true brightness and temperature of stars is called an __________.
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The fusion of groups of four hydrogen nuclei into a single helium nucleus is known as __________.
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A type of very dense matter that forms when electrons are displaced inward from their regular orbits around an atom's nucleus is called __________.
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An interstellar cloud of dust and gases is referred to as a __________.
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An exceptionally large star, such as Betelgeuse, with a radius about 800 times larger than the sun and a high luminosity is called a __________.
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A gaseous interstellar mass that absorbs ultraviolet light from an embedded or nearby hot star and reradiates this energy as visible light is called an __________.
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A collapsing cloud of gases and dust not yet hot enough to perform nuclear fusion but destined to become a star is called a __________.
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A star consisting of matter formed from the combination of electrons with protons that is smaller and more massive than a white dwarf is called a __________.
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A very large, cool, reddish colored star with high luminosity is referred to as __________.
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Stars exceeding three solar masses that have relatively short life spans and terminate in brilliant explosions are referred to as __________.
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When a dense cloud of interstellar matter is not close enough to a bright star to be illuminated, it is called a __________.
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A neutron star that radiates short bursts of radio energy, discovered in the early 1970s, is known as a __________.
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Galaxies are receding from us at a speed proportional to their distance is known as __________.
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The brightness of a star, if it were viewed from a distance of 32.6 light years is called its __________.
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A type of galaxy with an ellipsoidal shape that ranges from nearly spherical and lacks spiral bands is known as an __________ galaxy.
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A unit used to express stellar distance; equal to 9.5 trillion kilometers is called a __________.
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An interstellar cloud that glows because of its proximity to a very hot blue star is referred to as a __________.
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An object even smaller and denser than a neutron star, with a surface gravity so immense that light cannot escape is called a __________.
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An interstellar cloud of gases and dust that merely reflects the light of nearby stars is known as a __________.
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The Milky Way is a __________.
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The theory which proposes that the universe originated from a single mass that subsequently exploded is known as the __________.
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Our own group of galaxies is called our __________, which contains at least 28 galaxies.
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Stars that fluctuate regularly in brightness by expanding and contracting in size are known as __________.
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A system of galaxies containing from several to thousands is called a __________.
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A star that explosively increases in brightness is called a __________.
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Study Notes
Star Types and Characteristics
- Stars exhibit different colors based on their surface temperature; cooler stars appear red, while hotter stars are blue.
- Main-sequence stars, like the Sun, spend the majority of their life in this stable phase of stellar evolution.
- Stars evolve into red giants when they exhaust nuclear fuel; the Sun is expected to become one in the future.
- Neutron stars are the densest known stars, resulting from supernova events and the collapse of massive stars.
Stellar Distances and Measurements
- A light-year, equal to approximately 9.5 trillion kilometers, is commonly used to measure astronomical distances.
- The brightness of a star is quantified as its magnitude, with two types: apparent magnitude (brightness as seen from Earth) and absolute magnitude (brightness at a standard distance).
Cosmic Phenomena
- The universe is expanding, as evidenced by the redshifts in distant galaxies, leading to the Big Bang theory, which suggests all matter originated from a singular explosion.
- Hubble's Law states that galaxies recede at speeds proportional to their distances from Earth, confirming universal expansion.
Galaxy Classifications
- Galaxies are categorized primarily into elliptical, spiral, and irregular types, with elliptical galaxies being the most common.
- The Milky Way is classified as a spiral galaxy, and it is part of a larger structure known as the Local Group containing at least 28 galaxies.
Nebulae and Stellar Evolution
- Nebulae are interstellar clouds of dust and gas, with types including bright nebulae (illuminated by nearby stars), reflection nebulae (reflected light from nearby stars), and dark nebulae (not illuminated).
- A planetary nebula forms when a medium mass star transitions from a red giant to a white dwarf, creating an expanding shell of gas.
- The Hr diagram plots stars according to their luminosity and temperature, illustrating their evolutionary processes.
Variable Stars
- Pulsating variables are stars that regularly change in brightness by contracting and expanding, showcasing distinct phases in their life cycles.
This structured overview encompasses the critical components of star classification, measurement, and the evolution of cosmic structures as represented in the study material.
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Description
Test your knowledge with these flashcards from Earth Science Chapter 24. This quiz covers essential concepts about star classification, including magnitudes and the characteristics of different main-sequence stars. Perfect for reviewing key terms and concepts before your exam.
