Astronomy Chapter 12 Test – Flashcards
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Which spectral class main sequence stars have the lowest mass?
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M
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Which velocity measurement of a star's motion uses the Pythagorean Theorem?
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Space Velocity
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A surface temperature of 2900 K and a luminosity of 100 times that of the Sun is what type of star?
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Red Giant
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Which velocity of a star measures the path across the sky, while knowing its distance?
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Tangential Velocity
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Compared to a star in the middle of the H-R Diagram, a star on the upper right part is ___.
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Larger
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The velocity of a star, measured by using the Doppler Effect, when moving towards the observer or away from the observer.
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Radial Velocity
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List the special classification of stars in correct order of decreasing temperature from left to right.
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OBAFGKM
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Distances can obscure star size and luminosity. How does absolute magnitude relate to this?
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Takes stars and hypothetically places ten parsecs, and compare
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What is a parsec?
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Sun to object with parallax angle of one arsecond distance
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How many degrees are in a circle
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360
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What is an arcsecond?
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1/3600th of a one degree angle
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Two stars have the same apparent brightness and are not hidden by gas or dust clouds.
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They may be at different differences or farther one may be more luminous
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What can a parallax angle do for an astronomer?
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Can help determine the distance of a far away object
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If two stars differ by one magnitude, then the ratio of their brightness is about ___.
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2.5
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When discussing apparent magnitude, we are talking about ___.
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The amount of light received from an object
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Which type of star has the smallest radius?
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White Dwarf
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Is there a difference between luminosity and brightness?
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Yes, luminosity is actual light. Brightness is appearance
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Which spectral type represents a star whose blackbody curve peaks at yellow wavelengths?
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G
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Cepheid variables are important because there is a relationship between their ___.
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Average absolute magnitude and their period of pulsation
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A regular "wobble" in the path of a star is evidence that it ___.
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Has a companion revolving around it
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Two stars that have small angular separation as seen from Earth but not bound by gravity
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Optical Double
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An orbiting pair of stars that can be resolved (via telescope) as two separate stars
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Visual Binary
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A system of two stars that are gravitationally bound so that they orbit one another
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Binary Star System
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An orbiting pair of stars that can be distinguished as two via the Doppler Shift
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Spectroscopic Binary
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Binary star systems are important because they allow us to calculate this part of stars
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Masses
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How do Binary star systems orbit?
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Revolve around a point somewhere near their centers
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What are Cepheid variables?
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Stars that pulsate in regular periods
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Cepheid variables are stars that are extremely useful in calculating very large ___.
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Distances
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What is the proper name of the H-R Diagram?
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Hertzsprung-Russell Diagram
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Our Sun is what kind of spectral class star?
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G2
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On the H-R Diagram, White Dwarfs are located in the ___.
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Bottom left corner
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On the H-R Diagram, our Sun is found ___.
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Along the Main Sequence
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What is the most-commonly used mnemonic for spectral classification?
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Oh, Be A Fine Girl/Guy, Kiss Me
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On the H-R Diagram, Giants and Supergiants are found in the ___.
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Upper right corner
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On the H-R Diagram, 90% of stars are found ___.
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Along the Main Sequence
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What does the H-R Diagram plot?
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Spectral Class and Absolute Magnitude
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On the H-R Diagram, how do we know that a star is a Giant or a Supergiant?
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They are very bright, in spite of their low temperature
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How can we use the H-R Diagram to calculate the distance to a star?
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Compare absolute magnitude with the apparent magnitude
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"The rate that electromagnetic radiation is emitted" describes ___.
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Luminosity
