Podcast
Questions and Answers
In comparing first magnitude Deneb with second magnitude Polaris, how much brighter does Deneb appear to us than Polaris?
In comparing first magnitude Deneb with second magnitude Polaris, how much brighter does Deneb appear to us than Polaris?
What is the motion of a star across the sky, perpendicular to our line of sight, called?
What is the motion of a star across the sky, perpendicular to our line of sight, called?
Proper motion
Why are astronomers much more interested in the luminosity of a star than its apparent brightness?
Why are astronomers much more interested in the luminosity of a star than its apparent brightness?
Because the luminosity tells us how bright a star really is, while apparent brightness only tells us how bright it happens to look from Earth.
What term is given to a pair of stars that appear to change positions in the sky, indicating that they are orbiting one another?
What term is given to a pair of stars that appear to change positions in the sky, indicating that they are orbiting one another?
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Perhaps the greatest of the Greek astronomers, __________ compiled the first catalog of stars, accurately measured their positions, and defined the basic system of stellar brightnesses.
Perhaps the greatest of the Greek astronomers, __________ compiled the first catalog of stars, accurately measured their positions, and defined the basic system of stellar brightnesses.
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How much electrical charge does an atom with 6 protons, 6 neutrons, and 5 electrons have?
How much electrical charge does an atom with 6 protons, 6 neutrons, and 5 electrons have?
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What will a star moving towards the Sun show?
What will a star moving towards the Sun show?
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How did the astronomer measure the average speed of a star moving away from the Sun?
How did the astronomer measure the average speed of a star moving away from the Sun?
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What can we conclude if one object has a large redshift and another has a small redshift?
What can we conclude if one object has a large redshift and another has a small redshift?
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Why do different types of atoms give off or absorb different spectral lines?
Why do different types of atoms give off or absorb different spectral lines?
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What will the light from an object moving tangentially to your left or right exhibit?
What will the light from an object moving tangentially to your left or right exhibit?
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If an atom of iron has an atomic number of 26 and an atomic mass number of 56, how many protons, neutrons, and electrons does it have if it is neutral?
If an atom of iron has an atomic number of 26 and an atomic mass number of 56, how many protons, neutrons, and electrons does it have if it is neutral?
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If several lines in the spectrum of a distant star come from titanium oxide molecules, what spectral type is the star likely to be?
If several lines in the spectrum of a distant star come from titanium oxide molecules, what spectral type is the star likely to be?
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What can be inferred if star A and star B have the same temperature, but star B is more luminous than star A?
What can be inferred if star A and star B have the same temperature, but star B is more luminous than star A?
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By which method can gas density, axial rotation, and the magnetic field of a star be deduced from its spectrum?
By which method can gas density, axial rotation, and the magnetic field of a star be deduced from its spectrum?
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The absolute magnitude of a star is its brightness as seen from a distance of how many parsecs?
The absolute magnitude of a star is its brightness as seen from a distance of how many parsecs?
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When an atom absorbs a photon containing energy, which of the following can happen except?
When an atom absorbs a photon containing energy, which of the following can happen except?
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What kind of instrument would it be smart to use to find type L stars, which are cooler than traditional spectral type M stars?
What kind of instrument would it be smart to use to find type L stars, which are cooler than traditional spectral type M stars?
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In general, the narrower the spectral line of a star, what can be said about the star?
In general, the narrower the spectral line of a star, what can be said about the star?
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What are we seeing when an electrified glass tube containing very thin neon gas glows with a rich red color?
What are we seeing when an electrified glass tube containing very thin neon gas glows with a rich red color?
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How do astronomers learn what elements are present in a given star?
How do astronomers learn what elements are present in a given star?
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In a visual binary system with circular orbits, if the two stars' position angles have shifted by 30 degrees in 20 years, what must the pair's period be?
In a visual binary system with circular orbits, if the two stars' position angles have shifted by 30 degrees in 20 years, what must the pair's period be?
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Which of the following can astronomers NOT learn from studying the spectrum of a star?
Which of the following can astronomers NOT learn from studying the spectrum of a star?
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Study Notes
Stellar Magnitudes and Brightness
- Deneb is approximately 2.5 times brighter than Polaris, highlighting differences in first and second magnitude stars.
- Luminosity indicates a star's true brightness, while apparent brightness is how bright it appears from Earth.
Star Motion and Position
- Proper motion refers to a star's motion perpendicular to our line of sight.
- A star moving toward the Sun displays spectral lines shifted toward the blue end of the spectrum.
- The Doppler shift in a star's spectrum is used to measure its speed relative to the Sun.
Types of Star Systems
- Visual binaries are pairs of stars appearing to change positions as they orbit each other.
- The absolute magnitude of a star is measured from a distance of ten parsecs.
Elements and Atomic Structure
- An atom with 6 protons, 6 neutrons, and 5 electrons has a net positive charge of +1.
- An atom of iron (atomic number 26, atomic mass 56) contains 26 protons, 30 neutrons, and 26 electrons when neutral.
Spectroscopy and Star Characteristics
- Different atoms have distinct spectral lines due to varying energy levels.
- The presence of titanium oxide in a star's spectrum suggests it is of spectral type M.
- The line shape in a star's spectrum can provide insights into gas density, axial rotation, and magnetic fields.
- The narrower a star's spectral line, the larger the star is likely to be.
Star Discovery and Classification
- Astronomers have identified new spectral type L stars that are cooler than traditional type M, often requiring sensitive infrared telescopes for detection.
Emission and Absorption Spectra
- When energized neon gas in a glass tube glows red, it produces an emission spectrum.
- Astronomers determine the presence of elements in stars by analyzing absorption lines in their spectra.
Binary Systems and Orbital Mechanics
- In a visual binary with circular orbits, a 30-degree shift in position angles over 20 years indicates a period of 240 years for the pair.
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Description
Test your knowledge on essential concepts from chapter 3 of astronomy. This quiz covers topics such as star brightness and proper motion, offering a quick reference for key definitions. Perfect for students looking to enhance their understanding of astronomical principles.
