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Questions and Answers
The overall brightness of a star differs from luminosity in that ________
The overall brightness of a star differs from luminosity in that ________
brightness depends on the distance to the star
The brightness of a star at 10 parsecs is called the star's ________.
The brightness of a star at 10 parsecs is called the star's ________.
absolute magnitude
The temperature and composition of a star's photosphere can be determined from the properties of its starlight.
The temperature and composition of a star's photosphere can be determined from the properties of its starlight.
True
Molecular absorption lines indicate a star is which of the following spectral types?
Molecular absorption lines indicate a star is which of the following spectral types?
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The hotter the star, the bluer it appears. This is a consequence of ________.
The hotter the star, the bluer it appears. This is a consequence of ________.
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The technique of combining the light from two or more smaller telescopes to obtain an image equivalent to that of a much larger telescope is called ________.
The technique of combining the light from two or more smaller telescopes to obtain an image equivalent to that of a much larger telescope is called ________.
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The total amount of energy that a star emits each second is called its ________.
The total amount of energy that a star emits each second is called its ________.
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Two orbiting stars revolve around a point of balance called the ________.
Two orbiting stars revolve around a point of balance called the ________.
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The star temperature classification that is just cooler than the sun is the F-class star.
The star temperature classification that is just cooler than the sun is the F-class star.
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Measuring the orbital period and semimajor axis of a binary star will give us each star's own mass.
Measuring the orbital period and semimajor axis of a binary star will give us each star's own mass.
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If you know a star's temperature and use the Stefan-Boltzmann law you can find ________.
If you know a star's temperature and use the Stefan-Boltzmann law you can find ________.
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Binary stars are used to measure ________.
Binary stars are used to measure ________.
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Stars whose absorption lines move back and forth are called ________.
Stars whose absorption lines move back and forth are called ________.
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Our sun is a G-type star.
Our sun is a G-type star.
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The absorption lines in a star's spectral signature give insight into its composition because ________.
The absorption lines in a star's spectral signature give insight into its composition because ________.
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An eclipsing binary can tell us each star's radius if we observe ________.
An eclipsing binary can tell us each star's radius if we observe ________.
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New interferometry techniques have measured many sizes of stars far from Earth.
New interferometry techniques have measured many sizes of stars far from Earth.
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We can measure the temperature of a star by ________.
We can measure the temperature of a star by ________.
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This type of binary star system is detected by using the Doppler shift: ________.
This type of binary star system is detected by using the Doppler shift: ________.
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The Balmer lines in a spectrum are the signature of ________.
The Balmer lines in a spectrum are the signature of ________.
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Using the Stefan-Boltzmann law to find luminosity requires ________.
Using the Stefan-Boltzmann law to find luminosity requires ________.
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40 percent of visible stars are binary systems.
40 percent of visible stars are binary systems.
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The surface temperature of an O-type star is around ________.
The surface temperature of an O-type star is around ________.
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A technique to find diameters of stars using short exposures is called ________.
A technique to find diameters of stars using short exposures is called ________.
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The person who first started the magnitude scale for stars was ________.
The person who first started the magnitude scale for stars was ________.
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Scientists have recently defined three new stellar spectral types, L, T, and Y, which describe objects ________.
Scientists have recently defined three new stellar spectral types, L, T, and Y, which describe objects ________.
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M-type stars have a surface temperature of about ________.
M-type stars have a surface temperature of about ________.
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In astronomy, a standard candle is a star ________.
In astronomy, a standard candle is a star ________.
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Eclipsing binaries cannot be used to measure masses of stars.
Eclipsing binaries cannot be used to measure masses of stars.
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Absolute magnitude is the brightness of a star in the night sky.
Absolute magnitude is the brightness of a star in the night sky.
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Apparent double stars are two stars going around each other.
Apparent double stars are two stars going around each other.
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Our sun will die as a white dwarf.
Our sun will die as a white dwarf.
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Stars that are forming are called ________.
Stars that are forming are called ________.
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The lower limit for a normal star is about 0.1 solar masses.
The lower limit for a normal star is about 0.1 solar masses.
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What are the main components of comet nuclei?
What are the main components of comet nuclei?
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Stars near the same position on the H-R diagram have approximately the same mass.
Stars near the same position on the H-R diagram have approximately the same mass.
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On the H-R diagram, the radius and surface area of stars ________.
On the H-R diagram, the radius and surface area of stars ________.
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Most stars are not on the main sequence.
Most stars are not on the main sequence.
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The North Star, Polaris, is a ________.
The North Star, Polaris, is a ________.
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A cloud of ejected gas surrounding a dying star is called a(n) ________.
A cloud of ejected gas surrounding a dying star is called a(n) ________.
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Stars that pulsate in and out are called ________.
Stars that pulsate in and out are called ________.
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________ are small, bright, dead cores of stars like our sun.
________ are small, bright, dead cores of stars like our sun.
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When a new star ejects gas in opposite directions, this is known as ________.
When a new star ejects gas in opposite directions, this is known as ________.
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Stellar computer models help us trace a star's life from birth to death.
Stellar computer models help us trace a star's life from birth to death.
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A star's first energy source comes from gravitational collapse.
A star's first energy source comes from gravitational collapse.
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A star's life cycle ultimately depends upon its mass.
A star's life cycle ultimately depends upon its mass.
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A molecular cloud contains mainly hot gases.
A molecular cloud contains mainly hot gases.
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More luminous stars on the main sequence are smaller in size.
More luminous stars on the main sequence are smaller in size.
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________ of stars will lie on the main sequence.
________ of stars will lie on the main sequence.
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A main sequence star has a luminosity class of ________.
A main sequence star has a luminosity class of ________.
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These small dark areas in molecular gas clouds may be prime stellar formation areas: ________.
These small dark areas in molecular gas clouds may be prime stellar formation areas: ________.
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A protostar becomes a main-sequence star when ________.
A protostar becomes a main-sequence star when ________.
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Objects with masses between about 0.08 and 0.016 times the mass of the Sun are called ________.
Objects with masses between about 0.08 and 0.016 times the mass of the Sun are called ________.
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The best place to find star formation is in a ________.
The best place to find star formation is in a ________.
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A plot of surface temperature vs. luminosity for stars is known as the ________.
A plot of surface temperature vs. luminosity for stars is known as the ________.
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According to the Stefan-Boltzmann Law, if two stars with the same surface temperature have different luminosities, then ________.
According to the Stefan-Boltzmann Law, if two stars with the same surface temperature have different luminosities, then ________.
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A protostar is heated to fusing temperature by ________.
A protostar is heated to fusing temperature by ________.
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The pulsation period of very luminous Cepheid variable stars can be used with the standard candle formula to measure distances to galaxies millions of light-years away.
The pulsation period of very luminous Cepheid variable stars can be used with the standard candle formula to measure distances to galaxies millions of light-years away.
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Once core hydrogen is used up, gravitational contraction heats hydrogen in ________ to fusion temperatures.
Once core hydrogen is used up, gravitational contraction heats hydrogen in ________ to fusion temperatures.
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The stars with the shortest main sequence lifetimes will be ________.
The stars with the shortest main sequence lifetimes will be ________.
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The Sun will ascend into the giant region of the H-R diagram ________.
The Sun will ascend into the giant region of the H-R diagram ________.
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As soon as any star's core becomes degenerate, it collapses into a black hole.
As soon as any star's core becomes degenerate, it collapses into a black hole.
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Many of the pulsating stars in the instability strip have an unstable layer that is responsible for alternately absorbing and releasing the energy flowing from the center of the star. This layer is made up of ________.
Many of the pulsating stars in the instability strip have an unstable layer that is responsible for alternately absorbing and releasing the energy flowing from the center of the star. This layer is made up of ________.
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Cepheid variable stars have pulsation periods in the range of ________.
Cepheid variable stars have pulsation periods in the range of ________.
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The sun is expected to live about ________ years.
The sun is expected to live about ________ years.
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The more luminous a Cepheid variable star is, the slower it pulsates.
The more luminous a Cepheid variable star is, the slower it pulsates.
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For helium fusion to occur, a low-mass star must be compressed ________ a high-mass star.
For helium fusion to occur, a low-mass star must be compressed ________ a high-mass star.
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Stars with less than about 0.4 times the mass of the Sun are probably ________.
Stars with less than about 0.4 times the mass of the Sun are probably ________.
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Without a source of energy, the Sun would ________.
Without a source of energy, the Sun would ________.
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We can use the ________ relation to help measure the distance to a Cepheid variable star.
We can use the ________ relation to help measure the distance to a Cepheid variable star.
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The time stars spend as a giant during their life cycle is equal to the time spent as a main sequence star.
The time stars spend as a giant during their life cycle is equal to the time spent as a main sequence star.
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The Sun's luminosity will continue to increase to around double its current value in the next 5 billion years.
The Sun's luminosity will continue to increase to around double its current value in the next 5 billion years.
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As the Sun's core heats up, helium will begin to fuse in a process called ________.
As the Sun's core heats up, helium will begin to fuse in a process called ________.
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Geological studies show Earth's temperature has remained stable due to constant increases in greenhouse gases.
Geological studies show Earth's temperature has remained stable due to constant increases in greenhouse gases.
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When electrons are forced very close together, they can stop the collapse of a star. This is known as ________.
When electrons are forced very close together, they can stop the collapse of a star. This is known as ________.
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Pulsating variable stars experience regular changes in luminosities while maintaining a constant diameter.
Pulsating variable stars experience regular changes in luminosities while maintaining a constant diameter.
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Before it leaves the main sequence, the Sun's luminosity will ________.
Before it leaves the main sequence, the Sun's luminosity will ________.
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Very massive stars live relatively short lives.
Very massive stars live relatively short lives.
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On the H-R diagram, most variable stars in the instability strip are ________ stars.
On the H-R diagram, most variable stars in the instability strip are ________ stars.
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Stars with a core temperature in excess of 20 million K probably have this hydrogen fusion type: ________.
Stars with a core temperature in excess of 20 million K probably have this hydrogen fusion type: ________.
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A protostar becomes a main-sequence star when ________.
A protostar becomes a main-sequence star when ________.
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When the core of our Sun begins to fuse helium, ________.
When the core of our Sun begins to fuse helium, ________.
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A type ________ supernova can result when a white dwarf receives enough extra mass from its companion star to fuse carbon and oxygen.
A type ________ supernova can result when a white dwarf receives enough extra mass from its companion star to fuse carbon and oxygen.
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Stars like our Sun will become ________ stars in their final phases.
Stars like our Sun will become ________ stars in their final phases.
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Eventually a white dwarf cools to a black dwarf.
Eventually a white dwarf cools to a black dwarf.
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Type II supernovas are white dwarf explosions.
Type II supernovas are white dwarf explosions.
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Spiraling gas around a white dwarf is known as a(an) ________.
Spiraling gas around a white dwarf is known as a(an) ________.
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Helium core fusion in the Sun will last about ________ years.
Helium core fusion in the Sun will last about ________ years.
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High mass stars are those above ________ solar masses.
High mass stars are those above ________ solar masses.
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A type ________ supernova is a single massive star exploding.
A type ________ supernova is a single massive star exploding.
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The production of heavy atoms from light atoms inside of a star is called ________.
The production of heavy atoms from light atoms inside of a star is called ________.
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A white dwarf can explode in a supernova if it ________.
A white dwarf can explode in a supernova if it ________.
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The sun will become a supernova.
The sun will become a supernova.
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A high-mass star typically begins its life as a ________.
A high-mass star typically begins its life as a ________.
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A recurrent nova usually occurs in a binary star system.
A recurrent nova usually occurs in a binary star system.
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Large massive stars create a series of nested shells of fusion as they age.
Large massive stars create a series of nested shells of fusion as they age.
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The Chandrasekhar limit is about ________.
The Chandrasekhar limit is about ________.
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Stars like our sun will leave this type of remnant after they die: ________.
Stars like our sun will leave this type of remnant after they die: ________.
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A white dwarf will stay hotter than the sun for about ________.
A white dwarf will stay hotter than the sun for about ________.
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The process that generates energy in a white dwarf is ________.
The process that generates energy in a white dwarf is ________.
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Study Notes
Brightness and Luminosity
- Brightness of a star is distance-dependent, unlike luminosity, which is an intrinsic property.
- Absolute magnitude defines a star's brightness at a standard distance of 10 parsecs.
Star Temperature and Composition
- Properties of starlight allow determination of a star's photosphere temperature and composition.
- Molecules contribute to spectral lines, indicating a star's spectral type.
Special Laws and Techniques
- Wien's Law explains why hotter stars appear bluer.
- Interferometry combines light from multiple telescopes for improved imaging.
- The Stefan-Boltzmann law connects temperature to a star's luminosity.
Binary Stars
- Binary systems revolve around a shared center of mass.
- Spectroscopic binaries exhibit moving absorption lines.
- Eclipsing binaries can reveal star radii from eclipse duration and speed.
- Mass measurement in binary stars relies on orbital periods and axes.
Stellar Classification
- Our sun is classified as a G-type star, while F-type stars are actually hotter.
- Newly defined spectral types L, T, and Y describe brown dwarfs.
- M-type stars have surface temperatures around 3000 K.
Main Sequence Characteristics
- About 90% of stars are on the main sequence, where they fuse hydrogen.
- Luminosity class V indicates a main sequence star.
Star Lifecycles
- Stars form from molecular clouds and evolve based on their mass.
- Protostars become main-sequence stars upon hydrogen fusion in their cores.
- High-mass stars have shorter life cycles than low-mass stars.
Synthesis and Remnants
- Stellar nucleosynthesis produces heavy elements from lighter ones within stars.
- White dwarfs are remnants of stars like our sun; they can become black dwarfs over immense timescales.
- Type II supernovae come from massive single stars, while Type Ia supernovae arise from white dwarfs gaining mass.
Variable Stars
- Cepheid variables are pulsating stars vital for measuring galactic distances; their pulsation periods are 1-70 days.
- Variables exhibit regular luminosity changes, but maintain constant diameters during pulsation.
Stellar End Stages
- After exhausting core hydrogen, the sun's core will compress, leading to helium fusion (triple alpha process).
- Electron degeneracy pressure prevents collapse of stellar cores under certain conditions.
- The sun's final phases will lead to a Mira variable star status before becoming a white dwarf.
Miscellaneous Facts
- The Chandrasekhar limit defines the maximum mass for a stable white dwarf at approximately 1.4 solar masses.
- Bok Globules are dense regions in molecular gas clouds, potential sites for star formation.
- The North Star, Polaris, is categorized as a yellow giant and variable star.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge with these flashcards for Astronomy Exam 4. Each card covers important concepts related to star brightness, absolute magnitude, and starlight properties. Perfect for students looking to review crucial astronomical terms and definitions.
