Stellar Classification and Evolution Flashcards
What does a star’s luminosity measure?
Luminosity is a measurement of the amount of light energy emitted by an object.
What is a star’s apparent magnitude?
Apparent magnitude is a measurement of how bright a star is from an observer on Earth.
What is a star’s absolute magnitude?
Absolute magnitude is a measurement of how bright a star is if the star were at a distance of 10 parsecs from Earth.
What characteristic of a star does its color identify?
The color of a star is related to its surface temperature.
What is spectral classification of a star?
Spectral classification is a letter designation OBAFGKM that is related to the star’s surface temperature.
What characteristic of a star does its absorption spectra indicate?
A star’s absorption spectra indicates what elements the star is made of.
What is a nebula?
A collection of gas and dust from which a star can form
What is a Hertzsprung-Russell diagram?
A scatter plot of a star’s temperature versus its luminosity.
If two stars have the same surface temperature, what other property will they have in common?
They will have the same spectral classification.
If two stars have the same luminosity, what other property will they have in common?
They will have the same absolute magnitude.
What is the main sequence of a H-R diagram?
It is a diagonal region from cool, dim stars to hot, bright stars.
Stars with which two characteristics fall into the Red Giant region of the H-R diagram?
Red Giant stars are cool and bright.
Stars with which two characteristics fall into the White Dwarf region of the H-R diagram?
White Dwarf stars are hot and dim.
What is a protostar?
A large, hot sphere of gas that forms when a nebula collapses.
What must occur for a protostar to become a star?
Nuclear fusion of hydrogen into helium in its core.
Which characteristic of a star determines its life cycle?
The star’s mass
A low mass star will spend approximately how long in the main sequence?
Low mass stars spend trillions of years in the main sequence.
A mid-mass star will spend approximately how long in the main sequence?
Mid-Mass stars spend billions of years in the main sequence.
A high-mass star will spend approximately how long in the main sequence?
A high-mass star will spend millions of years in the main sequence.
Why does a star with a higher mass spend less time in the main sequence?
A high mass star needs to produce more energy to balance the gravitational attraction of its large mass.
When nuclear fusion of hydrogen in the core of a mid-mass star ends, what type of star will form next?
A red giant
What forms when a red giant collapses and ejects its outer layers?
A planetary nebula
What is the stellar core at the end of the lifetime of a mid-mass star?
A white dwarf
When nuclear fusion of hydrogen stops in a high mass star, what type of star forms next?
A supergiant star
