Astronomy unit 7 practice test
light
Almost everything we know about stars comes to us through careful analysis of the _____ they emit.
hydrogen-helium
The _____ cycle process ends with the production of helium-4.
carbon
The _____ cycle/process begins and ends with the same element.
triple-alpha
The _____ cycle/process only occurs in really hot stars.
Our Sun is a G2 yellow star of above-average size.
Which of the following sentences best describes our Sun?
Mass
_____ dictates what characteristics a star shows throughout all stages of its activity.
White dwarfs
_____ do not shrink further because their electrons cannot get any closer together.
Singularity
_____ is the point where gravity compresses an object to infinite density and to almost no volume.
Absolute magnitude
_____ measures the total energy output of a star.
Bright-line
_____ spectra indicate the presence of specific elements and confirm the heat necessary to vaporize them.
Dark-line
_____ spectra indicate the presence of specific elements because those elements absorb white light.
Pulsars
_____ spin rapidly because they are governed by the spin rate of their original star being concentrated into a drastically shrunken condition.
H-R Diagram
a chart of the absolute magnitudes of stars plotted against their temperatures
isotope
a form of an element having the same number of protons, but having more or fewer than the usual number of neutrons
black hole or neutron star
a form of degenerate matter that can occur after a star explodes
Henry Russell
plotted the absolute magnitude of stars against their spectral classes
logarithm
the exponent to which a base must be raised to produce a given number
V
Main-sequence stars are all designated by luminosity class _____.
parsec
a unit of distance equal to 3.0857 × 1013 km
pulsar
A _____ is a neutron star that emits narrow beams of energy as it spins on its axis.
iron
Formation of _____ marks the end of a blue star's life because it cannot be fused into another element.
lower right
Stars toward the _____ of the main sequence fuse hydrogen at a slower rate because they have less internal nuclear activity.
Hydrostatic equilibrium
_____ is a term describing fluids at rest.
Apparent magnitude
_____ is how bright a star looks in our sky.
helium flash
occurs after helium begins to fuse with carbon in the triple-alpha process
Big Scrunch
occurs when a star's iron heart suddenly compresses its mass in tenths of a second from stellar death
Enjar Hertzsprung
plotted the absolute magnitude of individual stars within clusters against their colors
giants and supergiants
plotted to the upper right on the H-R diagram
lattice
As a white dwarf cools, the carbon and oxygen ions lock themselves into a crystal _____, or three-dimensional pattern of atoms.
slit
The _____ permits light only from a selected source.
light year
approximately 9,460,000,000,000 km
luminoity
indicated by adding a Roman numeral to the letter and number that designates a star's class
Joseph von Fraunhofer
invented the spectroscope
convection
keeps helium from accumulating in the core of a red dwarf
main-sequence
the center curving line in the H-R diagram
nova
A(n) _____ is a star that suddenly flares up, then fades after a few weeks or months.
binary star
A _____ is two stars orbiting a common center of gravity.
visual binary
A _____ is when both stars in a system can be seen separately through a telescope.
long-term variable
A red variable is a _____ star that is a red giant or supergiant.
helium
A star leaves the main sequence when it stops fusing hydrogen into _____ in its core.
