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