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_____ is a clue to a star's temperature


________ stars can be used to determine stellar mass


The ____________ stars have the largest parallax angles, while those of distant stars are too small to measure.

how big it is, how hot it is, and how far away it is.

Three Factors that control the apparrent brightness of a star as seen from earth?

Hertzsprung-Russel diagram

_________ shows the relationship between the absolute magnitud and temperature of stars.

10 million

When the core of a protostar has reached at least ______________ K, pressure within is so great that fusion of hydrogen begins, and a star is born.


All stars, regardless of their size, eventually run out of fuel and collapse due to __________.

nebula, main-sequence

Stars like the sun begin as a ___________, spend much of their lives as __________ stars, become red giants, planetary nebulae, white dwarfs, and finally , black dwarfs.

milky way, spiral, 100,000, 10,000

The ___________ is a large ________ galaxy whose disk is about _____________ light-years wide and about _______ light-years thick at the nucleus.


In addition to size and shape, one of the major differences among different types of galaxies is the ____ of their stars.

red, expanding

The _______ shifts of distant galaxies indicate that the universe is ________.

big bang theory, ball, 13.7

______ states that at one time, the entire universe was confined to a dense, hot, supermassive _____. Then about _____ billion years ago, a violent explosion occurred, hurling this material in all directions.


How much a star wobbles is related to its ______.


brightness of a star

apparent magnitude

How bright a star appears is _____.

absolute magnitude

how bright a star actually is ______.


the ________ the star the brighter the star.


age; irregular stars


age; spiral stars


age; elliptical stars

egg shaped

shape; elliptical stars


unit to express stellar distance


milk way; age

the outward expansion will follow, expand forever

The future of the universe; 2 paths


More ______ the closer they come together

absolute magnitude

surface temperature related to its______


color depends on the ________.


most stuff, big ____


White dwarfs final stage of evolution when they collapse to very small _____.


white dwarf is extremely ______.


shite dwarf is made up of _________ matter


the sun begins as a ___________.


Order of sun begins _________


smallest white dwarf is ________ massive gravity so it "squeezes more tightly.


_________ stars are thought to be remnants of supernova events. pea size sample 100 million tons.

density of the nucleus of the atom

the density of neutron stars=

supernova, neutron, magnetic

during this the outer layer of a star is ejected. forms a visible nebula. and the core becomes a ________ star. Has a strong _______ field.

pulsar, crab

radio waves , found in the _________ nebula-during the 1970s is undoubtedly the remains of the supernova of 1054.


________ holes are the most massive stars that produce even more dense remnants after a supernova. Gravity prevents its escape from anything.


________ dwarf star is a star that has exausted most or all of its nuclear fuel and has collapsed to a very small size, believed to be near its final stage of evolution.


_____ sequence star , once fusion begins a star becomes this.


Where it starts on the sequence is based on the its __________ mass


more massive stars begin as large _____ stars


less massive stars begin somewhere _______ the main sequence


stars _______ at different rates


massive stars us fuel ______.


_______ stars use fuel slowly an exist for perhaps hundreds of billions of years

hydrogen, helium, outward

as _________ fuses into _______________ in the interior, the fusion migrates ______


surface cools and becomes _______


star spends almost ______ % of its life as a main-sequence star


an apparent group of stars originally named for the mythical characters; the sky is presently divided into 88 constellations

cepheid variable

a star whose brightness varies periodically because it expands and contracts a type of pulsating star.


a star that explosively increases in brightness

binary star

one of two stars revolving around a common center of mass under their mutual gravitational attraction


a group of stars, dust, and gases held together by gravity.

galaxy cluster

a system of galaxies containing from several to thousands of member galaxies.

hubbles law

a law that states that the galaxies are retreating from the milky way at a speed that is proportional to their distance.


a very large, very bright red giant star

red giant

a large, cool star of high luminosity; a star occupying the upper- right portion of the H-R diagram


cloud of gas and dust in space


a collapsing cloud of gas and dust destined to become a star; a developing star not yet hot enough to engage in nuclear fusion.

reflection nebula

made mostly of dust, reflects light of a nearby star

dark nebula

far from any stars so they do not reflect or absorb energy from an stars, not dense has as much matter as a star/planet system.


protostar glows _____


if cool then____


if hot then _____

medium bright

if medium temp ____


The difference in the brightness of two stars with the same surface temperature is attributable to their ____.

temperature and absolute magnitude

A Hertzsprung-Russell (H-R) diagram shows the relationship between ____.


Which main-sequence stars are the most massive?

the hottest

According to Figure 25-1, which main-sequence stars are brightest?


According to Figure 25-1, the sun has an absolute magnitude of ____.

a protostar reaches a temperature high enough for nuclear fusion to begin

A star is said to be born when ____.


In the Milky Way, the most abundant gas in emission nebulae is ____.

neutron stars

Which stars are composed of matter in which electrons have combined with protons?

elliptical galaxies

About 60 percent of all known galaxies are classified as ____.

cepheid variables

Some stars, called ____________________, get brighter and fainter in a regular pattern


A(n) ____________________ is a developing star not yet hot enough to engage in nuclear fusion.


In addition to size and shape, one of the major differences among galaxies is the ____________________ of their stars.



A(n) ____________________ galaxy is a type of galaxy that lacks symmetry.

doppler effect

The apparent change in wavelength of radiation caused by the relative motions of the source and the observer is called the ____________________.

round or oval



30 percent of galaxies are ____ galaxies


most common

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