life cycle of stars review

when a star formation begins, hydrogen gas clumps together. as more hydrogen is pulled in by gravity, contraction causes what two things to increase?

pressure and tempature

at what temperature does hydrogen ignite and begin to fuse into helium?

100 million K

what two forces must equalize (balance) before the star is considered a main sequence star?

initial mass and temperature

put the following events in order of correct time frame. protostar, molecular cloud, main sequence, t tauri star.

molecular cloud, protostar, t tauri, main sequence

the death of a low mass star ends with what type of nebula?

planetary nebula

what type of star remains when a low-mass star dies?

white dwarfs

when hydrogen runs out, what is the next element that starts fusing?

helium

what is the last element to get produced (through the fusion of helium) in a low mass star?

carbon

high mass stars continue the fusion process. what is the last element to get produced by a high mass star?

iron

what happens to a star after this element is produced?

type 2 supernova

stars with a solar mass between 3 and 8 usually become what type of star when they die?

neutron star

a star greater than 8 solar mass becomes what when it dies?

black hole

when a white dwarf pulls material from its companion star, it can produce what type of supernova?

type 1a

what is the name of this mass limit? how many solar masses is this limit?

the chandrasekhar limit. 1.4 solar masses

what is the difference between a type 1 a supernova and type 2 supernova?

a type ia supernova occurs in a binary star system with a white dwarf exploding due to mass transfer, while a type II supernova happens in a massive star that collapses and explodes.

when a neutron has a companion star and pulls material away from it, its rotation can be detected on earth. this type of neutron star that creates sound in radio waves detected on earth is called?

millisecond pulsar

what is a variable star and list two main groups?

stars that go through periods of instability. intrinsic (physical changes) and extrinsic (rotation of the star)

what are the two main classes of intrinsic variable stars?

pulsating and eruptive

what are two types of pulsating variable stars?

cepheid variables and RR lyrae variables

what is the relationship between a cepheid variable’s “period” and its “absolute magnitude” ?

longer periods are more luminous and have higher absolute magnitudes

what is the name of the “radius” in which any object must be compressed to become a black hole?

schwarzschild radius

the “theoretical” surface of a black hole, or the no point of return is called the

event horizon

where do we find supermassive black holes?

central regions of a galaxy

when a supermassive black hole feeds too quickly on a large amount of material, it “spits out” this material. this the brightest object in the universe. what do we call this object?

quasar