Astro Test Ii

Front 1

dense portions of molecular clouds begin to collapse due to

Back 1

Self-Gravity

Front 2

the most abundant of heavier molecules in molecular clouds

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CO2 (carbon dioxide)

Front 3

fragmentation of a molecular cloud into smaller pieces is caused by

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turbulence

Front 4

a shrinking solar nebula does three things:

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1. heats up because of gravitational potential energy is converted into kinetic thermal energy

2. spins or rotates due to conservation of angular momentum

3. flattens into a disk because of collisions between particles

Front 5

protostar maintains an ever changing balance between

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pressure and gravity

Front 6

a body with a mass <0.08sun is too small to be a true star and is usually called a

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brown dwarf

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solar nebula shrank to a diameter of 200AU it became a flattened spinning disk. three conditions:

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1. orderly motion
2. highest density and temperature at the center
3. nearly circular orbits

Front 8

train rushes towards a stationary observer standing by the tracks, the pitch of the train's whistle ____, and this effect is called

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1. goes up
2. blueshift

Front 9

an imaginary line between the orbits of Mars and Jupiter where temperature remain <150 K is called the ____ line

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frost

Front 10

the process of planetary growth by

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accretion

Front 11

correct order of the major steps of the solar system

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collapse, condensation, accretion

Front 12

angular momentum

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1. angular momentum is also known as spinning momentum
2. angular momentum is expressed as m x v x r
3. A.M. of an object can be changed by a twisting force, or torque

Front 13

the distance to an object with a parallax of 1 arcsecond is

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1 parsec

Front 14

how to determine the distances to nearby stars

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measure parallax of the star and use trigonometry to determine the distance

Front 15

if a star was moved twice as far away what would happen to its brightness

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it would get four times fainter

Front 16

a star luminosity is proportional to its

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surface area

Front 17

as a black body heats up, the wavelength at which maximum emission occurs

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shorter (gets bluer)

Front 18

emission occurs when an electron

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emits a photon, drops to a lower energy state, and produces a bright spectral line

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as radiations from a star's interior passes through its cooler atmosphere_______ lines are seen in its spectrum

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emission

Front 20

stellar spectral classes in order from hottest to coolest are

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OBAFGKM

Front 21

the orbital period of binary stars depends on masses of stars and the size of orbits is important because

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this is the main way to determine the masses of the stars

Front 22

The lowest-mass stars have a mass equal to

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.08Msun

Front 23

to determine the orbit of a spectroscopic binary, astronomers use

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The doppler shift

Hint 23

`

Front 24

These are things that can be plotted on the x-axis in an H-R diagram

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color, temperature, spectral type

Front 25

these two energy sources can help a star maintain hydrostatic equilibrium

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nuclear fusion and gravitational contraction

Front 26

atomic nuclei are held together by a powerful but short-range force called

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the strong nuclear force

Front 27

for fusion to occur in the sun, there must be ___ and a ____

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high temperature and high density of protons

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fusion in the sun works by the process known as the

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proton-proton chain

Front 29

two mechanism transport energy from the Sun's core to its surface

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radiative transfer and convention

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nuclear fusion in the sun releases ergy and small, nearly massless particles called

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neutrions

Front 31

hiloseismologists study

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sound waves

Front 32

the sun appears to have a sharp outline, even though it has no true surface, due to the phenomenon called limb darkening

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we look through less material at the sun;s edge than we do when we view the sun's middle portion

Front 33

solar activity includes

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sunspots, solar prominences, solar flares, coronal mass ejections

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causes the greatest hazard to communications satellites

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protons from sun carried by a CME

Front 35

sunspot activity practically ceased between 1645 and 1715, this was known as

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Maunder minimum

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low mass stars are ___ or fewer solar masses

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8

Front 37

a stars evolutionary track is established by its

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mass

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more massive stars generate energy at a ___ rate than low-mass stars and have a ___ luminosity than now-mass stars

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higher/higher

Front 39

the lifetime of a massive star near the top of the main sequence compared to the suns

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a significantly much shorter time

Front 40

the luminosity of a typical main sequence star like the will ____ over time

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increase

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a main sequence star will

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fuse hydrogen into helium in its core

Front 42

at the end of the first red giant stage, a low-mass star's core has become degenerate through contraction and hot enough to initiate helium fusion through the ___ process at a temperature of ___ K

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triple alpha / 100 million

Front 43

a star on the horizontal branch is

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fusing helium to carbon in its core

Front 44

when a low-,ass star reaches the asymptotic giant branch, it will become thermally unstable and eject much of its atmosphere into space that will become a

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planetary nebula

Front 45

when a low-mass star reaches the AGB on its evolutionary track, it has a non-degenerate carbon core surrounded by ___ shells in which fusion is still occurring

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2

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the white dwarf is the core of the previous AGB star, is main composed of ___ is supported by ____, and ____.

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carbon/ electron degeneracy/ no longer supports fusion

Front 47

a star leaves main sequence when

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it depends on its mass and when the hydrogen is used up

Front 48

high-mass main sequence stars make their energy via

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CNO (carbon-nitrogen-oxygen) cycle

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A substance that enabled a reaction but is unaltered in the process

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catalyst

Front 50

when in the red giant stage, high-mass stars differ from low-mass stars in one important way

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following core hydrogen fusion, high-mass stars develop a dense core of helium not supported by electron degeneracy

Front 51

pulsating variable stars that follow a ____ relationship are important for determining distances

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period-luminosity

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the class of pulsating variable star that are more valuable for determining distance and were use by Hubble to measure the distance to the Andromeda Galaxy

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Cepheid variables

Front 53

massive star have high stellar __ that result in significant mass loss by the end of their lives

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winds

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the element ___ cannot generate energy though either fusion or fission

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iron

Front 55

in the final days of a high mass tar, each successive stage of nuclear burning (in which new elements are formed) takes less time as each fuel is used up more quickly. this accelerated pace of fusion occurs largely because of

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neutrino cooling

Front 56

when the core in the high-mass collapses, it is the resulting ___ that actually causes the outer layers of the star to be biolently ejected into space

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core bounce

Front 57

A supernova leaves behind a remnant called

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black hole or neutron star

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following a supernoca explosion if the remaining dense core has a mass of at least ___M it will form a black hole

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3

Front 59

special relativity states that traveling very close to the speed of light will result in

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time dilation and length contraction