Chapter 12

Front 1

absolute magnitude

Back 1

brightness of a star at this distance. To compensate for distance differences astronomers calculate the brightness that stars would appear to have if they were all at a defined standard distance 32.6 light years

Front 2

apparent magnitude

Back 2

classification scheme for different levles of brightness

Front 3

combo of 3 factors responsible for the brightness of a star

Back 3

1. amt of light produced by the stars; 2. size of star 3. distance of star

Front 4

big bang theory

Back 4

Universe had explosive beginning /expansion of universe; background radiation;abudance of elements helium = 24%

Front 5

black hole

Back 5

collapsed star with a mass of about 3 solar masses or more. Overwhelms all nucleon forces plus repulsive forces between all charged particles

Front 6

Cepheid variable

Back 6

variable star is a star that changes in brightness over time. A Cepheid variable is a bright variable star that is used to measure distances

Front 7

Cepheid variable

Back 7

variable star is a star that changes in brightness over time. A Cepheid variable is a bright variable star that is used to measure distances

Front 8

convection zone

Back 8

17ths of the way to the surface of the sun where density of the plasma is about 1%of the density of water;

Front 9

convection zone

Back 9

17ths of the way to the surface of the sun where density of the plasma is about 1%of the density of water;

Front 10

core

Back 10

nuclear fusion reactions release gamma and x-rays density of the core is about 12x that of solid lead

Front 11

core

Back 11

nuclear fusion reactions release gamma and x-rays density of the core is about 12x that of solid lead

Front 12

dark energy

Back 12

matter which is causing galaxies to accelerate rather than to expand at a constant rate.

Front 13

dark energy

Back 13

matter which is causing galaxies to accelerate rather than to expand at a constant rate.

Front 14

dark matter

Back 14

missing matter & mysterious variations in the orbit of galaxies and stars

Front 15

dark matter

Back 15

missing matter & mysterious variations in the orbit of galaxies and stars

Front 16

Cepheid variable

Back 16

variable star is a star that changes in brightness over time. A Cepheid variable is a bright variable star that is used to measure distances

Front 17

convection zone

Back 17

17ths of the way to the surface of the sun where density of the plasma is about 1%of the density of water;

Front 18

core

Back 18

nuclear fusion reactions release gamma and x-rays density of the core is about 12x that of solid lead

Front 19

Cepheid variable

Back 19

variable star is a star that changes in brightness over time. A Cepheid variable is a bright variable star that is used to measure distances

Front 20

dark energy

Back 20

matter which is causing galaxies to accelerate rather than to expand at a constant rate.

Front 21

convection zone

Back 21

17ths of the way to the surface of the sun where density of the plasma is about 1%of the density of water;

Front 22

dark matter

Back 22

missing matter & mysterious variations in the orbit of galaxies and stars

Front 23

core

Back 23

nuclear fusion reactions release gamma and x-rays density of the core is about 12x that of solid lead

Front 24

dark energy

Back 24

matter which is causing galaxies to accelerate rather than to expand at a constant rate.

Front 25

dark matter

Back 25

missing matter & mysterious variations in the orbit of galaxies and stars

Front 26

galactic clusters

Back 26

gravationally bound subgroups of as many as one thousand stars that move together w/in the Milky way

Front 27

galaxy

Back 27

the billions and billions of stars that form the basic unit of the universe

Front 28

globular clusters

Back 28

clusters which are more symmetrical and tightly packed containing as many as a million stars

Front 29

Hertzsprund-Russell diagram

Back 29

temperature-luminosity graph plot with temperature indicated by spectral types and the true brightness indicated by absolute magnitude

Front 30

light-year

Back 30

is the distance the light travels in one year about 9.5 x 10 12

Front 31

main sequence stars

Back 31

normal, mature stars using their nuclear fuel at a steady rate

Front 32

nebulae

Back 32

clouds which are between stars

Front 33

neutron star

Back 33

remains of the compressed core after the supernova has a remaining mass greater than 1.4 solar masses. compressional forces of the supernova explosion are great enough to collapse nucleim forcing protons and electrons together forming the core of a neutron star

Front 34

protostar

Back 34

is a cloud of gas atoms which begins to condense b gravitational attraction to a protostar an accumulation of gases that will become a star

Front 35

pulsar

Back 35

very strongly magnetized neutron star that emits a uniform seriew of equally saced electromagnetic pulses.

Front 36

radiation zone

Back 36

as being less dense than the core and having a density about the same density as water. energy in the form of gamma and xrays from the core is absorbed here

Front 37

red giant stars

Back 37

bright but low temperature stars found on the upper right hadn of the h-R diagram

Front 38

supernova

Back 38

is the star that collapses and rebounds like a compressed spring into a catastrophic explosion

Front 39

white dwarf stars

Back 39

located lower left because theyare faint white hot stars very dense with a mass aprox equal to the sun

Front 40

ff

Back 40

ff

Front 41

pulsar

Back 41

strongly magnetized neutron star that emits a uniform series of equally spaced electromagnetized pulses

Front 42

asteroids

Back 42

between the orbits of Mars and Jupiter is a region of thusands of small rocky bodies called asteroids

Front 43

comet

Back 43

relatively small solid body of frozen water

Front 44

astronomical unit

Back 44

distance from earth sun earth is 1 AU from sun

Front 45

dwarf planet

Back 45

as an object that is orbiting the sun nearly sherical but has not cleared matter from its orbital zon and in not a satellite

Front 46

giant planets

Back 46

Jupiter Saturn Uranus and Neptune hydrogen helium methane

Front 47

Kuiper belt

Back 47

disk shaped region of small icy bodies which range from 30 to 100 AU from the sun

Front 48

meteor

Back 48

falling star burns up after reaching an altitude of 100 km

Front 49

meteroids

Back 49

remnants of comets and asteroids

Front 50

meteor shower

Back 50

occurs when the earth passes through a stream of particles left by a comet

Front 51

Oort cloud

Back 51

source of high period comets with orbital periods of more than two hundred years

Front 52

planet

Back 52

orbits the sun nearly spherical and large enough to clear allmatter from its orbital zone

Front 53

protoplanet nebular model

Back 53

widely accepted theory of origin of the solar system - earliest stage in the formation of a planet

Front 54

small solar system bodies

Back 54

all other objects orbiting the sun are referred to collectively as small solar system bodies

Front 55

terrestial planets

Back 55

interior planets of mercury venus and mars have densities and compositions similar to earth so these along with earth are called