Life Cycle of Stars

Question 1

the word photosphere means

Answer 1

sphere of light

Question 2

the word chromosphere means

Answer 2

sphere of color

Question 3

the corona extends several million kilometers and gradually becomes the

Answer 3

solar wind

Question 4

what part of the sun’s atmosphere can only be seen during a total solar eclipse?

Answer 4

chromosphere

Question 5

what elements make up the sun’s interior in what percentages?

Answer 5

hydrogen 73.4%, helium 24%

Question 6

nuclear fusion takes place in what part of the sun?

Answer 6

core

Question 7

what is the source of the sun’s energy?

Answer 7

nuclear fusion

Question 8

where does the energy come from in a nuclear reaction?

Answer 8

difference in mass

Question 9

who developed the famous equation E=mc^2?

Answer 9

Einstein

Question 10

nuclear fusion can only happen under what conditions?

Answer 10

high temperature, high pressure

Question 11

what occurs during this reaction?

Answer 11

2 protons turn into 2 neutrons

Question 12

the sun has enough hydrogen left to continue fusion for how much longer?

Answer 12

5 billion years

Question 13

hydrostatic equilibrium, inward 1.)________ force must be balanced by outward pressure from the 2.)______ ________ reaction: this means that the sun is not 3.)________ nor 4.)_________ this time

Answer 13

1.) gravitational
2.) Hydrogen fusion
3.) expanding
4.) contracting

Question 14

when do sunspots form?

Answer 14

when distorted by magnetic field lines

Question 15

why do sunspots appear dark?

Answer 15

they are cooler than their surroundings

Question 16

solar_________ is large sheet of ejected gas

Answer 16

prominence

Question 17

_______ _______ escapes the sun mostly through coronal holes, which can be seen in X-ray images

Answer 17

solar wind

Question 18

list and describe the four fundamental forces in nature

Answer 18

1. gravity - weak, always attractive, and infinite range
2. electromagnetic - strong, either attractive or repulsive, infinite range
3. weak nuclear force - responsible for beta decay; short range, weak
4. strange nuclear force - keeps nucleus together; short range, strong

Question 19

chromosphere

Answer 19

the lower layer of the atmosphere, below the photosphere

Question 20

convection

Answer 20

the transfer of energy by motion of fluid

Question 21

convection zone

Answer 21

the layer just under the surface where energy is transferred by convection

Question 22

corona

Answer 22

the outermost layer of the atmosphere that extends several kilometers and becomes the solar wind

Question 23

luminosity

Answer 23

energy radiated by the sun can be calculated from the fraction of energy that reaches earth

Question 24

nuclear fusion

Answer 24

the combining of 2 or more small atomic nuclei into a large atomic number

Question 25

photosphere

Answer 25

“sphere of light” is what we see at the surface of the sun

Question 26

radiation

Answer 26

the transfer of energy through space by electromagnetic waves

Question 27

radiation zone

Answer 27

the core of the sun where energy is transferred by radiation

Question 28

solar wind

Answer 28

escapes the sun mostly through coronal holes, which is seen in X-ray images

Question 29

when does star formation occur and where?

Answer 29

when dust clouds begin to contract under gravitational force; the core

Question 30

star formation happens when part of a dust cloud (nebulae) begins to _____ under its own _______ force.

Answer 30

contract, gravitational

Question 31

it then collapses and the center becomes hotter and hotter until ________ ________ begins in the core.

Answer 31

hydrogen fusion

Question 32

Interstellar cloud starts to contract, probably triggered by a ______ wave or pressure wave from a nearby star. The protostar has finally become a star

Answer 32

shock

Question 33

why are some protostars unable to fuse hydrogen?

Answer 33

does not have enough mass to have a high temperature

Question 34

pleiades is an example of

Answer 34

an open cluster

Question 35

brown dwarf

Answer 35

planet like object

Question 36

closed star clusters (globular clusters)

Answer 36

old, large, spherical

Question 37

hydrostatic equilibrium

Answer 37

inward gravitational force must be balanced by outward pressure from hydrogen fusion reaction, not expanding

Question 38

open star clusters

Answer 38

young, small, randomly shaped

Question 39

protostar

Answer 39

not a nebula that glows because the pressure of gravity

Question 40

main sequence star

Answer 40

when a protostar has enough mass to fuse hydrogen

Question 41

red giant star

Answer 41

large, glows red, fuses helium and other elements

Question 42

white dwarf

Answer 42

dying star, gradually cooling off (dimming)

Question 43

black dwarf

Answer 43

dead star, reaching does not give off light

Question 44

neutron star

Answer 44

core left after a supernova, made of neutrons

Question 45

nebula

Answer 45

huge cloud of gas and dust, made of hydrogen

Question 46

black hole

Answer 46

star that collapses on itself because of gravity, light can’t escape

Question 47

what important characteristic determines the way a star moves through its life cycle?

Answer 47

mass

Question 48

what is left after a star fuses hydrogen?

Answer 48

helium

Question 49

supernova

Answer 49

explosion of a star after it can’t fuse elements in the core

Question 50

absolute magnitude

Answer 50

true brightness of stars