chapter 16

Question 1

the stages of development that a star goes through over its life cycle

Answer 1

stellar evolution

Question 2

main sequence star with a mass greater than ~8 solar mass

Answer 2

high mass star

Question 3

main sequence star with a mass between 3 to 8 solar mass

Answer 3

medium mass star

Question 4

main sequence star with a mass less than 3 solar mass

Answer 4

low mass star

Question 5

main sequence star with a mass between .08 and .5 solar mass

Answer 5

very low mass

Question 6

• small red dwarfs (0.4-0.5 SM) accounts for most stars in the galaxy, but are very small and faint
• remain on the main sequence for 13.8 billion yrs

Answer 6

lowest mass star (2)

Question 7

• matter in which electrons are packed as closely as possible
• 100,000 times denser than lead

Answer 7

electro-degenerate (2)

Question 8

pressure exerted by closely packed electrons in the collapsing core of a star

Answer 8

degeneracy pressure

Question 9

the fusion of hydrogen in a shell surrounding a degenerate core

Answer 9

hydrogen shell fusion

Question 10

a low-mass star that has evolved beyond the main-sequence and fuses hydrogen in a shell around a helium core

Answer 10

red giant

Question 11

• a giant star that is smaller & less luminous than a normal giant
• H - ions form in the atmosphere to regulate its temp

Answer 11

subgiant (2)

Question 12

region of the H-R diagram defined by stars that have left the main-sequence but have not reached the red giant branch

Answer 12

subgiant branch

Question 13

region on the H-R diagram defined by stars evolving from the main sequence towards the horizontal branch

Answer 13

red giant branch

Question 14

100 million Kelvin

Answer 14

temp for hydrogen to fuse to helium

Question 15

the nuclear fusion reaction that combines 3 helium-4 nuclei into a single carbon

Answer 15

triple alpha process

Question 16

• helium-4; consisting of 2 protons and 2 neutrons
• 2 helium-4 fuse to become beryllium-8
• if a beryllium-8 collides with another helium-4, it fuses into carbon-12

Answer 16

alpha particle (3)

Question 17

the runaway explosive fusion of helium in the degenerate helium core of a red giant star

Answer 17

helium flash

Question 18

• a region on the H-R diagram defined by stars fusing helium into carbon in a stable core
• remains on the horizontal branch for 100 million years

Answer 18

the horizontal branch (2)

Question 19

the loss of mass from the outermost layers of a star’s atmosphere during the star’s evolution

Answer 19

stellar mass loss

Question 20

the path on the H-R diagram that goes from the horizontal branch toward higher luminosities and lower temperatures; approaching then rising above the red giant branch

Answer 20

asymptotic giant branch

Question 21

the remaining outer layers of a star are ejected into space at the end of a star’s ascent of the AGB

Answer 21

planetary nebula

Question 22

• the stellar remnant left at the end of the evolution of a low-mass star
• has a mass of .6 SM, and a size equal to earth
• made of non-fusing, electron-degenerate carbon
• cools as it continues to radiate away energy

Answer 22

white dwarf (4)

Question 23

the hourglass-shaped volume of space surrounding 2 stars, which constrains material that is gravitationally bound

Answer 23

roche lobes

Question 24

the transfer of mass from one star to another in a binary system

Answer 24

mass transfer

Question 25

• a stellar explosion that results from runaway nuclear fusion in a layer of material on the surface of a white dwarf in a binary system
• can repeat multiple times as material builds up and ignites again

Answer 25

novae (2)

Question 26

supernova explosion with a calibrated peak luminosity that occurs from runaway carbon fusion

Answer 26

type Ia supernovae

Question 27

expanding shells of dust and gas

Answer 27

supernova remnants