Exam 2 review Flashcards

Question

What happens to absorption lines when atmospheric pressure increases

Answer 1

absorption lines get broader as pressure increases

Answer 2

Stars that are seen to vary in brightness

Answer 3

a light curve

Answer 4

such stars have essentially the same luminosity curve, with periods from 0.5 to 1 day, all have the same luminosity

Answer 5

Cepheid periods range from about 1 to 100 days, have a luminosity that is strongly correlated with the period of their oscillations

Answer 6

The interstellar medium consists of gas and dust. Gas is atoms and small molecules, dust is larger clumps of particles

Answer 7

one atom of gas per cubic centimeter

Answer 8

90% hydrogen, 9% helium, and 1% heavier elements

Answer 9

Gas that is found in Emission nebulae

Answer 10

hot, glowing area associated with the formation of large stars usually part of a larger dust cloud

Answer 11

Found in cold regions without stars between dust clouds

Answer 12

Found in cold dark dust clouds

Answer 13

Emission Nebulae, they are composed of atomic hydrogen gas that is ionized by near-by stars

Answer 14

When an electron switches its spin direction, it is a way to emit energy without changing atomic orbital

Answer 15

Dust clouds absorb blue light, interstellar matter exists in dark regions

Answer 16

A region of space that is clearly distinguishable through a telescope, but is not sharply defined like a planet or a star

Answer 17

Nebula's are MASSIVE with low density

Answer 18

a third class of particle in interstellar space, high-speed atomic nuclei and electrons

Answer 19

supernova explosions, difficult to tell because of direction change due to magnetic fields

Answer 20

Interstellar cloud starts to contract, usually triggered by shock or pressure wave from nearby star. As it contracts, cloud fragments into smaller pieces. Takes a couple million years.

Answer 21

individual cloud fragments begin to collapse, once the density is high enough there is no further fragmentation. this contraction produces energy.

Answer 22

Spherical gas ball about the size of our solar system,. density is massive, radiation cannot escape. interior is about 10,000 K

Answer 23

The core of the cloud is now a protostar, and makes its first appearance on the H-R diagram

Answer 24

The protostar is still not in equilibrium -- outward pressure is becoming a force, but all heating still comes from the gravitational collapse. gets nebular disk, possibly planets.

Answer 25

violent surface activity, extremely strong protostellar winds, interaction of winds and disk cause bipolar "jets" emitting energy

Answer 26

The core reaches 10 million K, and nuclear fusion begins, PROTOSTAR HAS BECOME A STAR, star continues to contract and increase in temperature, lasts 30,000,000 yr or so

Answer 27

The star is in equilibrium, it has reached the main sequence and will remain there as long as it has hydrogen to fuse in its core

Answer 28

luminosity increases drastically as temperature rises (stephan boltzman)

Answer 29

if the mass of the original nebular fragment is too small, nuclear fusion will never begin, failed star, jupiter

Answer 30

loose irregular cluster, found mainly in the plane of the Milky Way, contains few hundred to a thousand stars

Answer 31

spherical clusters of stars with the absence of massive main-sequence stars, and the heavily populated red giant region, found away from the galactic plane, at least 10 billion years

Answer 32

planet outside the solarsystem

Answer 33

an old star that is shedding its outer layers

Answer 34

subgiant status, 100 mill yrs. when the fuel in the core depletes, the core contracts, hydrogen fuses in a shell outside the core --> energy production increases and star gets brighter

Answer 35

red giant status its luminosity increases enormously due to its large size. He core is tiny, but has 25% of the stellar mass.

Answer 36

helium fusion the helium flash- when helium fuses rapidly, luminosity spikes huge for a short period of time

Answer 37

giant branch, asymptotically helium in cor fuses to carbon and oxygen now there are two shells, outward pressure swells the star

Answer 38

turn off point lowers the older the star cluster gets

Answer 39

NO, stars between 4M and 10M do NOT undergo helium flashes

Answer 40

Hydrogen, Helium, Carbon, Oxygen, Neon, Magnesium, Silicon, Iron

Answer 41

higher mass, lower lifespan

Answer 42

Fusion ceases, the envelope blows off, leaving a white dwarf to slowly cool

Answer 43

White dwarf continues to cool, no more contraction due to electron pressure remains the size of Earth, temperature approaches 0 k, 1 trillion years --> star is dead.

Answer 44

A star that is so dense that electrons are squeezed into the atomic nucleus. They then combine with protons to form neutrons and neutrinos

Answer 45

one time violent explosion, once it happens, there is little or nothing left of the progenitor star

Answer 46

Fusion of iron core ceases, temperature is 10 bill k protons and electrons are crushed together, creates shock wave

Answer 47

Type Ia - posses Si lines in the spectra Type Ib - Posses He lines in the spectra Type Ic - anything else

Answer 48

post supernova, so dense even electromagnetic radiation cannot escape

Answer 49

a star that flares up very suddenly and then returns slowly to its former luminosity

Answer 50

A maximum mass that a white dwarf can have before it collapses and supernovas