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Flashcards in Stars Deck (57)
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1
Q

more massive stars, due to greater gravity, are..?

A

squeezed into smaller, more densely packed objects than less massive stars

2
Q
A
3
Q

hottest, brightest and more massive stars

A

Blue stars

4
Q

90% of the stairs

A

Main sequence stars

5
Q

stars exceeding eight solar masses, with short life spans

A

High-Mass Stars

6
Q

Stellar Evolution of Medium-mass (sun-like) stars

A

Nebular > protostar > main-sequence > red giant > planetary nebula > white dwarf

7
Q

Red Giant Stage

A

begins when the hydrogen is consumed, leaving a helium-rich core > core no longer has the gas pressure that resist the inward pull of gravity > core contracts, temperature increase > expansion of the star > as the star expands, its surface cools (red) > eventually the star’s gravity stops expansion > gravity and gas pressure, again achieve balance > star enters a stable state, but is much larger > astonishing increase in temperature, converts helium into carbon and oxygen

8
Q

largest white dwarfs = ?

A

least massive

9
Q

smaller and more massive than white dwarfs

A

Neutron Stars

10
Q

“average star”

A

Sun

11
Q

radiates short pulses of radio energy named pulsar (pulsating radio source)

A

Neutron Stars

12
Q

without fuel ->no balance between gas pressure and gravity > it collapses > enormous implosion resulting in a shock wave > this energetic shock wave blasts the star’s outer shell into space generating ..

A

SUPERNOVA

13
Q

terminate in brilliant explosions (supernova)
*during supernova, these stars become millions of times brighter

A

High-mass stars

14
Q

terminate in brilliant explosions (supernova)
*during supernova, these stars become millions of times brighter

A

High-mass stars

15
Q

*much fainter and smaller than the main-sequence stars of the same temperature
*some are almost the same size of Earth

A

White Dwarfs

16
Q

form if the core of a remaining star exceeds the three solar mass limit (neutrons can withstand the gravity)

A

Blackhole

17
Q

90% of star-life

A

Main-sequence stage

18
Q

some red giants alternately contract and expand

A

variable stars

19
Q

Hertzsprung-Russell Diagram

A
20
Q

Protostar Stage

A

gravitational contraction continues rapidly > core heats much faster > temperature: 10 million K > start to initiate nuclear fusion (hydrogen fusion) > will reach a point wherein inward pull of gravity will be balanced by temperature of hydrogen fusion

21
Q

with masses ranging between 1/2 and eight times that of the Sun

A

Medium-Mass Stars

22
Q

Stellar Evolution of Massive Stars

A

Nebula > protostar > main sequence (blue) > Red supergiants > supernova explosion > neutron star or blackhole

23
Q

spirals around a “void”

A

accretion disk

24
Q

main sequence = ?

A

active years

25
Q

electrons are displaced inward from their regular orbits around an atom’s nucleus

A

Degenerate matter

26
Q

Why is it called protostar?

A

heat is not enough to initiate nuclear fusion (source of energy)

27
Q

coolest, dimmest and less massive stars

A

Red stars

28
Q

without sources of energy, white dwarfs..

A

slowly cool and dim

29
Q

never become bloated red giants and remain a stable main-sequence star until they ran out of hydrogen fuel and collapse into a white dwarf

A

Low-mass stars

30
Q

first black hole to be discovered

A

Cygnus X-1

31
Q

Stellar Remnant

A

* white dwarf
* neutron star
* black hole

32
Q

found in the center of galaxies are estimated to be millions of solar masses

A

Larget blackholes (supermassive)

33
Q

densed, Earth-sized objects

A

White Dwarfs

34
Q

stars with 0.5 solar mass

A

Low-mass stars

35
Q

have masses 10 times that of the Sun, but are only about 20 miles across

A

Small black holes

36
Q

*stars with large radiating surfaces
*appear in the upper right position of H-R diagram

A

Red Giants

37
Q

electrons are forced to combine with protons in the nucleus to produce neutrons

A

Neutron Stars

38
Q

found in the center of galaxies are estimated to be millions of solar masses

A

it should become extremely hot and emit a flood of X-rays before it is engulfed

39
Q

have 10 billion years

A

Yellow stars (sun-like)

40
Q

useful tool for understanding Stellar Evolution

A

Hertzsprung-Russell Diagram

41
Q

stars experience minimal change in size or energy output (balance maintained)

A

Main-sequence stage

42
Q

gases that are pulled from the companion form an accretion disk while emitting a steady stream of X-rays

A

Black holes

43
Q

gravitational attraction within a nebula causes..?

A

cloud to collapse on itself

44
Q

Stellar Birth

A

interstellar clouds, rich in gas and dust > gravitational contraction, pulling particles into the center > as the cloud collapses, gravity is converted to thermal energy (increase in temperature)

45
Q

extremely hot, their surface gravity is so immense that even light cannot escape

A

Black holes

46
Q

smallest white dwarfs = ?

A

most massive

47
Q

Stellar Evolution of Low Mass Stars

A

Nebula > protostar > main sequence (red) > white dwarf

48
Q

>as a red giant, they fuse hydrogen and helium at accelerated rates and once fuel is exhausted, they collapse into a white dwarf
>without a source of nuclear energy, white dwarfs become cooler and dimmer

A

Medium-Mass Stars

49
Q

>independently studied the relationship between true brightness (absolute magnitude) and temperature of stars

>astronomers survey a portion of the sky and plot each star according to luminosity

A

Ejner Hertzsprung and Henry Russell

50
Q

radiate energy more, depletion of fuel in just few billion years

A

Blue Stars

51
Q

Every stage of a star’s life is ruled by..?

A

gravity

52
Q

very immense stars

A

Super giants

53
Q

have masses 1,000 times the Sun

A

intermediate black holes

54
Q

with radius 800 times that of the sun

A

Betelgeuse

55
Q

with rising temperature and pressure…

A

A star is born

56
Q

radiate energy more, depletion of fuel in just few billion years

A

Red Stars

57
Q

smallest white dwarfs were produced from…?

A

collapse of larger, more massive main-sequence stars