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Astronomy > Test 2 > Flashcards

Test 2 Flashcards

0
Q

Extinction

A

Loss of star light

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1
Q

Emission Nebula

A

Excited, glowing hydrogen gas.
Reddish color
Brand new, younger than reflection nebulaes

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3
Q

Reddening

A

Changing color as it passes through interstellar medium

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4
Q

Dark Nebulae

A

Dust is thick enough to block light.

Black color

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5
Q

Shedding angular momentum

A

1) bipolar outflow: material flies out of two poles. Low mass stars.
2) stellar winds: high mass stars.
3) split into 2 stars.

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7
Q

Hyashi tracks

A

As stars are forming they change positions on the HR diagram making “tracks”

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8
Q

Lifetime of stars equation

A

t = 1/m^2.5

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9
Q

To form a star

A

1) Start with a GMC
2) trigger collapse of GMC
- collide GMCs
- supernova explosion
- density waves
3) cloud continues to collapse and spins in a disk
4) once core is hot and dense enough, nuclear fusion occurs
5) stellar winds clear out remaining gas and dust

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10
Q

Russell-Vogt Theorem

A

The mass and chemical composition of a star determines all it’s other properties.

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11
Q

Most efficient ways to create energy

A

Low mass star: portion-proton chain

High mass star: CNO cycle

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12
Q

Approximately how long does is take a star like the sun to form?

A

10,000,000 years

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13
Q

CNO cycle

A

Method which high mass stars use to convert H to He.

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14
Q

Does a planetary nebula come from high mass or low mass stars?

A

Low mass stars

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15
Q

Which spectral type of stars is the rarest?

A

O

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16
Q

What is the term for light changing colour as it passes through the interstellar medium?

A

Reddening

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17
Q

What process is converting hydrogen to helium in low mass main sequence stars?

A

Proton-proton chain

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18
Q

What is the maximum mass of a white dwarf?

A

1.4 solar masses

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19
Q

What’s occurring in the core of a red giant branch star?

A

Helium core with a shell of hydrogen to helium burning

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20
Q

GMC

A

Giant molecular cloud: gas clouds in the disk of the Milky Way in which new stars are formed.

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21
Q

Who was the first one to discover pulsars?

A

Jocelyn Bell

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22
Q

What type of stellar remnant will the sun eventually become?

A

White dwarf

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23
Q 
Which of the following is a method used to shed angular momentum during stellar formation?
A. Inward spiral deprecation
B. atmospheric oscillations
C. Disk fracturing
D. Bipolar outflow
E. None of the above
A

D.

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24
Q

Planetary nebula

A

Outer envelope is ejected into space, exposing the core.

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26
Q

What creates the blue colour seen in a reflection nebula?

A

Dust reflecting starlight

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27
Q

Which is the shortest amount of time?
A. The lifetime of an M spectral type star.
B. the formation of the sun.
C. The amount of time a high mass star burns silicon into Fe in it’s core.
D. The age of the universe.
E. None of the above.

A

C.

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28
Q

R and S processes

A

Rapid and slow neutron capture. Method which creates heavy elements in the universe.

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29
Q

Triple Alpha Process

A

Helium burning into carbon

30
Q

Neutron star

A

Remnant of a type II supernova explosion with mass greater than 1.4 solar masses but less than 3 solar masses.
20 km radius on average.

31
Q

Asymptotic Giant Branch Star

A

Double shell burning phase in a low mass star.
Carbon oxygen core is shrinking and not fusing (degenerate core).
He to C shell.
H to He shell.
Envelope expands and cools.

32
Q

Event horizon

A

Boundary marking the limits of a black hole. At the event horizon, the escape velocity is equal to the speed of light. Since general relativity states that nothing can travel faster than the speed of light, nothing inside the event horizon can ever cross the boundary and escape beyond it, including light.

33
Q

Horizontal branch star

A

Low mass star with a core burning He to C.
Shell of H to He.
Core expands as envelope shrinks.

34
Q

Supernova type 1

A

When a white dwarf gets more than 1.4 solar masses rapidly, it will explode.

35
Q

Helium Flash

A

Point on HR diagram where He begins fusing into carbon in low mass stars.
Triple alpha process happens.
100,000,000 K

36
Q

Globular star cluster

A

100,000 to 1,000,000 stars
Found in halo of galaxy
Old stars
Low metallicity

37
Q

Photon sphere

A

Region around black holes where photons orbit.

38
Q

Pulsar

A

Spinning neutron star which emits regular pulses.

39
Q

White dwarf

A 
Remnant of a low mass star. Exposed degenerate core. 
Carbon oxygen composition. 
Earth sized. 
More mass = smaller radius. 
Can't be more than 1.4 solar masses.
40
Q

Supernova type II

A

Last stage in a high mass stars evolution. Once it becomes iron it collapses and the rebounding shock wave blows up the star.

41
Q

List the three properties that change when comparing a reference frame close to the speed of light with one that is not moving.

A

1) time
2) mass
3) length in direction if travel

42
Q

What is the evolutionary stage of a star when it has two shells around a degenerate carbon oxygen core, one shell burning He to C and the other H to He?

A

Asymptotic Giant Branch

43
Q

What is the stellar remnant which has between 1.4 and 3 solar masses?

A

Neutron star

44
Q

Which spectral type of stars is the most abundant?

A

O

45
Q

Which spectral types of stars will live the longest?

A

O

46
Q

What causes spaghettification to occur as one falls into a low mass black hole?

A

Tidal forces in which your feet feel a much greater pull than your head.

47
Q

Evolution of a low mass star

A

1) main sequence
2) red giant branch
3) helium flash
4) horizontal branch
5) asymptotic branch
6) planetary nebula
7) white dwarf

48
Q

What is the term for the balance between gas pressure outward and gravity pulling inward?

A

Hydrostatic equilibrium

49
Q

Triggering mechanisms

A

1) collide GMCs
2) supernova explosion
3) density waves

50
Q

High mass stellar evolution

A

1) main sequence: CNO cycle, blue star, very bright, forms fast and does fast.
2) He —-> C core. Shell H —> He

3) C —> O core. Shells: H —> He,
He —> C

4) O —> Ne core. Shells: H —> He
He➡️C, C➡️O. 1 year.

5) Ne➡️Si (silicon) core. Shells: H➡️He, He➡️C, C➡️O, O➡️Ne. 6 months.
6) Si➡️Fe (iron) core. Shells: H➡️He, He➡️C, C➡️O, O➡️Ne, Ne➡️Si. 1 day.

7) iron core collapsesin in about 1/10 second.
Temp reaches 5 billion K.
Gamma rays destroy iron core
Envelope falls in.
Left is a solid core of neutrons and matter bounces off it along with neutrinos.
It’s ejected into space creating a type II supernova.

51
Q

Black hole

A

An object where the escape velocity is greater than the speed of light.

52
Q

Nova

A

A nova is a cataclysmic nuclear explosion in a white dwarf, which causes a sudden brightening of the star.

53
Q

Supernova Type I

A

Faster rate of transfer

54
Q

Star clusters

A

Stars are born in groups

Properties:

1) same age
2) same distance
3) same chemical composition

55
Q

Turn off points

A

Where main sequence stars leave the main sequence (seen in star clusters).

56
Q

Roche lobes

A

The Roche lobe is the region of space around a star in a binary system within which orbiting material is gravitationally bound to that star.

57
Q

Lagrange points

A

Specific points where an object will stay indefinitely.

58
Q

Algol paradox

A

There’s a red giant star and a main sequence star. The MS star weighs more than the red giant. Since they are binary stars the red giant “gave” it’s mass to the MS star when it evolved. Semi connect binary.

60
Q

How long is the sunspot cycle?

A

11 years

61
Q

Accretion disk

A

a disklike flow of gas, plasma, dust, or particles around any astronomical object in which the material orbiting in the gravitational field of the object loses energy and angular momentum as it slowly spirals inward.

62
Q

What is found in the center of a planetary nebula?

A

White dwarf

63
Q

Red Giant Branch

A

Runs out of H.
He in core is not fusing.
Envelope increases and cools. Core shrinks.
H to He shell.

81
Q

Reflection Nebula

A

Light reflected off interstellar dust grain.
Bluish color
Ex: Pleiades

82
Q

Open clusters

A

100-500 stars
Found in disk of galaxy
Fairly young
High metallicity

83
Q

Gamma ray busters

A

The creation of a black hole thru a type II supernova or binary stars colliding, releases a burst of gamma rays.

84
Q

Photosphere

A

Sunspots

5800 k

85
Q

Chromosphere

A

Prominences
Solar flares
30,000k

86
Q

Corona

A

Coronal holes

2,000,000 K

87
Q

Why do some black hole emit X-rays?

A

Gas falling into the black hole spirals in and heats up to millions of degrees.

Astronomy (2 decks)

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