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Astronomy > Astronomy Test 4 > Flashcards

Astronomy Test 4 Flashcards

1
Q

The three factors that determine internal pressure

A

Temperature, rotation, and magnetic fields

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2
Q

The 4 regions of star formation

A
  1. Cold regions in interstellar space (H1 regions)
  2. H2 regions
  3. Dark nebula
  4. Bok Globules
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3
Q

Lamda(emission of protons) = 21 cm due to the spin flip of the electrons in the hydrogen atom. what regions on the DR diagram does this occur?

A

H1 regions

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4
Q

Molecular hydrogen only forms in very cold regions but radiates very little. what regions on the DR diagram does this occur?

A

H2 regions

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5
Q

Small round nebula. What does this describe?

A

Bok Globules

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6
Q

A cloud of gas collapses by what?

A

Mutual gravitational attraction

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7
Q

How do gas clouds become dark nebulas?

A

Inner regions cool and further collapse after gravitational attraction

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8
Q

What happens after a gas cloud becomes a dark nebula

A

Internal temperatures and pressures rise and fight collapse

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9
Q

Since cooling can never be efficient enough to reduce the internal pressure enough according to current theories “something” causes further collapse. What is it?

A

Shockwaves

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10
Q

Where do shockwaves come from? (3 things)

A

Newly formed stars, supernova explosions, and galactic spiral arms

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11
Q

Further collapse of cloud fragments from dark nebula’s become small, round what?

A

Bok Globules

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12
Q

Globules further collapse and form what?

A

Proto-stars

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13
Q

After 1000’s of years a proto-star becomes a star and appears on the ______ on the H-R diagram

A

Birthline

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14
Q

Dust that surrounds a proto-star and absorbs light

A

Cocoon nebula

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15
Q

Problems with star formation?

A

How does a single,isolated star not in a spiral galaxy form? And what if there’s no shocks around?

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16
Q

In the death of low mass stars, Helium fuses to ____ at _______K

A

Carbon, 100,000,000 Kalvin

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17
Q

In the death of low mass stars, as H is depleted in the core, the core collapses and heats up a H shell around the core and begins to burn and envelope expands. What stage is this?

A

Red Giant

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18
Q

In the death of low mass stars, the core continues to collapse until T= 100,000,000K. Helium burns explosive because of what?

A

Quantum degeneracy (all He is at the same temperature)

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19
Q

In the death of low mass stars, outer layers are blown off into interstellar space (planetary nebula) and hot, solid cargo core becomes a ______

A

White dwarf

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20
Q

In the death of high mass stars, what is the onion skin model. (6 layers)

A
  1. H to He
  2. He to Carbon
  3. C to Magnesium and Neon
  4. N to Mg and O
  5. O to silicon
  6. S to Fe
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21
Q

In the death of high mass stars, as outer layers crash onto the core, the envelope material is blown off and a _______ results.

A

Supernova

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22
Q

In the death of high mass stars, if core mass is less than 1.4 then the core remnant is a

A

White dwarf

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23
Q

In the death of high mass stars, if core mass is greater than 1.4 then the core remnant becomes a

A

Neutron star

24
Q

In the death of high mass stars, if core mass exceeds about 3, then the core remnant becomes a

A

Black hole

25
Q

No spectroscopic evidence of Hydrogen, light curves rapidly, ejected material has velocities of 10,000 to 20,000 Km/sec. These supernova are the result of nuclear detonations on the surface of a CO white dwarf in a binary system

A

Type 1 supernova

26
Q

Spectrum dominated by hydrogen lines, light curves, rise, move slowly, ejects material at speeds of 5,000 mm/sec. Strong radio emitters. These supernovas are the results of a massive single star dying.

A

Type 2 supernova

27
Q

Observed in the large Magellenic cloud. Type 2 super nova. Core remnant is probably a neutron star.

A

Supernova 1978A

28
Q

First neutron discovers in ____ as a ___

A

1968; pulsar

29
Q

Highly magnetized rotating neutron stars, rotate very rapidly, several hundred times per second.

A

Pulsars

30
Q

Light emitted by electrons moving in strong magnetic fields.

A

Synchrotron radiation

31
Q

When the gravity is so strong that not even nuclear forces can support the star, it collapses to infinity. Thus the star becomes infinitely dense. It becomes a

A

Black hole

32
Q

A collection of stars and dust that are gravitationally bound together

A

Galaxy

33
Q

The galaxy that we are located in, a spiral galaxy.

A

Milky Way

34
Q

The first person to see that the Milky White band that stretches across the night sky is actually made up of myriad of stars

A

Galileo

35
Q

During the ____’s who determined we were in the center of the universe after counting stars in 683 regions of the Milky Way

A

1780’s; William Herschel

36
Q

Why was Herschel wrong about us being in the center of the Galaxy

A

He didn’t take into account the gas and dust in the galactic plane that blocks out light from distant stars

37
Q

Plotted the direction and distances to the star clusters. Studied globular clusters that happens to contain RR Lyrae type variables which can lead us to determine distance to clusters.

A

Harlow Shapely

38
Q

Tightly bound clusters of stars

A

Globular clusters

39
Q

Variables are pulsating stars which have a period-luminosity relationship, the period of pulsation depends on the absolute magnitude.

A

RR Lyrae

40
Q

In the 1930’s ____ discovered interstellar gas and dust

A

Trumpler

41
Q

The sun is how many light years away from the center of the Milky Way

A

25,000 Ly

42
Q

O and b stars, open clusters, high metal content, type 1 cepheid variables

A

Stellar population 1

43
Q

Low mass stars, globular clusters, low metal content, type 2 cepheids

A

Stellar population 2

44
Q

The angular change in position due to stellar motions

A

Proper motion

45
Q

The speed of a star across the line-of-sight. It is related to the proper motion and depends on the distance of the star.

A

Tangential velocity

46
Q

The speed along the line-of-sight measure using the Doppler shift of spectral lines

A

Radial velocity

47
Q

The sum of tangential and radial velocities

A

Space velocity

48
Q

A point in space that has a velocity equal to the average velocity of all stars including the sun lying within 100 parsecs of the sun. The velocity is around 230 km/sec

A

Local standard of rest

49
Q

Once we determine the sun’s distance from the galactic center and the orbital speed, we can calculate the

A

Orbital period

50
Q

We can measure the speed of objects around the galactic center at different radii, this is called the

A

Galactic rotation curves

51
Q

We live in a spiral galaxy, we’re located in the (not the Milky Way)

A

Galactic disk between spiral arms

52
Q

Which types of waves penetrate the gas and dust so that we can study the galactic center.

A

Gamma-rays and radio waves.

53
Q

Helium burns causing explosions. This is known as

A

Helium flash

54
Q

What determines the life of a star

A

It’s mass

55
Q

Do Starr’s move up and down the main sequence?

A

No

56
Q

Depends solely on the mass of the star

A

Gravity

Astronomy (3 decks)

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