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ASTR 121 > Astro old final exam. > Flashcards

Astro old final exam. Flashcards

1
Q

What is the length of Light-years?

A

one light year is 63,241 AU,

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2
Q

Newton’s Law of Gravitation?

A
  1. remains moving unless acted on.
  2. the change of motion in the direction of the force acting on it.
  3. For every action there’s an equal and opposite reaction.
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3
Q

The composition of the sun

A

Core, Radiative zone, Convective zone, Photosphere, Chromosphere, Corona

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4
Q

The sun’s source of power

A

The sun gets energy by nuclear fusion. (proton-proton chain) you need High temperature and High densities.

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5
Q

The relationship between apparent brightness, luminosity, and distance

A

As Temperature and radius increases so does luminosity. Distance also forms different brightness.

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6
Q

The relationship between stellar color and temperature (highest to lowest)

A

Blue(25,000 K), white(10,000 K), yellow(6000 K), Orange(4000K),
Red(3000K)

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7
Q

What are brown dwarfs?

A

Failed stars that stop fusion.

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8
Q

what is stellar wind?

A

When accelerated material is emitted
from stellar objects at high velocity.

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9
Q

What two elements are the most obtundent in the universe.

A

Hydrogen, and helium

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10
Q

what are the wavelengths from highest to lowest?

A

Gamma, X-ray, Ultra-violet, Visible light< infrared, Microwave, and Radio waves.

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11
Q

What happens to electrons when it gains and losses energy?

A

When it gains energy distance to proton increases. When is loses energy it decreases distance.

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12
Q

What is the inverse square law?

A

As the distance between two objects
increases x fold, the force between
them decreases by x2.

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13
Q

What is the unit of measurement for Temperature.

A

Kelvin

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14
Q

What are the Spectral Classes of stars (highest to lowest)?

A

(OBAFGKM)

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15
Q

What is the Doppler effect?

A

When stars are moving towards you they shift blue. When stars move away they shift red.

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16
Q

What are binary stars?

A

These are stars that orbit each other.

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17
Q

how can you find the radius of binary stars?

A

by using light curves

18
Q

What is Kepler’s third law?

A

To find the sum masses of the binary stars.

19
Q

What does the HR diagram represent.

A

The plotting of surface temperature versus luminosity.

20
Q

What is the middle section of the HR diagram called?

A

Main sequence.

21
Q

What are at the top right of the HR diagram?

A

low temperature but high luminosity.(giant)

22
Q

What are at the bottom left of the HR diagram?

A

High temperature, low luminosity,(small)

23
Q

what spectral classes are the biggest to smallest.

A

O,B,A,F,G,K,M

24
Q

How do you measure the distance to a star.

A

by using a parallax, with the unit of parsec.

25
Q

What elements do main sequence stars fuse.

A

They burn hydrogen into helium.

26
Q

What is a white dwarf?

A

A former core of a star that has no fusion and is slowly cooling off.

27
Q

What is a neutron star?

A

Remnant cores of larger stars, extremely hot and dense.

28
Q

What is interstellar medium?

A

The space between stars in a galaxy.

29
Q

What is an accretion disk?

A

material in the disk is the slowly end up into a star.

30
Q

How does a protostar star.

A

When collapsing gas reaches a high
enough temperature and density.

31
Q

What are star clusters

A

The stars that form from a single
giant molecular cloud.

32
Q

What are the 3 different types of clusters?

A

Open clusters (young stars no cloud)
Embedded Clusters (open cluster with young stars)
Globular clusters (stars with gravitational bound)

33
Q

How long do stars stay on the main sequence?

A

O class stars are on the shortest and M type live the longest.

34
Q

What happens to a star after running out of hydrogen?

A

The start will collapse into a red giant. making the star also inflate in size.

35
Q

what stars mainly turn into red giants?

A

Most main sequence stars.

36
Q

What element gets fused in the Triple alpha process

A

helium

37
Q

Why does a core go to electron degenerate.

A

during a helium flash the core gets so dense there is no space between elements.

38
Q

What are the 4 phases of a star with the mass of the sun.

A

Main sequence, becomes red giants, helium fusion, Giant again.

39
Q

What is the alpha process.

A

If the star is massive
enough, the carbon and
oxygen can burn. creating heavier elements.

40
Q

how does a planetary nebulae form.

A

Stellar winds take the outside of the star away just leaving the core.

41
Q

what do planetary nebulas look like.

A

color gases, lit up by a hot star remnant at the center.

ASTR 121 (7 decks)

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