final practice questions Flashcards

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1
Q

Theoretical upper limit for the mass of a star

A

150-200 solar masses

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2
Q

How stars orbit in our galaxy

A

Disk: orbit in the same direction with little vertical motion
Bulge/halo: random orientations

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3
Q

Neutron star limit to create a black hole?

A

3 Msun

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4
Q

Put these eras in order from least to most recent: Planck Era, Era of Atoms, Particle Era, GUT Era

A

Planck, GUT, Particle, Atoms

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5
Q

What is a flaw of the original, pre-inflation Big Bang Theory?

A

Fails to explain large-scale uniformity of the temperature of the universe

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6
Q

What evidence is used to detect potential black holes?

A

Gravitational waves
Motion of stars and gas nearby
Materials in the surrounding accretion disk fading from view

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7
Q

How would a larger Hubble constant affect our understanding of the age of the universe?

A

The universe would be younger

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8
Q

How to measure distance from the center of the Milky Way?

A

Use RR Lyrae variable stars to measure distance to globular clusters

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9
Q

The cause of the first accelerating expansion of the universe

A

inflation

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10
Q

Why are white dwarf supernovae good standard candles?

A

They have about the same luminosity due to the Chandrasekhar limit

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11
Q

Difference between a nova and a supernova

A

Supernovae leave nothing behind; novae leave a white dwarf behind

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12
Q

Where does energy come from in a black hole?

A

Kinetic energy comes from matter falling into the black hole

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13
Q

What do different colors in the Cosmic Microwave Background represent?

A

Temperature

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14
Q

What electron degeneracy pressure?

A

High electron density, high speed of electron movement

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15
Q

What supports white dwarves against the crush of gravity?

A

Electron degeneracy pressure

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16
Q

Major galaxy types

A

Spiral
Elliptical
Irregular

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17
Q

Evidence supporting the Big Bang Theory

A

The universe is expanding
Correctly predicts the abundance of helium and other light elements
Detected leftover thermal radiation from the Big Bang

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18
Q

What percentage of our universe are ordinary matter, dark matter, and dark energy?

A

4% ordinary matter
22% dark matter
74% dark energy

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19
Q

What is the geometry of our universe?

A

Flat; at critical density

20
Q

What happens to light emitted near the event horizon of a black hole?

A

It is redshifted and appears to stretch out

21
Q

What likely contributes to formation of elliptical galaxies in densely populated galactic clusters?

A

Frequent collisions and mergers with other galaxies

22
Q

According to Hubble’s law, galaxies that are farther away are…

A

moving away faster

23
Q

How do new stars form when galaxies collide?

A

Clouds of gas and dust combine to create star-making regions

24
Q

Why might distant regions in the CMB appear similar?

A

They were once close together, but moved apart due to inflation

25
Q

What must a star’s mass be to create a Massive Star Supernova?

A

> 8Msun

26
Q

What must a star’s mass be to create a White Dwarf Supernova?

A

1.4Msun

27
Q

What happens to angles on a curved surface?

A

On a convex surface, an angle will be more than it usually is

28
Q

What color indicates ongoing star formation?

A

Blue

29
Q

What type of sensors are best for observing earliest galaxies in the universe?

A

Infrared

30
Q

If total density of matter and energy in the universe were to slightly exceed critical density, what would be the geometry of the universe?

A

spherical

31
Q

Rank parts of the galaxy from youngest to oldest

A

Outer arms, middle arms, center, halo

32
Q

Suppose the total density of matter and energy is less than the critical density. What could we conclude about the universe?

A

Hyperbolic geometry

33
Q

How do elliptical galaxies differ from spiral galaxies in composition?

A

Less gas and dust than spiral galaxies

34
Q

During what era in the universe’s history would you find conditions for fusion of protons and neutrons into helium nuclei

A

Nucleosynthesis

35
Q

What significant change followed the era of nucleosynthesis?

A

Formation of neutral atoms as the universe cooled

36
Q

Spiral galaxies’ rotation curves can be measured with…

A

The doppler shift of the 21cm line of atomic hydrogen

37
Q

Cosmological Principle

A

The universe looks relatively the same no matter where you are in it

38
Q

Which force is present in the GUT era of the universe?

A

gravity

39
Q

What is the Hubble Tension

A

tension between seemingly incompatible measurements of the rate of expansion of the universe

40
Q

What will eventually happen to a main sequence star with a mass similar to our sun’s?

A

It will become a red giant, then a planetary nebula, then a white dwarf

41
Q

Why can’t dark matter be made of protons, neutrons, or electrons?

A

Protons, neutrons, and electrons affect and interact with photons

42
Q

How to measure amount of dark matter in an elliptical galaxy?

A

measure speeds of different stars at different radii from the center of the galaxy, and determine how much mass is inferior to the orbit

43
Q

Order these objects from most to least luminous: galaxy, supernova, brown dwarf, quasar, white dwarf, pulsar

A

Quasar, supernova, galaxy with 100 million stars, pulsar, white dwarf, brown dwarf

44
Q

What is WIMP?

A

Weakly Interacting Massive Particle; a potential explanation for dark matter

45
Q

What can cepheid variable stars be used for?

A

Their periods can be used to determine luminosity