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College > Citizen Astronomy Final > Flashcards

Citizen Astronomy Final Flashcards

1
Q

How far away is sun from center of milky way galaxy

A

28,000 Light years

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2
Q

Halo stars

A

very old stars (and bunches of stars called globular clusters) that form an almost spherical halo around the Galaxy

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3
Q

Which stars are almost as old as the universe itself

A

Halo Stars

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4
Q

Disk of the Galaxy

A

host to massive amounts of gas and dust, and the stars there are much younger

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5
Q

how are disk stars formed

A

large collections of gas called molecular clouds

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6
Q

Bulge

A

dense collection of older stars, believed to be the remnants of previous collisions of smaller galaxies that eventually formed the Milky Way.

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7
Q

older stars are ____ than younger stars, and that means that they appear _____ than young stars. Hot young stars in the disk appear _____

A

Cooler
redder
bluer

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8
Q

hot objects like stars will radiate all colors of light, but the amount of each color of light depends of the _____ of the gas.

A

temperature

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9
Q

How are stars formed

A

Gas collapses under it’s own self gravity. Heats up allowing nuclear fusion in the core. Gas and dust flattens into a disk.

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10
Q

Stars in the Halo are on average bluer than stars in the Disk.

A

False

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11
Q

Which has older stars, the Disk or the Halo of the Milky Way?

A

Halo

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12
Q

The stars Vega and Fomalhaut

A

are older than 5 million years old.

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13
Q

The Disk Hunters citizen science project makes use of images from the

A

Wide-Field Infrared Survey Explorer

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14
Q

The Milky Way is

A

a galaxy

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15
Q

interstellar medium

A

collection of gas, dust, plasma (remember the ionized gas in the Sun from Module 2), and magnetic fields

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16
Q

How bubbles form on infrared images

A

ultraviolet radiation (UV) from the hot, massive stars will ionize the interstellar medium in there vicinity, forming the holes or “bubbles” in the infrared images

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17
Q

the more massive the star, the _____ its lifespan (in runs out of fuel),

A

shorter

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18
Q

Massive stars have UV Light and

A

strong stellar wind, which push gas and dust into the interstellar medium.

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19
Q

How is a shock wave is formed

A

When these winds are faster than the speed of sound in the surrounding gas,

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20
Q

How do some stars get slingshotted into the interstellar medium

A

when stars are forming in clusters where close gravitational encounters are frequent

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21
Q

What happens when stars get slingshotted into the interstellar medium

A

the shockwave is bent into a bow shock

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22
Q

For every low-mass star that forms in the interstellar medium, is there are many more high-mass stars.

A

False

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23
Q

Two stars are born at the same time, one high-mass and one low-mass. Which one will live longer?

A

The low-mass star

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24
Q

A shock is formed in the interstellar medium when

A

the stellar winds of a massive star are moving faster than the local speed of sound

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25
Q

Interstellar dust grains are on average

A

about ten times smaller than a grain of sand

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26
Q

Bow shocks show up as ______ in the WISE images.

A

red features

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27
Q

The total number of galaxies in our observable universe ranges from

A

200 billion to 2 trillion

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28
Q

3 types of galaxies

A

spiral, elliptical, and irregular

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29
Q

Spiral galaxies

A

tend to have lots of gas, and thus are constantly making new stars. Milky Way

30
Q

Elliptical galaxies

A

spherical or elongated spheroids that lack the gas and dust to make new star

31
Q

Population of stars in elliptical galaxies

A

old, low-mass, and cool (often called “red and dead” because the cooler stars are redder in color than the hot massive stars that dominate a spiral galaxy’s disk)

32
Q

Irregular galaxies

A

have no regular shape, and are likely the results of recent collisions between galaxies.
some have gas and are making new stars, while other have had their gas stripped away and are not.

33
Q

Dark Matter

A

. The missing mass , NOT stars, gas, and dusT
particles that float about the Universe, clumping up and interacting gravitationally with itself and other matter, but it could pass right through your body without you ever feeling it

34
Q

Many supernovae are the result of

A

the violent deaths of massive stars,

35
Q

Which type of galaxy has more gas for making stars?

A

Spiral

36
Q

Which type of galaxy appears more blue (has more hot stars)?

A

Spiral

37
Q

Which type of galaxy has most likely undergone a recent collision with another galaxy?

A

Irregular

38
Q

In what environment do mergers between galaxies have the largest effect?

A

In the outskirts of clusters or in small groups

39
Q

There is more Dark Matter in the Universe than ordinary matter (like atoms).

A

True

40
Q

that the expansion of the Universe is

A

Speeding up

41
Q

Chandrasekhar limit

A

When the white dwarf reaches a critical mass of about 1.4 times the mass of the Sun,

42
Q

What happens after the Chandrasekhar limit

A

it will collapse under its own gravity to create a neutron star. Release of energy is so bug is will outshine the rest of the galaxy it’s in

43
Q

What is important for the discovery of the accelerated expansion of the Universe is that the total energy given off by these supernovae

A

should all be about the same, as they occur under the exact same condition

44
Q

How are astronomers able to calculate an accurate distance to the galaxy

A

With the known energy of an object and the observed brightness, . These distances are the critical measurements for calculating the expansion of the Universe

45
Q

Type Ia supernovae occur when

A

a white dwarf accretes enough gas to explode and turn into a neutron star.

46
Q

The Chandrasekhar limit is

A

the mass at which a white dwarf collapses to a neutron star.

47
Q

A black hole will form when

A

a high-mass star runs out of fuel and its core has a mass of 5 times that of the Sun or more

48
Q

Elements heavier than iron are made

A

in supernovae

49
Q

Pulsars are

A

neutron stars

50
Q

the first to come up with a universal theory of gravity (1687)

A

Newton

51
Q

Newton

A

any object will attract any other object with a force whose strength is proportional to the product of the masses of the objects, and inversely proportional to the square of the distance separating them.

52
Q

Who presented the special theory of relativity and general theory of relavtivity

A

Einstein

53
Q

special theory of relativity

A

that nothing could travel faster than the speed of light

54
Q

general theory of relativity

A

objects with mass bend space and time, and that the gravity that other objects feel is simply those objects moving through warped space-time

55
Q

one of the strange predictions of this theory of gravity

A

rapidly accelerating objects, like two massive stars orbiting very close together, should produce ripples in space-time that should propagate through the Universe.

56
Q

gravitational waves

A

The ripples in space time from 2 massive stars orbiting close together

57
Q

indirect evidence for gravitational waves was found by

A

measuring the rate at which two neutron stars lost energy as they orbited each other.

58
Q

How many direct detections of gravitational waves have been found

A

3

59
Q

Gravitational waves where first detected indirectly detected using

A

orbiting neutron stars

60
Q

The first gravitational wave to be directly detected is believed to be caused by

A

two orbiting black holes

61
Q

In Einstein’s theory, what is gravity?

A

The reaction of masses to space-time that has been warped by other masses.

62
Q

The change in length of a 4 km long arm of the LIGO observatory by a gravitational wave is about

A

10,000 times smaller than the diameter of a proton

63
Q

A major consequence of Einstein’s theory was that

A

massive objects should deflect light rays

64
Q

black holes

A

objects whose gravity was so strong that light would not be able to escape.
most being the remnants of the collapse of very massive stars during a supernova

65
Q

supermassive black holes

A

Larger black holes, found at center of most galaxies like milky way

66
Q

How to see monster black holes

A

by the X-rays given off by the hot gas around them, or by the radio waves emitted when they launch gas out in jets from the center of the galaxy

67
Q

The Milky Way has a supermassive black hole in its core.

A

True

68
Q

is Light is the only particle (or wave) not affected by the curvature of space-time.

A

false

69
Q

Which particle has more mass, an electron or a muon?

A

muon

70
Q

What kind of light is the Veritas telescope (array) looking for?

A

Cherenkov light

71
Q

Most of the points of light in a radio image of the sky come from

A

supermassive black holes

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