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Astronomy > Unit 10: Black Holes and Galaxies Cosmology > Flashcards

Unit 10: Black Holes and Galaxies Cosmology Flashcards

1
Q

What is escape speed

A

this is the ability to escape the gravitational pull of a planet

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2
Q

If two stars have equal masses, which has a greater escape speed

A

smaller objects have greater escape speeds

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3
Q

What is earths escape speed

A

11.2 km/ second

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4
Q

What is the suns escape speed

A

618 km/s

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5
Q

What is the escape speed of a white dwarf

A

7000 km/s

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6
Q

What is the escape speed of a neutron star

A

160,000 km/s

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7
Q

What is the escape speed of a black hole

A

> 300,000 km/s

the escape speed of a black hole is equal to speed of light

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8
Q

Is the escape speed an heavier object compared to a small massed object

A

escape speed from heavier objects are greater than from the objects with smaller masses

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9
Q

What is the super power that causes the core to collapse and to transform into a black hole?

A

gravity

- the mass does not change, but the size gets smaller

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10
Q

What is inside a black hole

A

there is a singularity

but we do not know

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11
Q

What is the formula for the radius of a black hole

A 
Rsch= GM
         ----------
         c^2
G= gravity
C= speed of light
M- Mass
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12
Q

What is the event horizon

A

Cannot be passed,

no information below the event horizon can escape or be reached

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13
Q

What would the Rsch for 5M be

A

15 km

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14
Q

How do we identify black holes

A

with Quantum Gravity

not yet known

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15
Q

Pulsars around black holes are sources of ____ and _______.

A

X rays and Gamma rays

instead of radio waves

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16
Q

Where do photons around black holes come from

A

normal particles from outside black holes

-remember that nothing escapes the event horizon

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17
Q

What are “light small” black holes

A

black holes that appear as a result of massive supernova explosions
- there is a lower limit of the black hole mass.

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18
Q

Where is a supermassive black hole

A

in the centre of the M87 galaxy

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19
Q

How big are giant black holes

A

up to billions of solar masses

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20
Q

What do black holes accumulate

A

stars and matter

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21
Q

Does the milky way have a black hole

A

yes

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22
Q

What would the radius of earth mass black hole

A

about 4.4

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23
Q

what does the existence time of black holes depend on

A

the radius

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24
Q

Where are supermassive black holes located

A

found in the centre of the galaxy

- they help to control the shape of galaxies

25
Q

What does the milky way look like from edge on

A

an edge with a nuclear bulge in the centre where the black hole exists
- the thickness of the bugle is about 7-8 times the mass

26
Q

What does the face view of the milky way look like

A

spiral structure of our galaxy

27
Q

How many stars in the milky way galaxy

A

100-200 billion stars

28
Q

what is the diameter of the milky way

A

100,000 LY

29
Q

All stars in our galaxy orbit ________

A

the galactic centre

  • orbit speed of 230 km/s
  • orbital period (galactical year) 230 million years
30
Q

what is the estimation of the galaxies mass

A

1.10 billion solar masses

1 hundred and ten solar masses

31
Q

what are gobular clusters

A

numerous stars

32
Q

What does the blue curve in the galaxies rotation curve show

A

the orbital speeds of stars and gas in the galaxy

33
Q

What does the red curve in the galaxies rotation curve show

A

keplerian orbits due to the gravitational force from know objects

34
Q

What are Keplerian Orbits

A

if there were no material beyond the visible edge of the galaxy, orbital speeds at large distances should decline as shown. Though this is not what is observed

35
Q

There is not a decline in the blue curve of our galaxies rotation, what does this imply

A

apparently there is an abundance of dark matter that extends ti great distances from the galactic centre
- this additional mass gives the outer stars higher speeds than they would have otherwise

36
Q

The orbital speed _______ as we move ____ from the centre of the galaxy

A

increases as we move away

37
Q

What is dark matter? How can we detect it

A

hidden mass

  • substance or material which is electromagnetically neutral, does not emit
  • detect it by its gravity
38
Q

What gives outer stars in our galaxy to have higher speeds than they would have otherwise

A
  • dark matters gravitational pull
39
Q

What are the basic types of galaxies

A
  1. Spiral M83 spiral galaxy
    example- milky way
  2. NGC 4363 Elliptical galaxy
  3. Irregular Galaxy (large magellanic Cloud LMC)
40
Q

Who is our closest galaxy neighbour

A

Andromeda Nebula

- 2.5 million LY from the milky way

41
Q

How many galaxies are there and what percentage of each type of galaxy is seen

A

77% spiral
20% elliptical
3% irregular

42
Q

What are clusters and superclusters

A

galaxies that are close,

they apply gravitational pull to each other and then bond making clusters of galaxies

43
Q

What is the Fornax cluster

A

group of galaxies about 60 million LY from earth

44
Q

How are galaxies in clusters bounded

A

gravitationally bounded

45
Q

What are poor clusters

A

up to 10 galaxies

our local group of galaxies is one of these

46
Q

What are rich clusters

A

hundreds of thousands of galaxies

47
Q

Are galaxies and clusters equally distributed

A

Stars are not evenly distributed, galaxies are not evenly distributed, they form clusters, and even clusters are not evenly distributed, they form superclusters

48
Q

What is the Cartwheel Galaxy

A

a ring shaped assemblage 500 million LY from earth

- likely resulted from one galaxy having passed through the middle of the larger one

49
Q

What happens when two galaxies collide

A

the galaxies change their shapes
- it Is not likely they will collide with other stars
aka collision causes no damage

50
Q

According to Newton, what is general relativity

A

Space is independent from material in space? According to newton
Space is like stage in theatre, empty space where actions take place
Space never changes
Time is independant

51
Q

What is general relativity

A

substance alters both space and time

52
Q

What is the “sponge” structure of the universe

A

galaxies and clusters of galaxies, in between them is empty space
- complete darkness

53
Q

what explains the sponge structure

A

dark matter

54
Q

What are Quasars

A

quasi stellar objects look like a star

  • emits energy like entire galaxy
  • they are deeper in space which means we are looking deeper in time
55
Q

How bright is a typical quasar

A

about 100 times brighter than milky way

56
Q

What is a quasars energy source

A

black hole model
supermassive black hole with massive accretion disk
- electromagnetic radiation

57
Q

Why are quasars so far

A

they are the evaporation of a black hole

- looses mass, shrinks, and eventually disappears

58
Q

What does cosmos mean

A

order

- everything formed from chaos

Astronomy (10 decks)

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