Unit 10: Black Holes and Galaxies Cosmology Flashcards
What is escape speed
this is the ability to escape the gravitational pull of a planet
If two stars have equal masses, which has a greater escape speed
smaller objects have greater escape speeds
What is earths escape speed
11.2 km/ second
What is the suns escape speed
618 km/s
What is the escape speed of a white dwarf
7000 km/s
What is the escape speed of a neutron star
160,000 km/s
What is the escape speed of a black hole
> 300,000 km/s
the escape speed of a black hole is equal to speed of light
Is the escape speed an heavier object compared to a small massed object
escape speed from heavier objects are greater than from the objects with smaller masses
What is the super power that causes the core to collapse and to transform into a black hole?
gravity
- the mass does not change, but the size gets smaller
What is inside a black hole
there is a singularity
but we do not know
What is the formula for the radius of a black hole
Rsch= GM
----------
c^2
G= gravity
C= speed of light
M- MassWhat is the event horizon
Cannot be passed,
no information below the event horizon can escape or be reached
What would the Rsch for 5M be
15 km
How do we identify black holes
with Quantum Gravity
not yet known
Pulsars around black holes are sources of ____ and _______.
X rays and Gamma rays
instead of radio waves
Where do photons around black holes come from
normal particles from outside black holes
-remember that nothing escapes the event horizon
What are “light small” black holes
black holes that appear as a result of massive supernova explosions
- there is a lower limit of the black hole mass.
Where is a supermassive black hole
in the centre of the M87 galaxy
How big are giant black holes
up to billions of solar masses
What do black holes accumulate
stars and matter
Does the milky way have a black hole
yes
What would the radius of earth mass black hole
about 4.4
what does the existence time of black holes depend on
the radius
Where are supermassive black holes located
found in the centre of the galaxy
- they help to control the shape of galaxies
What does the milky way look like from edge on
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
What does the face view of the milky way look like
spiral structure of our galaxy
How many stars in the milky way galaxy
100-200 billion stars
what is the diameter of the milky way
100,000 LY
All stars in our galaxy orbit ________
the galactic centre
- orbit speed of 230 km/s
- orbital period (galactical year) 230 million years
what is the estimation of the galaxies mass
1.10 billion solar masses
1 hundred and ten solar masses
what are gobular clusters
numerous stars
What does the blue curve in the galaxies rotation curve show
the orbital speeds of stars and gas in the galaxy
What does the red curve in the galaxies rotation curve show
keplerian orbits due to the gravitational force from know objects
What are Keplerian Orbits
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
There is not a decline in the blue curve of our galaxies rotation, what does this imply
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
The orbital speed _______ as we move ____ from the centre of the galaxy
increases as we move away
What is dark matter? How can we detect it
hidden mass
- substance or material which is electromagnetically neutral, does not emit
- detect it by its gravity
What gives outer stars in our galaxy to have higher speeds than they would have otherwise
- dark matters gravitational pull
What are the basic types of galaxies
- Spiral M83 spiral galaxy
example- milky way - NGC 4363 Elliptical galaxy
- Irregular Galaxy (large magellanic Cloud LMC)
Who is our closest galaxy neighbour
Andromeda Nebula
- 2.5 million LY from the milky way
How many galaxies are there and what percentage of each type of galaxy is seen
77% spiral
20% elliptical
3% irregular
What are clusters and superclusters
galaxies that are close,
they apply gravitational pull to each other and then bond making clusters of galaxies
What is the Fornax cluster
group of galaxies about 60 million LY from earth
How are galaxies in clusters bounded
gravitationally bounded
What are poor clusters
up to 10 galaxies
our local group of galaxies is one of these
What are rich clusters
hundreds of thousands of galaxies
Are galaxies and clusters equally distributed
Stars are not evenly distributed, galaxies are not evenly distributed, they form clusters, and even clusters are not evenly distributed, they form superclusters
What is the Cartwheel Galaxy
a ring shaped assemblage 500 million LY from earth
- likely resulted from one galaxy having passed through the middle of the larger one
What happens when two galaxies collide
the galaxies change their shapes
- it Is not likely they will collide with other stars
aka collision causes no damage
According to Newton, what is general relativity
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
What is general relativity
substance alters both space and time
What is the “sponge” structure of the universe
galaxies and clusters of galaxies, in between them is empty space
- complete darkness
what explains the sponge structure
dark matter
What are Quasars
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
How bright is a typical quasar
about 100 times brighter than milky way
What is a quasars energy source
black hole model
supermassive black hole with massive accretion disk
- electromagnetic radiation
Why are quasars so far
they are the evaporation of a black hole
- looses mass, shrinks, and eventually disappears
What does cosmos mean
order
- everything formed from chaos
