AST101 Exam 3: Chp 11-14

neutron star formation

formed from increasing density, making the core collapse and forcing protons to combine with electrons

neutron degeneracy pressure

what holds neutron stars up against gravity

pulsars

rotating neutron stars that emit beams of radiation, produced by high energies, that sweep around the sky

x-ray binaries

made up of a normal star and a collapsed star, it produces x-rays when they are close together and material is pulled from the normal star to the collapsed star

3 Msun

largest mass a neutron star can be

black hole formation

forms by collapsing to a zero radius causing its density and gravity to become infinite- a singularity

event horizon

boundary that marks the outer edge of a black hole

difference between event horizon and singularity

event horizon is an imaginary sphere around black hole, singularity is all matter of the black hole

singularity

all matter in a black hole, squeezed into a region of infinitely small volume

time dilation

time slows down in curved space-time

the strong gravitational fields stretch the fabric of space-time

how do black holes cause time dilation

gamma-ray bursts

where the intensity of gamma-rays rise to a max in seconds and fades away quickly, earthquake-like ruptures in surface crust of Magnetars cause these

magnetars

neutron stars with 100x stronger magnetic fields

magnitude-distance formula

d=10^(mv-Mv+5)/5

central bulge, disk, spherical component, halo, spiral arms, and nucleus

structures of the Milky Way galaxy

disk component of milky way galaxy

contains most of galaxy’s stars and its gas and dust

orbital motions of milky way galaxy

different in two components of the galactic flat plane among disk stars, which orbit on the same plane, and halo stars, which orbit in ellipses

mass of an object

find this by observing the motion of another object orbiting it

spiral arms of the milky way galaxy

dynamically stable regions of compressed interstellar medium that move slowly around the galaxy, molecular clouds are concentrated here

spiral arm formation

gravitational effects of the bars rotation disturb the galaxy’s disk and creates the formation of these density waves

grand-design galaxies

type of spiral galaxy with bold, symmetrical two-armed patterns

flocculent galaxies

type of spiral galaxy with many short spiral segments

population I stars, located in spiral arms and disk

young stars of a galaxy, rich in metals, orbit center at high speed

population II stars, located in halo and central bulge

old stars of a galaxy, low abundance of heavier metals, highly elliptical orbits that are randomly oriented in direction

infrared and radio wavelengths

what did researchers use to detect the supermassive black holes in the center of galaxies

bottom-up and top-down

what two hypothesis’ do we think is how the Milky Way was formed

bottom-up hypothesis

proposes Milky Way was partly assembled from smaller units, absorbing other galaxies and infalling gas clouds

top-down hypothesis

proposes a protogalaxy gaseous cloud contracted to form the Milky Way 13 billion years ago

elliptical, spiral, irregular

different types of galaxies

elliptical galaxies

has no disk, no spiral arms, and almost no gas and dust

spiral galaxies

disk-shaped, has spiral arms, typically contains gas and dust, can have variations of barred spiral and lenticular galaxies

irregular galaxies

shapeless and tend to be rich in gas and dust

distance

what do you need to determine first to calculate the diameter, luminosity, and mass of a galaxy

cepheid method

measure cepheid period, find luminosity & compare it to apparent magnitude, find distance

Type Ia Supernovae

have standard luminosities & compare it to apparent magnitude, find distance

V=Hd

Hubble Law formula

recession velocity

what is the V in the Hubble Law formula

Hubble constant= 70km/s/Mpc

what is the H in the Hubble Law formula

distance

what is the d in the Hubble Law formula

what the Hubble Law calculates

distance of galaxies that are moving away from our Milky Way

velocity dispersion method

method using escape velocity of a galaxy to find the mass

cluster method

method that measures the motion of galaxies within a cluster to find mass

small with low luminosity

luminosity & size of irregular galaxies

large with high luminosities

luminosity & size of most spiral galaxies

wide range of both

luminosity & size of elliptical galaxies

Active Galactic Nuclei

galaxies with extremely violent energy release in their nuclei

quasars and Seyfert galaxies

classes of active galactic nuclei (AGN)

quasars

active nuclei in elliptical galaxies with more powerful central sources than Seyfert galaxies, far away and highly luminous (by 10-1000x more)

Seyfert galaxies

25% have peculiar shapes, suggesting tidal interactions with other galaxies

AGN galaxies can terminate star formation

what we found about galaxy formation by observing AGN galaxies

forming clusters

how do galaxies change into different types over the age of the universe

rich clusters of galaxies

1000+ galaxies, diameter of ~3 Mpc, condensed around a large, central galaxy

poor clusters of galaxies

less than 1000 galaxies, diameter of a few Mpc, generally not condensed towards the center

they collide and interact

what occurs between galaxies, typically occurs in rich clusters

ring galaxies

left behind by high-speed, face-on collisions of galaxies

distortion of tides that produce tidal tails and shells of stars and rapid star formation

occurs during collision and interaction of galaxies

starburst galaxies

stars currently being born at a high rate

motions of galactic nuclei

what produces the complex shapes of jets and radio lobes

nucleus of galaxy

at visual wavelength this is hidden by interstellar dust, can only be seen using infrared and radio waves

spherical component of galaxy

made up of the halo and nucleus, nearly all stars inside it are old

jets

powered by accretion of matter onto a supermassive black hole, matter falls toward central black hole, then is ejected

radio lobes

inflated by jets of excited gas emerging from the nucleus of the central galaxy

Cosmic Microwave Background Radiation

Radiation from an early phase of the Universe that is still detected today, has a blackbody spectral distribution, has traces of gravity waves

open, closed, flat

types of curvature of universes

the shape of space

gradual stretching of space-time lengthens the wavelengths of photons on their way from distant galaxies to Earth creates what

open universe

universe with curvature that doesn’t curve back on itself

flat universe

universe with zero curvature

closed universe

universe with curvature that folds back on itself like a saddle

dark matter

nonbaryonic matter that makes up most of the mass of galaxies

dark energy

influences the accelerated expansion of the universe, the ultimate fate of the Universe depends on the nature of it

detect and measure the mass of dark matter

according to general relativity, light beams bend toward a massive object when passing it, this principle can be used to do what?

through gravitational effects

how do we know the presence of dark matter

flat, expanding

astronomers conclude from the model that we have a ___ universe that is __

inflation hypothesis

theory that the Universe briefly went through superexpansion when it was a fraction of a second old

flatness and horizon of the universe after the Big Bang

what does the inflation theory explain

theory of dark energy

it’s the dominant force in the cosmos, is the cause of acceleration

cosmological constant

cause of acceleration that represents an antigravity force that is part of the fabric of space-time

quintessence

cause of acceleration with totally empty space, the vacuum, containing energy that drives acceleration

Big Bang theory

current model astronomers use today

hot, compact, expanding, cooling

the Big Bang shows us that the Universe was ___ and ___ at the beginning, but since then has been ____ and ____

brighter, distant, older

in AGN galaxies, quasars are ____ in light, more ____ in distance, and ____ in age than Seyfert galaxies

hot, rapidly, strong

neutron stars are ___, spin ____, and have ___ magnetic fields

T=2×10³ K

at one-millionth of a sec old, Universe was filled with high-energy photons with…

Hubble time

estimate of the age of the Universe

cosmological principle

any observer in any galaxy sees the same general properties of the Universe: there are no special places and the Universe can have no center or edge

cosmological redshift

phenomenon where the expansion of the Universe stretches light traveling through space, related to Einstein’s theroy of relativity where space and time are one entity