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How does a white dwarf form?
a low mass star is near the end of its life, core shrinks and cools, it is very dense and held together by electron degeneracy pressure
What is the Chandrasekhar limit?
1.4 solar masses
How does a neutron star form?
stars above 1.4 solar masses push the protons and electrons together to form neutrons, and it may explode with a type 2 supernova, and only neutrons remain, and it will begin to rotate faster and faster
How do black holes form?
if the remaining mass of a neutron star is greater than 2-3 solar masses, then it will collapse into a black hole
What is a pulsar?
a rapidly rotating neutron star, discovered by bell and hewish from observing repeating radio bursts
What is the binary pulsar?
a binary system with two pulsars that were tested and confirmed the GTR
How was the GTR tested with the binary pulsar?
it predicted the intense gravity would change orbital paths by 4 degrees each year,
What is gravitational radiation/waves?
-ripples through space-time with no mass and that travel at the speed of light; sudden change in the curvature of space (move a mass) due to an acceleration of a mass
How does an Xray binary form?
material from a companion star is accreted and it causes the star to rotate faster and hot spots, which emit xrays
What are millisecond pulsars?
Very old neutron stars, believed to have very weak magnetic fields so they dont slow
What is gravitational redshift?
the redshift experienced by gravity acting on light escaping a white dwarf
Why must a white dwarf be in a binary system to measure redshift?
Gravitational redshift cant be discerned from doppler redshift, so we must know their velocities to account for GR
Why are stars brighter than black holes?
black holes' gravity is so powerful that light literally bends back into the infinitely small point
What 3 properties describe a black hole?
mass, rotation rate, electric charge
What are the two regions of interest in a black hole?
the singularity, where all the matter is contained, and the event horizon, the (schwarzchild) radius at which gravity is too strong for light to escape
if the sun was a black hole what would happen to earth?
nothing, the mass is the same so the earth's orbit would stay the same
How can we observe black holes?
1.gravitational lensing, deflects light produces multiple images 2. measurement of binary system mass 3. binary system accretions 4. measuring gravitational radiation
What is the Spaghettification effect?
The stretching out of your body as you enter a black hole that pulls your feet faster than your head
How is the event horizon affected by mass?
(it is directly proportional, double mass, double radius)
What is the Angol Paradox?
when the more evolved star in a binary system is less massive, due to mass transfer (gains mass ---> evolves faster, and vice versa)
What is the difference between type 1 and 2 supernovae?
type 2- hydrogen found in spectra type 1- no hydrogen
what is a "standard candle"?
any object with an easily recognizable appearance and known luminosity which can be used in estimating distances
how far is the sun from the galactic center?
28,000 light years
What are the parts of a spiral galaxy?
halo, bulge, disk (arms)
Where do pop II stars (older) lie in the MWG?
halo bulge an globular clusters, orbits not bound to center
Where do population I stars(younger) lie in the MWG?
disk, orbit galactic center
how old is the MWG?
about 13.5 billion years
What is the nuclear bulge in the MWG?
center of galaxy with a massive black hole and densely packed pop II stars and ISD and gas
What is the disk in the MWG?
the lage pinwheel structure that orbits the galactic center, contains young stars and ISD and gas
What is the halo in the MWG?
the spherical region that surrounds the galaxy, contains dark matter and dust
what are the contents of the MWG?
1. ISD and gas 10% of mass 2. stars 3. open and globular clusters 4. emission, reflection and dark, nebs 5. dark matter
What is barionic matter?
tangible material, things made of protons neutrons and electrons
What is in the outer halo of the MWG?
non luminous matter, known because of its attraction to luminous matter
What are reflection nebulae and dark nebulae?
r - reflects light from nearby stars d - thick nebs that have dust that inhibits view behind
What is an H2 region?
a region where hydrogen is ionized
WHat is interstellar extinction?
when dust diminishes the light from a star, also referred to as interstellar reddening because of wavelength shift
what are the two forms of Interstellar extinction?
scattering and absorption
what is the interstellar medium?
gas and dust between stars, not uniform, perfect vacuum
what are molecular clouds?
cool and dense regions containing dust, thought to be nurseries for star formation
What is neutral hydrogen emission?
when a neutral hydrogen atom emits 21 cm radiation due to a flip of electron spin from a collision
what is the density wave?
the theory that higher density regions will orbit more slowly as in the traffic demonstration
what are the four kinds of galaxies?
elliptical, spiral, lenticular, irregular
what is the mass to light ratio?
the ratio of ML in solar mass to solar light; hot stars are <1, cool stars are >1
what is a radio galaxy?
a galaxy that emits strong nonthermal radio radiation
what is a seyfert galaxy?
a spiral galaxy with a big ass nucleus
what is a quasar?
or QSO, a large and active galaxy
what is the basic model?
a model of a massive black hole with an accretion disk
what is olber's paradox?
the night sky should be bright if the universe is full of stars, but light would take to long to reach us and might be redshifted
What is Hubble's law?
An expression of the idea that more distant galaxies move away from us faster; the expansion of the universe
What is the cosmological principle?
The idea that matter in the universe is evenly distributed, without a center or an edge, homogeneous and isotropic
What is CMBR!?
microwave radiation filling the universe coming from radiation caused by the original explosion
what is cosmic nucleosynthesis?
fusion of protons and neutrons into elements after the big bang
what is dipole anisotropy?
the motion of the sun throughout the universe, measured by the CMBR
What is interferometry?
Have two telescopes look at same object and feed two signals together, tricking recorder into thinking it's one telescope Allows for huge objective diameter.

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