PHYS 170 Test 3
At the center of our galaxy scientist have noted since the _______very complex system of ____ waves suggesting strong magnetic fields
1960's, radio waves
Evidence for black holes was not well accepted and/or understood until the
1990's
What are the correct percentages for dark energy, dark matter and regular matter in the universe
70, 26, 3.5
In a galaxy the Dark Matter makes up ____ of galaxy and was initially hypothesized when scientist sought to explain ______
90-95%, rotation curves
Hydrostatic Equilibrium is
A balance between the gravity and internal pressure pushing out on a star
As a ______ star forms it can begin to rotate causing_______
A protostar; gases to be ejected at the poles is called bipolar flows
Both a neutron star and black hole
Are left after a supernova, Are the end results for a massive star, Are extremely compact objects with ;large gravitational fields
In the 1960's and 1970's Hawking and Roy and others developed theories about
Black holes
What steps do stars go through on their path to becoming stars
BokGlobule (molecular cloud), protostar, premain sequence , cross the zero age main sequence line, main sequence
Who cataloged and categorized the smears of light in the sky before the 20th century
Both Meissner and the Herschel's
What are the parts of our galaxy
Bulge, halo, disk (spiral arms)
What are the conditions for a star to form in a molecular cloud
Cool and dense
Which is a remnant of the supernova seen in the 1000's in China
Crab nebula
Scientist believe that there must be ________ because the arms of the galaxy move faster than the center.
Dark matter
Shapley used the luminosity and periods of stars in clusters to determine the
Distance
A black hole's strong gravitational field can pull in material and an accretion disk will form creating a great deal of energy that can result in
Emission of X-rays
We know the galaxy is _____ because____
Flat ,of how the stars are distributed
Scientist realized that pulsars must be neutron stars when they
Found a pulsar in the center of the Crab nebula
A star that is above 30Msun will
Fuse to iron, supernova and form a black hole
For the range of stars between 0.8 - 2Msun they undergo which fusion steps:
H => He => He flash => C => O
Stars that move off of main sequence first are
High Mass stars since the gravity is so great their Hydrogen gets used up faster
What technique is used to determine the distance of the farthest objects and how does it work
Hubble's Law, graph of recession velocity versus distance
The discovery of the pulsar occurred in what decade and by whom
In the 1960's by Jocelyn Bell
A black hole
Is a dense compact object whose gravity is so great that light cannot be emitted
Once a star runs out of the majority of its H what is true
It expands and forms a Giant, It moves off of main sequence to the upper right
Earth is composed of rock made of Silicon and metals where is this material come from
It was produced by nuclear fusion in stars and through supernova
If a galaxy begins to run out of hydrogen what does this suggest
It's very old and stars have gone through several deaths and reformations
The supernova of 1987 showed scientist that even a ____ star could supernova
Large blue
LGM stood for ______and was actually a ______
Little green men, pulsar (neutron star)
How have scientist searched for black holes
Looking for effects of event horizon, Look for another star orbiting something invisible, x-rays emanating as object goes into the black hole
What abbreviations did they use to categorize these smears of light
M+ number (M22) and NGC (new general catalog)
Henrietta Leavitt in the 1920's discovered a relationship between these and were called
Period of fluctuations and luminosity, Cepheid's
At what stage will fusion begin
Pre-Main sequence star after accretion ceases
A star will move from a position of higher luminosity to lower luminosity as it moves from being a _______ and crosses______
Protostar , main sequence
Scientist used ____ to study the center of the galaxy because it has a _____wavelength that won't be scattered by all the dust and gases
Radio, long
What type of star fuses its H and the is left mostly with He burning slowly
Red dwarf
Which type of stars are most abundant
Red dwarfs
What are the three types of nebula?
Reflection, emission, dark
It is hypothesized that all AGN's are in fact
SMBH with accretion disk
The scientist believe the center of the galaxy is located near _________ constellation because of the dense concentration of _____ clusters
Sagittarius, globular
In a high mass star _____ fuses in a shell while _____ migrates to center where it builds up eventually resulting in a super nova
Si,Fe
As you get close to a black hole the time _____ and the size of an object ___
Slows down , stretched
The theory of general relativity describes how gravity (large mass) affects ______ and was developed by
Space and time, Einstein
The hypothesis for dark energy comes from
The accelerating expanding Universe
As a star runs out of H it undergoes a series of fluctuations caused by
The idea that as one material fuses and moves out consecutive layers of fusing elements cause expansions and the contractions
The 1987 supernova gave scientist their first experience
To test their theories, To use modern equipment to make measurements, To see if they could detect neutrinos
On March 20th will be
Vernal Equinox
What is the best working hypothesis for what dark matter is
WIMPs (weakly interacting massive particles)
Protostars that are below 0.08 Msun
Will not change since they do not begin to fuse in first place, these stars are Brown Dwarfs
When a low mass star sloughs off its outer layer
You are left with a White Dwarf that is composed of mostly C/O it is hot but not luminous
An E0 is
a compact circular ellipse sphere
Out of the four models for how the Universe will evolve the one that fits best with data is
accelerating
AGN stands for
active galactic nuclei
What kind of galaxy? hurricane
barred spiral
There are 3 models for the Universe
closed, flat, open
What is used as an explanation for this acceleration
dark energy
Outside of the Milky Way is the large and small Megallanic clouds which are actually
dwarf galaxies
What major astronomical information was released recently
first image of a supermassive black hole
Calculations show that the best theory for the Universe is it best matches with actual CMB
flat
What were the two problems with the initial Big Bang theory and what was the solution
flatness and horizon, a period of rapid inflation
Hubble developed the ______ as an organizing tool for all of the galaxies
fork
As was verified by the CMB discovery in the beginning the Universe was actually ____ but appears ____ due to _____
hot, cool, red shift
What type of galaxy? typical
irregular
The biggest effect of interacting galaxies
is their tidal affects
What is gravitational lensing
it is in accordance with Einstein's theory of gravity that light is affected by mass
In the early part of the 20th century we finally realized that the smears of light in the sky are actually
other galaxies
The theorist starting as early as the 1940's and working into the 1960's
predicted that the early universe would emit a low energy radiation
Where did the name quasars come from?
quasi-stellar radio sources
The Universe was initially governed by ___ and later by ____
radiation, matter
Which AGN emits mostly in the radio range and has large jets
radio
Hubble's law
receding velocity and distance
What is the evidence for a dark matter
rotation curves, lensing and galaxy clusters
The AGN discovered in the 1940's and is a spiral galaxy is
seyfert galaxy
Which galaxies are most plentiful
spiral
What are the 3 main types of galaxies
spiral, elliptical, and irregular
What is the edge problem
that if there is an edge what would be on other side so there is no edge
The Big Bang
the beginning when all that existed was energy (EM) radiation that expanded and cooled eventually leading to formation of matter
What discovery led to the expanding Universe suggesting a beginning
the farther we look back in time the more red shifted objects are suggesting they are expanding an once we're close together
What is cosmology
the study of the evolution of the Universe across all time
What sets AGN's apart from other galaxies
they are very far but very luminous
A nova can occur with a white dwarf
when they pull material from a neighboring star
