AST Exam Flashcards

Milky Way galaxy
Terms Definitions
Forces outward
Stony Meteorites
Rocky meteorites
retrograde motion
occasional westward movement
Great Hunter. brightest winter constellation.
distance over unit time (miles/hour)
cosmological constant
Quantity originally introduced by Einstein into general relativity to make his equations describe a static universe. Now one of several candidates for the repulsive "dark energy" force responsible for the observed cosmic acceleration. A recent discovery, based on observation of Type I (carbon-detonation) supernovae is that the expansion of the universe is accelerating. The reason for this acceleration is unknown, but a mysterious force known as dark energy, which is neither matter nor energy, seems to exert a repulsive force on the universe and produces an acceleration of the expansion. Cosmologists suggest that a mysterious force known as the cosmological constant and effective only on very large scales is also responsible for the acceleration. Although models based on the cosmological constant are consistent with observational data, astronomers do not have a clear understanding of this concept. It cannot be explained by the laws of physics. According to the most recent studies, cosmologists now believe that the universe is of precisely critical density and that the density is due to both matter and dark energy. Based on current data, the composition of the universe is 4% normal matter, 23% dark matter, and 73% dark energy.
waxing crescent
phase two of the moon
the process that protoplanets are extremely HOT and are in a LIQUID state ad that the materials making up protoplanets bodies begin to separate
Calculate Cosmic Background Microwave Radiation
T=2.7(1+z) K
What kind of reflecting telescope has its eyepiece on the side of the tube near the end of the telescope farthest from the ground?
Big Bang
Event that cosmologists consider the beginning of the universe, in which all matter and radiation in the entire universe came into being. Hubble's law describes the expansion of the universe and allows the distance to remote galaxies to be determined. It may also be used to determine the time required for any galaxy to reach its present distance from us. Recall that the value of Hubble's constant is somewhat uncertain but is belived to be between 50 and 80 km/s/Mpc On page 460, it is shown that if the value of Hubble's constant is taken to be 70 km/s/Mpc, the time required for any galaxy to reach its present distance from us is about 14 billion years. It is important to note that the time is independent of distance. This implies that 14 billion years ago, all matter and energy in the universe was confined to a single point. According to the Big Bang theory, this point flew apart in an unbelievably gigantic explosion. The Big Bang was the beginning of the universe and the present locations and velocities of the galaxies are a direct consequence of this primordial explosion. It should be noted that Hubble's constant is not known precisely and the recession velocities of the galaxies has been slowed by gravity so that the time elapsed since the Big Bang is uncertain, but the important idea is that the age of the universe is finite. Olber's paradox can now be resolved. We see only the part of the universe within about 14 billion light years. The light from beyond this distance has not yet reached us.
The Big Bang was not an explosion in an empty universe. It involved the entire universe and the universe itself is expanding. At the time of the Big Bang, the entire universe was a point. The galaxies are not receding into the "rest of the universe." As the universe expands, the galaxies are carried with it. There is no empty space beyond the galaxies and the universe remains homogeneous at all times. These concepts are illustrated quite well by attaching coins to the surface of a balloon (Figure 17.3, page 461). Let the coins represent galaxies and the surface of the balloon represent the fabric of the universe. This simple model of the universe obeys the cosmological principle - all points on the balloon are quite similar. If the balloon is inflated, it expands and the coins recede from each other.
Spinning neutron stars are usually observed to be at the center of:
supernova remnants
Which element is critical to the formation of the volcanic surface of Io?
An objects combination of mass and velocity.
a Cehpheid variable star with luminosity 1000 times that of the Sun has a pulsation period of roughly
4 days
A relatively small, icy object that orbits a star. Like asteroids, comets are officially considered part of a category known as "small solar system bodies.
stands for the semimajor measured in AU's
How much (fraction) of the solar system's mass is taken up by the sun?
Which of the following stars have the largest diameters?
RR Lyrae variable
Variable star whose luminosity changes in a characteristic way. All RR Lyrae stars have more or less the same average luminosity. One of two types of variable stars that have played central roles in determining the dimensions of the Milky Way Galaxy and distances to other galaxies.
Main sequence
star fuse hydrogen into helium and thus supply energy.
planet whose core is surrounded by ICE and ROCK
Protostar Phase
pressure and gravity and not precisely balanced
radius much lager than the Sun
energy generated by gravitational contraction
luminosity much greater than the Sun
Doppler Effect
the apparent change in frequency of electromagnetic or sound waves caused by the relative motions of the source and the observer
Due to their great masses, all four Jovian worlds are much denser than the earth.
Earth is nearly twice as large as Venus.
Barred Spiral Galaxies
galaxies that have an ELONGATED nucleus with spiral arms springing from the ends the bar
The relatively rigid outer layer of a planet; generally encompasses the crust and the uppermost portion of the mantle.
Binary Star
A star system that contains two stars.
halo (of galaxy)
The spherical region surrounding the disk of a spiral galaxy.
Dark Matter
90% of the matter in our galaxy.
intracluster gas.
The x-rays are believed to be produced by intracluster gas, superhot intergalactic matter. Intracluster gas accounts for some of the discrepancy between the masses of visible matter and dark matter, but there is far too little intracluster gas to solve the dark-matter problem.
A protostar:
is an early stage of a star's life-cycle before it becomes a main-sequence star and may develop bi-polar flows
Which of the layers of the Earth is unique among the terrestrial planets?
sidereal day
earth's 23 hours and 56 min. day measured by timing how long it takes any star to make one full circuit through our sky, (means "related to the starts")
the best frequency range in which to study the hot (million-kelvin) gas found among the galaxies in the Virgo cluster would be
in x-rays
hydrogen shell-burning
Hydrogen fusion that occurs in a shell surrounding a stellar core
The highest point on the sky is called the:
Large Magellanic Cloud
One of two small, irregular galaxies (the other is the Small Magellanic Cloud) located about 150,000 light-years away; it probably orbits the Milky Way Galaxy.
2. Horizontal branch
Core nuclear fusionConvert He to C. Leaves the horizontal branch when the core runs out of He.
On what day will the Sun cross the celestial equator heading southward?
Autumnal Equinox
8 minutes
how long it takes for the sun's light to reach us
Doppler Spectroscopy
If a star is accompanied by a planet, the radial velocity (speed of object in line of sight, as determined by the doppler effect) of the star will periodically change as the star moves toward and then away from a distant observer.
The part of Earth's crust that is youngest is:
The midoceanic ridge.
2. Disk-
Young, Blue stars (Pop I) in spiral galaxies Gas and dust.
Newton's Third Law
To every action there is an equal and opposite reaction
Interstellar dust consists mostly of _____.
microscopic particles of carbon and silicon
These tiny, solid particles are very important, even though their total mass makes up less than 1% of the interstellar medium.
Planet Property - Density
mass (kg)/vol (m^3)
can give a clue to chemical composition
8. In a disk around a white dwarf, the gas that is farther from the white dwarf is
(a) colder
The Drake Equation:
N= R. fs .fp. ne. fl .fi .fc .L
Which are the four Galilean moons of Jupiter?
Io, Europa, Ganymede, and Callisto
Which is used observationally to determine the age of a star cluster
the luminosity of the main sequence turn off point
Why is Venus' surface hotter on average than Mercury's?
Carbon dioxide in Venus' atmosphere traps heat radiating from its surface, thereby making it warmer.
An 'Astronomical Unit' (AU) is what?
The distance between the Sun and the Earth
The Phase of the Moon when the Sun and Moon are at right angles in the sky is:
Quarter (first or second)
habitable zone surrounding a main sequence K-type star
Is larger than that of an M-type star
How did the Ptolemaic model explain the apparent retrograde motion of the planets?
The planets moved along smal circles that moved on larger circles around the Earth.
Measuring Di with eclipsing Binaries
The light curve of an E.B. gives the relative Di of the two stars
Ch.20 Q#2: What are the three major types of galaxies, and how do their appearances differ?
The three major types are: spiral galaxies: contains disk, bulge, halo. If it had spiral arms then it is a barred spiral galaxy and if none the lenticular which looks like a circle. Spiral are more white as it has a mix of old and young stars and most are huge. Elliptical galaxies do not have disks and look like red spots and mostly small/dwarf.Irregular galaxy fall neither as they can be any shape but are also whitish as they are filled with young stars and are few but possible were frequent in the early universe.
The LEAST well known factor in the Drake Equation is
the average lifetime of a technology competent civilization
What was the problem with the contraction theory, and who discovered this problem?
The sun could only burn by contraction for 20-40 million years; Lord Kelvin
The Tharis region on Mars has so few craters which suggests
it's the youngest region on the planet
Why does heat allow the cloud to remain expanded?
The greater heat, the faster the atoms move; the faster they move, the more energy they have to keep it inflated
What is the main, overall reason that planets form within these disks?
The disks spin, as the inner part of the galaxy is moving faster than the outer
red supergiant
surface temperature
5800 K
newton's law of gravity
Titan, Mimas
the two Saturn's moons
Large volcano on Mars:
Olympus Mons.
the second planet from the sun
2900000 light years
the Andromeda galaxy is......away
Energy source of the sun
thermonucleur fusion
variable star
a star whose luminosity varies
The sun is classified by astronomers as a(n) ___ star
general relativity
According to Einstein's theory of general relativity, space is curved and the extent of curvature is determined by the total density of the universe. Also, Einstein stated that matter and energy are equivalent, so that the determination of the density of the universe must include all matter and energy. If the universe is homogeneous, it must have the same curvature everywhere and there are three possible geometries for the universe.
Weins Law
Lambda_Max varies inversely with T. Thus if T_1 / T_2 = 2 then Lambda_Max1 / Lambda_Max2 = 1/2
T/F The Earth's core generated a stable and permanent magnetic field much as a regular bar magnet
Light is what type of wave
Electromagnetic Wave
The weak magnetic fields around Europa and Ganymede were found during flybys of
State of the sun
Ionized, electrons move freely
asserted that the universe is governed by physical laws
At what temperature, kelvin, does the freezing occur on earth?
What is the most common element found in our Sun?
A galaxy is an extremely large system of stars and interstellar matter isolated in space and held together by gravity. The sun is a star in the Milky Way Galaxy.
Stellar balancing act
dynamic equilibrium. A star spends most of its lifetime at a relatively constant size, temperature, luminosity, etc. while it fuses some fraction of its hydrogen into helium. During this time there is a balnce between the forces inward and the forces outward
they are small, rocky objects. Most of them lie between Mars and Jupiter
The light we see from galaxies comes mostly from ___ in the galaxies.
____ is one possibility for an object in equilibrium.
Which planet shows the widest range of surface temperatures between day and night?
absolute magnitude
a measure of an object's luminosity; defined to be the apparent magnitude that a star would have if it were viewed from a distance of 10 parsecs from the earth
An apparent **** in the direction of an object in observational position that provides a new line of sight
dwarf galaxy/dwarf elliptical galaxy
Relatively small galaxies, consisting of less than about 10 billion stars. / A small elliptical galaxy with less than about a billion stars.
Where could I find Mercury at sunset?
In the West.
rich galaxy cluster
The Virgo Cluster (Figure 15.13, page 413) is about 18 Mpc (60 million light years) from the Milky Way Galaxy. This rich cluster contains 2500 galaxies. Thousands of galaxy clusters are known and have been cataloged. The Coma Cluster, shown in Figure 15.1 on page 404 is a rich galaxy cluster that lies approximately 100 Mpc (approximately 300 million light years) from the Milky Way. Figure 15.14 on page 413 shows a Hubble Space Telescope image of the extremely distant rich galaxy cluster Abell 1689. This galaxy cluster lies approximately 2 billion parsecs (6 billion light years) from the Milky Way. Although most galaxies are members of a galaxy cluster, it is believed that 20-30 percent of galaxies are not members of a cluster.
The interstellar medium contains:
atoms and ions, dust, and molecules
The Huygens probe of the ESA made a succesful landing on
Spring Tides
Tides that occur when the Sun, Earth, and Moon are all lined; High tides are higher than average and low tides are lower than average; occur at new moon and full moon.
The best way to study young stars hidden behind interstellar dust clouds would be to use
Infrared light
late stage in the life cycle of a massive star in which the core heats up, heavy elements form by fusion, and the star expands, raising in diameter and lowering density; can eventually explode to form a supernova
Suppose its full mon. What phase of the Earth would someone on the Moon see at this time?
New Earth.
recombination (era of)
Assembly of neutral atoms from ions and electrons as old stars swell and cool *not sure if right*
2. Cold Dark Matter:
Fairly massive Proton mass Particles that travel slowly through the galaxy. Can have a patchy distribution in the galaxy.
Milky Way Galaxy
The spiral galaxy in which the Sun resides. The disk of our Galaxy is visible in the night sky as the faint band of light known as the Milky Way.---Diameter of Milky Way Galaxy (30 kpc or 100,000 light years)
Our most detailed maps of Venus come from
the Magellan spaceprobe
Gravitational Potential Energy
energy stored by objects due to their position above the Earth's surface
Planet Property - Diameter
distance and angular size will give diameter
200,000 x diameter/distance = angular size
Mars is most like Earth in that:
None of the above.
The Great Red Spot is a feature on the planet ___.
An asterism is best described as:
an easily recognizable pattern of stars.
The General Theory of Relativity
was developed by Albert Einstein in the early 1900s, describes our Universe as four-dimensional space-time, states that mass curves space-time, and provides an explanation of gravity
_____ ______ is another non-accelerating motion possibility for a mass in equilibrium.
Constant Velocity (no change in speed or direction)
asymptotic giant branch
Helium burns at a fast rate as a result of the extremely high temperature in the core and creates carbon "ash" (star becomes a larger red giant)
spectral class
temperature of stars, O B A F G K M
We can still find lots of planetesimals, left over from the time of solar system formation
in orbit between Mars and Jupiter.
The far side of the Moon was first mapped
by early Russian spacecraft
nebular theory of solar system formation
The detailed theory that describes how our solar system formed from a cloud of interstellar gas and dust.
The fact that part of the earth's core is liquid comes from:
Analysis of earthquake waves.
How does a main-sequence star's luminosity depend upon its mass?
the more massive the star, the more luminous
Small deviations in a planets orbital motion imply
the nearby presence of a massive body
In the H-R diagram, what are the two most important (common) types of data plotted
spectral classes (temperature) and absolute magnitudes (luminosity)
Which of the following types of data provide evidence that helps us understand the life tracks of low-mass stars?
H-R diagrams of globular clusters.
A globular cluster is comprised of stars that formed at about the same time, and the globular clusters in the Milky Way are full of old low-mass stars in various stages of evolution.
How is the length of a star's lifetime related to the mass of the star?
Higher-mass stars run through their lives faster and have shorter lifetimes.
Ch.19 Q#4: How can we use orbital properties to learn about the mass of the galaxy? What have we learned?
using newtons version of keplers 3rd law we can find the mass if we know the period and average distance of a much smaller object in orbit around it.
The precession of the earth's rotation axis:
Is a slow wobble that takes 26,000 years to complete and means that in AD 14,000, Vega will be a pole star.
To a distant observer, what happens to your time as you approach a black hole?
The observer sees that your time is running at a slower rate than her time is, and it appears to slow more and more as you get near the event horizon.
The nucelus o a comet is typically
a few kilometers in size and very low in density
What is an Astronomical Unit? Who was it founded by.
The measure of distance in the Solar System. Giovanni Cassini in 1672.
If the original star had more than 25 solar masses: How does it end up?
A black hole. Nothing can support the core and it shrinks forever.
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