Astronomy Final Flashcards
By exchanging the eyepiece in a telescope with one having a longer focal length, you are _____ the ______ power
decreasing; light gathering
what advantages is the jwst telescope’s mirror (larger and hexagonal) going to have compared to the HST (small and round)
an increase in light gathering power and better resolving power
true or false: the sun radiates most of its light as visible electromagnetic radiation
true
true or false: the doppler effect can change the wavelength of electromagnetic radiation
true
true or false: electromagnetic radiation behaves like both a wave and a particle
true
true or false: longer wavelength electromagnetic waves have more energy per photon
false
true or false: all form of EM radiation travel at the same speed in a vaccuum
true
what number expressed in powers of 10 notation with different units, best represents the distance to a nearby star (not the sun)
10^1 lightyear
study page 2 of test 1
got it
the astronomical unit (AU) is defined as the average distance between the earth and the sun. it’s value is 1.5E8 km. Saturn orbits the sun at approximately 10 AU. what number best describes this distance in km (in notations of ten)
10^9 km
how long does it take for light to travel from the earth to the moon about 300,000 km away?
about a second
Imagine that you are the head of a funding agency that can afford to build only one telescope. what telescope would be best to support
a gamma ray telescope in orbit above earth
what has the lowest frequency
a radio wave
a cloud of warm hydrogen gas is moving toward earth. what best completes the following statement describing the spectrum of this cloud?
A(n) _______ spectrum that is ______ relative to a stationary gas cloud
emission; blueshifted
gamma ray, xray, ultraviolet, visible, infrared, microwave, radio
the phrase above has values increasing to the right. what parameter could this number line represent?
wavelength only
Sirius, the brightest star in the night sky, is about 9 light-years away. if the speed of light were half of its present value, what would the distance of Sirius be?
18 light years.
study questions 14 and 15 in exam 1
gotcha
study questions 18 through 20 on exam 1
ok
how do you determine whether or not a black body spectra of two objects have the same temperature?
they have the same peak and same end location (y axis)
how do you determine size on a black body spectra of two objects?
wavelength
how do refracting telescopes collect light?
lenses
how do reflecting telescopes collect light?
mirrors
what type of most large astronomical telescopes today?
reflecting
why do we want light gathering power in telescopes?
the more lgp there is, the better the image will look
why do we want resolving power in telescopes?
the smaller the resolving power, the better the image
why do we want to build bigger telescopes? (light gathering power)
the bigger the distance from end to end of the telescopes mirror, the larger the lgp, thus getting a better image (LGP = Distance squared
why do we want to build bigger telescopes? (resolving power)
the bigger the distance from end to end of the telescopes mirror, the smaller the resolving power, thus getting a better image (RP = wavelength/distance)
how much greater is the lgp of a 6 meter telescope compared to a 3 meter telescope?
4 times better
on an energy level diagram, how is absorption with the least energy shown
shortest arrow going up
on an energy level diagram, how is emission with the shortest wavelength shown
longest arrow going down
study question 28 on exam 1
okie dokie
the description of “produced by typical stars” most appropriately belongs to which of the different types of spectra
absorption
the description of “produced by a red-colored light sign” most appropriately belongs to which of the different types of spectra
emission
the description of “not all wavelengths present” most appropriately belongs to which of the different types of spectra
absorption and emission
what is the primary reason as to why some telescopes are placed in space above earths atmosphere
some of the light from extraterrestrial sources is absorbed by earths atmosphere
rank the distances from nearest to farthest from earth
jupiter, the closest star other than the sun, the center of the milky way, the closest galaxy, the closest galaxy cluster.
when would we see a star that is neither redshifted nor blueshifted?
when the star is moving parallel to the observer
which portions of wavelength best represents reflected sunlight?
blue green and red
what does the peak of the wavelength tell us about the spectrum
temperature
what feature of a spectrum indicate the color of it,
the peak of intensity
What is light pollution
the lights that civilization gives off “pollutes” the vision of the night sky, making the stars not as easily seen
what is a solution to light pollution?
setting up at a remote location away from the lights of civilization such as on a mountain top or a desert
what is atmospheric turbulence
the atmosphere deflects some of the light given by stars and thus blurs the looks of them
what is a solution to Atmospheric turbulence
setting up in regions with calm atmospheric flow, such as the coastline. they also use adaptive optics
Barnard’s star is a main sequence star with M2 spectral type. As a result, what is always true about this star
it will live longer than a class B spectral type main sequence star
what is a solution for atmospheric absorption
set up on a higher and drier locations such as on a mountaintop or in space
what is always true about two stars that share the same absolute maganitude
they have the same luminosity
a star has an apparent magnitude of -1.0 and an absolute magnitude of +3.0. if it were moved 10 times further away from earth as it is now, what could happen?
it’s apparent magnitude number would increase (get bigger)
a star has an apparent magnitude of -1.0 and an absolute magnitude of +3.0. if it were moved 10 times further away from earth as it is now, what could happen?
it’s apparent magnitude number would increase (get bigger)
star A is an M spectral type star that is 1000 times more luminous than the Sun. Star B has the same absolute magnitude as the sun and belongs to spectral type G. which star has the greatest surface temperature?
star A
how do you find the parallax of a star
1/distance
compared to the sun’s photosphere, the corona is:
higher in temperature and less dense
Alpha Centauri A is a G2 V star at distance of 1.5 parsecs and an apparent magnitude of 0.0. what is the most likely value for the absolute magnitude
-4.4
study questions 15-22 in exam 2 hard
got it
study questions 10-14 in exam 2
alright
study questions 10-14 in exam 2
alright
how are you going to get a lot of white dwarfs
if you have a lot of hot young blue stars
how do you determine a cluster’s age on an HR diagram
by looking at where the cluster branches off (the lower, the older)
study questions 23-25 on exam 2
got’em
during the process of star formation, which force dominates the collapse of a cloud of gas and dust?
gravitational force
what is the range of the spectral types
OBAFGKM (oh boy a fine girl kiss me) (hottest to coolest)
what causes sunspots?
concentrations of magnetic fields that reduce the surface temperature of a region of the star
you should suspect that a dense molecular cloud has a protostar forming inside of it. which type of telescope would be the best to confirm your suspicion
an infrared telescope
what is the evolutionary path for a star like our sun?
main sequence star, giant star, planetary nebula, white dwarf
imagine observing a cluster where the main sequence stars with the same spectral type as our sun have apparent magnitudes of +8.0. if the absolute magnitude of the sun is +4.4, what can you say about the cluster’s distance?
it’s more than 10 parsecs
Star A has a mass of 4 solar masses, and star B has a mass of 8 solar masses. how will the fusion rates, lifetimes, and luminosities of Star A and Star B compare when they are on the main sequence
Star A will have a lower fusion rate, lower luminosity, and a longer lifetime than star B
x-ray images of the sun generally reveal the nature and structure of which of the sun’s layers?
the corona
the parallax angle of the bright star in the Vega is approximately 0.13”. how would this angle change is vega were moved to a distance 10 times as far from earth as it is now?
it would get smaller
which of the following stars would have the largest radius: A. A0 I B. O7 V C. K5 III D. M1 I E. M5 V
D. M1 I
what is the significance of the roman numerals of spectral types?
size from largest to smallest (I being supergiant stars and V being main sequence stars
what is the order of the numeral sizes
I supergiant II Asymptotic giants and horizontal branch III red giant IV subgiant V main sequence
what is the most massive nuclei that can be fused in the core of a 1 solar mass star
helium
what type of stars are most common in a newly formed star cluster
M type main sequence stars
what does a type 2 supernova leave behind?
either a black hole or a neutron star
What is the list of methods for determining distance in the correct order from nearest to farthest
parallax, spectroscopic parallax, Cepheid variables, white dwarf supernova, Hubble’s law
what is the formula for Hubble’s constant
Ho = v/d (recessional velocity divided by distance in megaparsecs)
imagine you discover two white dwarfs in orbit around each other in a binary system your observations reveal that they have the same temperature but one is 10x more luminous than its companion. what is the correct explanation for your observations
the more luminous white dwarf is less massive than its companion
what is the relationship between size and mass in white dwarfs
the more massive a white dwarf is, the smaller the star is
what is the max mass a white dwarf can have
1.4 Msun
why can Cepheid variable stars can be used as standard candles for determining distances to galaxies
they show a distinct, linear correlation between their pulsation periods and their luminosities
the bulges of spiral galaxies often appear reddish in color because they contain what?
numerous cool, old, faint red stars
imagine you can travel at the speed of light. Approximately how long would it take you to transverse the full diameter of the milky way’s disk
100,000 years
the characteristic of “lots of gas and dust” most appropriately belongs in which position of the galaxy
disk
the characteristic of “many globular clusters” most appropriately belongs in which position of the galaxy
halo
the characteristic of “contains faint cool red stars” most appropriately belongs in which position of the galaxy
disk, bulge, and halo ( all three parts)
the characteristic of “metal-rich stars (population I)” most appropriately belongs in which position of the galaxy
disk
the characteristic of “clusters of hot young stars” most appropriately belongs in which position of the galaxy
disk
the characteristic of “coplanar, circular stellar orbits” most appropriately belongs in which position of the galaxy
disk
what can the radius of a stars orbit and its orbital velocity be used to estimate
the mass interior to the stars orbit
what statement best describes the change in percentage of heavy elements of stars in the disk of the milky way galaxy over time
the percentage of heavy elements in disk stars increases over time
what characteristic does the Hubble “tuning fork” diagram use to classify galaxies
a galaxies morphology
what is a possible outcome of a merger between two small elliptical galaxies
a large elliptical galaxies
why do stars in colliding galaxies not collide themselves
the distances between stars is very large compared to the sizes of the stars themselves
what likely happened to an elliptical galaxy that appears to be populated by mostly cool, red main sequence stars
it has been around long enough such that the blue stars have evolved into the cool red main sequence stars we see
in the early 20th century, astronomers deduced that the sun is not at the center of the milky way galaxy for what reason?
by observing the distribution of globular clusters in the halo of the galaxy
what type of telescope would be best used to observe the distribution of cool, neutral hydrogen gas in a nearby galaxy
a radio telescope
the ratio of the number of spiral galaxies to the number of elliptical galaxies is observed to have a specific value for nearby galaxies. how will this ratio change as the universe ages
it will decrease
if the Schwarzschild radius for a 1 Msun black hole is 3 km, what is the Schwarzschild radius for a black hole having a mass of 100 Msun
300 km
the characteristic of “composed of a spheroidal and disk component” most appropriately belongs in which type galaxy
spiral
the characteristic of “very common in dense galaxy clusters” most appropriately belongs in which position of the galaxy
elliptical
the characteristic of “no active star formation” most appropriately belongs in which position of the galaxy
elliptical
the characteristic of “contains a large amount of hot young blue stars” most appropriately belongs in which position of the galaxy
spiral and irregular
the characteristic of “the end result of a merger between two elliptical galaxies” most appropriately belongs in which position of the galaxy
spiral or elliptical
what properties must a neutron star have it we are to observe it as a pulsar
must have a rapid motion, a strong magnetic field, a misaligned rotation and magnetic axis, a beam that sweeps periodically past earth
study questions 35-40 on exam 3
ok
imagine that you measure the distance to a galaxy to be 100 Mpc and its recessional velocity is only 7,000 km/s. what would the distance to a galaxy be if its recessional velocity is only 700 km/s?
10 Mpc
how would an astronaut falling into a black hole be “spaghettified”
tidal forces - the pull of gravity at his/her feet would be much greater than at his/her head
why do astronomers believe that nearly all galaxies are redshifted
spacetime between galaxies is stretching due to the big bang
which two things are needed to determine a standard candle’s distance from earth
apparent brightness and luminosity
true or false: disks contain lots of bright, hot blue stars but are completely devoid of cool faint red stars
false, the disks produces all types of stars, with faint low mass cool red stars being the most common
