Astro 7N Unit 3 and 4 Test Flashcards
A high-luminosity star …
emits more light than a low-luminosity star
If a red giant appears the same brightness as a red main sequence star, which one is farther away?
the red giant
The heaviest nuclei of all are formed …
during a supernova explosion
Fill in the blank in the following chemical reaction that occurs in the Sun:
Hydrogen-2 + proton = _____ + energy:
Helium-3
Which has the smallest radius?
neutron star
Why does the main sequence part of a star’s life end?
The Hydrogen in the core is exhausted.
Which of the following will have the shortest lifetime on the main sequence?
main sequence star with surface temperature 20000 K
Many of the brightest 100 stars viewed from Earth are not on the main sequence (even though most stars are) because ..
the most luminous stars are giants and supergiants that have already finished their main sequence lifetimes.
A 2-solar-mass main sequence star is at the same distance as a 0.2-solar-mass main sequence star. Which star appears brighter?
the 2 solar mass main sequence star appears brighter
The temperature of the photosphere of the Sun is closest to ..
6000 Kelvin
An estimate of the number of communicating / technological civilizations that we expect in our Galaxy would be a larger number if ..
the average number of planets that could support life for each star were larger
If the Sun had twice its mass, then which of these planets would be in its habitable zone?
Jupiter
Question13
What is the exoplanet’s orbital period, and the percent brightness drop in light, for
the case in the image above from the Kepler Exoplanet Transit Hunt activity?
5 days and 0.30 %
How do astronomers measure the temperature of stars?
By looking at which absorption lines are present in the star’s spectrum
Question 15
In the inverse square law activity above, what would the wattage of the top
lightbulb need to be, such that it appeared as bright as the bottom lightbulb which
is a 25-Watt bulb?
100 Watts
The largest fraction of nearby stars (e.g., within 100 light years) are ..
red main sequence stars
Question 17
Which of the stars, in the diagram above, is the hottest?
D (most far left and highest)
Question 18
If they were all formed at the same time, which of the stars in the diagram above
will live the longest?
B (farthest right and lowest)
The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the distance to the star?
50 parsecs
Which of the following is the sequence of events for a 40-solar mass star (one of the most-massive stars)?
stellar nursery, protostar, blue star on main sequence, Type II supernova, black hole
Star A is 9 times as luminous as Star B. The two stars appear the same brightness. What is true about their distances?
Star A is 3 times farther away than Star B
Question 22
In the p-p chain, shown in the above diagram, what particles must be input in order to produce one 4He nucleus?
6 protons, but 2 of them are returned when the 4He is produced
What is the name of the slightly cooler layer of the Sun just outside the photosphere?
chromosphere
How does a star move on the H-R diagram during the period of time it is converting
hydrogen to helium in its core?
It remains nearly fixed at a certain point on the main sequence and does
not move on the H-R diagram.
If the entire mass of Earth were concentrated in a region the size of a marble, the resulting object would be ..
a black hole
Which is the smallest object?
a neutron star
A galaxy has an H-alpha emission line observed at a wavelength 10 percent larger than the rest wavelength of H-alpha. What is the redshift of the galaxy?
0.1
Question 28
What is in this image?
supernova remnant (check study guide)
Which is the most luminous?
quasar
Which contains the most stars?
a spiral galaxy
Galaxy A appears twice the angular size of Galaxy B. Assuming the two galaxies have the same physical size in kiloparsecs, which of the following is true?
Galaxy B is 2 times farther away than Galaxy A
What fundamental particles make up a Helium-3 atom?
5 up quarks, 4 down quarks, 2 electrons
Check 33 on study guide
Which statement is FALSE about planetary nebulae?
planetary nebulae usually have black holes at their centers
Which statement is TRUE about stars?
Stars form in molecular clouds, where temperatures are about 10 Kelvin.
How tiny a spot is the Hubble Deep Field?
the size of President Roosevelt’s eye on a dime held at arm’s length
What is the last thing that happens in the history of the Universe?
electrons join with nuclei to make atoms
If a galaxy had no dark matter, we would observe ..
the rotation velocity would decrease with increasing distance like the Keplerian curve in our Solar System
How many times bigger is the Local Group of galaxies in which the Milky Way resides than the Milky Way itself?
about 100 times bigger
Which one of the following is FALSE about galaxy collisions?
Galaxy collisions destroy most of the stars in the galaxies involved
If a galaxy is moving away from us the wavelength of the light it emits will be ..
increased
The stars in the halo of our Milky Way Galaxy are ..
older and redder than those in the disk
The supermassive black hole in the center of the Milky Way has a mass of ..
4 million solar masses
Question 44
Which force has the photon as its boson
electromagnetic
Which mysterious phenomena do scientists attribute to dark energy?
The increasing rate of expansion of the Universe.
Why can we NOT see back the whole way to the time Big Bang expansion began?
The radiation scatters off matter frequently so the Universe is opaque.
What are the “standard candles” that were used to determine the Universe is accelerating?
Type Ia supernovae
An older star cluster ..
has a main sequence turnoff farther to the right on the H-R diagram.
Which of the following statements is TRUE about Supernovae?
Type II supernovae are produced by the death of a massive star
Which of the following does physics professor Bernard Bates assert as essential in order for living organisms to develop advanced technology?
living on land
If you wanted to design a form of animal life capable of living on the very young Earth (about 4 billion years ago), which of these gases would at that time be most plentiful for it to breathe?
carbon dioxide
Which of the following do several contributors in your reading articles suggest is a good model of an intelligent “alien” species already living on Earth?
octopus
What are the three primary colors of light, and what happens when they are combined?
Red, green, and blue are the primary colors and they can be combined in different proportions to make any color of light that is visible to the eye
When red, green, and blue light are combined in equal proportions the result is?
white light
Light of different colors is emitted from different stars because ..
The stars have different temperatures, with redder stars being cooler than bluer stars.
The degree of purity of a color (with 0% being black) is called its ..
saturation
If the hue of red light is 0 degrees, then the hue of green light would be .
120 degrees because it is separated by that many degrees on the color wheel
In subtractive color mixing, like with ink on paper, when all three primary colors are combined the result is ..
black / dark color
What kind of cells in the human eye perceive color?
cones
What secondary color is made by mixing red and green in the “RGB” additive-color scheme for light?
yellow
What is the name for colors opposite each other (180 degrees apart) on the color wheel?
Complementary colors
