Exam 2 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
Hydrogen -2 + proton = _______ + energy
Hydrogen-3
Which of the following has the smallest radius?
A: type A main sequence star B: main sequence star with surface temperature 8000 K C: type K main sequence star D: white dwarf E: neutron star
E. 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?
A: main sequence star with surface temperature 20000 K
B: main sequence star with surface temperature 3000 K
C: main sequence star with luminosity one tenth that of the Sun
D: the Sun
E: main sequence star with mass 2 times the Sun’s
main sequence star with surface temperature 20000K
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 supergiant’s 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?
A : depends on the phase of the Moon
➔ B: the 2 solar mass main sequence star appears brighter
C: the stars are approximately the same brightness
D: the 0.2 solar mass main sequence star appears brighter
E: we cannot tell with the information given
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
How do astronomers measure the temperature of stars?
By looking at which absorption lines are present in the star’s spectrum
The largest fraction of nearby stars (e.g. within 100 light years) are…
red main sequence
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 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 distance?
Star A is 3 times farther away than star B
Which of the following do several contributions in your reading articles is a good model of an intelligent “alien” species already living on earth?
Octopus
The corona of the Sun:
is visible during a solar eclipse
What is the name of the slightly cooler layer of the Sun just outside the photosphere?
corona
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.
How many protons does a Hydrogen atom have?
1 proton, and the different forms can have 1 or 2 neutrons
In the transit method of finding extrasolar planets, the distance of the planet from its star is found from:
Kepler’s 3rd Law using the period of the planets orbit (how often a transit occurs)
Which of the following is true?
Habitable planets have been found around red dwarfs as well as around sun-like stars.
Order the following object from small to large: the Sun black hole neutron star white dwarf
small: black hole, neutron star, white dwarf, the Sun :Large
What type of life found on earth, could survive in the clouds of Venus?
Acidophiles
Star A is four times further away from the Sun than Star B. The parallax angle of Star B is:
FOUR TIMES LARGER than that of Star A
Stars that include Mercury in their habitable zone are
About half the mass of the sun
The sequence of events for the Sun-like star is
Stellar nursery, protostar, sun-like star on main sequence, red giant, planetary nebula, white dwarf.
What is the heaviest chemical element produced in the core of any star?
Iron
How many times bigger are galaxy lusters than individual galaxies?
Hundreds of times bigger
True statement: Stars form in molecular clouds, where temperature are about 10 degrees Kelvin.
False statements …
If I 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
The supermassive black hole in the center of the Milky Way has a mass of
4 million solar masses
Why can’t we see back the whole way to the time the Big Bang expansion began?
The radiation scatters off matter frequently so the Universe is opaque.
Which of the following main-sequence turnoffs indicates the oldest globular cluster?
K5
Roughly how many stars are in the Milky Way Galaxy?
400 billion
The open clusters were a population of relatively young stars, so where would you expect to see them from here?
In the disk
Which force has the gluon as its boson?
Strong
True Statement: There is no center in the universe
Compared to spiral galaxies, elliptical galaxes have
less gas, redder colors, and less new star formation
The redshifts of galaxies are found to be larger for
Galaxies that are further away
Which of the following is not true about dark matter?
Dark matter and dark energy are two aspects of the same phenomenon
What fundamental particles make a Helium-3 atom?
5 up quarks, 4 down quarks, 2 electrons
How many up and down quarks make up a proton?
two ups, one down
What combined with what right before the universe became transparent?
Electrons combined with Hydrogen - 1 nuclei and with Helium-4 nuclei
How many stars are there in a normal-sized galaxy like the Milky Way?
1 billion to 100 billion
When will the Milky Way and the Andromeda galaxy collide?
In about 5 billion years
Extreme environments on Earth are found to have life. Which other Solar System environment COULD NOT have life?
Atmosphere of the Sun
What is one way the concentric rings of the Cat’s Eye Nebula might have formed?
The gas might have been ejected in pulses
