Astronomy ch 9/10/11/12

t/f A star of apparent magnitude +5 looks brighter than one of the apparent magnitude +2

False

t/f Red giants are very bright because they are extremely hot

False

t/f Star A appears brighter than star B, as seen from earth. Therefore, star A much be closer to earth than star B

False

t/f the radius of a star can be determined if the stars distance and luminosity are known

False

t/f there are no billion year old main sequence O or type B stars

True

How much bigger is the Sun's radius compared to Earth's radius? a) 100 b) 1000 c) 100,000 d) 1,000,000

a) 100

Interstellar gas is composed primarily of a) 90% hydrogen, 9% helium, and 1% heavier elements. b) molecules including water and CO2. c) 50% hydrogen, 50% helium. d) hydrogen, oxygen, and nitrogen. e) 99% hydrogen, and 1% heavier elements.

a) 90% hydrogen, 9% helium, and 1% heavier elements.

In the stellar magnitude system invented by Hipparchus, a smaller magnitude indicates a _____ star. a) brighter b) hotter c) cooler d) fainter e) more distant

a) brighter

a white dwarf is supported by the pressure of tightly packed a) electrons b) protons c) neutrons d) photons

a) electrons

solar energy is produced by a) fusion of light nuclei into heavier ones b) fission of heavy nuclei into lighter ones c) the release of heat left over from the suns formation d) solar magnetism

a) fusion of light nuclei into heavier ones

a white dwarf can dramatically increase in brightness only if it a) has another star nearby b) can avoid nuclear fusion in its core c) is spinning very rapidly d) is descended from a very massive star

a) has another star nearby

A white dwarf can explode when a) its mass exceeds the Chandrasekhar limit. b) its electron degeneracy increases enormously. c) fusion reactions increase in its core. d) iron in its core collapses. e) the planetary nebula stage ends.

a) its mass exceeds the Chandrasekhar limit.

astronomers on venus would measure a solar constant a)larger than b) smaller than c) the same as on earth

a) larger than

How far away from Earth is the nearest star? a) 1.3 pc b) 1 AU c) 0.53" d) 10 ly e) 10 pc

b) 1 AU

If the parallax of a star is measured to be 0.1 seconds of arc, its distance is a) 10 astronomical units b) 10 parsecs c) 1 parsec d) 0.1 parsec e) 0.1 astronomical units

b) 10 parsecs

The density of the Sun is most similar to that of a) a comet. b) Jupiter. c) Earth. d) interstellar gas. e) an asteroid.

b) Jupiter

Sunspots appear dark because they are a) holes in the photosphere through which you can see deeply into the solar interior. b) a bit cooler, thus dimmer than the rest of the photosphere. c) large opaque structures that block light from the glowing solar surface. d) causing retinal damage.

b) a bit cooler, thus dimmer than the rest of the photosphere.

a typical solar granule is about the size of a) a US city b) a larger US state c) the moon d) earth

b) a large US state

Elements heavier than carbon were created a) in the Big Bang. b) by nucleosynthesis in massive stars. c) in the cores of stars like the Sun. d) within planetary nebula. e) They have always existed.

b) by nucleosynthesis in massive stars.

nuclear fusion in the sun will a) never create elements heavier than helium b) create elements up to and including oxygen c) create all elements up to an including iron d) create some elements heavier than iron

b) create elements up to and including oxygen

compared with a star of absolute magnitude -2 at a distance of 100 pc, a star of absolute magnitude 5 at a distance of 10 pc will appear a) brighter b) fainter c) to have the same brightness d) bluer

b) fainter

The reddish color of emission nebulae indicates that a) gas and dust is moving away from Earth. b) hydrogen gas is present. c) dying stars have recently exploded. d) cool red stars are hidden inside. e) dust is present.

b) hydrogen gas is present.

the red glow of an emission nebula a) is emitted by warm gas falling onto the stars at the center b) is produced by hydrogen gas heated to high temperatures by massive stars within the nebula c) is a reflection of light from stars near the nebula d) is the unresolved light of many faint red stars within the nebula

b) is produced by hydrogen gas heated to high temperatures by massive stars within the nebula

Stars are formed from cold interstellar gas clouds made up of a) atomic gas of mostly hydrogen, oxygen, carbon, and nitrogen. b) molecular hydrogen gas and dust grains. c) some hydrogen gas, comets, and asteroids. d) stars are formed from very HOT gas.

b) molecular hydrogen gas and dust grains.

a protostar that will eventually turn into a star like the sun is significantly a) smaller b) more luminous c) fainter d) less massive than the sun

b) more luminous

The light from the East limb (edge) of the Sun is blue shifted and the light from the West limb is redshifted. This is because a) different kinds of atoms emit light at the opposite edges. b) the Sun is rotating. c) the distance from the Sun to Earth changes. d) the two sides of the Sun are at different temperatures.

b) the Sun is rotating.

what is probably responsible for the increase in temperate of the corona far from the suns surface? a) the higher rate of fusion b) the Sun's magnetism c) higher radiation pressures d) absorption of X rays e) convection currents

b) the Sun's magnetism

most of the carbon in our bodies originated in a) the core of the sun b) the core of a giant red star c) supernova d) a nearby galaxy

b) the core of a giant red star

stars of spectral class M do not show strong lines of hydrogen in their spectra because a) they contain very little hydrogen b) their surfaces are so cool that most hydrogen is in the ground state c) their surfaces are so hot that most hydrogen is ionized d) the hydrogen lines are swamped by even stronger lines of other elements

b) their surfaces are so cool that most hydrogen is in the ground state

a star like the sun will end up as a a) blue giant b) white dwarf c) binary star d) red dwarf

b) white dwarf

the sun is roughly a) the same size b) 10 times larger c) 100 times larger d) 1 million times larger than earth

c) 100 times larger

Two identical stars, one 5 ly from Earth, and a second 50 ly from Earth are discovered. How much fainter does the farther star appear to be? a) square root of 10. b) 10. c) 100. d) 1,000. e) the farther star does not appear fainter, since it's identical.

c) 100.

the time between successive sunspot maxima is about a) a month b) a year c) a decade d) a century

c) a decade

For two stars of the same apparent brightness, the star closer to the Sun will generally have a) a higher flux b) a hotter temperature c) a lower luminosity d) identical physical properties

c) a lower luminosity

The photosphere (the visible surface) of the Sun is like a) the surface of Earth; you could stand on it, if you could survive the heat. b) the surface of the ocean; you couldn't stand on it, but you would clearly be able to detect differences above and below it. c) an apparent surface; you would notice very little change as you go through it, as when you fly through a cloud. d) the surface of a trampoline; you could land on it, but the intense pressure would push you away again.

c) an apparent surface; you would notice very little change as you go through it, as when you fly through a cloud.

A star like our Sun will spend most of its "shining" lifetime a) as a protostar. b) as a red giant. c) as a main-sequence star. d) as a white dwarf. e) evolving from type O to type M.

c) as a main-sequence star.

Tremendous pressure is created at the Sun's center due to its own gravity. The Sun is kept from collapsing by a) neutrinos and other particles generated by nuclear fusion. b) a hard inner core. c) gas pressure created by the heat of nuclear fusion. d) gas pressure created from left over heat from the formation of the Sun.

c) gas pressure created by the heat of nuclear fusion.

The proton-proton cycle involves what kind of fusion process? a) carbon (C) into oxygen (O) b) helium (He) into carbon (C) c) hydrogen (H) into helium (He) d) neon (Ne) into silicon (Si) e) oxygen (O) into iron (Fe)

c) hydrogen (H) into helium (He)

cool stars can be very luminous if they are very a) small b) hot c) large d) close to our solar system

c) large

the sun spins on its axis roughly once each a) hour b) day c) month d) year

c) month

Objects more massive than our Sun form into stars a) much slower, over billions of years. b) in about the same time. c) much faster, over tens of thousands of years. d) not at all - they are unstable.

c) much faster, over tens of thousands of years.

Some regions of the Milky Way's disk appear dark because a) there are no stars there. b) stars in that direction are obscured by interstellar gas. c) stars in that direction are obscured by interstellar dust. d) numerous black holes capture all the starlight behind them.

c) stars in that direction are obscured by interstellar dust.

How many radians in 60 degrees? a) 3.14159 b) π/6 c) π/3 d) 2π/60

c) π/3

Two stars have the same surface temperature, but the radius of one is 10 times that of the other. The larger star is a) the same luminosity b) twice as luminous c) 10 times as luminous d) 100 times as luminous e) 1000 times as luminous

d) 100 times as luminous

from a distance of 1 parsec, the angular size of Earths orbit would be a) 1 degree b) 2 degrees c) 1 arc minute d) 2 arc seconds

d) 2 arc seconds

Which spectral classification and type corresponds to a star like the Sun? a) B81A b) GIII c) M5V d) G2V e) K2V

d) G2V

of the following telescopes, one best suited to observing dark dust clouds is a) an X-ray telescope b) a large visible light telescope c) an orbiting ultraviolet telescope d) a radio telescope

d) a radio telescope

the mass of a star may be determined s) by measuring it luminosity b) by determining its composition c) by measuring it Doppler shift d) by studying its orbit around a binary companion

d) by studying its orbit around a binary companion

Solar energy is produced by a) the release of heat leftover from the Sun's formation. b) solar magnetism. c) fission of heavier nuclei into lighter ones. d) fusion of light nuclei into heavier ones.

d) fusion of light nuclei into heavier ones.

If an interstellar cloud contracts to become a star, it is due to which force? a) electromagnetic b) nuclear strong c) nuclear weak d) gravitational e) centrifugal

d) gravitational

The Sun will evolve away from the main sequence when a) its core begins fusing iron. b)its supply of hydrogen is used up. c) the carbon core detonates, and it explodes as a Type I supernova. d) helium builds up in the core, while the hydrogen-burning shell expands. e) the core loses all of its neutrinos, so all fusion ceases.

d) helium builds up in the core, while the hydrogen-burning shell expands.

Wien's law tells us that the hotter an object, the _____ the peak wavelength of its emitted light. a) longer b) more green c) heavier d) shorter e) more constant

d) shorter

The absolute magnitude of a star is its brightness as seen from a distance of a) one million km. b) one Astronomical Unit. c) one light-year. d) ten parsecs. e) ten light-years.

d) ten parsecs.

Astronomers use the term nebula to refer to a) outer envelopes of dying stars that drift gently into space. b) remnants of stars that die by supernova. c) clouds of gas and dust in interstellar space. d) distant galaxies seen beyond our Milky Way. e) All of the above are correct.

e) All of the above are correct.

Which of the following quantities do you need in order to calculate a star's luminosity? a) apparent brightness b) Doppler shift of spectral lines c) color of the star d) distance to the star e) a and d

e) a and d

What is a T-Tauri star? a) a collapsing cloud of gas about to become a protostar b) a dying star c) a cool main sequence star d) a star releasing a planetary nebula e) a protostar about to become a star

e) a protostar about to become a star

t/f a nova is a sudden outburst of light coming from an old main sequence star

false

t/f a planetary nebula is the disk of matter around a star that will eventually form in a planetary system

false

t/f because of stellar nucleosynthesis, the spectra of old stars show more heavy elements than those of young stars

false

t/f brown dwarfs take a long time to form, but will eventually become visible as stars on the lower main sequence

false

t/f emission nebulae radiate mainly in the ultraviolet part of the electromagnetic spectrum

false

t/f in a spectroscopic binary, the orbital motion of the component stars appear as variations in the overall apparent brightness of the system

false

t/f interstellar matter is quite evenly distributed throughout the milky way galaxy

false

t/f neutrinos have never been detected experimentally

false

t/f sunspots appear dark because they are hotter than the surrounding gas of the photosphere

false

t/f the density and temperature in the solar corona are much higher than in the photosphere

false

t/f the proton proton chain releases energy because mass is created in the process

false

t/f there are as many absorption lines in the solar spectrum as there are elements present in the sun

false

t/f twenty one centimeter radiation can be used to probe the interiors of molecular clouds

false

nuclear fusion in the core of a massive star cannot create elements much heavier than iron

true

t/f all of the single red-dwarf stars that ever formed are still on the main sequence

true

t/f astronomers can distinguish between main sequence and giant stars by purely spectroscopic means

true

t/f flares are caused by magnetic disturbances in the lower atmosphere of the sun

true

t/f in a core collapse supernova, the outer part of the core rebounds from the inner, high density core, destroying the entire outer part of the star

true

t/f it takes less and less time to fuse heavier and heavier elements inside a high mass star

true

t/f more massive stars form more rapidly

true

t/f most stars form as members of groups or clusters

true

t/f the formation of the first high mass stars in a collapsing cloud tends to inhibit further star formation within that cloud

true

t/f the most abundant element in the sun is hydrogen

true

t/f the sun will get brighter as it begins to run out of fuel in its core

true