Astronomy Test 5 - The Sun and Stars 4/11/03

Please put your name on the back of the last sheet only, near the staple. Good luck!

___ The Sun will exhaust its nuclear fuel in about
1-5000 AD.
2-5 billion years.
3-50 billion years.
4-5 million years.

___ What two physical processes compete in gravitational equilibrium in stars?
1-The strong force and the electromagnetic force.
2-The gravitational force and outward pressure.
3-The gravitational force and surface tension.
4-The strong force and the weak force.

___ Every second, the Sun converts 600 million tons of hydrogen into 596 million tons of helium. The remaining 4 million tons
1-is ejected into space in a coronal mass ejection.
2-is reabsorbed as molecular hydrogen.
3-is ejected into space by solar flares.
4-is converted to other forms of energy and ultimately emitted in the form of radiation.

___ Contorted magnetic fields on the Sun can cause all of the following EXCEPT
1-satellite failure.
4-power outages.

___ The total amount of power a star radiates is its
1-absolute brightness.
3-apparent brightness.

___ The oldest star clusters are
1-galactic clusters.
2-the Pleiades.
3-open clusters.
4-globular clusters.

___ Cepheids with long periods are
1-small stars.
2-large stars.
3-hot stars.
4-distant stars.

___ If star 35679 has an apparent magnitude of 3 and 111267 has an apparent magnitude of 4, which star is brighter as seen from Earth?
1-Star 35679
2-I do not have enough information.
3-Star 111267

___ Which one of the following stars will likely have the longest lifetime?
1-Wolf 359, type M, absolute magnitude = 16.6
2-Rigel, type B, absolute magnitude = -1.3
3-Achernar, type F, absolute magnitude = 2.7
4-Arcturus, type A, absolute magnitude = -2.5

___ Stars begin their life composed mostly of

___ During some phase of their lifetime, all stars become
1-black holes.
2-red giants.
3-white dwarfs.

___ Planetary nebulae are
1-the dust disks that form planets.
2-expanding shells of gas around white dwarfs.
3-planetary atmospheres that extend far from a planet's surface.
4-failed stars too cool to maintain fusion.

___ Compared to very old stars, recently formed stars have
1-formed in globular clusters.
2-a higher abundance of heavy elements like carbon.
3-higher core temperatures.
4-only hydrogen and helium.

___ What element is the most common element in the universe?

___ A white dwarf is a/an
1-end-state for most stars.
2-early stage of a neutron star.
3-brown dwarf that has exhausted its fuel.
4-precursor to a black hole.

___A nova can occur if
1-a white dwarf has a nearby binary companion.
2-a neutron star has a nearby companion, forming an x-ray binary.
3-the white dwarf has a strong magnetic field.
4-the white dwarf is more than 8 times the mass of our Sun.

___ If a black hole is accreting material from a nearby companion binary, it would best be observed by the
1-Compton Gamma Ray Observatory.
2-Arecibo Radio Observatory.
3-Hubble Space Telescope.
4-Chandra X-Ray Observatory.

___ If two stars have the same luminosity but different temperatures, the cooler star will be
1-smaller and redder
2-smaller and bluer
3-larger and redder
4-larger and bluer

___ The sun is
1-brighter than most stars
2-larger than most stars
3-hotter than most stars
4-a typical star

___ Which of these is measured in watts (like a light bulb?)
1-apparent magnitude

___ Only the hottest stars can contain spectral lines from
4-ionized calcium

___ The two most fundamental properties of a star are
1-mass and luminosity
2-age and luminosity
3-mass and age
4-luminosity and age

___ A star with about ten times the mass of the sun will most likely end up as
1-a black hole
2-a neutron star
3-a white dwarf
4-a worm hole

___ Which is most dense? A
1-white dwarf
2-neutron star
4-black hole

___ The most recent supernova in or near our galaxy appeared in
1-1054 AD

___ If the sun were made of coal, it would burn it all up in about
1-10 billion years.
2-10,000 years
3-10 million years.
4-50 billion years.

___ The source of energy responsible for the Sun's high luminosity is
2-magnetic fields.
4-gravitational collapse.

___ Compared to the photosphere, sunspots are
1-higher in temperature.
2-lower in density.
3-larger in diameter.
4-lower in temperature.

___ If star A has a larger parallax angle than star B, star A is
1-the same luminosity.

___ How do astronomers find the mass stars?
1-They measure a star's color.
2-They measure the relative velocities and separations of binary stars.
3-They measure a star's light.
4-They measure the star's parallax angle.

1. What is special about a white dwarf supernova that makes it a great distance indicator?

2. What is the most famous equation in physics? What does each letter stand for?

3. What is the sunspot cycle? Sketch a rough graph of it.

4. Where were the C, O, and Fe atoms in your body made? How did they come to be a part of us?

5. An object is detected in space emitting radio pulses every 1.23456 s. What is the object called? What is inside it causing the pulses?

6. What is meant by the term "differential rotation of the sun?"

7. Draw below an HR diagram carefully labeling the main sequence, the sun, white dwarfs, red giants, and the proper scales on the x and y axes.