Astronomy chapter 4 study guide

Spectroscopic Parallax refers to

a method for finding distances to stars.

focal plane

a plane perpendicular to the principal axis that passes through either focal point of a lens

The idea that a supernova is preceded by a huge burst of neutrinos is

a prediction that has now been observed.

Type II supernovas have the following properties:

a spectrum with hydrogen lines and a variable maximum brightness.

The problem of stars "twinkling" due to atmospheric turbulence

can be corrected by using a guide star.

When a red giant star begins to burn helium, its diameter

decreases but not to its main sequence size.

Ham radio operators sometimes operate receivers for the 2 meter wavelength band. The 2 meters refers to the

distance from one maximum of the radio waves to the next.

The core of a red supergiant star stops shrinking because its

electrons touch each other.

The point at which even an outwardly directed light ray is pulled into a black hole is called the

event horizon.

Stars that are much more massive than our Sun

form faster and burn out faster.

converging lens

lens such that a beam of light passing through it is brought to a point or focus

to see a large but faint object such as a nebula, you would need a telescope with large

light gathering power.

On a HR diagram, a visible white dwarf star is in the

lower left corner. upper right corner.

When a white dwarf star collects matter from a neighboring star, fusion reactions on the surface of the white dwarf cause

novas.

diffraction limit

one-wavelength turning angle

A hydrogen atom with its electron removed (a H⁺ ion in other words) is actually a

proton.

A star that is cooler than most other stars will probably look

red.

Our Sun is a type G2V star on the main sequence. As it ages and uses up its fuel we expect it to

remain a G2V star until it leaves the main sequence.

Which of the following magnitudes corresponds to the brightest star?

0.

The mass of a carbon atom is 12.00amu while the mass of a helium-4 atom is 4.003amu. If a gamma ray photon splits a carbon atom into three Helium atoms, how much energy is converted into mass?

0.009amuv

A star is seen to move by 0.2 seconds of arc between February 1, 1999 and August 1, 1999 and then back to its starting point on February 1, 2000. What is the parallax angle for this star?

0.1 seconds of arc.

The apparent brightness of our Sun is roughly 1000 watts per square meter. At a distance of 30 times the Earth-Sun distance, the apparent brightness of our Sun would be

1.1 watts per square meter.

A star with a distance modulus of zero is at a distance of

10 parsecs.

Our Sun is a G2V star with absolute magnitude 4.8. Suppose that a star of spectral type G2V is observed to have apparent magnitude 9.8. How far away is it?

100 parsecs.

A star is observed to have an apparent brightness which is 10⁻⁴ times its absolute brightness. How far away is it?

1000 parsecs.

A star with an absolute magnitude of 5.7 and an apparent magnitude of -1.2 would appear in our sky as a star

1000 parsecs.

A star whose apparent brightness is 1/100 times that of a sixth magnitude star would have magnitude

11.

Suppose that a flash of lightning from a cloud 2500 meters away is followed by a clap of thunder two seconds later. Assume that the light arrived in a negligible time and calculate the speed of the sound waves.

1250m/s

the velocity of sound waves is roughly the same for all wavelengths. Suppose that a sound wave has a wavelength of one meter and a frequency of 1000Hz. The wavelength of a 500Hz sound wave would then be

2 m.

The star delta-Eridani shows a heliocentric stellar parallax of almost exactly 1/9 seconds of arc. The distance from our Sun to delta-Eridani is

9 parsecs.

A mirror that is shaped like a shallow bowl sitting on a glass table with its open end facing up will focus light that comes

A mirror that is shaped like a shallow bowl sitting on a glass table with its open end facing up will focus light that comes

interferometer.

Collection of two or more telescopes working together as a team, observing the same object at the same time and at the same wavelength. The effective diameter of an interferometer is equal to the distance between its outermost telescopes.

Which of these answers describes the fundamental assumption that is behind all of the methods that astronomers refer to as the "distance ladder?"

Distant objects are similar to nearby objects.

The star Wemadeit shows a stellar parallax angle of 0.3 seconds of arc while the star Waytoofar shows a stellar parallax angle of 0.4 seconds of arc. From this, you can conclude that

Waytoofar is closer to our Sun than Wemadeit.

When an interstellar cloud fragment does not have enough mass to form a star powered by nuclear fusion, but gets hot enough to glow for a while, it is called

a brown dwarf.

astronomical telescope

a magnifier viewing the focal plane of a large concave mirror

Coude focus

adds a mirror to the Cassegrain design and diverts the light out the side to a location that can stay fixed as the telescope moves.

The first red giant stage of a one solar mass star's life usually ends with

an explosion in the helium core.

The luminosity class of a star is

an indication of the broadening of its spectral lines.

Because of the electrical repulsion between atomic nuclei, nuclear fusion happens only

at high temperatures.

A star that forms an iron core most likely has a mass of

between 15 and 20 solar masses.

High protostellar winds of ejected gas occur

between the initial contraction and the ignition of nuclear burning.

To measure the heliocentric stellar parallax of a star, you mostly need a telescope with

high resolving power.

magnification power

if the power of telescope. for example, and 200x telescope makes images appear 200 times larger

In the Hertzsprung-Russell Diagram, a main sequence star might be found

in the lower right or upper left.

For stars on the main-sequence, stars with increasing mass have

increasing surface temperature and absolute brightness.

light gathering power

is proportional to the area of the main mirror

Resolving power

is the angular size of the smallest feature that can be seen and is limited by the size of the mirror and the wavelength of light.

Suppose that a star has a spectrum that includes red, blue, and violet lines spaced in the pattern of the lines from hydrogen but the red line is has a wavelength of 660 nm instead of the usual 656 nm. From this evidence, you can conclude that the star is

moving away from us.

The average energy of motion of an atom or molecule in a gas is called its

temperature.

The "Little Green Men Standard Time" hypothesis for the repeating radio signals seen in 1968 was rejected partly because the repetition rate was

slowing down.

A spectroscopic binary star system is one in which we see

spectral lines shifting back and forth.

Think of the `front' of a telescope as the end that light enters. A telescope with Newtonian Focus has the eyepiece

sticking out the side near the front.

Stellar Astronomy

study of stars including their creation, evolution and death

When the hydrogen fuel runs out at the center of a main sequence star, the star

swells up and becomes a red giant.

We can see the star Sirius and its companion, the Pup, moving around each other. Careful measurement of this motion can provide

the masses of both stars in the system.

Because mirrors only use one surface, they have a big advantage over lenses: They can be

thinner and larger in diameter.

In a Hertzsprung-Russell diagram, the surface temperature of stars increases going

to the left.

prime focus

uses the natural focal plane and places the eyepiece in a cage inside the telescope tube.