Astronomy a beginners guide to the universe 8th CHaisson mcmillan chapter 14 clicker questions

Explanation: The Sun orbits the center of the Galaxy within the disk, taking about 225 million years to complete one orbit... High-speed motion of gas and stars near the Milky Way Galaxy

The location of the Galactic center was identified early in the 20th century using

The location of the Galactic center was identified early in the 20th century using

Our Sun is located in the Milky Way Galaxy

a) about 30 Kpc from the

center in the halo

b) 30,000 light-years from the

center in a globular cluster

c) at the outer edge of the

Galactic disk, in the plane

d) about halfway from the

center, in the spiral arms

e) in the bulge, near the Orion arm

Our Sun is located in the Milky Way Galaxy

a) about 30 Kpc from the

center in the halo

b) 30,000 light-years from the

center in a globular cluster

c) at the outer edge of the

Galactic disk, in the plane

center, in the spiral arms.

e) in the bulge, near the Orion arm

Explanation: The Sun orbits the center of the Galaxy within the disk, taking about 225 million years to complete one orbit

The period–luminosity relationship is a crucial component of

a) measuring distances with

Cepheid variable stars

b) identifying the mass of the

Galaxy’s central black hole

c) determining the masses of

stars in an eclipsing binary system

d) using spectroscopic parallax

to measure distances to stars

The period–luminosity relationship is a crucial component of

Cepheid variable stars.

b) identifying the mass of the

Galaxy’s central black hole

c) determining the masses of

stars in an eclipsing binary system

d) using spectroscopic parallax

to measure distances to stars

Explanation: Cepheid variable stars with longer periods have higher actual luminosities; short-period Cepheids are dimmer

High-speed motion of gas and stars near the Milky Way Galaxy’s center is explained by

a) tidal forces from

the Andromeda Galaxy

b) accretion disks

around neutron stars

c) gamma-ray bursts

d) gravitation from globular clusters

e) a supermassive black hole

High-speed motion of gas and stars near the Milky Way Galaxy’s center is explained by

a) tidal forces from

the Andromeda Galaxy

b) accretion disks

around neutron stars

c) gamma-ray bursts

d) gravitation from globular clusters

Explanation: Recent observations estimate the black hole to be 4 million solar masses

Detailed measurements of the disk suggest that our Milky Way is

Detailed measurements of the disk suggest that our Milky Way is

imply the disk has a diameter

about 30 times the disk thickness Embedded in the

disk are spiral arms and a short bar near the center

What two observations allow us to estimate the Galaxy’s mass?

a) The Sun’s mass and velocity in orbit around the Galactic center

b) The rotation of the bulge and disk components

c) The Sun’s age and age of the globular cluster stars

d) The motion of spiral arms and the mass of the central black hole

e) The orbital period and distance from the Galactic center of objects near the edge of the Galaxy

What two observations allow us to estimate the Galaxy’s mass?

a) The Sun’s mass and velocity in orbit around the Galactic center

b) The rotation of the bulge and disk components

c) The Sun’s age and age of the globular cluster stars

d) The motion of spiral arms and the mass of the central black hole

Galaxy

Explanation: Use the modified form of Kepler’s law to find the mass: total mass = (orbital size)3 / (orbital period)2

In the formation of our Galaxy, the

a) spiral arms formed first

b) globular clusters formed first

c) disk component started out thin and grew

d) spiral density waves formed first

e) bar in the bulge formed first

In the formation of our Galaxy, the

a) spiral arms formed first

c) disk component started out thin and grew

d) spiral density waves formed first

e) bar in the bulge formed first

Explanation: Globular clusters

contain very old stars, no gas

or dust, and orbit around the

center randomly

Twenty-one centimeter radio radiation is useful in studying our Galaxy because

a) the waves penetrate dusty cocoons to reveal star formation

b) it reflects from the Galaxy’s core

c) the waves are not absorbed by Galactic black holes

d) it can be used to map out the cool hydrogen in spiral

arms

e) radio waves provide a distance measurement like parallax

Twenty-one centimeter radio radiation is useful in studying our Galaxy because

a) the waves penetrate dusty cocoons to reveal star formation

b) it reflects from the Galaxy’s core

c) the waves are not absorbed by Galactic black holes

arms.

e) radio waves provide a distance measurement like parallax

Explanation: The Doppler shifts of 21-cm radiation from hydrogen in the spiral arms provides astronomers with a tool to map out the Galaxy’s structure

Which of these is NOT a typical part of our Galaxy’s spiral arms?

Which of these is NOT a typical part of our Galaxy’s spiral arms?

Explanation: The spiral arms

contain gas, dust, molecular

clouds, new clusters, and

Population I stars

What suggests that the mass of our Galaxy extends farther than its visible disk?

a) 21-cm maps of the spiral arms

b) The rotation curve of the outer edges of the Galaxy

c) Orbits of open clusters in the disk

d) Infrared observations of new star-forming regions

e) X-ray images of other galaxies

What suggests that the mass of our Galaxy extends farther than its visible disk?

a) 21-cm maps of the spiral arms

c) Orbits of open clusters in the disk

d) Infrared observations of new star-forming regions

e) X-ray images of other galaxies

Explanation: The outer edges

of the Galaxy’s disk rotate much

faster than they should Most

of the mass of the Galaxy must

be dark matter