Stars in the giant branch of the H-R diagram that pulsate in brightness because of the expansion and contraction of their layers.

• a. Cepheid variables

• b. luminosity

• c. RR Lyrae variables

• d. Sagittarius

• e. variable stars

Stars that have periods of pulsations between 1.5 hours and 1 day, and on average, have the same luminosity.

• a. Cepheid variables

• b. luminosity

• c. RR Lyrae variables

• d. Sagittarius

• e. variable stars

Stars with pulsation periods between 1 day and more than 100 days.

• a. Cepheid variables

• b. luminosity

• c. RR Lyrae variables

• d. Sagittarius

• e. variable stars

By measuring a star's period of pulsation, astronomers can determine this.

• Cepheid variables

• luminosity

• RR Lyrae variables

• Sagittarius

• variable stars

Radio waves are used to map the Milky Way because they can penetrate the interstellar gas and dust without being scattered or absorbed.

• True

• False

Tags

NGSS.HS-PS4-3

The Milky Way's galactic nucleus is surrounded by a nuclear bulge that sticks out of the galactic disk.

• True

• False

Around the Milky Way's nuclear bulge and disk is the halo, where the globular clusters are located.

• True

• False

The Sun is located in the Milky Way's minor arm Orion at a distance of 28,000 ly from the galactic center.

• True

• False

Tags

NGSS.MS-ESS1-2

The mass located within the circle of the Sun's orbit through the galaxy is about ________ times the mass of the Sun. Because the Sun is of average mass, astronomers have concluded there are about 100 billion stars within the disk of the ________.

• 2.6 million; galaxy

• 26 thousand; universe

• 260 thousand; cluster

• 2.6 billion; nebula

Astronomers have found evidence that much more mass exists in the outer galaxy. The stars and ________ that orbit in the outer disk are moving faster than they would if the galaxy's mass were concentrated near the________ of the disk. What are the correct terms to fill in the blanks?

• gas clouds; center

• stellar remnants; halo

• dark matter; supermassive black hole

• galaxy; 2.6 million

Tags

NGSS.HS-PS2-4