Test 3 ch 25

Spiral arms are _______

Regions of active star formation

Where would you look for the youngest stars in the Milky Way Galaxy?

in the disk

globular clusters can be found in the

Halo

stars with the smallest abundance of heavy elements can be found in the

Halo

The halo of the galaxy is ______

a large, spherical region that contains few bright stars

An open cluster is ______

a relatively young star cluster found in the disk of a galaxy

A hot, blue main-sequence star lives ___

a shorter life than a cool, red main-sequence star

The disk of the galaxy __________ than the bulge

extends to much greater distances from the galactic center

The disk of the Milky Way Galaxy is about _____________________ in diameter

100,000 light years

The disk of the Milky Way Galaxy is _______________ thick.

1000 light-year

What is the typical percentage (by mass) of elements other than hydrogen and helium in stars that are forming right now in the vicinity of the Sun?

2%

High mass stars can be found in the

Disk

Star formation occurs primarily in the galaxy's ______

Disk

stars that all orbit in nearly the same plane can be found in the

Disk

The Sun is an example of

Disk star

are the youngest type of stars

Disk stars

Our galaxy consists of a large, nearly flat____ with a central ____, all surrounded by a vast______.

Disk, bulge, halo

We find __________________ of stars primarily in the galaxy's halo

Globular clusters

are the oldest type of stars

Halo stars

Where would you be most likely to find an ionization nebula?

In the disk

We refer to the gas and dust that resides in our galaxy as the

Interstellar medium

As gravity shrunk the protogalactic cloud that gave birth to our galaxy, the first region to take shape was _____.

The halo

By studying main-sequence turn-off points, astronomers have learned that globular clusters __________.

are always very old; typically 12 to 13 billion years old

You should always expect two stars to be approximately the same age if ______

both are members of the same star cluster

Old stars are generally ___

of low mass and red

Our Milky Way Galaxy is what type of galaxy?

spiral

The basic difference between the disk and halo in shape is _________

the disk is flat and the halo is spherical