CH 21 Quiz Astronomy

The first ordinary star (other than our own Sun) around which planets were definitely discovered was:

51 Pegasi

Astronomers call a ball of matter that is contracting to become a star

a protostar

If an astronomer wants to find and identify as many stars as possible in a star cluster that has recently formed near the surface of a giant molecular cloud (such as the Trapezium cluster in the Orion Nebula), what instrument would be best for her to use?

an infra-red telescope (and camera)

Planets in the habitable zone of their stars:

are at a temperature where water can exist as a liquid

The star now called Kepler-444 is 11 billion years old (much older than the Sun) and has five planets orbiting close to it. What has this system taught astronomers about the history of star formation?

if such an old star has planets close to it, where it's really warm, those planets must be made of heavier elements. So heavier elements must have formed before the time this star formed.

When a star settles down to a stable existence as a main-sequence star, what characteristics determines where on the main sequence in an H-R diagram the star will fall?

its mass

Astronomers believe that disks of material will form around protostars that are spinning. Which of the following observed phenomena is a good indication of the presence of a disk around a protostar?

jets and Herbig-Haro objects

In figuring out the evolutionary tracks on the H-R diagram, astronomers

make model stars on a computer and then follow how their characteristics will change with time

Which of the following is a reason that astronomers have not found giant planets with the orbit of Neptune around other stars?

neptune takes 165 years to go around the Sun; getting information about just one cycle of such a planet's orbit around another star would take astronomers 165 years

The big surprise about the first planet discovered around another regular star was that it

orbited so close to its star it took only 4 days to go around

Which of the following is NOT one of the reasons planets around other stars are so difficult to detect?

planets only form very late in the life of a star, just when it is ready to die, and thus last only a very short fraction of the star's life

Why was the Kepler mission not able to find planets smaller than Mars, even though it was in space (and had no Earth atmosphere to deal with)?

such planets make dips in the light of the star that are too small for Kepler to detect

With our current techniques, astronomers can typically only measure the minimum mass of a planet orbiting another star. To know the precise mass of the planet, they must also be able to determine

the angle at which the planet s orbit is tilted relative to us

Which of the following are the small regions that are the embryos of stars (where individual stars are most likely to be born)?

the cores within the clumps of molecular clouds

What observations about disks of dusty material around young stars suggest that planets may be forming in such disks?

the disks show lanes that are empty of dust within them

The first (living) star other than our own Sun found to have more than one planet orbiting it is called

upsilon Andromedae

Astronomers studying regions like the Orion Giant Molecular Cloud have observed that a wave of star formation can move through them over many millions of years. What sustains such a wave of star formation in a giant molecular cloud?

when massive stars form, their ultraviolet radiation and later their final explosions compress the gas in the cloud and cause a new group of stars to form