W10

The event in the life of a star that begins its expansion into a giant is

almost all the hydrogen in its core that was hot enough for fusion has been turned into helium

A star whose temperature is decreasing but whose luminosity is roughly constant moves in what direction on the H-R diagram?

to the right

When the outer layers of a star like the Sun expand, and it becomes a giant, which way does it move on the H-R diagram?

toward the upper right

Which of the following stages will our own Sun NOT go through in the future:

supernova

Which of the following types of stars will spend the shortest time (the greatest number of years) on the main sequence?

O

As a cluster of stars begins to age, which type of star in the cluster will move off the main sequence of the H-R diagram first?

O and B type stars

Why can a star with a mass like our Sun not fuse (produce) further elements beyond carbon and oxygen?

because they just cannot get hot enough for the fusion of heavier nuclei

Really massive stars differ from stars with masses like the Sun in that they

can fuse elements beyond carbon and oxygen in their hot central regions

The oldest structures in our Galaxy turn out to be

globular clusters

If you want to find stars that are just being born, where are the best places to search?

in giant molecular clouds

How long a main sequence star remains on the main sequence in the H-R diagram depends most strongly on

its mass

What determines where on the main sequence a star will first plot on the HR diagrma?

its mass

Astronomers were surprised to find so many Jupiter-mass planets so close to their stars. According to their best theories and models, such "hot Jupiters"

must have formed further out from the star and must have "migrated inward" early on

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

What is part of the process in estimating the age of a cluster of stars?

plot an H-R diagram for the stars in the cluster

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

protostar

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

To measure how dense a planet is (to know whether it is made of rock or gas and liquid) they must be able to measure the planet's mass from the Doppler shift and

the planet's radius using the transit method

Astronomers identify the "birth" of a real star (as opposed to the activities of a protostar) with what activity in the star?

when nuclear fusion reactions begin inside its core