ASTR 101 Chapter 12

The three bins represent three important properties of stars. Drag the items that we must measure in order to determine each property into the appropriate bin.

To place a star on an H-R diagram, we must know its ______________.

On the H-R diagram, most stars fall into the region labeled ________________.

Among main sequence stars, those with the highest surface temperatures have _______________.

Suppose you observe two clusters of stars: -Cluster A contains main sequence stars of nearly all masses. -Cluster B contains only low-mass main sequence stars, along with many giants. What can you conclude about their ages?

Two stars, X and Y, have the same temperature. Star X is ten times more luminous than Star Y. Which star has the larger radius?

Two stars, X and Y, have the same luminosity, but star X is very blue while star Y is very red. Which star has the larger radius?

Fomalhaut is an A star with a luminosity 14 times that of the Sun. Fomalhaut is therefore a

Sirius B is a B star with a luminosity equal to 0.024 Lsun. Our Sun is a G star. Which is more massive?

Use the H-R diagram to list the following three main sequence stars in order of increasing mass: The Sun, Spica, and Barnard's Star.

Spica is a main sequence star, having a surface temperature of 26,000 K. In order for a star with a surface temperature of only 6000 K to have the same luminosity as Spica, its radius must be

The rate of fusion (the number of helium nuclei produced per second) in the core of the star Vega (a main sequence star with a temperature of about 10,000 K) is roughly

A star with the same radius as the Sun but a surface temperature five times as high would have a luminosity

A main sequence star with twice the mass of the Sun (and surface temperature of about 8000 K) will have a luminosity roughly

The figure shows a standard Hertzsprung-Russell (H-R) diagram. Label the horizontal and vertical axes using the two blanks nearest the center of each axis, and label the extremes on the two axes using the blanks on the ends of axes.

Use the labels to identify what kinds of stars inhabit each region of the H-R diagram.

Consider the four stars shown following. Rank the stars based on their surface temperature from highest to lowest.

Five stars are shown on the following H-R diagrams. Rank the stars based on their surface temperature from highest to lowest. If two (or more) stars have the same surface temperature, drag one star on top of the other(s)

Five stars are shown on the following H-R diagrams; notice that these are the same five stars shown in Part B. Ranks the stars based on their luminosity form the highest lowest. If two (or more) stars have the same luminosity, drag one star on top of the other(s).

Five stars are shown on the following H-R diagrams. Rank the stars based on their surface temperature from highest to lowest. If two (or more) stars have the same surface temperature, drag one star on top of the other(s).

Five stars are shown on the following H-R diagrams. Rank the stars based on their luminosity from highest to lowest; notice that these are the same five stars shown in Part D. If two (or more) stars have the same surface temperature, drag one star on top of the other(s).

Five stars are shown on the following H-R diagrams; notice that these are the same five stars shown in Part F. Rank the stars based on their luminosity from highest to lowest. If two (or more) stars have the same luminosity, drag one star on top of the other(s)

Listed following is a set of statements describing individual stars or characteristics of stars. Match these to the appropriate object category.

Suppose we wanted to represent all of these objects on the 1-to-10-billion scale from Chapter 1, on which the Sun is about the size of a grapefruit. Approximately how large in diameter would the star Aldebaran be on this scale?

Approximately how large in diameter would the star Betelgeuse be on this same scale?

Approximately how large in diameter would the star Procyon B be on this same scale?

What is the approximate luminosity of a star whose mass is 10 times that of the Sun?

What is the approximate lifetime of a star whose mass is 10 times that of the Sun?

What is the approximate luminosity of a star whose mass is 3 times that of the Sun?

What is the approximate lifetime of a star whose mass is 3 times that of the Sun?

What is the approximate luminosity of a star whose mass is twice that of the Sun?

What is the approximate lifetime of a star whose mass is twice that of the Sun?

Consider a relatively nearby, single star, that is, a star that is not a member of a binary system and has no known orbiting planets. Listed below are a few properties of this star. Classify each property as either something that we can observe or measure directly (with the aid of a telescope and instruments such as cameras or spectrographs) or something that we must infer indirectly (and hence is correct only if all of our assumptions are correct).

From Part A, you know that surface temperature is a stellar property that we infer indirectly. What must we measure directly so that we can infer a star's surface temperature?

Which of the following must true if we are to infer (calculate) a star's luminosity directly from the inverse square law for light? CHECK ALL THAT APPLY.

We found that mass must be inferred for the star described in Part A. However, we can measure a star's mass directly if ___________.

You should now see that the reason the mass of the star in Part A must be inferred is that the star has no known orbiting objects, which means we cannot apply Newton's version of Kepler's third law. Which of the following must be true if the star's inferred mass is to be accurate? CHECK ALL THAT APPLY.

Before we can use parallax to measure the distance to a nearby star, we first need to know _____________.

Which of the following is a valid way of demonstrating parallax for yourself?

What is the cause of stellar parallax?

The more distant a star, the ___________.

Approximately what is the parallax angle of a star that is 20 light-years away?

Suppose that a star had a parallax angle of exactly 1 arcsecond. Approximately how far away would it be, in light-years?

Compared to a main sequence star with a short lifetime, a main sequence star with a long lifetime is ______________.

Compared to a high-luminosity main sequence star, stars in the upper right of the H-R diagram are _____________.

Compared to a low-luminosity main sequence star, stars in the lower left of the H-R diagram are __________.

If the star Alpha Centauri were moved to a distance 10 times farther than it is now, its parallax angle would

What do we need to measure in order to determine a star's luminosity?

What two pieces of information would you need in order to measure the masses of stars in an eclipsing binary system?

Alpha Centauri: parallax angle of 0.7420 arcsecond. Give your answer in parsecs.

Alpha Centauri: parallax angle of 0.7420 arcsecond. Give your answer in light-years.

Procyon: parallax angle of 0.2860 arcsecond. Give your answer in parsecs.

Procyon: parallax angle of 0.2860 arcsecond. Give your answer in light-years.

Which of these stars has the coolest surface temperature?

Which of these stars is the most massive?

Which of these stars has the longest lifetime?

Which of these stars has the largest radius?

Which of these stars has the greatest surface temperature?

Which of these star clusters is oldest?