Chapter 9, The Interstellar Medium Video Solutions, Foundations of Astronomy

01:37

Problem 1

If a star has a parallax of 0.050 second of arc, what is its distance in parsecs? In light-years? In AU?

Donald Albin

Numerade Educator

01:19

Problem 2

If a star has a parallax of 0.016 second of arc and an apparent magnitude of $6,$ how far away is it, and what is its absolute magnitude?

Matthew Miranda

Numerade Educator

02:54

Problem 3

Complete the following table:

Bryan Lynn

Numerade Educator

01:12

Problem 4

If a main-sequence star has a luminosity of $400 \mathrm{L}_{\odot}$, what is its spectral type? (Hint: See Figure $9-14$ ).

Matthew Miranda

Numerade Educator

06:44

Problem 5

If a star has an apparent magnitude equal to its absolute magnitude, how far away is it in parsecs? In light-years?

Pritesh Ranjan

Numerade Educator

00:40

Problem 6

If a star has an absolute bolometric magnitude that is eight magnitudes brighter than the sun, what is the star's luminosity?

Ian Maurer

Numerade Educator

00:55

Problem 7

If a star has an absolute bolometric magnitude that is one magnitude fainter than the sun, what is the star's luminosity?

Julie Silva

Numerade Educator

01:34

Problem 8

An $08 \mathrm{V}$ star has an apparent magnitude of $+1 .$ Use the method of spectroscopic parallax to find the distance to the star.

Vishal Parmar

Numerade Educator

03:09

Find the luminosity of the sun, given the radius of Earth's orbit and the solar constant (Chapter 8). Make your calculation in two steps. First, use $4 \pi R^{2}$ to calculate the surface area (in square meters) of a sphere surrounding the sun with a radius of 1 AU. Second, multiply by the solar constant to find the total solar energy passing through the sphere in 1 second. That is the luminosity of the sun. Compare your result with that in Celestial Profile 1.

Donald Albin

Numerade Educator

00:52

Problem 10

In the following table, which star is brightest in apparent magnitude? Most luminous in absolute magnitude? Largest? Farthest away?

Julie Silva

Numerade Educator

06:36

Problem 11

What is the total mass of a visual binary system if its average separation is $8 \mathrm{AU}$ and its period is 20 years?

Matthew Miranda

Numerade Educator

06:11

Problem 12

Measure the wavelengths of the iron lines in Figure $9-17$ and plot a graph showing the radial velocities of the two stars in this system. What is the period? Assuming that the orbit is circular and edge-on, what is the total mass? What are the individual masses?

Andy Chen

Numerade Educator

00:56

Problem 13

If the eclipsing binary in Figure $9-21$ has a period of 32 days, an orbital velocity of $153 \mathrm{km} / \mathrm{s}$, and an orbit that is nearly edge-on, what is the circumference of the orbit? The radius of the orbit? The mass of the system?

Joseph Petrullo

Numerade Educator

02:23

Problem 14

If the orbital velocity of the eclipsing binary in Figure $9-21$ is 153 $\mathrm{km} / \mathrm{s}$ and the smaller star becomes completely eclipsed in 2.5 hours, what is its diameter?