As we read in the book, a star that appears to be 1 magnitude brighter will have approximately 2.5 times as much flux hitting an observer's detector/telescope/eye (i.e. a star with an apparent magnitude of 4 has approximately 2.5 times more flux hitting the detector as a star with an apparent magnitude of 5). With this in mind what is the approximate ratio of the flux hitting the a detector for a star with an apparent magnitude of 7 compared to a star with an apparent magnitude of 13? (hint: remember that magnitudes follow a logarithmic scale, not a linear one)

You are trying to take an image of a particular star with apparent magnitude m=10, and need to figure out how long you will need to expose for with your telescope. Your friend tells you that her telescope of diameter 0.07 meters can detect the star in 79 minutes. How long would it take for you to use your telescope (diameter 0.13 meters) to detect a star with an apparent magnitude m=12? (Answer in minutes)

If a T Tauri star is the same temperature as the Sun but is eighteen times more luminous, what is its radius relative to the Sun? (Hint: Use the luminosity-radius-temperature relation: L L  =    R R   2     T T   4   .) R R  =

Calculate by how many times Betelgeuse is brighter than the Sun, if its parallax is 0.006 arcsec, and its apparent magnitude is m = +.5. Can you first use the parallax to calculate the distance and then use the magnitude-distance formula to find the absolute magnitude of Betelgeuse and finally, compare it to the absolute magnitude of the Sun which is -26,74 because other experts used other methods and the answer was not correct.

A star has a luminosity (power output) of 9.2x1026 W and a diameter of 6.1x108 m. What is its surface temperature? (Give your answer in SI units and include the units in your answer.)

For a star with surface temperature 5,100 K, what is the peak frequency of light from the sun? Write your answer in THz (1012 Hz), to zero decimal places. Take the speed of light to be c=3 x 108 m/s.

We will take a moment to compare how brightly a white dwarf star shines compared to a red giant star. For the sake of this problem, lets assume a white dwarf has a temperature roughly twice as large as a red giant star. As for their stellar radii, the white dwarf has a radius about 1/10000th that of a red giant star. With this in mind, how does the luminosity of a red giant star compare to that of a white dwarf? (Put differently, find the ratio of their luminosities a.k.a. how many times more luminous is the red giant than the white dwarf? An answer of less than 1 means the white dwarf is more luminous, an answer of 1 means they have the same luminosity, and an answer greater than 1 means the red giant is more lu

One way to calculate the radius of a star is to use its luminosity and temperature and assume that the star radiates approximately like a blackbody. Astronomers have measured the characteristics of central stars of planetary nebulae and have found that a typical central star is 16 times as luminous and 20 times as hot (about 110,000 K) as the Sun. Find the radius in terms of the Sun’s. How does this radius compare with that of a typical white dwarf?

Imagine that you are an astronomer studying a star 4 parsecs away (a parsec is 3.09x1016 m). You measure the flux coming from this star with your telescope, getting a value of 2.3x10-12 W m-². What is the luminosity of this star?

The total intensity of light measured on earth, from an ecliptic binary, is plotted in the figure as a function of time (it's called a light curve). Careful measurements indicate that the intensities of the incident light from the stars corresponding to the minima are respectively 90 and 63 percent of the maximum intensity, Io. temperatures of two stars in an eclipsing binary are T1 and T2 (T1 > T2), and the corresponding radii (R1 > R2), respectively. received from both stars.Surface аге R1 and R2 Find the ratio T1/T2. Round you answer to two significant figures. 1.0- 0.8 1/1o =0.90 0.6- 04- 1|1. =0.63 0.2 1.0 2.0 3.0 4.0 5.0 6.0 Time (days)