Star A has a temperature of 5,000 K. How much energy per second (in J/s/m2) does it radiate from a square meter of its surface? If the temperature of Star A decreases by a factor of 2, the energy will decrease by a factor of Star B has a temperature that is 5 times higher than Star A. How much more energy per second (compared to Star A) does it radiate from a square meter of its surface? Part 1 of 4 The energy of a star is related to its temperature by E = GT4 where a = 5.67 x 10-8 J/s/m²/K4. Part 2 of 4 To determine how much energy Star A is radiating, we just plug in the temperature to solve for EA. EA = 3/s/m²

An astronomer observes several stars with different colors. Rank them in order from highest temperature to lowest temperature.  1 is the highest temperature, 2 is the next highest, 3. Third highest, 4. lowest temperature orange-red star bluish-white star yellowish-white star red star

Suppose that two stars in a binary star system are separated by a distance of 80 million kilometers and are located at a distance of 160 light years from earth. What is the angular separation of the two stars? Give your answer in arcseconds

12. A star with spectral type MO has a surface temperature of 3750 K and a radius of 0.63 Rsun: How many times more luminous is this star than the Sun? (if it is less luminous enter a number less than one) Answer: Submit All Answers Last Answer: 0.0923 Incorrect, tries 1/5. Hint: Use the Luminosity equation, which says that L is proportional to R^2 T^4. If you keep these as ratios compared to the sun, your L will also come out as a ratio compared to the Sun. This star has a mass of 0.4 Msun- Using the simple approximation that we made in class, what is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr. Answer: Submit All Answers Compare this to the lifetime of a MO star listed in Table 22.1 (computed using a more sophisticated approach). Is the value you calculated in the previous problem longer or shorter than what is reported in the table? (L for longer, S for shorter) (You only get one try at this problem.) Answer: Submit All Answers

A star is listed in a catalog as being a type G2V.a) What is the star’s spectral class?b) What is the star’s luminosity class?c) What is the peak color of the star?d) Name an example of a star that has this type.

Earth tugs the Sun around as it orbits, but it affects the radial velocity of the sun by only 0.09m/s. How large a shift in wavelength does this cause in the Sun's spectrum at 575 nm?

If Star A's temperature is 5000 K and Star B's wavelength of peak emission is 5/7 as long as that of Star A, what is the temperature of Star B (in K; don't write the units in the text box)?

A star has a surface area of 6.49x1018 m2. How much power does it radiate if it has a surface temperature of 6,225 K? Submit your answer in exponential form.  For example, 246000m or should be written as 2.46E5m .  These are example units, yours may not be in m .