A Crude Analysis: In about 5 billion years, the Sun is going to look a lot different. Our sun is going to turn into a red-giant, a bigger star whose core temperature is much higher than the Sun's current core temperature (you will learn about the red giants in the coming weeks). Assume the core temperature of the red-giant phase of the Sun does not go beyond 100 million degrees. Do you think the temperature is high enough for helium fusion to occur? Note that this question is about helium fusion not hydrogen fusion. How are you going about proving your claim? Question: What temperature in degrees Kelvin must the red-giant sun be at to allow for the helium-helium interactions to take place not considering the Quantum Mechanical effects (i.e. what temperature would allow helium atoms to breach the helium-helium potential wall without help from Quantum Mechanics)? Use wolfram alpha to find the values for the constants. Round your answer to two decimal places. Your answer i v [ Select ] 1.47 [ Select] 6.26 2.99

. The radius of the nebula is about 0.401 light-years. The gas is expanding away from the star at a rate of about 37 kilometers/second . Considering that distance = velocity x time, calculate how long ago the gas left the star if its speed has been constant the whole time. Make sure you use consistent units for time, speed, and distance. Answer in years.

Betelgeuse is a nearby supergiant that will eventually explode into a supernova. Let's see how awesome it would look. At peak brightness, the supernova will have a luminosity of about 10 billion times the Sun. It is 600 light-years away. All stellar brightnesses are compared with Vega, which has an intrinsic luminosity of about 60 times the Sun, a distance of 25 light-years, an absolute magnitude of 0.6 and an apparent magnitude of 0 (by definition). a) At peak brightness, how many times brighter will Betelgeuse be than Vega? b) Approximately what apparent magnitude does this correspond to? c) The Sun is about -26.5 apparent magnitude. What fraction of the Sun's brightness will Betelgeuse be?

If a neutron star has a radius of 13 km and a temperature of 9.0 x 10° K, how luminous is it? Express your answer in watts and also in solar luminosity units. (Hint: Use the relation . Use 5,800 K for the surface temperature of the Sun. The luminosity of the Sun is 3.83 × 1026 w.) luminosity in watts w luminosity in solar luminosity units Lo

How many times hotter than our sun is the hottest type O star, which has a surface temperature 40,000 K? Number times hotter =

Describe how energy generated in the core of a 1-solar-mass star gets to the star's surface.

A red giant star has a temperature of 3900  K and a luminosity of 13600 LSun. How many times bigger is this star than the Sun? Hint: You need the surface temperature of the sun for this problem. Use the value in the book, 5800K.

How can we know that the sun will “die” in about 5 billion years? Choose the correct answer. A. We can see the evolution and death in the spectra B. We can see the entire process as it plays out in a star C. We look at thousands of stars like the sun and can see them in all stages of development

Do this in 10 min. I will give like on answer

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