Describe the reaction that powers the sun during its main sequence lifetime. Be sure to include the basic ingredients and the basic products.

A main sequence star of mass 25 M⊙has a luminosity of approximately 80,000 L⊙. a. At what rate DOES MASS VANISH as H is fused to He in the star’s core? Note: When we say “mass vanish '' what we really mean is “gets converted into energy and leaves the star as light”. Note: approximate answer: 3.55 E14 kg/s b. At what rate is H converted into He? To do this you need to take into account that for every kg of hydrogen burned, only 0.7% gets converted into energy while the rest turns into helium. Approximate answer = 5E16 kg/s c. Assuming that only the 10% of the star’s mass in the central regions will get hot enough for fusion, calculate the main sequence lifetime of the star. Put your answer in years, and compare it to the lifetime of the Sun. It should be much, much shorter. Approximate answer: 30 million years.

The Local Bubble is: a. a region of low density intersteller gas extending several hundred LY around the Sun b. a region around any exploding star where material is expanding from the explosion c. the region around very hot stars where hydrogen is ionized

Match each characteristic below to the appropriate stellar end state. (Select W-White dwarf, N-Neutron star, B-Black hole. If the first is W and the rest N, enter WNNNNNNN). A) Has a mass no greater than 1.4 solar-masses. B) Sometimes appears as a pulsar. C) Size defined by its Schwarzschild radius. D) In a binary system it can explode as a supernova. E) Supported by electron degeneracy pressure. F) Typically about the size of Earth. G) Usually has a very strong magnetic field. H) Viewed from afar, time stops at its event horizon. Answer: Submit All Answers