What is Hydrogen Burning?
Hydrogen burning is a process that takes place in every star, whereby hydrogen nuclei are fused into helium at high temperatures and pressures. It is the most common type of process known as stellar nucleosynthesis. After the Big Bang, the universe consisted of approximately 75% hydrogen and 25% helium. Today, the proportions are not all that different, but there are new elements — the universe is about 74% hydrogen, 24% helium, and 2% other elements. These other elements, the most common being oxygen (1%), carbon (.4%), neon (.1%), iron (.1%) and nitrogen (.1%) are all products of stellar nucleosynthesis — the synthesis of heavier elements in stellar cores. Elements heavier than iron are created in supernovae. Star formation occurs in dense gas clouds in interstellar space. These are called H II regions or stellar nurseries. Eventually, a high concentration of mass appears in an area around the size of our solar system. This is called a Bok globule. When the temperature and pressure i
Why is hydrogen burning fundameiitally unlike the burning of a log in a fireplace? 12 Describe the Sun’s interior, including the main phvslcal processes that occur at various depths within the Sun. 13 What is a neutrino, and why are astronomers so interested in detecting neutrinos from the Sun? Ch.10 RQ 1, DQ 18 (p.247) Review Questions 1 How and why is the spectrum of a star related to its surface temperature? 2 Describe UBV filters and how an astronomer uses them to measure a star’s surface temperature. 3 Explain why the color index of a star is related to its surface temperature. 4 What is the primary chemical component of most stars? 5 Which is the hottest star listed in Table 10-1? Which is the coolest? 6 Draw an H-R diagrai-n and sketch the regions occupied by main sequence stars, red giants, and white dwarfs. Briefly discuss the different ways in which you could have labeled the axes of your graph. 7 How can observations of a visual binary lead to information about the masses of
