Question

Please give clear and correct solutions. Need help. University astronomy. Thanks

Briefing As we have seen, the Sun's energy comes from a series of nuclear fusion reactions (the p-p chain) in which 4 protons (Hydrogen nuclei) fuse to produce a "He nucleus. The original 4 protons have a higher net mass than the "He nucleus and the missing mass is converted to energy mostly in the form of gamma rays. Eventually, this energy (now degraded to visible light photons) is radiated into space from the Sun's photosphere. Clearly, in this process Hydrogen (the 'fuel) is converted to Helium (the 'ash') and Helium fusion requires (as we will see later) much higher temperatures than are present in the Sun's core. Ultimately, therefore, the Sun will exhaust the Hydrogen fuel in its core and the p-p reactions will cease. How long have we got before this happens Objective Using Einstein's mass-energy relation Eamc, estimate the time in years for which the Sun maintain its current luminosity Considerations What is the difference in mass between the original 4 protons and the resulting "He nucleus? How much energy does each p-p chain reaction release? What is the mass of Hydrogen that is available as "fuel" for fusion reactions in the core? It is thought that the core where it is hot enough for fusion reactions to occur contains only about 10% of the Sun's mass, but not all of this is Hydrogen. .The fusion reactions must generate enough energy to sustain the Sun's current luminosity How much Hydrogen is "burned" each year? .Be careful to use consistent units (e.g. don't mix kg and km). You will need to look up some data and physical constants. . Instructions You may work in a group of up to three for this exercise. Record the results of all calculations on the back of this sheet. If you need more space for notes and detailed calculations use separate sheets and attach them (don't forget to write your name on any attachments). Write down all the data you use for your calculation. You need submit only one set of answers (but make sure the names of all group members are included). 1 0/10/18

Answer 1

Mass of Hydrogen consumed per year, therefore what we know is that sun consumes about 600 million tons of hydrogen per second rightdoublearrow 1 year = 365 days = 365 times 24 hrs = 365 times 24 times 60 times 60 seconds = 31536 times 1000 seconds Mass of hydrogen consumed = 189216 times 10^16 tons or 1.89 times 10^15 million tons of hydrogen N* PP reactions P + P rightarrow deuterium + neutrino + positron downarrow deuterium + proton downarrow He - 3 + He - 3 downarrow He 4 + proton + proton 1. protons Fuses, proton - neutron pair is deuterium 2. Another proton collides with deuterium Forming He 3 3. Two helium -3 collide 4. Helium 4 is created + 2 extra protons \r\n Mass of H available in core of Hydrogen therefore Amount of mass of hydrogen in core, therefore Mass of sin is 2 times 10^30 kg