Astronomy Help: Minimum Mass of Stars & Sun's Energy Production Explained

[karol17]

Hey
can someone help me with the followng 2 questions, i am so confuzed and have no idea how to start and what formulas to use.


1. the minimum mass of a star is 0.08 solar mass or 80 Jupiter masses. If the fuel that powered stars was helium instead of hydrogen would the minimum mass of stars be more, les or still be 0.08 sollar mass? (hint: think of the number of protons in nuclei)

2. the sun emits as much energy as 3.9 *10^24 100- Watts light-bulbs (that’s a whole lot of light bulbs!) every second. We call that number its luminosity. Give that the radius of the sun is constant in time, how much energy is produced in the Sun every second? Is it more than, less than or equal to its luminosity? Justify your answer ( no calculations necessary)

 

[mgb_phys]

1, is a dumb question - depending on what level of course this is - are we supposed to just simply consider everything the same except the number of protons, go into the CNO cycle,conditions for direct He3 (He4) fusion or what?

2, Is this simply asking you how many J/s there are in 100W * 3.8e24 ?

Have you copied these questions down correctly or are you a victim of some stupid watered down 'modern' physics course? If so we will do our best - it's not your fault!

 

[karol17]

I am in an intro to astronomy course and these questions are straight from my assignment. i do not understand what any of it means so i don't even know how to go about solving them

thank you so much

 

[mgb_phys]

2, A watt is one joule (energy) per second. So a 100W light bulb emits 100J/s
Work out how many Joules/s the sun emits if it has 3.9x10^24 of these light bulbs.

ps do you know what numbers like 3.9x10^24 mean?