Astronomy Math

Oct 2019
6
2
Whidbey Island
I'm having some difficulty with my astronomy homework. I've submitted several answers using different formulas but none of them are correct.

1. What is the luminosity of a star having 3 times the radius of the Sun and a surface temperature of 10,000 Kelvin?

2. A certain star has a temperature twice that of the Sun and a luminosity 55 times greater than the solar value. What is its radius, in solar units?

As always, thanks for the help!
 

Debsta

MHF Helper
Oct 2009
1,285
586
Brisbane
Do you have a "formula" for luminosity?
 
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Oct 2019
6
2
Whidbey Island
Do you have a "formula" for luminosity?
Here is the formula provided by my professor.
Luminosity = (sigma x T^4) x (4 x pi x r^2)
T being temperature and r being radius.
 

Debsta

MHF Helper
Oct 2009
1,285
586
Brisbane
Is T measures in Kelvin?
and what's sigma?
and what's the radius of the sun?
and what's the temperature of the sun?
 

Debsta

MHF Helper
Oct 2009
1,285
586
Brisbane
Ok, so for Q1, what is the radius of the star in question? What is the temperature?
So where are you stuck?
 
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Oct 2019
6
2
Whidbey Island
Ok, so for Q1, what is the radius of the star in question? What is the temperature?
So where are you stuck?
Debsta,
Thank you for all your help! I solved it. The solution is 79.5 solar luminosities.
 
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Debsta

MHF Helper
Oct 2009
1,285
586
Brisbane
Ok, are you ok with Q2?
 
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