Original post by iamspiderman
Here's the Question:
Sirius A is 2.3 times the mass of the sun and about 20 times as bright. Is this consistent with the mass-luminosity law?
Need help.
Sirius A is 2.3 times the mass of the sun and about 20 times as bright. Is this consistent with the mass-luminosity law?
Need help.
Hey again :-)
So this is like the other question with getting you to think about the mass-luminosity relation/law.
As they haven't told you what type of star it is and asked you if it is consistent with the mass-luminosity relation which works for main sequence stars, you can assume its a main sequence star. [fyi Its an Am type star so it is main sequence
]A stars luminosity is a measure of how 'bright' it is, so they are telling you Sirius A has a luminosity that is about 20 times greater than that of the Suns.
The mass-luminosity equation for main sequence stars is:
(L_star/L_sun) = (M_star/M_sun)^3.5
where M_star=mass of the star, M_sun=mass of the Sun
If you plug the masses they gave you into the equation do you find that Sirius A has a luminosity about 20 times that of the Sun?
Explanation of the mass-luminosity relation here: http://hyperphysics.phy-astr.gsu.edu/hbase/astro/herrus.html
..
(edited 7 years ago)
Original post by iamspiderman
Hey again!
Thanks for replying.
I've filled in the stars mass (2.3) but they didn't give the sun's mass?
L star/ L sun = (2.3/ ? )^3.5
Thanks for replying.
I've filled in the stars mass (2.3) but they didn't give the sun's mass?
L star/ L sun = (2.3/ ? )^3.5
np
'they didn't give the sun's mass'
Its kinda like the other question where you’ll end up not needing to know its value
The question said that Sirius A has a mass 2.3 times the suns, not '2.3' i.e.
M_star=2.3*M_sun
if you substitute that into the equation instead of just '2.3' do you find any terms cancel?
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