1)The star Proxima Centuri is of apparent magnitude 11.05 and Absolute Magnitude
ID: 296312 • Letter: 1
Question
1)The star Proxima Centuri is of apparent magnitude 11.05 and Absolute Magnitude +15.4. Select the correct answer for the distance to the star in parsec (pc)?
2) The star Alpha Centuri is of apparent magnitude -0.01 and Absolute Magnitude +4.4. Select the correct answer for the distance to the star in parsec (pc)?
3) The star Barnard’s Star is of apparent magnitude +9.54 and Absolute Magnitude +13.2. Select the correct answer for the distance to the star in parsec (pc)?
4) The star Sirius is of apparent magnitude -1.46 and Absolute Magnitude +1.4. Select the correct answer for the distance to the star in parsec (pc)?
5) The star Betergeuse is of apparent magnitude +0.41and Absolute Magnitude -5.5. Select the correct answer for the distance to the star in parsec (pc)?
A) 1.3Explanation / Answer
Before answering this question let me tell you what is the difference between absolute brightness and apparent brightness.
Apparent brightness is how bright the star appears from earth which is a function of distance which means even if the star is less bright than other stars but if it closer to earth it appears brighter as compared to the distant star. So in case of apparent brightness we never ever able to judge the actual hotness of star.
Absolute brightness is how bright the star when we know its distance from earth. for reference, we use 10 parsecs as a distance to compare the star brightness.
There is an equation to find the distance of the star from earth
m-M=5log(d/10)
or on further solving this equation we get
10 (m-M+5)/10 = d
where m is apparent magnitude
M is absolute magnitude
d is the distance between star and earth
so according to this equation
answer 1: A or 1.3(pc)
answer 2: B or 1.33(pc)
answer 3: A or 1.83(pc)
answer 4: D or 2.67(pc)
answer 5: C or 150(pc)
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