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## Our Sun is a G2V star with absolute magnitude 4.8. Suppose that a star of spectral type G2V is observed to have apparent magnitude -0.2. How

Question

Our Sun is a G2V star with absolute magnitude 4.8. Suppose that a star of spectral type G2V is observed to have apparent magnitude -0.2. How far away is it? A 1 parsec. B 5 parsecs. C 10 parsecs. D 100 parsecs. E 1000 parsecs.

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Physics
3 years
2021-07-27T13:07:25+00:00
2021-07-27T13:07:25+00:00 1 Answers
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## Answers ( )

Answer:Option DThe star is at a distance of 100 parsecs.

Explanation:The distance can be determined by means of the distance modulus:

(1)Where

Mis the absolute magnitude,mis the apparent magnitude anddis the distance in units of parsec.Therefore,

dcan be isolated from equation 1Then, Applying logarithmic properties it is gotten:

(2)The absolute magnitude is the intrinsic brightness of a star, while the apparent magnitude is the apparent brightness that a star will appear to have as is seen from the Earth.

Since both have the same spectral type is absolute magnitude will be the same.

Finally, equation 2 can be used:

Hence, the star is at a distance of 100 parsecs.Key term:Parsec: Parallax ofarcseconds