How would you determine the absolute magnitude of a relatively nearby (less than 50 parsec) star?

What types of observations/measurements would you have to make to determine the absolute magnitude of a relatively nearby (less than 50 parsec) star? Explain how you would use the measurements to get your answerHow would you determine the absolute magnitude of a relatively nearby (less than 50 parsec) star?The distance to stars within around 200 LY (60 parsecs) of the Sun can be determined by parallax (the position of the star against the background stars, is measured twice, six months apart and trigonometry is used to calculate the distance to the star). Once the distance is known, the apparent brightness is measured. Since absolute magnitude is the brightness a star would have at a distance of 10 parsecs, the actual brightness is converted to absolute brightness. An object at 20 parsecs would appear to be 4 times brighter at 10 parsecs. If the star was at 5 parsecs, it would appear to be 1/4 as bright at 10 parsecs.



Brightness increases or decreases by the square of the distance. Double the distance and the brightness is reduced to 1/4. Half the distance and the brightness increases 4 times. 3 X distance = 1/9 as bright, etc.How would you determine the absolute magnitude of a relatively nearby (less than 50 parsec) star?To expand on the answer given by David, once the distance to a star is measured, the absolute magnitude can be found by the following formula: Absolute Magnitude = Apparent Magnitude + (log(10/distance to star in parsecs)^2 / log(2.51)).

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