Unformatted text preview: used for the absolute magnitude. The G2 star is at a distance of = 10 × Sqrt [1/(1/25)] = 10 × Sqrt [25/1] = 50 parsecs from us. Distances to red giant and supergiant stars are found in a similar way but you need to investigate their spectra more closely to see if they are the very large stars you think they are. Their position in the calibrated H-R diagram is found and their apparent brightness gives you the distance. Also, this process can be used to find the distance of an entire cluster. The entire color-magnitude diagram for the cluster is compared with a calibration cluster's color-magnitude diagram. The calibration cluster is a known distance away. Some adjustments for the cluster's age and composition differences between the stars in the cluster and the calibration cluster must be made. Such fine-tuning adjustments are called ``main-sequence fitting''....
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- Fall '10
- Astronomy, spectral type, Spectroscopic Parallax