refresh ask box archive theme
Victoria Yin | Honors Physics | 2012
Did you know that more than 50% of all star systems are binary stars? Half of the stars we see are actually multiple stars, revolving around a common center of mass.







Distance Calculation 

The period-luminosity relationship can be used to determine the distance to a Cepheid.

  1. Apparent magnitudes can be taken through photometric observation and plotted to create light curves such as the one below. (Source)
  2. Using this data, the average apparent magnitude m and the period in days can be determined. Here the data has an average apparent magnitude of 15.56 and a period of 4.76 days.
  3. The absolute magnitude M can be determined by inserting it into the period-luminosity plot. M = -3.6 (Source)
  4. Plug into d = 10 (m - M + 5)/5
    d = 10 (15.57 - (-3.6) + 5)/5
    d = 10 24.17/5
    d = 10 4.834
    d = 68,230 parsecs
  5. This particular Cepheid is 68.2 kpc away.