Page 2 2. Finding the actual or absolute luminosity: Next you are going to use the data in the table below to plot a graph of period against absolute (actual) luminosity. There is a problem with this data as it stands - if you plot your graph you will find that the points do not lie more or less on a straight line, however, it is much easier to use a straight-line graph to read off information. Because of this, mathematicians and scientists often use special graph paper, called log graph paper, to convert data points on a curve into data points on a straight line. Star Period Absolute Star Period Absolute (days) Luminosity (days) Luminosity U Aq1 7 -3.66 SY Aur 10.1 -4.12 Sz Aq1 17.1 -4.78 YZ Aur 18.2 -4.86 TT Aq1 13.8 -4.51 FF Aur 2.1 -2.15 FF Aq1 4.5 -3.55 AD Cam 11.3 -4.25 FM Aq1 6.1 -3.48 SS CMa 12.4 -4.37 FN Aq1 9.5 -4.04 VY Car 18.9 -4.91 IU Aq1 22 -5.1 WZ Car 23 -5.16 V493 Aq1 3 -2.58 YZ Car 18.2 -4.86 V496 Aq1 6.8 -3.62 KN Cen 34 -5.65 V526 Aq1 4.2 -3.02 CP Cep 17.9 -4.84 V800 Aq1 20.1 -4.98 VX Cyg 20.1 -4.99 V1162 Aq1 5.4 -3.32 V396 Cyg 33.2 -5.62 V340 Ara 20.8 -5.03 V609 Cyg 31.1 -5.53 V475 Ara 1.5 -1.72 T Mon 27 -5.36 RX Aur 11.6 -4.29 X Pup 26 -5.31 Use the graph paper provided to plot these points and draw a line of best fit though them. When you have your striaght line, use it to find the absolute luminosity of the four Cepheids