Exercise

Examine the HR Diagrams of the Globular clusters below. Rank them from oldest to youngest. It’s important to note the Y axis on these plots are the apparent magnitudes. You cannot compare the numbers directly. Instead, you should use your knowledge of what the MS should look like and compare the shape of the main sequence amongst the clusters. You don’t need to determine absolute ages.

m67hrdiagram2_med.jpeg

M67 Stassun et al., 2002, A&A 382, 899

Pleiades

Pleiades Kharchenko et al., 2004 A&A 438 1163

fig 1

M71 Hodder et al. AJ 1992, 103 460      

ngc

M2: Lee & Carney, ApJ 1999 117 6