Relative Ages from Horizontal-Branch Morphology: Revisited

Young-Wook Lee, Hyun-chul Lee, Suk-Jin Yoon, Soo-Chang Rey, Brian Chaboyer
2002 Symposium - International astronomical union  
We present our recent revision of model constructions for the horizontal-branch (HB) morphology of globular clusters, which suggests the HB morphology is more sensitive to age compared to our earlier models. We also present our high precision CCD photometry for the classic second parameter pair M3 and M13. The relative age dating based on this photometry indicates that M13 is indeed older than M3 by 1.7 Gyr. This is consistent with the age difference predicted from our new models, which
more » ... a further support that the HB morphology is a reliable age indicator in most population II stellar systems.
doi:10.1017/s0074180900223449 fatcat:5wt34ufq4bf4ldux7fck45vrqi