# The uncertainty of age measurements in Globular Clusters by the variations of the 2$^{nd}$ parameter candidates

• Han, Sang-Il (Center for Space Astrophysics Department of Astronomy, Yonsei University) ;
• Lee, Young-Wook (Center for Space Astrophysics Department of Astronomy, Yonsei University)
• Published : 2004.04.01

#### Abstract

It is believed that age controls horizontal-branch (HB) morphology of Globular Clusters besides metallicity (first parameter). However, other second parameter candidates, such as He abundance and alpha elements enhancement, could also affect HB morphology. These effects may influence to the age measurements from the main-sequence turnoff (MSTO) as well. We will measure the variations of age caused by each second parameter candidate at HB and MSTO respectively, using the well known second parameter pair M3 and Ml3. (omitted)