The HST Large Programme on NGC 6752. III. Detection of the Peak of the White Dwarf Luminosity Function

L. R. Bedin, M. Salaris, J. Anderson, M. Libralato, D. Apai, D. Nardiello, R. M. Rich, A. Bellini, A. Dieball, P. Bergeron, A. J. Burgasser, A. P. Milone, A. F. Marino

Published 2019-07-15Version 1

We report on the white dwarf cooling sequence of the old globular cluster NGC 6752, which is chemically complex and hosts a blue horizontal branch. This is one of the last globular cluster white dwarf (WD) cooling sequences accessible to imaging by the Hubble Space Telescope. Our photometry and completeness tests show that we have reached the peak of the luminosity function of the WD cooling sequence, at a magnitude m_F606W=29.4+/-0.1, which is consistent with a formal age of ~14Gyr. This age is also consistent with the age from fits to the main-sequence turnoff (13-14Gyr), reinforcing our conclusion that we observe the expected accumulation of white dwarfs along the cooling sequence.