The HST large programme on NGC 6752 - IV. The White Dwarf Sequence
Date Issued
2023
Author(s)
•
M. Salaris
•
J. Anderson
•
M. Scalco
•
D. Nardiello
•
E. Vesperini
•
H. Richer
•
A. Burgasser
•
M. Griggio
•
R. Gerasimov
•
D. Apai
•
A. Bellini
•
M. Libralato
•
P. Bergeron
•
R. M. Rich
•
A. Grazian
Abstract
We present our final study of the white dwarf cooling sequence (WD CS) in the
globular cluster NGC 6752. The investigation is the main goal of a dedicated
Hubble Space Telescope large Program, for which all the observations are now
collected. The WD CS luminosity function (LF) is confirmed to peak at m_F606W =
29.3+/-0.1, consistent within uncertainties with what has been previously
reported, and is now complete down to m_F606W~29.7. We have performed robust
and conclusive comparisons with model predictions that show how the theoretical
LF for hydrogen envelope WD models closely follow the shape of the empirical
LF. The magnitude of the peak of the observed LF is matched with ages between
12.7 and 13.5 Gyr, consistent with the cluster age derived from the main
sequence turn off and subgiant branch. We also find that the impact of multiple
populations within the cluster on the WD LF for m_F606W below 27.3 is
negligible, and that the presence of a small fraction of helium envelope
objects is consistent with the data. Our analysis reveals a possible hint of an
underestimate of the cooling timescales of models in the magnitude range 28.1 <
m_F606W < 28.9. Finally, we find that hydrogen envelope models calculated with
a new tabulation of electron conduction opacities in the transition between
moderate and strong degeneracy provide WD ages that are too small in comparison
to the Main Sequence turnoff age.
Volume
518
Issue
3
Start page
3722
Issn Identifier
0035-8711
Rights
open.access
File(s)![Thumbnail Image]()
Loading...
Name
stac3219.pdf
Description
PDF editoriale
Size
2.53 MB
Format
Adobe PDF
Checksum (MD5)
08d0e05c3a3ab13a817441d21727fd14