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| Paper: |
A Study of the Effects of Metallicity on the Population of Galactic Disk White Dwarfs |
| Volume: |
493, 19th European Workshop on White Dwarfs |
| Page: |
389 |
| Authors: |
Cojocaru, R.; Torres, S.; Isern, J.; García–Berro, E. |
| Abstract: |
It is well established that stellar metallicity has a significant
impact on the determination of the ages of different Galactic stellar
populations when main sequence evolutionary tracks are used. Here we
study the role that metallicity plays on the age estimation for the
Galactic disk when the white dwarf luminosity function is employed. We
use a Monte Carlo population synthesis code that models the population
of disk white dwarfs. Our code includes the most up-to-date
evolutionary cooling sequences for white dwarfs with hydrogen-rich and
hydrogen-deficient atmospheres, for both carbon-oxygen and oxygen-neon
cores. We test two different models for the evolution of metallicity,
one where the metallicity is constant in time, but has a moderate
dispersion, and a second model in which the metallicity increases with
time. We find that, independently of the adopted age-metallicity law,
our simulated white dwarf luminosity functions are in very good
agreement with the luminosity functions derived from the Sloan Digital
Sky Survey and from the SuperCOSMOS Sky Survey. We find that the
age-metallicity law has no noticeable impact on the shape of the
bright branch of the white dwarf luminosity function. Thus, it can be
concluded that this branch can be safely employed to test the
theoretical evolutionary sequences. Also, we find that the location of
the cut-off in the luminosity function is almost insensitive to the
adopted age-metallicity relation. This ensures that its position can
be used as a robust indicator of the age of the Galactic disk. |
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