687 research outputs found
North Carolina Organic Vegetable Production Cost Study
Crop Production/Industries,
New full evolutionary sequences of H and He atmosphere massive white dwarf stars using MESA
We explore the evolution of hydrogen-rich and hydrogen-deficient white dwarf
stars with masses between 1.012 and 1.307 Msun, and initial metallicity of
Z=0.02. These sequences are the result of main sequence stars with masses
between 8.8 and 11.8 Msun. The simulations were performed with MESA, starting
at the zero-age main sequence, through thermally pulsing and mass-loss phases,
ending at the white dwarfs cooling sequence. We present reliable chemical
profiles for the whole mass range considered, covering the different expected
central compositions, i.e. C/O, O/Ne and Ne/O/Mg, and its dependence with the
stellar mass. In addition, we present detailed chemical profiles of hybrid
C/O-O/Ne core white dwarfs, found in the mass range between 1.024 and 1.15
Msun. We present the initial-to-final mass relation, mass-radius relation, and
cooling times considering the effects of atmosphere and core composition.Comment: 17 pages, 16 figures, 3 tables, accepted for publication in MNRAS.
Cooling tracks available at
ftp://cdsarc.u-strasbg.fr/pub/cats/J/MNRAS/480/154
Asteroseismology of PG 1541651 and BPM 31594 with TESS
We present the photometric data from TESS for two known ZZ Ceti stars, PG
1541+651 and BPM 31594. Before TESS, both objects only had observations from
short runs from ground-based facilities, with three and one period detected,
respectively. The TESS data allowed the detection of multiple periodicities, 12
for PG 1541651, and six for BPM 31594, which enables us to perform a
detailed asteroseismological study. For both objects we found a representative
asteroseismic model with canonical stellar mass ~ 0.61 Msun and thick hydrogen
envelopes, thicker than 10^(-5.3) M_*. The detection of triplets in the Fourier
transform also allowed us to estimate mean rotation periods, being ~22 h for PG
1541+651 and 11.6 h for BPM 31594, which is consistent with range of values
reported for other ZZ Ceti stars.Comment: 12 pages, 11 figures. Accepted for publication in MNRA
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