2014A&A...569A.106C


Query : 2014A&A...569A.106C

2014A&A...569A.106C - Astronomy and Astrophysics, volume 569A, 106-106 (2014/9-1)

Pulsating low-mass white dwarfs in the frame of new evolutionary sequences. I. Adiabatic properties.

CORSICO A.H. and ALTHAUS L.G.

Abstract (from CDS):

Many low-mass white dwarfs with masses M*/M≲0.45, including the so-called extremely low-mass white dwarfs (M*/M≲0.20-0.25), have recently been discovered in the field of our Galaxy through dedicated photometric surveys. The subsequent discovery of pulsations in some of them has opened the unprecedented opportunity of probing the internal structure of these ancient stars. We present a detailed adiabatic pulsational study of these stars based on full evolutionary sequences derived from binary star evolution computations. The main aim of this study is to provide a detailed theoretical basis of reference for interpreting present and future observations of variable low-mass white dwarfs.Our pulsational analysis is based on a new set of He-core white-dwarf models with masses ranging from 0.1554 to 0.4352M derived by computing the non-conservative evolution of a binary system consisting of an initially 1M ZAMS star and a 1.4M neutron star. We computed adiabatic radial (l= 0) and non-radial (l= 1, 2) p and g modes to assess the dependence of the pulsational properties of these objects on stellar parameters such as the stellar mass and the effective temperature, as well as the effects of element diffusion.We found that for white dwarf models with masses below ∼0.18M, g modes mainly probe the core regions and p modes the envelope, therefore pulsations offer the opportunity of constraining both the core and envelope chemical structure of these stars via asteroseismology. For models with M*>0.18M, on the other hand, g modes are very sensitive to the He/H compositional gradient and therefore can be used as a diagnostic tool for constraining the H envelope thickness. Because both types of objects have not only very distinct evolutionary histories (according to whether the progenitor stars have experienced CNO-flashes or not), but also have strongly different pulsation properties, we propose to define white dwarfs with masses below ∼0.18M as ELM (extremely low-mass) white dwarfs, and white dwarfs with M*>0.18M as LM (low-mass) white dwarfs.

Abstract Copyright:

Journal keyword(s): asteroseismology - stars: oscillations - white dwarfs - stars: evolution - stars: interiors - stars: variables: general

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* ZZ Cet WD* 01 36 13.6155835488 -11 20 32.631811638   14.328 14.16 14.4   DA4.0 265 0
2 HL Tau 76 WD* 04 18 56.6380318051 +27 17 48.312463115   15.40       DA4.3 132 0
3 SDSS J111215.82+111745.0 WD* 11 12 15.8349049637 +11 17 45.120926538   16.54 16.31 16.2   DA 27 0
4 V* GW Vir WD* 12 01 45.9728868857 -03 45 40.627851273   14.87 15.04     DOQZ1 470 0
5 SDSS J151826.68+065813.2 WD* 15 18 26.6911855312 +06 58 13.270670877           DA 25 0
6 SDSS J161431.28+191219.4 WD* 16 14 31.2887834597 +19 12 19.464640403       16.30   DA 15 0
7 GD 358 WD* 16 47 18.3926893312 +32 28 32.865420612 12.511 13.530 13.653 13.752 13.852 DB2 324 0
8 SDSS J184037.78+642312.3 WD* 18 40 37.7922396059 +64 23 12.283729115   18.6   19.4   DA 30 0
9 SDSS J222859.93+362359.6 WD* 22 28 59.9318269111 +36 23 59.634277930   16.9   16.7   DA 15 0

    Equat.    Gal    SGal    Ecl

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2021.07.27-07:28:05

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