منابع مشابه
The Halo White Dwarf WD 0346+246 Revisited
The extreme helium-rich atmospheric composition determined for the halo white dwarf WD 0346+246 is reexamined. This solution is shown to be improbable from an astrophysical point of view when accretion of hydrogen and metals from the interstellar medium is taken into account. An alternate solution is proposed where hydrogen and helium are present in the atmospheric regions in equal amounts. The...
متن کاملSimulating a White Dwarf-dominated Galactic Halo
Observational evidence has suggested the possibility of a Galactic halo which is dominated by white dwarfs (WDs). While debate continues concerning the interpretation of this evidence, it is clear that an initial mass function (IMF) biased heavily toward WD precursors (1<m/M⊙<8), at least in the early Universe, would be necessary in generating such a halo. Within the framework of homogeneous, c...
متن کاملThe Chemical Residue of a White Dwarf-Dominated Galactic Halo
Halo initial mass functions (IMFs), heavily-biased toward white dwarf (WD) precursors (i.e. ∼ 1 → 8 M ), have been suggested as a suitable mechanism for explaining microlensing statistics along the line of sight to the LMC. Such IMFs can apparently be invoked without violating the observed present-day WD luminosity function. By employing a simple chemical evolution argument, we demonstrate that...
متن کاملA Critical Examination of Halo White Dwarf Candidates
A detailed analysis of halo white dwarf candidates is presented, which is based on model atmosphere fits to observed energy distributions built from photoelectric or photographic magnitudes. Most of the candidates identified in reduced proper motion diagrams are shown to be too warm (Teff > 5000 K) and most likely too young to be members of the galactic halo, while the tangential velocities of ...
متن کاملWD 1953 − 011 – a magnetic white dwarf with peculiar field structure
We present Hα spectra of the magnetic white dwarf star WD1953−011 which confirm the presence of the broad Zeeman components corresponding to a field strength ∼ 500 kG found by Maxted & Marsh (1999). We also find that the line profile is variable over a timescale of a day or less. The core of the Hα line also shows a narrow Zeeman triplet corresponding to a field strength of ∼ 100 kG which appea...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2001
ISSN: 0004-637X,1538-4357
DOI: 10.1086/322316