相关论文: How much electric surcharge fits on ... a white dw…
We present the limits on possible time variation of the electric charges of quarks and leptons at the time of primordial nucleosynthesis within a model with dequantized electric charges which allows for the case of charged neutrino and…
Electron captures by atomic nuclei in dense matter are among the most important processes governing the late evolution of stars, limiting in particular the stability of white dwarfs. Despite considerable progress in the determination of the…
The critical charge $Z_c$ is estimated for elementary particles using a Newton-Wigner position operator inspired model. Particles with $Z \sim Z_c$ (maxicharged particles), if they exist at all, can have unusual properties which turn them…
Electrometers measure electric charge, but there must be a fundamental speed limit to measuring one electric charge. Since there are no dimensional inputs to this question, the answer must be expressible in terms of the fundamental physical…
Within the context of the Standard Model, quarks are placed in a $(\mathbf{3},\mathbf{2})\oplus (\mathbf{3},\bar{\mathbf{2}})$ matter field representation of $U_{EW}(2)$. Although the quarks carry unit intrinsic electric charge in this…
The upper bound on the number of relativistic species present at nucleosynthesis has been used to constrain particles with electric charge $\epsilon e$ ($10^{-8} < \epsilon <1$). We correct the bound previously calculated for milli-charged…
We examine 14 hot white dwarfs for signs of infrared excess using the Spitzer Space Telescope. Twelve of the objects are massive white dwarfs which have been suggested to be the result of binary mergers. The remaining two objects are…
The structure of a spherically symmetric stable dark 'star' is discussed, at zero temperature, containing 1) a core of quarks in the deconfined phase and antileptons 2) a shell of hadrons in particular $n$, $p$, $\Lambda$ and $\Sigma^-$ and…
White dwarfs that accrete the debris of tidally disrupted asteroids provide the opportunity to measure the bulk composition of the building blocks, or fragments, of exoplanets. This technique has established a diversity in compositions…
The electron-to-nucleon ratio or electron fraction is a key parameter in many astrophysical studies. Its value is determined by weak-interaction rates that are based on theoretical calculations subject to several nuclear physics…
We provide the modified TOV equations for the hydrostatic equilibrium of charged compact stars within the metric $f(R)$ gravitational background. We adopt the MIT bag model EoS for the dense matter and assume a charge distribution where the…
White dwarf stars composed of carbon, oxygen or heavier elements are expected to crystallize as they cool down below certain temperatures. Yet, simple arguments suggest that the helium white dwarf cores may not solidify, mostly because of…
White dwarf stars are the final stage of most stars, born single or in multiple systems. We discuss the identification, magnetic fields, and mass distribution for white dwarfs detected from spectra obtained by the Sloan Digital Sky Survey…
We conducted an analysis of the distribution of elements from lithium to europium in 200 dwarfs in the solar neighbourhood ~20 pc with temperatures in the range 4800-6200 K and metallicities [Fe/H] higher than -0.5 dex. Determinations of…
Electrostatic potential of electrons near the surface of static strange stars at zero temperature is studied within the frame of the MIT bag model. We find that for QCD parameters within rather wide ranges, and if the nuclear crust on the…
In this paper we investigate the electrodynamic surface properties of bare strange quark stars. The surfaces of such objects are characterized by the formation of ultra-high electric surface fields which might be as high as $\sim 10^{19}$…
The white dwarf luminosity function is well understood in terms of standard model physics and leaves little room for exotic cooling mechanisms related to the possible existence of new weakly interacting light particles. This puts…
We report the abundances of 30 elements in 23 metal-poor ([Fe/H] <-1.7) giants. These are based on 7774 equivalent widths and spectral synthesis of 229 additional lines. Hyperfine splitting is taken into account when appropriate. Our choice…
Near-infrared photometry and spectroscopy is obtained for a heterogeneous sample of nearby white dwarfs with possible excess flux as identified primarily in the Two Micron All Sky Survey. Among the sample of 43 stars are a number of white…
We describe observations and abundance analysis of a high-resolution, high-S/N survey of 168 stars, most of which are metal-poor dwarfs. We follow a self-consistent LTE analysis technique to determine the stellar parameters and abundances,…