1,554 research outputs found
A Refutation of Modern Higher Critical Arguments Against the Authenticity of the Davidic Psalms
Setting out to inspect literary productions, the higher critics seek to ascertain their dates, their authors and their value as they themselves may yield the evidence. It is our purpose here, however, to deal only with their considerations advanced in opposition to the conservative view, that David is the author of those Psalms ascribed to him in their titles (seventy-three in all), and in favor of the critical view, advocating a late origin in either exilic or post-exilic times. In classifying their arguments we find that there are essentially three modes of attack used against the authenticity of the Davidic Psalms
Experiments with the LECO Pegasus Gas Chromatograph/ Time-of-Flight Mass Spectrometer Phase 1: Fast GC Separations and Comparison of the GC/TOF-MS with Conventional Quadrupole GC/MS and Fast Quadrupole GC/MS
Contribution of White Dwarfs to Cluster Masses
I present a literature search through 31 July 1997 of white dwarfs (WDs) in
open and globular clusters. There are 36 single WDs and 5 WDs in binaries known
among 13 open clusters, and 340 single WDs and 11 WDs in binaries known among
11 globular clusters. From these data I have calculated WD mass fractions for
four open clusters (the Pleiades, NGC 2168, NGC 3532, and the Hyades) and one
globular cluster (NGC 6121). I develop a simple model of cluster evolution that
incorporates stellar evolution but not dynamical evolution to interpret the WD
mass fractions. I augment the results of my simple model with N-body
simulations incorporating stellar evolution (Terlevich 1987; de la Feunte
Marcos 1996; Vesperini & Heggie 1997). I find that even though these clusters
undergo moderate to strong kinematical evolution the WD mass fraction is
relatively insensitive to kinematical evolution. By comparing the cluster mass
functions to that of the Galactic disk, and incorporating plausibility
arguments for the mass function of the Galactic halo, I estimate the WD mass
fraction in these two populations. I assume the Galactic disk is ~10 Gyrs old
(Winget et al. 1987; Liebert, Dahn, & Monet 1988; Oswalt et al. 1996) and that
the Galactic halo is ~12 Gyrs old (Reid 1997b; Gratton et al. 1997; Chaboyer et
al. 1998), although the WD mass fraction is insensitive to age in this range. I
find that the Galactic halo should contain 8 to 9% (alpha = -2.35) or perhaps
as much as 15 to 17% (alpha = -2.0) of its stellar mass in the form of WDs. The
Galactic disk WD mass fraction should be 6 to 7% (alpha = -2.35), consistent
with the empirical estimates of 3 to 7% (Liebert, Dahn, & Monet 1988; Oswalt et
al. 1996). (abridged)Comment: 20 pages, uuencoded gunzip'ed latex + 3 postscrip figures, to be
published in AJ, April, 199
Impact of Systematics on SZ-Optical Scaling Relations
One of the central goals of multi-wavelength galaxy cluster cosmology is to
unite all cluster observables to form a consistent understanding of cluster
mass. Here, we study the impact of systematic effects from optical cluster
catalogs on stacked SZ signals. We show that the optically predicted
Y-decrement can vary by as much as 50% based on the current 2 sigma systematic
uncertainties in the observed mass-richness relationship. Mis-centering and
impurities will suppress the SZ signal compared to expectations for a clean and
perfectly centered optical sample, but to a lesser degree. We show that the
level of these variations and suppression is dependent on the amount of
systematics in the optical cluster catalogs. We also study X-ray
luminosity-dependent sub-sampling of the optical catalog and find that it
creates Malmquist bias increasing the observed Y-decrement of the stacked
signal. We show that the current Planck measurements of the Y-decrement around
SDSS optical clusters and their X-ray counterparts are consistent with
expectations after accounting for the 1 sigma optical systematic uncertainties
using the Johnston mass richness relation.Comment: 6 pages, 4 figures. Revised to match version accepted in the
Astrophysical Journa
Rocky Planetesimals as the Origin of Metals in DZ Stars
{Abridged}. An analysis of the calcium and hydrogen abundances, Galactic
positions and kinematics of 146 DZ stars from the Sloan Digital Sky Survey
demonstrates that interaction with the interstellar medium cannot account for
their externally polluted atmospheres. The calcium-to-hydrogen ratios for the
37 DZA stars are dominated by super-solar values, as are the lower limits for
the remaining 109 DZ stars. All together their metal-contaminated convective
envelopes contain 10^{20+-2} g of calcium, commensurate with the masses of
calcium inferred for large asteroids. It is probable that these stars are
contaminated by circumstellar matter; the rocky remains of terrestrial
planetary systems. In this picture, two predictions emerge: 1) at least 3.5% of
all main sequence A- and F-type stars build terrestrial planets; and 2) the DZA
stars are externally polluted by both metals and hydrogen, and hence constrain
the frequency and mass of water-rich, extrasolar planetesimals.Comment: Accepted to MNRA
Mode identification of Pulsating White Dwarfs using the HST
We have obtained time-resolved ultraviolet spectroscopy for the pulsating DAV
stars G226-29 and G185-32, and for the pulsating DBV star PG1351+489 with the
Hubble Space Telescope Faint Object Spectrograph, to compare the ultraviolet to
the optical pulsation amplitude and determine the pulsation indices. We find
that for essentially all observed pulsation modes, the amplitude rises to the
ultraviolet as the theoretical models predict for l=1 non-radial g-modes. We do
not find any pulsation mode visible only in the ultraviolet, nor any modes
whose phase flips by 180 degrees; in the ultraviolet, as would be expected if
high l pulsations were excited. We find one periodicity in the light curve of
G185-32, at 141 s, which does not fit theoretical models for the change of
amplitude with wavelength of g-mode pulsations.Comment: Accepted for publication in the Astrophysical Journal, Aug 200
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