2,999 research outputs found
Technology survey of computer software as applicable to the MIUS project
Existing computer software, available from either governmental or private sources, applicable to modular integrated utility system program simulation is surveyed. Several programs and subprograms are described to provide a consolidated reference, and a bibliography is included. The report covers the two broad areas of design simulation and system simulation
A differential chemical abundance scale for the globular cluster M5
We present LTE chemical abundances for five red giants and one AGB star in
the Galactic globular cluster (GC) M5 based on high resolution spectroscopy
using the MIKE spectrograph on the Magellan 6.5-m Clay telescope. Our results
are based on a line-by-line differential abundance analysis relative to the
well-studied red giant Arcturus. The stars in our sample that overlap with
existing studies in the literature are consistent with published values for
[Fe/H] and agree to within typically 0.04 dex for the alpha-elements. Most
deviations can be assigned to varying analysis techniques in the literature.
This strengthens our newly established differential GC abundance scale and
advocates future use of this method. In particular, we confirm a mean [Fe I/H]
of -1.33 +- 0.03 (stat.) +- 0.03 (sys.) dex and also reproduce M5's enhancement
in the alpha-elements (O,Mg,Si,Ca,Ti) at +0.4 dex, rendering M5 a typical
representative of the Galactic halo. Over-ionization of Fe I in the atmospheres
of these stars by non-LTE effects is found to be less than 0.07 dex. Five of
our six stars show O-Na-Al-Mg abundance patterns consistent with pollution by
proton-capture nucleosynthesis products.Comment: 12 pages, 7 figures, accepted for publication in the A
Low altitude temperature and humidity profile data for application to aircraft noise propagation
A data search of the weather statistics from 11 widely dispersed geographical locations within the continental United States was conducted. The sites, located long both sea-coasts and in the interior, span the northern, southern, and middle latitudes. The weather statistics, retrieved from the records of these 11 sites, consist of two daily observations taken over a 10-year period. The data were sorted with respect to precipitation and surface winds and classified into temperature intervals of 5 C and relative humidity intervals of 10 percent for the lower 1400 meters of the atmosphere. These data were assembled in a statistical format and further classified into altitude increments of 200 meters. The data are presented as sets of tables for each site by season of the year and include both daily observations
Structural Racism and Youth Development
Youth of color have experienced poor outcomes relative to their white counterparts historically, and these disparities persist today. Researchers have offered a number of explanations for these disparities, some of the more popular of which have focused on individual deficiencies. If one elucidates the underlying theories of change of dominant practices and public policies in the youth field, it appears that, despite variation in approach and emphasis, they too have focused on individual behavior. While behavior is clearly an important contributor to the outcomes that individuals experience, it is not the sole determinant. Rather, we contend that there are larger, structural factors that contribute to the racial disparities between youth of color and their white counterparts that deserve systematic and sustained attention
Alpha Enhancement and the Metallicity Distribution Function of Plaut's Window
We present Fe, Si, and Ca abundances for 61 giants in Plaut's Window
(l=-1,b=-8.5) and Fe abundances for an additional 31 giants in a second, nearby
field (l=0,b=-8) derived from high resolution (R~25,000) spectra obtained with
the Blanco 4m telescope and Hydra multifiber spectrograph. The median
metallicity of red giant branch (RGB) stars in the Plaut field is ~0.4 dex
lower than those in Baade's Window, and confirms the presence of an iron
abundance gradient along the bulge minor axis. The full metallicity range of
our (biased) RGB sample spans -1.5<[Fe/H]<+0.3, which is similar to that found
in other bulge fields. We also derive a photometric metallicity distribution
function for RGB stars in the (l=-1,b=-8.5) field and find very good agreement
with the spectroscopic metallicity distribution. The radial velocity and
dispersion data for the bulge RGB stars are in agreement with previous results
of the BRAVA survey, and we find evidence for a decreasing velocity dispersion
with increasing [Fe/H]. The [alpha/Fe] enhancement in Plaut field stars is
nearly identical to that observed in Baade's window, and suggests that an
[alpha/Fe] gradient does not exist between b=-4 and -8. Additionally, a subset
of our sample (23 stars) appear to be foreground red clump stars that are very
metal--rich, exhibit small metallicity and radial velocity dispersions, and are
enhanced in alpha elements. While these stars likely belong to the Galactic
inner disk population, they exhibit [alpha/Fe] ratios that are enhanced above
the thin and thick disk.Comment: Accepted for publication in ApJ. 38 pages, 11 figures, and 2 tables.
Requests for higher resolution figures and electronic versions of tables 1
and/or 2 in advance of publication may be sent to cijohnson[at]astro.ucla.ed
Draco 119: A Remarkable Heavy Element-deficient Giant
We report the abundance analysis of new high S/N spectra of the most
metal-poor ([Fe/H] ) star presently known to be a member of a dwarf
galaxy, the Draco dSph red giant, D119. No absorption lines for elements
heavier than Ni are detected in two Keck HIRES spectra covering the
3850--6655 \AA{} wavelength range, phenomenon not previously
noted in any other metal-poor star. We present upper limits for several heavy
element abundances. The most stringent limits, based on the non-detection of
\ion{Sr}{2} and \ion{Ba}{2} lines, indicate that the total s- and r-process
enrichment of D119 is at least 100 times smaller than Galactic stars of similar
metallicity. The light element abundances are consistent with the star having
formed out of material enciched primarily by massive Type II supernovae (M --25 M). If this is the case, we are forced to conclude that
massive, metal-poor Type II supernovae did not contribute to the r-process in
the proto-Draco environment. We compare the abundance pattern observed in D119
to current predictions of prompt enrichement and pair-instability supernovae
and find that the model predictions fail by an order or maginitude or more for
many elements.Comment: Published in the September 1, 2004 edition of Ap
Our Milky Way as a Pure-Disk Galaxy -- A Challenge for Galaxy Formation
Bulges are commonly believed to form in the dynamical violence of galaxy
collisions and mergers. Here we model the stellar kinematics of the Bulge
Radial Velocity Assay (BRAVA), and find no sign that the Milky Way contains a
classical bulge formed by scrambling pre-existing disks of stars in major
mergers. Rather, the bulge appears to be a bar, seen somewhat end-on, as hinted
from its asymmetric boxy shape. We construct a simple but realistic N-body
model of the Galaxy that self-consistently develops a bar. The bar immediately
buckles and thickens in the vertical direction. As seen from the Sun, the
result resembles the boxy bulge of our Galaxy. The model fits the BRAVA stellar
kinematic data covering the whole bulge strikingly well with no need for a
merger-made classical bulge. The bar in our best fit model has a half-length of
~ 4kpc and extends 20 degrees from the Sun-Galactic Center line. We use the new
kinematic constraints to show that any classical bulge contribution cannot be
larger than ~ 8% of the disk mass. Thus the Galactic bulge is a part of the
disk and not a separate component made in a prior merger. Giant, pure-disk
galaxies like our own present a major challenge to the standard picture in
which galaxy formation is dominated by hierarchical clustering and galaxy
mergers.Comment: 5 pages; emulateapj format; minor changes to match the ApJL accepted
version. A quicktime movie is available to illustrate the spectacular bending
instability that gives rise to the boxy pseudobulge:
http://www.as.utexas.edu/~shen/movies/2view_bending_inertialframe.mo
Coordinates and 2MASS and OGLE identifications for all stars in Arp's 1965 finding chart for Baade's Window
Aims: We seek to provide 2MASS and OGLE identifications and coordinates for
all stars in the finding chart published by Arp\,(1965). This chart covers the
low extinction area around NGC 6522, also known as Baade's window, at
coordinates (l,b)=(1.02,-3.92).
Methods: A cross correlation, using numerical techniques, was performed
between a scan of the original finding chart from Arp (1965) and 2MASS and
OGLE-II images and stellar coordinates.
Results: We provide coordinates for all stars in Arp's finding chart and
2MASS and OGLE identifications wherever possible. Two identifications in
quadrant II do not appear in the original finding chart.Comment: 30 pages, accepted by A&A as a Research Not
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