2,213 research outputs found
Cool carbon stars in the halo: new very red or distant objects
The goal of this paper is to present and analyse a new sample of cool carbon
(C)stars located in the halo. Twenty three new C stars were discovered. Spectra
are typical of N-type stars with C2 and CN bands and sometimes Halpha in
emission. ... Four objects are particularly red with J-K > 3, with 2 located at
more than 5 kpc. from the Galactic plane. Eight additional objects with similar
properties are found in the literature and our previous works. These 12 C stars
could be useful to study mass loss at low metallicity. Two objects are at
distances of 95 and 110 kpc. They are located in the region with galactocentric
Z < -60 kpc in which the model of Law et al. predicts the Sgr stream to have a
loop. (Abstact abridged)Comment: 16 pages, 12 figures, accepted by A
Applying Community-Based Participatory Research Partnership Principles to Public Health Practice-Based Research Networks
With real-world relevance and translatability as important goals, applied methodological approaches have arisen along the
participatory continuum that value context and empower stakeholders to partner actively with academics throughout the
research process. Community-based participatory research (CBPR) provides the gold standard for equitable, partnered
research in traditional communities. Practice-based research networks (PBRNs) also have developed, coalescing communities
of practice and of academics to identify, study, and answer practice-relevant questions. To optimize PBRN potential for
expanding scientific knowledge, while bridging divides across knowledge production, dissemination, and implementation,
we elucidate how PBRN partnerships can be strengthened by applying CBPR principles to build and maintain research
collaboratives that empower practice partners. Examining the applicability of CBPR partnership principles to public health (PH)
PBRNs, we conclude that PH-PBRNs can serve as authentic, sustainable CBPR partnerships, ensuring the co-production of
new knowledge, while also improving and expanding the implementation and impact of research findings in real-world settings.ECU Open Access Publishing Support Fun
Atomic data for neutron-capture elements I. Photoionization and recombination properties of low-charge selenium ions
We present multi-configuration Breit-Pauli AUTOSTRUCTURE calculations of
distorted-wave photoionization (PI) cross sections, and total and partial
final-state resolved radiative recombination (RR) and dielectronic
recombination (DR) rate coefficients for the first six ions of the trans-iron
element Se. These calculations were motivated by the recent detection of Se
emission lines in a large number of planetary nebulae. Se is a potentially
useful tracer of neutron-capture nucleosynthesis, but accurate determinations
of its abundance in photoionized nebulae have been hindered by the lack of
atomic data governing its ionization balance. Our calculations were carried out
in intermediate coupling with semi-relativistic radial wavefunctions. PI and
recombination data were determined for levels within the ground configuration
of each ion, and experimental PI cross-section measurements were used to
benchmark our results. For DR, we allowed dn=0 core excitations, which are
important at photoionized plasma temperatures. DR is the dominant recombination
process for each of these Se ions at temperatures representative of
photoionized nebulae (~10^4 K). To estimate the uncertainties of these data, we
compared results from three different configuration-interaction expansions for
each ion, and tested the sensitivity of the results to the radial scaling
factors in the structure calculations. We find that the internal uncertainties
are typically 30-50% for the direct PI cross sections and ~10% for the computed
RR rate coefficients, while those for low-temperature DR can be considerably
larger (from 15-30% up to two orders of magnitude) due to the unknown energies
of near-threshold autoionization resonances. The results are suitable for
incorporation into photoionization codes used to numerically simulate
astrophysical nebulae, and will enable robust determinations of nebular Se
abundances.Comment: 17 pages, 8 figures, accepted for publication in Astronomy and
Astrophysic
The evolutionary status of the semiregular variable QYSge
Repeated spectroscopic observations made with the 6m telescope of yielded new
data on the radial-velocity variability of the anomalous yellow supergiant
QYSge. The strongest and most peculiar feature in its spectrum is the complex
profile of NaI D lines, which contains a narrow and a very wide emission
components. The wide emission component can be seen to extend from -170 to +120
km/s, and at its central part it is cut by an absorption feature, which, in
turn, is split into two subcomponents by a narrow (16km/s at r=2.5) emission
peak. An analysis of all the Vr values leads us to adopt for the star a
systemic velocity of Vr=-21.1 km/s, which corresponds to the position of the
narrow emission component of NaI. The locations of emission-line features of
NaI D lines are invariable, which point to their formation in regions that are
external to the supergiant's photosphere. Differential line shifts of about
10km/s are revealed. The absorption lines in the spectrum of QYSge have a
substantial width of FWHM~45 km/s. The method of model atmospheres is used to
determine the following parameters: Teff=6250K, lg g=2.0, and microturbulence
Vt=4.5km/s. The metallicity of the star is found to be somewhat higher than the
solar one with an average overabundance of iron-peak elements of [Met/H]=+0.20.
The star is found to be slightly overabundant in carbon and nitrogen,
[C/Fe]=+0.25, [N/Fe]=+0.27. The alpha-process elements Mg, Si, and Ca are
slightly overabundant [alpha/H]=+0.12. The strong sodium excess, [Na/Fe]=+0.75,
is likely to be due to the dredge-up of the matter processed in the NeNa cycle.
Heavy elements of the s-process are underabundant relative to the Sun. On the
whole, the observed properties of QYSge do not give grounds for including this
star into the group of RCrB or RVTau-type type objects.Comment: 29 pages, 8 figures, 4 tables; accepted by Astrophys. Bulleti
Synthesis of the elements in stars: forty years of progress
Forty years ago Burbidge, Burbidge, Fowler, and Hoyle combined what we would now call fragmentary evidence from nuclear physics, stellar evolution and the abundances of elements and isotopes in the solar system as well as a few stars into a synthesis of remarkable ingenuity. Their review provided a foundation for forty years of research in all of the aspects of low energy nuclear experiments and theory, stellar modeling over a wide range of mass and composition, and abundance studies of many hundreds of stars, many of which have shown distinct evidence of the processes suggested by B2FH. In this review we summarize progress in each of these fields with emphasis on the most recent developments
Interstellar absorptions and shocked clouds towards supernova remnant RX J0852.0-4622
We present results of survey of interstellar absorptions towards supernova
remnant (SNR) RX J0852.0-4622. The distribution of KI absorbers along the
distance of the background stars is indicative of a local region (d<600pc)
strongly depopulated by KI line-absorbing clouds. This fact is supported by the
behavior of the interstellar extinction. We find four high-velocity CaII
components with velocities of >100km/s towards three stars and identify them
with shocked clouds of Vela SNR. We reveal and measure acceleration of two
shocked clouds at the approaching and receding sides of Vela SNR along the same
sight line. The clouds acceleration, velocity, and CaII column density are used
to probe cloud parameters. The total hydrogen column density of both
accelerating clouds is found to be similar (~6*10^{17} cm) which
indicates that possibly there is a significant amount of small-size clouds in
the vicinity of Vela SNR.Comment: accepted in MNRA
The Chemical Compositions of the Type II Cepheids -- The BL Her and W Vir Variables
Abundance analyses from high-resolution optical spectra are presented for 19
Type II Cepheids in the Galactic field. The sample includes both short-period
(BL Her) and long-period (W Vir) stars. This is the first extensive abundance
analysis of these variables. The C, N, and O abundances with similar spreads
for the BL Her and W Vir show evidence for an atmosphere contaminated with
-process and CN-cycling products. A notable anomaly of the BL Her
stars is an overabundance of Na by a factor of about five relative to their
presumed initial abundances. This overabundance is not seen in the W Vir stars.
The abundance anomalies running from mild to extreme in W Vir stars but not
seen in the BL Her stars are attributed to dust-gas separation that provides an
atmosphere deficient in elements of high condensation temperature, notably Al,
Ca, Sc, Ti, and -process elements. Such anomalies have previously been seen
among RV Tau stars which represent a long-period extension of the variability
enjoyed by the Type II Cepheids. Comments are offered on how the contrasting
abundance anomalies of BL Her and W Vir stars may be explained in terms of the
stars' evolution from the blue horizontal branch.Comment: 41 pages including 11 figures and 4 tables; Accepted for publication
in Ap
New observations of cool carbon stars in the halo
We report new results of our search for rare, cool carbon stars located at
large distances from the galactic plane. Eighteen new C stars were discovered.
Six are remarkable by showing the two peculiarities of a strong infrared excess
at 12 microns and a large height above the Galactic plane, from 1.7 to 6 kpc.
The number of C stars with these properties has been increased to 16. Mass-loss
rates were tentatively estimated by assuming that all these 16 stars are Miras
and by using the correlation between Mdot and the K-12 colour index. It is
found that several stars have large mass loss, with median Mdot around 4E-06
solar mass per year. It would be desirable to detect their CO emission ...
Eight stars might be at more than 30 kpc from the Sun, and two at the
unprecedented distance of 150 kpc (this abstract has been abridged).Comment: 15 pages; accepted by Astronomy and Astrophysic
Search for broad absorption lines in spectra of stars in the field of supernova remnant RX J0852.0-4622 (Vela Jr.)
Supernova remnant (SNR) RX J0852.0-4622 is one of the youngest and is most
likely the closest among known galactic supernova remnants (SNRs). It was
detected in X-rays, the 44Ti gamma-line, and radio. We obtain and analyze
medium-resolution spectra of 14 stars in the direction towards the SNR RX
J0852.0-4622 in an attempt to detect broad absorption lines of unshocked ejecta
against background stars. Spectral synthesis is performed for all the stars in
the wavelength range of 3740-4020AA to extract the broad absorption lines of Ca
II related to the SNR RX J0852.0-4622. We do not detect any broad absorption
line and place a 3-sigma upper limit on the relative depths of <0.04 for the
broad Ca II absorption produced by the SNR. We detect narrow low and high
velocity absorption components of Ca II. High velocity |V(LSR)|=100-140 km/s
components are attributed to radiative shocks in clouds engulfed by the old
Vela SNR. The upper limit to the absorption line strength combined with the
width and flux of the 44Ti gamma-ray line 1.16 MeV lead us to conclude that SNR
RX J0852.0-4622 was probably produced by an energetic SN Ic explosion.Comment: 9 pages, 8 figures, accepted in A&
Clinical observations on interferences of early father absence in the achievement of femininity
In clinical work, we have observed that the loss of the father through divorce has a significant effect on the young girl's developing sense of feminity. This paper briefly reviews the research findings from sex-role development theory and psychoanalytic theory, and presents clinical discussions of latency aged girls whose parents divorced during their daughter's early and oedipal years. The most common defensive or coping patterns seen in these child patients during latency are identified, with clinical material presented to illustrate both the existence of these patterns and implications for treatment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44356/1/10615_2004_Article_BF00756561.pd
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