610 research outputs found
Socio-cultural analysis of the phenomenon of mobile health in the context of information technology
Мобильность является одним из символов современной жизни, в которой значимым остается здоровье человека. Соединение технических инноваций и здоровья порождает новые социальные явления, которые автор рассматривает в рамках данной статьи.Mobility is one of the symbols of modern life, which remains a significant human health. Connection technological innovation and health creates new social phenomena, which the author considers the scope of this article
Formation of a tourism brand of Rostov region for foreign tourists
The authors of the article focus both on aspects of Linguocultural training of professionals to work with foreign tourists and on the problem of the choice of the tourism brand of Rostov Region, its historical stages, as well as the issue of the lack of a systematic approach to its formatio
Modeling the spectrum of V4334 Sgr (Sakurai's Object)
Theoretical spectral energy distributions were computed for a grid of
hydrogen-deficient and carbon-rich model atmospheres of T(eff) in the range of
5000-6250 K and log g = 1.0 - 0.0 by the technique of opacity sampling, taking
into account continuous, molecular band and atomic line absorption. These
energy distributions were compared with the spectrum of V4334 Sgr (Sakurai's
object) of April, 1997 in the wavelength interval 300-1000 nm. We show that (1)
the shape of the theoretical spectra depends strongly on T(eff) but only very
weakly on the hydrogen abundance; (2) the comparison of the observed and
computed spectra permits to estimate T(eff) approximately 5500 K for V4334 Sgr
in April, 1997, and its interstellar reddening (plus a possible circumstellar
contribution) E(B-V) approximately 0.70.Comment: 7 pages, 8 figures, LaTeX, accepted by Astronomy and Astrophysic
Boron in Very Metal-Poor Stars
We have observed the B I 2497 A line to derive the boron abundances of two
very metal-poor stars selected to help in tracing the origin and evolution of
this element in the early Galaxy: BD +23 3130 and HD 84937. The observations
were conducted using the Goddard High Resolution Spectrograph on board the
Hubble Space Telescope. A very detailed abundance analysis via spectral
synthesis has been carried out for these two stars, as well as for two other
metal-poor objects with published spectra, using both Kurucz and OSMARCS model
photospheres, and taking into account consistently the NLTE effects on the line
formation. We have also re-assessed all published boron abundances of old disk
and halo unevolved stars. Our analysis shows that the combination of high
effective temperature (Teff > 6000 K, for which boron is mainly ionized) and
low metallicity ([Fe/H]<-1) makes it difficult to obtain accurate estimates of
boron abundances from the B I 2497 A line. This is the case of HD 84937 and
three other published objects (including two stars with [Fe/H] ~ -3), for which
only upper limits can be established. BD +23 3130, with [Fe/H] ~ -2.9 and
logN(B)_NLTE=0.05+/-0.30, appears then as the most metal-poor star for which a
firm measurement of the boron abundance presently exists. The evolution of the
boron abundance with metallicity that emerges from the seven remaining stars
with Teff < 6000 K and [Fe/H]<-1, for which beryllium abundances were derived
using the same stellar parameters, shows a linear increase with a slope ~ 1.
Furthermore, the B/Be ratio found is constant at a value ~ 20 for stars in the
range -3<[Fe/H]<-1. These results point to spallation reactions of ambient
protons and alpha particles with energetic particles enriched in CNO as the
origin of boron and beryllium in halo stars.Comment: 38 pages, 11 Encapsulated Postscript figures (included), uses
aaspp4.sty. Accepted for publication in The Astrophysical Journal. The
preprint is also available at: http://www.iac.es/publicaciones/preprints.htm
High-Dispersion Optical Spectra of Nearby Stars Younger Than The Sun
We present high-dispersion (R~16,000) optical (3900-8700 A) spectra of 390
stars obtained with the Palomar 60 inch telescope. The majority of stars
observed are part of the Spitzer Legacy Science Program "The Formation and
Evolution of Planetary Systems." Through detailed analysis we determine stellar
properties for this sample, including radial and rotational velocities, Li I
6708 and Ha equivalent widths, the chromospheric activity index R'_HK, and
temperature- and gravity-sensitive line ratios. Several spectroscopic binaries
are also identified. From our tabulations, we illustrate basic age- and
rotation-related correlations among measured indices. One novel result is that
Ca II chromospheric emission appears to saturate at vsini values above ~30
km/s, similar to the well established saturation of X-rays that originate in
the spatially separate coronal regions.Comment: 1 electronic table; published in the Astronomical Journa
Metallicity and effective temperature of the secondary of RS Oph
The recurrent nova RS Oph undergoes nova eruptions every ~ 10-20years as a
result of thermonuclear runaway on the surface of a white dwarf close to the
Chandrasekhar limit. Both the progress of the eruption, and its aftermath,
depend on the (poorly known) composition of the red giant in the RS Oph system.
Our aim is to understand better the effect of the giant secondary on the
recurrent nova eruption. Synthetic spectra were computed for a grid of M-giant
model atmospheres having a range of effective temperatures 3200 < Teff < 4400
K, gravities 0 < log g < 1 and abundances -4 <[Fe/H] < 0.5, and fit to infrared
spectra of RS Oph as it returned to quiescence after its 2006 eruption. We have
modelled the infrared spectrum in the range 1.4-2.5 micron to determine
metallicity and effective temperature of the red giant. We find Teff = 4100 +/-
100 K, log g = 0.0 +/- 0.5, [Fe/H] = 0.0 +/- 0.5, [C/H] = -0.8 +/- 0.2, [N/H] =
+0.6 +/- 0.3 in the atmosphere of the secondary, and demonstrate that that
inclusion of some dust `veiling' in the spectra cannot improve our fits.Comment: 6 pages, 5 figs, 1 table, to appear in A&
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