463 research outputs found
Determination of the basic parameters of the dwarf nova EY Cygni
High-dispersion spectroscopy of EY Cyg obtained from data spanning twelve
years show, for the first time, the radial velocity curves from both emission
and absorption line systems, yielding semi-amplitudes K_{em}=24+/- 4 km s^-1
and K_{abs}=54+/- 2 km s^-1. The orbital period of this system is found to be
0.4593249(1)d. The masses of the stars, their mass ratio and their separation
are found to be M_1 sin^3 i = 0.015+/-0.002 M_sun, M_2 sin^3 i = 0.007+/-0.002
M_sun, q = K_1/K_2 = M_2/M_1 = 0.44+/-0.02 and a sin i = 0.71+/-0.04 R_sun. We
also found that the spectral type of the secondary star is around K0,consistent
with an early determination by Kraft(1962). From the spectral type of the
secondary star and simple comparisons with single main sequence stars, we
conclude that the radius of the secondary star is about 30 per cent larger than
a main sequence star of the same mass. We also present VRI CCD photometric
observations, some of them simultaneous with the spectroscopic runs. The
photometric data shows several light modulations, including a sinusoidal
behaviour with twice the frequency of the orbital period, characteristic of the
modulation coming from an elongated, irradiated secondary star. Low and high
states during quiescence are also detected and discussed. From several
constrains, we obtain tight limits for the inclination angle of the binary
system between 13 and 15 degrees, with a best value of 14 degrees obtained from
the sinusoidal light curve analysis. From the above results we derive masses
M_1 = 1.10+/-0.09 M_sun, M_2 = 0.49+/-0.09 M_sun, and a binary separation a =
2.9+/- 0.1 R_sun.Comment: 14 pages, 14 figures, accepted for publication on A&
On the Orbital Period of the Intermediate Polar 1WGA J1958.2+3232
Recently, Norton et al. 2002, on the basis of multiwavelength photometry of
1WGA J1958.2+3232, argued that the -1 day alias of the strongest peak in the
power spectrum is the true orbital period of the system, casting doubts on the
period estimated by Zharikov et al. 2001. We re-analyzed this system using our
photometric and spectroscopic data along with the data kindly provided by Andy
Norton and confirm our previous finding. After refining our analysis we find
that the true orbital period of this binary system is 4.35h.Comment: 4 pages, 5 figures, Accepted for publication in A&A Letter
El papel del beneficio en el ordenamiento económico-societario y su repercusión en la configuración empresarial
En el mundo de la empresa el beneficio constituye un concepto con muy diversas acepciones y con grandes dificultades, o mejor dicho, con enorme imposibilidad para determinarlo en función de las múltiples premisas que le afectan. Aquí no nos vamos a ocupar de su determinación empresarial, de sus problemas y valoraciones. Vamos más bien a entrar en el papel que juega el beneficio tanto en el ordenamiento económico-social como en las perspectivas económicas y empresariales, así como en sus consideraciones éticas y societarias en los actuales momentos de cambio y de transformación.-----In the business world, it's hard to define profit. It's a very complex concept with different meanings and various conditioning factors. Here we will not take care of business its determination, its problems and values. Because of this complexity in this work we will not approach the definition of the concept. Instead we will focus on the role of the profit in the socioeconomic system (business and economy) and the aftermath of ethics and society at the present time of change and transformation
New Spectroscopy of U Gem
We present new optical spectroscopic observations of U Geminorum obtained
during a quiescent stage. We performed a radial velocity analysis of three
Balmer emission lines yielding inconsistent results. Assuming that the radial
velocity semi amplitude accurately reflects the motion of the white dwarf, we
arrive at masses for the primary which are in the range of M_wd= 1.21 - 1.37
M_Sun. Based on the internal radial velocity inconsistencies and results
produced from the Doppler tomography -- wherein we do not detect emission from
the hot spot, but rather an intense asymmetric emission overlaying the disc,
reminiscent of spiral arms -- we discuss the possibility that the
overestimation of the masses may be due to variations of gas opacities and a
partial truncation of the disc.Comment: 16 pages, 10 figures, 3 tables, to be published on RevMexAA. arXiv
admin note: text overlap with arXiv:2112.0343
The Expanding Nebular Remnant of the Recurrent Nova RS Ophiuchi (2006): II. Modeling of Combined Hubble Space Telescope Imaging and Ground-based Spectroscopy
We report Hubble Space Telescope imaging, obtained 155 and 449 days after the
2006 outburst of the recurrent nova RS Ophiuchi, together with ground-based
spectroscopic observations, obtained from the Observatorio Astron\'omico
Nacional en San Pedro M\'artir, Baja California, M\'exico and at the
Observatorio Astrof\'isico Guillermo Haro, at Cananea, Sonora, M\'exico. The
observations at the first epoch were used as inputs to model the geometry and
kinematic structure of the evolving RS Oph nebular remnant. We find that the
modeled remnant comprises two distinct co-aligned bipolar components; a
low-velocity, high-density innermost (hour glass) region and a more extended,
high-velocity (dumbbell) structure. This overall structure is in agreement with
that deduced from radio observations and optical interferometry at earlier
epochs. We find that the asymmetry observed in the west lobe is an instrumental
effect caused by the profile of the HST filter and hence demonstrate that this
lobe is approaching the observer. We then conclude that the system has an
inclination to the line of sight of 39 degrees. This is in
agreement with the inclination of the binary orbit and lends support to the
proposal that this morphology is due to the interaction of the outburst ejecta
with either an accretion disk around the central white dwarf and/or a
pre-existing red giant wind that is significantly denser in the equatorial
regions of the binary than at the poles. The second epoch HST observation was
also modeled. However, as no spectra were taken at this epoch, it is more
difficult to constrain any model. Nevertheless, we demonstrate that between the
two HST epochs the outer dumbbell structure seems to have expanded linearly.Comment: 33 pages, 9 figures, 1 table, accepted for publication in Ap
Estudio del climaterio en una muestra de mujeres uruguayas
Durante el climaterio la mujer experimenta una serie de cambios fisiológicos, que causan frecuentemente tanto patologías físicas como manifestaciones psicosomáticas, conocidas como “síndrome climatérico”. Nuestro país posee escasos antecedentes de estudios sobre este tema, a pesar de la importancia que dicha fase de vida tiene para la población femenina. Para este estudio se analizan los datos obtenidos a partir de fichas médicas y de encuestas aplicadas a una muestra de 200 mujeres entre 40 y 65 años de edad, residentes en Montevideo y otras poblaciones del interior del país. Se observa la influencia de diferentes variables que inciden en los síntomas que se presentan durante el período climatérico: el historial reproductivo, hábitos de vida y nutrición, así como también indicadores socioeconómicos.Asociación de Antropología Biológica de la República Argentin
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