5,799 research outputs found
Multiwavelength optical observations of chromospherically active binary systems V. FF UMa (2RE J0933+624): a system with orbital period variation
This is the fifth paper in a series aimed at studying the chromospheres of
active binary systems using several optical spectroscopic indicators to obtain
or improve orbital solution and fundamental stellar parameters. We present here
the study of FF UMa (2RE J0933+624), a recently discovered, X-ray/EUV selected,
active binary with strong H_alpha emission. The objectives of this work are, to
find orbital solutions and define stellar parameters from precise radial
velocities and carry out an extensive study of the optical indicators of
chromospheric activity. We obtained high resolution echelle spectroscopic
observations during five observing runs from 1998 to 2004. We found radial
velocities by cross correlation with radial velocity standard stars to achieve
the best orbital solution. We also measured rotational velocity by
cross-correlation techniques and have studied the kinematic by galactic space-
velocity components (U, V, W) and Eggen criteria. Finally, we have determined
the chromospheric contribution in optical spectroscopic indicators, from Ca II
H & K to Ca II IRT lines, using the spectral subtraction technique. We have
found that this system presents an orbital period variation, higher than
previously detected in other RS CVn systems. We determined an improved orbital
solution, finding a circular orbit with a period of 3.274 days. We derived the
stellar parameters, confirming the subgiant nature of the primary component and
obtained rotational velocities (vsini), of 33.57 km/s and 32.38 km/s for the
primary and secondary components respectively. From our kinematic study, we can
deduce its membership to the Castor moving group. Finally, the activity study
has given us a better understanding of the possible mechanisms that produce the
orbital period variation.Comment: Latex file with 16 pages, 18 figures. Available at
http://www.ucm.es/info/Astrof/invest/actividad/actividad_pub.html Accepted
for publication in: Astronomy & Astrophysics (A&A
Dynamics of two interacting particles in classical billiards
The problem of two interacting particles moving in a d-dimensional billiard
is considered here. A suitable coordinate transformation leads to the problem
of a particle in an unconventional hyperbilliard. A dynamical map can be
readily constructed for this general system, which greatly simplifies
calculations. As a particular example, we consider two identical particles
interacting through a screened Coulomb potential in a one-dimensional billiard.
We find that the screening plays an important role in the dynamical behavior of
the system and only in the limit of vanishing screening length can the
particles be considered as bouncing balls. For more general screening and
energy values, the system presents strong non-integrability with resonant
islands of stability.Comment: REVTEX manuscript, 4 figures (1 ps + 3 gif, Postscript versions
available upon request). Also available at
http://www.phy.ohiou.edu/~ulloa/ulloa.htm
Unitized regenerative polymeric fuel cell modeling
The research's objective is to have a single machine to function as fuel cell and electrolyser based and needs, that is to say, unitized regenerative fuel cell (when fed to the machine with electric power and water flows will be obtained and H2 and O2 and conversely when the machine is fuelled with H2 and O2 will get water, heat and electricity) The study focuses on polymeric fuel cells and polymeric electrolysers. The development of this machine will make a very significant cost reduction (currently to use hydrogen as an energy store needed the electrolyser and fuel cell) as a single machine may replace the fuel cell and electrolyser. The achievement of the objective mentioned above, have been going by completing a series of stages. The stages addressed in this work are:
¿ A first stage, which will be studied in detail the polymeric fuel cells and polymeric electrolysers, in order to see the similarities between the machines and to design the unitized regenerative fuel cell.
¿ A second stage of simulation, which will develop models to show the behaviour of the unitized regenerative fuel cell and compare results with those obtained from the theoretical.
¿ A third stage of model verification generated polymer fuel cells and electrolyzers polymer on the market
The massive multiple system HD 64315
The O6 Vn star HD 64315 is believed to belong to the star-forming region
known as NGC 2467, but previous distance estimates do not support this
association. We explore the multiple nature of this star with the aim of
determining its distance, and understanding its connection to NGC 2467. A total
of 52 high-resolution spectra have been gathered over a decade. We use their
analysis, in combination with the photometric data from All Sky Automated
Survey and Hipparcos catalogues, to conclude that HD 64315 is composed of at
least two spectroscopic binaries, one of which is an eclipsing binary. HD 64315
contains two binary systems, one of which is an eclipsing binary. The two
binaries are separated by 0.09 arcsec (or 500 AU) if the most likely distance
to the system, around 5 kpc, is considered. The presence of fainter companions
is not excluded by current observations. The non-eclipsing binary (HD 64315
AaAb) has a period of 2.70962901+/-0.00000021 d. Its components are hotter than
those of the eclipsing binary, and dominate the appearance of the system. The
eclipsing binary (HD 64315 BaBb) has a shorter period of 1.0189569+/-0.0000008
d. We derive masses of 14.6+-2.3 M for both components of the BaBb
system. They are almost identical; both stars are overfilling their respective
Roche lobes, and share a common envelope in an overcontact configuration. The
non-eclipsing binary is a detached system composed of two stars with spectral
types around O6 V with minimum masses of 10.8 M and 10.2 M, and
likely masses aprox. 30 M. HD 64315 provides a cautionary tale about
high-mass star isolation and multiplicity. Its total mass is likely above 90
M,but it seems to have formed without an accompanying cluster. It
contains one the most massive overcontact binaries known, a likely merger
progenitor in a very wide multiple system.Comment: 14 pages, 13 figures, 8 Table
Multiwavelength optical observations of chromospherically active binary systems. IV. The X-ray/EUV selected binary BK Psc (2RE J0039+103)
We present high resolution echelle spectra taken during four observing runs
from 1999 to 2001 of the recently X-ray/EUV selected chromospherically active
binary BK Psc (2RE J0039+103). Our observations confirm the single-lined
spectroscopic binary(SB1) nature of this system and allow us to obtain, for the
first time,the orbital solution of the system as in the case of a SB2 system.
We have determined precise radial velocities of both components: for the
primary by using the cross correlation technique, and for the secondary by
using its chromospheric emission lines. We have obtained a circular orbit with
an orbital period of 2.1663 days, very close to its photometric period of 2.24
days (indicating synchronous rotation). The spectral type (K5V) we determined
for our spectra and the mass ratio (1.8) and minimum masses (Msin^{3}i)
resulting from the orbital solution are compatible with the observed K5V
primary and an unseen M3V secondary. Using this spectral classification, the
projected rotational velocity (vsini, of 17.1 km/s}) obtained from the width of
the cross-correlation function and the data provided by Hipparcos, we have
derived other fundamental stellar parameters. The kinematics and the
non-detection of the LiI line indicate that it is an old star. The analysis of
the optical chromospheric activity indicators from the CaII H & K to CaII IRT
lines, by using the spectral subtraction technique, indicates that both
components of the binary system show high levels of chromospheric activity.
H_alpha emission above the continuum from both components is a persistent
feature of this system during the period 1999 to 2001 of our observations as
well as in previous observations.Comment: Latex file with 13 pages, 5 figures tar'ed gzip'ed. Full postscript
(text and figures) available at http://www.ucm.es/info/Astrof/pub_dmg.html
Accepted for publication in: Astronomy & Astrophysic
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