21 research outputs found
YY CMi: contact or near contact system?
New V photoelectric observations of the eclipsing system YY CMi, obtained at
La Silla, Chile, and Merate Observatory, Italy, are presented. New times of
minima and ephemeris based on our observations are also given. The V light
curve was analysed by using the WD code to derive the geometrical and physical
parameters of the system. Since no spectroscopic mass ratio is available, the
q-search method was applied to yield the preliminary range of the mass ratio in
order to search for the final solution. First the unspotted solution was
carried out by using the unperturbed parts of the light curve and applying the
DC program of the WD code. The solution was performed by assuming contact (mode
3) and semi-detached (mode 4) configuration, since no classification of the
system is possible from the shape of the light curve. The solution in mode 4
does not lead to an acceptable model, since the secondary was found to be
slightly overcontact. Therefore the contact solution was finally adopted.
Moreover the light curve peculiarities (Max II fainter than Max I and excess of
light around the phase 0.32) were explained by assuming a cool and a hot spot
on the surface of the secondary (cooler) component. The degree of contact is
very small (f about 3%) and the thermal contactis poor (T1-T2) about 650 K.
These results together with the high photometric mass ratio q about 0.89
indicate that YY CMi is very probably a system at the beginning or the end of
the contact phase.Comment: 7 pages, 7 ps figures. Accepted for Astronomy and Astrophysics,
Supplement Serie
Period changes in six contact binaries: WZ And, V803 Aql, DF Hya, PY Lyr, FZ Ori, and AH Tau
Six contact binaries lacking a period analysis have been chosen to search for
the presence of a third body. The O-C diagrams of these binaries were analyzed
with the least-squares method by using all available times of minima. Ten new
minima times, obtained from our observations, were included in the present
research. The Light-Time Effect was adopted for the first time as the main
cause for the detailed description of the long-term period changes. Third
bodies were found with orbital periods from 49 up to 100 years, and
eccentricities from 0.0 to 0.56 for the selected binaries. In one case (WZ
And), a fourth-body LITE variation was also applied. The mass functions and the
minimal masses of such bodies were also calculated and a possible angular
separation and magnitude differences were discussed for a prospective
interferometric discovery of these bodies.Comment: 7 pages, 8 figures, 2009 New Astronomy 14, 12
The double-mode nature of the HADS star GSC 00144-03031 and the Petersen diagram of the class
The double--mode pulsation of GSC 00144-03031 has been detected when
searching for COROT targets. A very large dataset composed of 4722 photometric
measurements was collected at six observatories in Europe and America. There is
no hint of the excitation of additional modes (down to 0.6 mmag) and therefore
GSC 00144-03031 seems to be a pure double--mode pulsator, with a very short
fundamental radial mode (P=84 min). From Stromgren photometry and evolutionary
tracks it appears to be a Pop. I star with M=1.75 solar masses, located in the
middle of the instability strip, close to the Zero--Age Main Sequence. We also
discovered other new double--mode pulsators in the databases of large--scale
projects: OGLE BW2_V142, OGLE BW1_V207, ASAS3 094303-1707.3, ASAS3
000116-6037.0, NSVS 3234596 and NSVS 3324715. An observational Petersen diagram
is presented and explained by means of new models. A common sequence connecting
Pop. I stars from the shortest to the longest periods is proposed and the
spreads in the period ratios are ascribed to different metallicities (at the
shortest periods) and to different masses (at the longest ones). The paper is
based on data collected at S. Pedro Martir and Sierra Nevada Observatories and
on the contributions from several amateur astronomers.Comment: 9 pages, 5 pages, accepted for publication in Astronomy and
Astrophysic
A Photometric study of the near-contact system RU Ursae Minoris
The near-contact system RU UMi with an F0 primary and a K5 secondary was observed in U, B and V wavelengths in May and July 1998, as well as in March, May and July 1999. Six new observed times of minima are given and a new ephemeris is proposed. The basic parameters of the system extracted by our observations were used for spot modelling of the light curves. A simple spot distribution was determined, based on a model with one relatively small cool spot on the surface of the secondary. Absolute elements were calculated and the evolutionary status was determined. Our data favor a semi-detached configuration, with the secondary filling its inner Roche lobe; the primary must also be near the limits of its lobe
On the performance of GAIA on photometry of eclipsing binaries: The case of four near-contact and contact systems
The light curves of four eclipsing binaries (two near-contact and two
contact) are analysed by means of light curve synthesis techniques to derive
the geometric and photometric elements and the physical parameters of the systems.
For the analysis we used ground based photometric observations and
Hipparcos/Tycho photometric data, which mimic the photometric observations that
should be obtained by GAIA, the approved Cornerstone 6 mission by ESA. The
results are compared and the achievable precision
of the basic stellar parameters derived by GAIA photometry is discussed
A photometric study of BH Cas
New CCD observations of the contact binary system BH Cas are presented in this paper. New times of minima and an ephemeris based on our observations are also given. Complete light curves obtained in the V, R and I filters have been analyzed with the Wilson-Devinney code to derive the geometrical and physical parameters of the system. The final solution leads to a contact configuration (f ≈ 21-22%). We have found that the photometric mass ratio differs from the spectroscopic one by about 13%, a discrepancy which is not uncommon for other W UMa systems. The absolute elements of the system are used to study its evolutionary status. The results show that BH Cas is a fairly evolved W-type W UMa system
YY canis minoris: Contact or near contact system?
New V photoelectric observations of the eclipsing system YY CMi,
obtained at La Silla, Chile, and Merate Observatory, Italy, are
presented. New times of minima and ephemeris based on our observations
are also given. The V light curve was analysed by using the WD code to
derive the geometrical and physical parameters of the system. Since no
spectroscopic mass ratio is available, the q-search method was applied
to yield the preliminary range of the mass ratio in order to search for
the final solution. First the unspotted solution was carried out by
using the unperturbed parts of the light curve and applying the DC
program of the WD code. The solution was performed by assuming contact
(mode 3) and semi-detached (mode 4) configuration, since no
classification of the system is possible from the shape of the light
curve. The solution in mode 4 does not lead to an acceptable model,
since the secondary was found to be slightly overcontact. Therefore the
contact solution was finally adopted. Moreover the light curve
peculiarities (MaxII fainter than MaxI and excess of light around the
phase 0.32) were explained by assuming a cool and a hot spot on the
surface of the secondary (cooler) component. The degree of contact is
very small (f approximate to 3%) and the thermal contact is poor (T-1 -
T-2) approximate to 650 K. These results together with the high
photometric mass ratio q approximate to 0.89 indicate that YY CMi is
very probably a system at the beginning or the end of the contact phase
A photometric study of BH Cas
New CCD observations of the contact binary system
BH Cas are presented in this paper. New times of minima and
an ephemeris based
on our observations are also given. Complete light curves
obtained in the V, R and I filters have been analyzed with the
Wilson-Devinney code to derive the geometrical and physical parameters
of the system. The final solution leads to
a contact configuration (). We have found that the
photometric mass ratio differs from the spectroscopic one by about 13% ,
a discrepancy which is not uncommon for other W UMa systems.
The absolute elements of the system
are used to study its evolutionary status. The results show that BH Cas
is a fairly evolved W-type W UMa system
The Argonautica Orphica version of the voyage of the Argonauts: a geo-analysis
This study traces and analyzes the itinerary followed by Argo and her crew, according to the unknown author
of Argonautica Orphica: The voyage of the Argonauts from Iolcos to Colchis and their return following a
different path, from Phasis River through central Europe to the Atlantic Ocean and then through the
Mediterranean Sea. Conclusions are drawn about whether such a voyage could be possible in the remote
antiquity and the \u201cproblematic\u201d points of the description are pointed out