307 research outputs found
Eclipsing Binaries with Possible Light-Time Effect
The period changes of six eclipsing binaries have been studied with focus on
the light-time effect. With the least squares method we also calculated
parameters of such an effect and properties of the unresolved body in these
systems. With these results we discussed the probability of presence of such
bodies in the systems with respect to possible confirmation by another method.
In two systems we also suggested the hypothesis of fourth body or magnetic
activity for explanation of the "second-order variability" after subtraction of
the light-time effect of the third body.Comment: 4 pages, 1 figure, 2 tables, conference proceeding
TOWARDS DETERMINATION OF THE LAPLACE GRAVITY PARAMETER h
Abstract We review a compressive model for material inertia and the effect of gravitation which follows naturally from it. We show that this model is consistent with the relativity principle, and suggest how a slight departure in the observed advance of the perihelion of the orbit of Mercury could put an upper limit on the Laplace screening parameter h
A study of the interacting binary V 393 Scorpii
We present high resolution J-band spectroscopy of V 393 Sco obtained with the
CRIRES at the ESO Paranal Observatory along with a discussion of archival IUE
spectra and published broad band magnitudes. The best fit to the spectral
energy distribution outside eclipse gives = 19000 500 for the
gainer, = 7250 300 for the donor, = 0.13 0.02
mag. and a distance of = 523 60 pc, although circumstellar material
was not considered in the fit. We argue that V 393 Sco is not a member of the
open cluster M7. The shape of the He I 1083 nm line shows orbital modulations
that can be interpreted in terms of an optically thick pseudo-photosphere
mimicking a hot B-type star and relatively large equatorial mass loss through
the Lagrangian L3 point during long cycle minimum. IUE spectra show several
(usually asymmetric) absorption lines from highly ionized metals and a narrow
L emission core on a broad absorption profile. The overall behavior of
these lines suggests the existence of a wind at intermediate latitudes. From
the analysis of the radial velocities we find = 0.24 0.02
and a mass function of = 4.76 0.24 M. Our observations favor
equatorial mass loss rather than high latitude outflows as the cause for the
long variability.Comment: 13 pages, 14 figures, 7 tables. Accepted for publication in MNRAS,
main journa
High resolution mapping of a novel late blight resistance gene Rpi-avll, from the wild Bolivian species Solanum avilesii
Both Mexico and South America are rich in Solanum species that might be valuable sources of resistance (R) genes to late blight (Phytophthora infestans). Here, we focus on an R gene present in the diploid Bolivian species S. avilesii. The genotype carrying the R gene was resistant to eight out of 10 Phytophthora isolates of various provenances. The identification of a resistant phenotype and the generation of a segregating population allowed the mapping of a single dominant R gene, Rpi-avl1, which is located in an R gene cluster on chromosome 11. This R gene cluster is considered as an R gene “hot spot”, containing R genes to at least five different pathogens. High resolution mapping of the Rpi-avl1 gene revealed a marker co-segregating in 3890 F1 individuals, which may be used for marker assisted selection in breeding programs and for further cloning of Rpi-avl
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