102,035 research outputs found
Particle deposition onto a flat plate with various slopes
In this work, a numerical simulation of the deposition of small suspended particles onto a flat plate with various degrees of inclination is performed. The particle deposition rates are obtained for various Reynolds and Rayleigh number groups
Time evolution and rotation of starspots on CoRoT-2 from the modelling of transit photometry
CoRoT-2, the second planet-hosting star discovered by the CoRoT satellite, is
a young and active star. A total of 77 transits were observed for this system
over a period of 135 days. Small modulations detected in the optical light
curve of the planetary transits are used to study the position, size,
intensity, and temporal evolution of the photospheric spots on the surface of
the star that are occulted by the planetary disk. We apply a spot model to
these variations and create a spot map of the stellar surface of CoRoT-2 within
the transit band for every transit. From these maps, we estimate the stellar
rotation period and obtain the longitudes of the spots in a reference frame
rotating with the star. Moreover, the spots temporal evolution is determined.
This model achieves a spatial resolution of 2\circ. Mapping of 392 spots vs.
longitude indicates the presence of a region free of spots, close to the
equator, reminiscent of the coronal holes observed on the Sun during periods of
maximum activity. With this interpretation, the stellar rotation period within
the transit latitudes of -14.\circ 6 \pm 10 \circ is found to be 4.48 days.
This rotation period is shorter than the 4.54 days as derived from the
out-of-transit light modulation. Since the transit data samples a region close
to the stellar equator, while the period determined from out-of-transit data
reflects the average rotation of the star, this is taken as an indication of a
latitudinal differential rotation of about 3% or 0.042 rad/d.Comment: 8 pages, 12 figure
Ricci dark energy in Chern-Simons modified gravity
In this work, we have considered the Ricci dark energy model, where the
energy density of the universe is proportional to the Ricci scalar curvature,
in the dynamic Chern-Simons modified gravity. We show that in this context the
evolution of the scale factor is similar to that displayed by the modified
Chaplygin gas.Comment: 7 pages; to appear in EPJ
A coordinate-dependent superspace deformation from string theory
Starting from a type II superstring model defined on in
a linear graviphoton background, we derive a coordinate dependent -deformed
, superspace. The chiral fermionic coordinates
satisfy a Clifford algebra, while the other coordinate algebra remains
unchanged. We find a linear relation between the graviphoton field strength and
the deformation parameter. The null coordinate dependence of the graviphoton
background allows to extend the results to all orders in .Comment: 14 pages, reference added, accepted for publication in JHE
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