23 research outputs found
Combined effects of tidal and rotational distortions on the equilibrium configuration of low-mass, pre-main sequence stars
In close binary systems, rotation and tidal forces of the component stars
deform each other and destroy their spherical symmetry. We present new models
for low-mass, pre-main sequence stars that include the combined distortion
effects of tidal and rotational forces on the equilibrium configuration of
stars. We investigate the effects of interaction between tides and rotation on
the stellar structure and evolution. The Kippenhahn & Thomas (1970)
approximation, along with the Clairaut-Legendre expansion for the gravitational
potential of a self-gravitating body, is used to take the distortion effects
into account. We obtained values of internal structure constants for low-mass,
pre-main sequence stars from stellar evolutionary models that consider the
combined effects of rotation and tidal forces due to a companion star. We also
derived a new expression for the rotational inertia of a tidally and
rotationally distorted star. Our distorted models were successfully used to
analyze the eclipsing binary system EK Cep, reproducing the stellar radii,
effective temperature ratio, lithium depletion, rotational velocities, and the
apsidal motion rate in the age interval of 15.5-16.7 Myr. In the low-mass
range, the assumption that harmonics greater than j=2 can be neglected seems
not to be fully justified, although it is widely used when analyzing the
apsidal motion of binary systems. The non-standard evolutionary tracks are
cooler than the standard ones, mainly for low-mass stars. Distorted models
predict more mass-concentrated stars at the zero-age main-sequence than
standard models
Not Available
Not AvailableRemoval of soil particles by wind is an active landdegradation
process in the Indian Thar Desert. To
compute the soil loss due to wind erosion, eroded
aeolian masses are mostly collected by samplers, which
are available with different designs at desert areas of
the world. In the Indian Thar Desert, dust catcher in
the design of Bagnold sampler was generally used to
collect eroded masses at different heights from the
surface, but this had a few drawbacks. Keeping in
mind the constraints of the existing sampler, a new
wind-erosion sampler was designed, fabricated, tested
and installed in the Indian Thar Desert at Jaisalmer.
This erosion sampler has the ability to adjust its orifice
towards the wind direction and thus is capable of
collecting aeolian masses from any direction. With
this sampler, eroded aeolian masses were collected
and analysed during several dust-storm events and
periodic wind-erosion events during June–September
2009. Computation of mass flux (ML–2 T–1) and soil
loss from the collected aeolian mass data successfully
captured the intensity of dust-storm/wind-erosion
events and their variation within a season. Therefore,
the new erosion sampler may be used as a tool to
monitor and assess dust-storm events in the Indian
Thar Desert.Not Availabl