5 research outputs found
Modelling polarization properties of comet 1P/Halley using a mixture of compact and aggregate particles
Recently, the result obtained from `Stardust' mission suggests that the
overall ratio of compact to aggregate particles is 65:35 (or 13:7) for Comet
81P/Wild 2 (Burchell et al. 2008). In the present work, we propose a model
which considers cometary dust as a mixture of compact and aggregate particles,
with composition of silicate and organic. We consider compact particles as
spheroidal particles and aggregates as BCCA and BAM2 aggregate with some size
distribution. For modeling Comet 1P/ Halley, the power-law size distribution
n(a)= a^{-2.6}, for both compact and aggregate particles is taken. We take a
mixture of BAM2 and BCCA aggregates with a lower and upper cutoff size around
0.20 and 1. We also take a mixture of prolate, spherical and
oblate compact particles with axial ratio (E) from 0.8 to 1.2 where a lower and
upper cutoff size around 0.1 and 10 are taken. Using T-matrix
code, the average simulated polarization curves are generated which can best
fit the observed polarization data at the four wavelengths =
0.365, 0.485, 0.670 and 0.684. The suitable mixing
percentage of aggregates emerging out from the present modeling corresponds to
50% BAM2 and 50% BCCA particles and silicate to organic mixing percentage
corresponds to 78% silicate and 22% organic in terms of volume. The present
model successfully reproduces the observed polarization data, especially the
negative branch, more effectively as compared to other work done in the past.
It is found that among the aggregates, the BAM2 aggregate plays a major role,
in deciding the cross-over angle and depth of negative polarization branch.Comment: 7 pages, 5 figures (accepted for publication in MNRAS on May 4, 2011
<b style="">Wild edible fruits of Tripura</b>
302-305Tripura
is one of the eight jewels of the North-Eastern States and the state weather is
characterized by subtropical, warm and humid condition, which favours the
luxuriant growth of various edible fruit crops. In addition to the major fruits
grown (Mango, Litchi, Pineapple, Orange, Banana and Jackfruit) in this state,
there are many edible fruits exist naturally in forest as well as in cultivable
areas. These fruit plants are playing a vital role in providing nutritional and
economic security to the poor masses in rural areas but the commercial
importance and market value of these wild fruits is unknown to them. This paper lists the wild edible fruits and
their uses for further exploratio