3,263 research outputs found
RR Lyrae stars in the inner LMC: Where did they form?
RR Lyrae stars (RRLS) belong to population II and are generally used as a
tracer of the host galaxy halo. The surface as well as vertical distribution of
RRLS in the inner Large Magellanic Cloud (LMC) are studied to understand
whether these stars are actually formed in the halo. RRLS identified by the
OGLE III survey are used to estimate their number density distribution. The
scale-height of their distribution is estimated using extinction corrected
average magnitudes of ab type stars. The density distribution mimics the bar,
confirming results in the literature. The distribution of their scale height
indicates that there may be two populations, one with smaller scale-height,
very similar to the red clump stars and the other, much larger. The
distribution of the reddening-corrected magnitude along the minor axis shows
variation, suggesting an inclination. The inclination is estimated to be i =
31.3 (3.5) degrees, very similar to the inclination of the disk. Thus, the RRLS
in the inner LMC mimic the bar and inclination of the disk, suggesting that a
major fraction of RRLS is formed in the disk of the LMC. The results indicate
that the RRLS in the inner LMC trace the disk and probably the inner halo. They
do not trace the extended metal-poor halo of the LMC. We suggest that a major
star formation event happened in the LMC at 10-12 Gyrs ago, resulting in the
formation of most of the inner RRLS, as well as probably the globular clusters,
inner halo and the disk of the LMC.Comment: A&A Letters (in press
Developing a Scale to Measure the Indigenous Wisdom Orientation of Rice Farmers
The traditional rice farmers had adopted various indigenous technologies in rice farming which in due course of time was forgotten after the advent of high yielding varieties that warranted excessive use of chemical inputs. Hence a study was designed to develop a scale to measure the indigenous wisdom orientation of stakeholders in rice farming. The study was conducted in Palakkad district of Kerala. Fifty statements reflecting the indigenous wisdom orientation were generated. Likert’s method was employed in the scale construction and the final scale comprising 14 statements was standardized
Disk of the Small Magellanic Cloud as traced by Cepheids
The structure and evolution of the disk of the Small Magellanic Cloud (SMC)
are traced by studying the Cepheids. We aim to estimate the orientation
measurements of the disk, such as the inclination and the position angle of the
line of nodes, and the depth of the disk. We used the V and I band photometric
data of the fundamental and first-overtone Cepheids from the Optical
Gravitational Lensing Experiment survey. The period-luminosity relations were
used to estimate the relative distance and reddening of each Cepheid. A
weighted least-square plane fitting method was then applied to estimate the
structural parameters. The line-of-sight depth and then the orientation
corrected depth or thickness of the disk were estimated from the relative
distance measurements. The period-age-colour relation of Cepheids were used to
derive the age of the Cepheids. A break in the PL relations of the
fundamental-mode and first-overtone Cepheids at P ~ 2.95 days and P ~ 1 day are
observed. An inclination of 64.40.7 and a
PA=155.36.3 are obtained from the full sample. A reddening
map of the SMC disk is also presented. The orientation-corrected depth or
thickness of the SMC disk is found to be 1.76 0.6 kpc. The scale height
is estimated to be 0.82 0.3 kpc. The age distribution of Cepheids matches
the SMC cluster age distribution. The radial variation of the disk parameters
mildly indicate structures/disturbances in the inner SMC (0.5 r 2.5
degree). Some of the Cepheids found in front of the fitted plane in the eastern
regions are possibly the youngest tidally stripped counterpart of the H {{\sc
i}} gas of the Magellanic Bridge. The Cepheids behind the fitted plane are most
likely the population in the Counter Bridge predicted in recent numerical
simulations. Different scenarios for the origin of the extra-planar Cepheids
are also discussed.Comment: Accepted for publication in the journal Astronomy & Astrophysics, 18
pages, 18 figure
Structure of the Large Magellanic Cloud from the Near Infrared magnitudes of Red Clump stars
The structural parameters, like the inclination, i and the position angle of
the line of nodes (PA_lon) of the disk of the Large Magellanic Cloud (LMC) are
estimated using the JH photometric data of red clump stars from the Infrared
Survey Facility - Magellanic Cloud Point Source Catalog (IRSF-MCPSC). The
observed LMC region is divided into several sub-regions and stars in each
region are cross identified with the optically identified red clump stars to
obtain the near infrared magnitudes. The peak values of H magnitude and (J-H)
colour of the observed red clump distribution are obtained by fitting a profile
to the distributions and also by taking the average value of magnitude and
colour of the red clump stars in the bin with largest number. Then the
dereddened peak H0 magnitude of the red clump stars in each sub-region is
obtained. The RA, Dec and relative distance from the center of each sub-region
are converted into x, y & z Cartesian coordinates. A weighted least square
plane fitting method is applied to this x,y,z data to estimate the structural
parameters of the LMC disk. A reddening map based on (J-H) colour of the RC
stars is presented. When the peaks of the red clump distribution were
identified by averaging, an inclination of 25.7 +/- 1.6 and PA_lon = 141.5 +/-
4.5 were obtained. We estimate a distance modulus of 18.47 +/- 0.1 mag to the
LMC. Extra-planar features which are in front as well as behind the fitted
plane are identified which match with the optically identified extra-planar
features. The bar of the LMC is found to be part of the disk within 500 pc. The
estimates of the structural parameters are found to be independent of the
photometric bands used for the analysis. We find that the inner disk, within
3.0, is less inclined and has larger value of PA_lon when compared to the outer
disk.Comment: 13 pages, 16 figures, Accepted for publication in the journal
Astronomy & Astrophysic
Alveolar exostosis – revisited: A narrative review of the literature
AbstractAn exostosis is a localized, peripheral overgrowth of bone of unknown etiology of benign nature. It may be a nodular, flat or pedunculated protuberance located on the alveolar surfaces of the jawbones. The etiology of oral bony exostosis is still not clear. Racial, autosomal dominant factors, dental attrition, and even nutritional factors have been suggested as having an influence. In the jaws, depending on the anatomic location they are named as torus palatinus (TP), torus mandibularis (TM), or buccal bone exostoses (BBE). The clinical importance of exostosis lies in surgical removal of these to permit proper flap adaptation, most importantly in the posterior maxilla, and to the potential use of the mandibular and palatal tori as sources of autogenous cortical bone for grafting
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