Temperatures and metallicities of M giants in the galactic Bulge from low-resolution K-band spectra

With the existing and upcoming large multi-fibre low-resolution spectrographs, the question arises how precise stellar parameters such as Teff and [Fe/H] can be obtained from low-resolution K-band spectra with respect to traditional photometric temperature measurements. Until now, most of the effective temperatures in galactic Bulge studies come directly from photometric techniques. Uncertainties in interstellar reddening and in the assumed extinction law could lead to large systematic errors. We aim to obtain and calibrate the relation between Teff and the $\rm ^{12}CO$ first overtone bands for M giants in the galactic Bulge covering a wide range in metallicity. We use low-resolution spectra for 20 M giants with well-studied parameters from photometric measurements covering the temperature range 3200 < Teff < 4500 K and a metallicity range from 0.5 dex down to -1.2 dex and study the behaviour of Teff and [Fe/H] on the spectral indices. We find a tight relation between Teff and the $\rm ^{12}CO(2-0)$ band with a dispersion of 95 K as well as between Teff and the $\rm ^{12}CO(3-1)$ with a dispersion of 120 K. We do not find any dependence of these relations on the metallicity of the star, making them relation attractive for galactic Bulge studies. This relation is also not sensitive to the spectral resolution allowing to apply this relation in a more general way. We also found a correlation between the combination of the NaI, CaI and the $\rm ^{12}CO$ band with the metallicity of the star. However this relation is only valid for sub-solar metallicities. We show that low-resolution spectra provide a powerful tool to obtain effective temperatures of M giants. We show that this relation does not depend on the metallicity of the star within the investigated range and is also applicable to different spectral resolution.Comment: 6 pages, accepted for publication in Astronomy&Astrophysic

Shrimp fishery by stake nets in Cochin barmouth area with special reference to Metapenaeus monoceros (Fabricius)

A general account on the shrimp fishery of Cochin backwaters based on stake net catch landed at Thoppumpady and Vypeen during January-December 1991 is give

Observations on the fishery of banana prawn along the North Kanara Coast with notes on its schooling behavior and migration

The article provides observational details about the migration and schooling behavior of banana prawn (Fenneropenaeus merguiensis) in relation to fishery. The sporadic occurrence of the species in different landing centers of Karnataka coast successively during June to August of 1984 was suggested to be a possible cause of migratory behavior of the shoal. The study demands extensive large scale tagging experiments to validate the fact

Fishery of the speckled shrimp Metapenaeus monoceros (Fabricius) along Cochin coast

The average annual landing of this species at Cochin Fisheries Harbour was 192 tonnes with catch per unit effort of 3.67 kg. Between 1991 and 93 the catch and catch rate increased by 5.33 and 37.97% respectively. As the speckled shrimp is nocturnal, success of its fishery depends on trawling during nights in grounds of 30-45 meters iepth range. The fishing season extends from December to May with peak availability during March -May

Categorification via blocks of modular representations for slsl_n

Bernstein, Frenkel, and Khovanov have constructed a categorification of tensor products of the standard representation of $\mathfrak{sl}_2$, where they use singular blocks of category $\mathcal{O}$ for $\mathfrak{sl}_n$ and translation functors. Here we construct a positive characteristic analogue using blocks of representations of $\mathfrak{sl}_n$ over a field $\textbf{k}$ of characteristic $p$ with zero Frobenius character, and singular Harish-Chandra character. We show that the aforementioned categorification admits a Koszul graded lift, which is equivalent to a geometric categorification constructed by Cautis, Kamnitzer, and Licata using coherent sheaves on cotangent bundles to Grassmanians. In particular, the latter admits an abelian refinement. With respect to this abelian refinement, the stratified Mukai flop induces a perverse equivalence on the derived categories for complementary Grassmanians. This is part of a larger project to give a combinatorial approach to Lusztig's conjectures for representations of Lie algebras in positive characteristic

M Giants with IGRINS II. Chemical Evolution of Fluorine at High Metallicities

The origin and evolution of fluorine in the Milky Way galaxy is still in debate. In particular, the increase of the [F/Fe] in metal-rich stars found from near-IR HF-lines is challenging to explain theoretically. We determine the fluorine abundances from 50 M giants in the solar neighbourhood spanning a broad range of metallicities (-0.9<[Fe/H]<0.25 dex). These stars are cool enough to have an array of HF lines in the K band. We observed the stars with the IGRINS and investigate each of ten HF molecular lines in detail. Based on a detailed line-by-line analysis of ten HF lines, we find that the R19, R18 and R16 lines should primarily be used for abundance analysis. The R15, R14 and R13 lines can also be used, but the trends based on these lines show increasing dependencies with the stellar parameters. The strongest HF lines, namely R12, R11, R9 and R7 should be avoided since the abundances from them show significant trends with the stellar parameters, and a high sensitivity to variations in the microturbulence, especially for coolest metal-rich stars. This leads to a huge scatter and high fluorine abundances for supersolar metallicity stars, not seen in the trends from the weaker lines for the same stars. When estimating the final mean fluorine abundance trend versus metallicity, we neglect the fluorine abundances from the four strongest lines (R7, R9, R11 and R12) for all stars and use only those derived from R16, R18, and R19 for the coolest metal-rich stars. We confirm the flat trend of [F/Fe] found in other studies in the metallicity range of -1.0<[Fe/H]<0.0. We also find a slight enhancement at supersolar metallicities (0<[Fe/H]<0.15) but we cannot confirm the upward trend seen at [Fe/H]>0.25. We need more observations of M giants at super solar metallicities with a spectrometer like IGRINS to confirm if the metal-rich fluorine abundance upturn is real or not.Comment: 11 pages, 6 figures, Accepted for publication in A&

Innovative exploitation of deepsea crustaceans along the Kerala coast

Exploratory surveys carried out since 1965 by fishing vessels belonging to different governmental agencies have revealed the occurrence of commercially Important deep sea crustaceans in trawlable concentration along the south-west coast of India

The "karikkadi" fishery of Kerala

Parapenaeopsis stylifera, (called 'Karikkadi Chemmeen' ) is the most important species of prawn contributing to the commercial fishery of Kerala coast. An experimental shrimp trawling conducted for a period of two years has shown that during the non-monsoon period (September/October to May) most of the shrimp stocks occupy the coastal waters within the 20 m depth contour. With the commencement of southwest monsoon and the consequent changes in the environmental conditions, the prawns leave the inshore areas in large numbers to the deeper zones. The wide annual fluctuations observed at important centres, the occurrence of juvenile prawns in large quantities noticed quite often in the fishery, call for proper management and conservation measures

Observations on the prawn fishery off Sakthikulangara in the light of monsoon trawling ban

Sakthikulangara is the most important prawn landing center in Kerala. Study on the prawn fishery exploited by shrimp trawlers for a period of 15 years during 1986-200b at rnis centre indicated a decline in the landings in the first five year period followed by improved fishery between 1991 and 1995. However, decline in catch and catch rate was registered in the next 5 years. Contribution of Sakthikulangara to the Kerala prawn fishery declined from 51% in seventies to 30% in eighties and 24% in nineties. 'Karikkadi' (Parapenaeopsis stylifera) contributed to 68% of the average annual production during 1986 - 2000. Extension of trawling to middle shelf waters and introduction of night trawling transformed the complexion of prawn fishery in the nineties with the addition of nonconventional species such as Trachypenaeus curuirostris, Solenocera choprai and Penaeus canaliculatus. Analysis of data on prawn fishery at Sakthikulangara for a period of 20 years (1981-2000) to study the impact of ban on monsoon trawling has indicated that trawling ban for a short duration of 45 days in the first half of the season is advantageous to the 'Karikkadi' fishery