Supernova SN 2012dn: A spectroscopic clone of SN 2006gz

We present optical and UV analysis of the luminous type Ia supernova SN 2012dn covering the period $\sim -$11 to +109 days with respect to the $B$ band maximum, that occurred on JD 2456132.89 $\pm$ 0.19, with an apparent magnitude of $m_{B}^\text{max}$ = 14.38 $\pm$ 0.02. The absolute magnitudes at maximum in $B$ and $V$ bands are $M_{B}^\text{max} = -19.52 \pm 0.15$ and $M_{V}^\text{max} = -19.42 \pm 0.15$, respectively. SN 2012dn is marginally luminous compared to normal type Ia supernovae. The peak bolometric luminosity of $\log L_\text{bol}^\text{max} = 43.27 \pm 0.06$ erg s$^{-1}$ suggests that $0.82 \pm 0.12$ M$_\odot$ of $^{56}$Ni was synthesized in the explosion. The decline rate $\Delta m_{15}(B)_\text{true}= 0.92 \pm 0.04$ mag is lower than that of normal type Ia supernovae, and similar to the luminous SN 1991T. However, the photometric and spectroscopic behaviour of SN 2012dn is different from that of SN 1991T. Early phase light curves in $R$ and $I$ bands are very broad. The $I$ band peak has a plateau-like appearance similar to the super-Chandra SN 2009dc. Pre-maximum spectra show clear evidence of C\,{\sc ii} 6580 \AA\, line, indicating the presence of unburned materials. The velocity evolution of C\,{\ sc ii} line is peculiar. Except for the very early phase ($\sim-$13 d), the C\,{\sc ii} line velocity is lower than the velocity estimated using the Si\,{\sc ii} line. During the pre-maximum and close to maximum phase, to reproduce observed shape of the spectra, the synthetic spectrum code {\sc syn++} needs significantly higher blackbody temperature than those required for normal type Ia events. The photospheric velocity evolution and other spectral properties are similar to those of the carbon-rich SN 2006gz.Comment: Accepted for publication in MNRAS, 19 pages, 20 figure

Exploring the optical behaviour of a type Iax supernova SN 2014dt

We present optical photometric (upto $\sim$410 days since $B$$_{max}$) and spectroscopic (upto $\sim$157 days since $B$$_{max}$) observations of a Type Iax supernova (SN) 2014dt located in M61. SN 2014dt is one of the brightest and closest (D $\sim$ 20 Mpc) discovered Type Iax SN. SN 2014dt best matches the light curve evolution of SN 2005hk and reaches a peak magnitude of $M$$_B$ $\sim$-18.13$\pm$0.04 mag with $\Delta m_{15}$ $\sim$1.35$\pm 0.06$ mag. The early spectra of SN 2014dt are similar to other Type Iax SNe, whereas the nebular spectrum at 157 days is dominated by narrow emission features with less blending as compared to SNe 2008ge and 2012Z. The ejecta velocities are between 5000 to 1000 km sec$^{-1}$ which also confirms the low energy budget of Type Iax SN 2014dt as compared to normal Type Ia SNe. Using the peak bolometric luminosity of SN 2005hk we estimate $^{56}$Ni mass of $\sim$0.14 M$_{\odot}$ and the striking similarity between SN 2014dt and SN 2005hk implies that a comparable amount of $^{56}$Ni would have been synthesized in the explosion of SN 2014dt.Comment: 12 figures, 7 tables, Accepted for publication in MNRA

The hot Gamma-Doradus and Maia stars

The hot $\gamma$~Doradus stars have multiple low frequencies characteristic of $\gamma$~Dor or SPB variables, but are located between the red edge of the SPB and the blue edge of the $\gamma$~Dor instability strips where all low-frequency modes are stable in current models of these stars. Though $\delta$~Sct stars also have low frequencies, there is no sign of high frequencies in hot $\gamma$~Dor stars. We obtained spectra to refine the locations of some of these stars in the H-R diagram and conclude that these are, indeed, anomalous pulsating stars. The Maia variables have multiple high frequencies characteristic of $\beta$~Cep and $\delta$~Sct stars, but lie between the red edge of the $\beta$~Cep and the blue edge of the $\delta$~Sct instability strips. We compile a list of all Maia candidates and obtain spectra of two of these stars. Again, it seems likely that these are anomalous pulsating stars which are currently not understood.Comment: 10 pages, 8 figures, 2016, MNRAS, 460, 131

Time-resolved photometric and spectroscopic analysis of a luminous Ap star HD103498

We present the results on the photometric and spectroscopic monitoring of a luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using three-channel fast photometer attached to the 1.04-m optical telescope at ARIES, Nainital. The photometric data of five nights of year 2007 show clear signature of 15-min periodicity. However, the follow-up observations during 2007--2009 could not repeated any such periodicity. To confirm the photometric light variations, the time-series spectroscopic observations were carried out with the 2.56-m Nordic Optical Telescope (NOT) at La Palma on February 2, 2009. Any radial velocity variations were absent in this data set which is in full agreement with the photometric observations taken near the same night. Model atmosphere and abundance analysis of HD103498 show that the star is evolved from the Main Sequence and its atmospheric abundances are similar to two other evolved Ap stars HD133792 and HD204411: large overabundances of Si, Cr, and Fe and moderate overabundances of the rare-earth elements. These chemical properties and a higher effective temperature distinguish HD103498 from any known roAp star.Comment: 8 Figures, 2 Tables, 9 Pages, Accepted for publication in MNRA

A spectroscopic analysis of the chemically peculiar star HD207561

In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is slightly evolved from the main-sequence and located well within the delta-Scuti instability strip. The abundance analysis indicates the star has slight under-abundances of Ca and Sc and mild over-abundances of iron-peak elements. The spectro-polarimetric study of HD207561 shows that the effective magnetic field is within the observational error of 100 gauss (G). The spectroscopic analysis revealed that the star has most of the characteristics similar to an Am star, rather than an Ap star, and that it lies in the delta-Scuti instability strip; hence roAp pulsations are not expected in HD207561, but low-overtone modes might be excited.Comment: 8 pages, 7 figures, 3 tables. Accepted for pubblication in MNRA

A Hybrid Microgrid Operated by PV Wind and Diesel Generator with Advanced Control Strategy

All for a local area that gets its power from a solitary diesel generator (DG), this examination presents an efficient power energy choice for a microgrid. A twin feed enlistment generator draws power from a sun oriented photovoltaic (PV) cluster and the breeze to run this microgrid's electrical gear (DFIG). Two voltage source converters (VSCs) are sequentially coupled on the rotor side of the DFIG and share a DC transport that at last prompts the photovoltaic modules. Likewise associated with a similar DC transport as the DFIG stator is a bidirectional buck/help DC converter and a battery energy capacity (BES) to retain any overflow power. Most extreme energy collecting from the breeze and sun is accomplished by regulation of the bidirectional buck/help DC converter and the rotor side VSC. A changed form of the irritate and notice (P&O) technique is introduced for of expanding the energy result of a PV framework. Endeavors are being made to change VSC on the heap side to further develop DG's eco-friendliness. The ideal fuel-use reference DG power result may now be resolved utilizing a new, more broad methodology. Using the Sim Power Systems toolbox in MATLAB, we model and simulate many scenarios, including fluctuating wind speeds, fluctuating insolation, the impact of fluctuating load conditions on a bidirectional converter, and an unbalanced nonlinear load linked at the point of common coupling (PCC). Finding sinusoidal and balanced DG and DFIG stator currents

Chemical composition of Abrus precatorius L. seeds

Aims: A. precatorius seed powder is traditionally used in Ayurveda, Siddha and Unani medicine. The objective of present work is to describe the oil, starch, protein, polyphenol and mineral composition of A. precatorius seeds. Methodology: Legumes from A. precatorius were collected, and seeds were manually separated. Dried seeds in powder form were employed for the various analyses: solvent extraction was used for elucidation of the oil percentage value; starch content was determined by the enzymatic method; total polyphenol and flavonoid contents were spectrophotometrically analyzed using Folin-Ciocalteu and aluminum chloride as the color developing reagents, respectively; and X-ray fluorescence (XRF) was used for the mineral contents assessment. Results: The seed kernel consisted of stored oil (3.2%), protein (92.0%) and starch (4.8%). The total polyphenol and flavonoid contents were 24710 and 2520 mg/kg (dw). A remarkably high content of polyphenols was observed in the seed coat and the seed pod. P, S and (mainly) K nutrients were hyper-accumulated in the seed kernel. The seeds showed a glass transition at -21°C, two endothermic peaks at 109°C (dehydration and protein unfolding) and at 209°C, and a calorific value (~406 kcal/100 g dw) that exceeded those of Pisum sativum L., Lens culinaris Medik. and other common pulses. Conclusions: The seed kernel from A. precatorius was mainly composed of stored protein, with low oil and starch contents. High contents of polyphenols, K, Mg, Ca and Fe were found in the seeds. Heavy metals were below the safety limits established for human consumption