Subhash Bose

Supernova 2012aw - a high-energy clone of archetypal type IIP SN 1999em

We present densely-sampled UBV RI/griz photometric and low-resolution (6-10u optical spectroscopic observations from 4 to 270 days after explosion of a newly discovered type II SN 2012aw in a nearby (�9.9 Mpc) galaxy M95. The light-curve characteristics of apparent magnitudes, colors, bolometric luminosity and the presence and evolution of prominent spectral features are found to have striking similarity with the archetypal IIP SNe 1999em, 1999gi and 2004et. The early time observations of SN 2012aw clearly detect minima in the light-curve of V , R and I bands near 37 days after explosion and this we suggest to be an observational evidence for emergence of recombination phase. The mid-plateau MV magnitude ( 16.67 ± 0.04) lies in between the bright (� 18) and subluminous (� 15) IIP SNe. The mass of nickel is 0.06±0.01 M⊙. The SYNOW modelling of spectra indicate that the value and evolution of photospheric velocity is similar to SN 2004et, but about �600 kms −1 higher than that of SNe 1999em and 1999gi at comparable epochs. This trend is more apparent in the line velocities of Hα and Hβ. A comparison of ejecta velocity properties with that of existing radiation-hydrodynamical simulations indicate that the energy of explosion lies in the range 1-2×10 51 ergs; a further comparison of nebular phase [Oi] doublet luminosity with SNe 2004et and 1987A indicate that the mass of progenitor star is about 14-15 M⊙. The presence of high-velocity absorption features in the mid-to-late plateau and possibly in early phase spectra show signs of interaction between ejecta and the circumstellar matter; being consistent with its early-time detection at X-ray and radio wavebands.

Distance Determination to Eight Galaxies Using Expanding Photosphere Method

Type IIP supernovae (SNe) are recognized as independent extragalactic distance indicators; however, keeping in mind the diverse nature of their observed properties as well as the availability of good quality data, more and newer events need to be tested for their applicability as reliable distance indicators. We use early photometric and spectroscopic data of eight Type IIP SNe to derive distances to their host galaxies by using the expanding photosphere method (EPM). For five of these, the EPM is applied for the first time. In this work, we improved EPM application by using SYNOW estimated velocities and by semi-deconvolving the broadband filter responses while deriving color temperatures and blackbody angular radii. We find that the derived EPM distances are consistent with that derived using other redshift-independent methods.

SN 2013ej - A type IIL supernova with weak signs of interaction

We present optical photometric and spectroscopic observations of supernova 2013ej. It is one of the brightest type II supernovae exploded in a nearby (

SN 2013ab : A normal type IIP supernova in NGC 5669

\sim 10

Light curve and spectral evolution of the Type IIb supernova 2011fu

Mpc) galaxy NGC 628. The light curve characteristics are similar to type II SNe, but with a relatively shorter (

Probing final stages of stellar evolution with x-ray observations of SN 2013ej

\sim85

SN 2012aa: A transient between Type Ibc core-collapse and superluminous supernovae

day) and steeper (

Photometric and polarimetric observations of fast declining Type II supernovae 2013hj and 2014G

\sim1.7

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

mag (100 d)

Unveiling the structure of the progenitors of type-IIP Supernovae through multi-waveband observations

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