The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.

Early‐time optical observations of supernova (SN) 2005cs in the Whirlpool Galaxy (M51) are reported. Photometric data suggest that SN 2005cs is a moderately underluminous Type II plateau SN (SN IIP). The SN was unusually blue at early epochs (U−B≈−0.9 about three days after explosion) which indicates very high continuum temperatures. The spectra show relatively narrow P Cygni features, suggesting ejecta velocities lower than observed in more typical SNe IIP. The earliest spectra show weak absorption features in the blue wing of the He i 5876‐Å absorption component and, less clearly, of Hβ and Hα. Based on spectral modelling, two different interpretations can be proposed: these features may either be due to high‐velocity H and He i components, or (more likely) be produced by different ions (N ii, Si ii). Analogies with the low‐luminosity, 56Ni‐poor, low‐velocity SNe IIP are also discussed. While a more extended spectral coverage is necessary in order to determine accurately the properties of the progenitor star, published estimates of the progenitor mass seem not to be consistent with stellar evolution models.

A system of ferromagnetic β phase Ni–Co–Al alloys with an ordered B2 structure that exhibits the shape memory effect has been developed. The alloys of this system within the composition range Ni (30–45 at. %) Co–(27–32 at. %) Al, undergo a paramagnetic/ferromagnetic transition as well as a thermoelastic martensitic transformation from the β to the β′(L10) phase. The Curie and the martensitic start temperatures in the β phase can be controlled independently to fall within the range of 120–420 K. The specimens from some of the alloys undergoing martensitic transformation from ferromagnetic β phase to ferromagnetic β′ phase are accompanied by the shape memory effect. These ferromagnetic shape memory alloys hold great promise as new smart materials.

Aims. We present a study of the optical and near-infrared (NIR) properties of the Type Ia Supernova (SN Ia) 2003du.Methods. An extensive set of optical and NIR photometry and low-resolution long-slit spectra was obtained using a number of facilities. The observations started 13 days before B-band maximum light and continued for 480 days with exceptionally good time sampling. The optical photometry was calibrated through the S-correction technique. Results. The UBVRIJHK light curves and the color indices of SN 2003du closely resemble those of normal SNe Ia. SN 2003du reached a B-band maximum of 13.49 ± 0.02 mag on JD2 452 766.38 ± 0.5. We derive a B-band stretch parameter of 0.988 ± 0.003, which corresponds to ∆m 15 = 1.02 ±0.05, indicative of a SN Ia of standard luminosity. The reddening in the host galaxy was estimated by three methods, and was consistently found to be negligible. Using an updated calibration of the V and JHK absolute magnitudes of SNe Ia, we find a distance modulus µ = 32.79 ± 0.15 mag to the host galaxy, UGC 9391. We measure a peak uvoir bolometric luminosity of 1.35(±0.20) × 10 43 erg s −1 and Arnett's rule implies that M56 Ni 0.68 ± 0.14 M of 56 Ni was synthesized during the explosion. Modeling of the uvoir bolometric light curve also indicates M56 Ni in the range 0.6−0.8 M . The spectral evolution of SN 2003du at both optical and NIR wavelengths also closely resembles normal SNe Ia. In particular, the Si ii ratio at maximum R(Si ii) = 0.22 ± 0.02 and the time evolution of the blueshift velocities of the absorption line minima are typical. The pre-maximum spectra of SN 2003du showed conspicuous high-velocity features in the Ca ii H&K doublet and infrared triplet, and possibly in Si ii λ6355, lines. We compare the time evolution of the profiles of these lines with other well-observed SNe Ia and we suggest that the peculiar pre-maximum evolution of Si ii λ6355 line in many SNe Ia is due to the presence of two blended absorption components.

Extensive optical and near‐infrared (NIR) observations of the Type IIb supernova (SN IIb) 2008ax are presented, covering the first year after the explosion. The light curve is mostly similar in shape to that of the prototypical SN IIb 1993J, but shows a slightly faster decline rate at late phases and lacks the prominent narrow early‐time peak of SN 1993J. From the bolometric light curve and ejecta expansion velocities, we estimate that about 0.07–0.15 M⊙ of 56Ni was produced during the explosion and that the total ejecta mass was between 2 and 5 M⊙, with a kinetic energy of at least 1051 erg. The spectral evolution of SN 2008ax is similar to that of SN Ib/IIb 2007Y, exhibiting high‐velocity Ca ii features at early phases and signs of ejecta–wind interaction from Hα observations at late times. NIR spectra show strong He i lines similar to SN Ib 1999ex and a large number of emission features at late times. Particularly interesting are the strong, double‐peaked He i lines in late NIR spectra, which – together with the double‐peaked [O i] emission in late optical spectra – provide clues for the asymmetry and large‐scale Ni mixing in the ejecta.

We present the one-year long observing campaign of SN 2012A which exploded in the nearby (9.8 Mpc) irregular galaxy NGC 3239. The photometric evolution is that of a normal type IIP supernova, but the plateau is shorter and the luminosity not as constant as in other supernovae of this type. The absolute maximum magnitude, with M B = −16.23 ± 0.16 mag, is close to the average for SN IIP. Thanks also to the strong U V flux in the early phase, SN 2012A reached a peak luminosity of about 2 × 10 42 erg s −1 , which is brighter than those of other SNe with a similar 56 Ni mass. The latter was estimated from the luminosity in the exponential tail of the light curve and found to be M( 56 Ni) = 0.011 ± 0.004 M ⊙ , which is intermediate between standard and faint SN IIP.The spectral evolution of SN 2012A is also typical of SN IIP, from the early spectra dominated by a blue continuum and very broad (∼ 10 4 km s −1 ) Balmer lines, to the late-photospheric spectra characterized by prominent P-Cygni features of metal lines (Fe II, Sc II, Ba II, Ti II, Ca II, Na I D). The photospheric velocity is moderately low, ∼ 3 × 10 3 km s −1 at 50 days, for the low optical depth metal lines. The nebular spectrum obtained 394 days after the shock breakout shows the typical features of SNe IIP and the strength of the [O I] doublet suggests a progenitor of intermediate mass, similar to SN 2004et (∼ 15 M ⊙ ).A candidate progenitor for SN 2012A has been identified in deep, pre-explosion K ′ -band Gemini North (NIRI) images, and found to be consistent with a star with a bolometric magnitude −7.08±0.36 (log L/L ⊙ = 4.73±0.14 dex). The magnitude of the recovered progenitor in archival images points toward a moderate-mass 10.5 +4.5 −2 M ⊙ star as the precursor of SN 2012A.The explosion parameters and progenitor mass were also estimated by means of a hydrodynamical model, fitting the bolometric light curve, the velocity and the temperature evolution. We found a best fit for a kinetic energy of 0.48 foe, an initial radius of 1.8 × 10 13 cm and ejecta mass of 12.5 M ⊙ . Even including the mass for the compact remnant, this appears fully consistent with the direct measurements given above.

Ultraviolet, optical and near‐infrared observations of the Type IIP supernova (SN) 2007od, covering from maximum light to late phases, allow detailed investigation of different physical phenomena in the expanding ejecta. These data turn this object into one of the most peculiar SNe IIP ever studied. The early light curve of SN 2007od is similar to that of a bright IIP, with a short plateau, a bright peak (MV=−18 mag), but a very faint late‐time optical light curve. However, with the inclusion of mid‐IR observations during the radioactive tail, we derive an ejected mass of 56Ni of M(56Ni) ∼2 × 10−2 M⊙. By modelling the bolometric light curve, ejecta expansion velocities and blackbody temperature, we estimate a total ejected mass of 5–7.5 M⊙ with a kinetic energy of at least 0.5 × 1051 erg. The early spectra reveal a boxy Hα profile and high‐velocity features of the Balmer series that suggest the possible interaction of the ejecta with a close circumstellar matter (CSM). The interaction with the CSM and the presence of dust formed inside the ejecta are evident in the late‐time spectra. The episodes of mass‐loss shortly before explosion, the bright plateau, the relatively small amount of 56Ni and the faint [O i] emission observed in the nebular spectra are consistent with a super‐asymptotic giant branch progenitor (M∼ 9.7–11 M⊙).

Lead-free (Na 0:5 K 0:5 )NbO 3 (NKN) powders and thin films were fabricated from stoichiometric (Na/K ¼ 50=50), 4 mol % excess (52/52, 53/51, and 55/49), and 10 mol % excess (55/55, 56/54, 58/52, and 60/50) precursor solutions by the sol-gel process. The NKN55/55 powder heat-treated at 800 C showed an orthorhombic phase and rectangular grains whose size was estimated to be about 300 nm. With increasing Na/K ratio, grain size increased to about 1 mm and the cubic-tetragonal (T c ) phase transition peak emerged at 392 C in a differential thermal analysis (DTA) curve. On the other hand, single-phase NKN thin films were fabricated at 600 C from the (Na,K)-excess precursor solutions (58/52 and 60/50). In particular, the NKN58/ 52 thin film showed a low leakage current density (10 À7 A/cm 2 at 40 kV/cm), and the maximum polarization P max and dielectric constant " r at 1 kHz were 9.1 mC/cm 2 and 725, respectively.