We present an analysis of the diversity of V -band light-curves of hydrogen-rich type II supernovae. Analyzing a sample of 116 supernovae, several magnitude measurements are defined, together with decline rates at different epochs, and time durations of different phases. It is found that magnitudes measured at maximum light correlate more strongly with decline rates than those measured at other epochs: brighter supernovae at maximum generally have faster declining light-curves at all epochs. We find a relation between the decline rate during the 'plateau' phase and peak magnitudes, which has a dispersion of 0.56 magnitudes, offering the prospect of using type II supernovae as purely photometric distance indicators. Our analysis suggests that the type II population spans a continuum from low-luminosity events which have flat light-curves during the 'plateau' stage, through to the brightest events which decline much faster. A large range in optically thick phase durations is observed, implying a range in progenitor envelope masses at the epoch of explosion. During the radioactive tails, we find many supernovae with faster declining light-curves than expected from full trapping of radioactive emission, implying low mass ejecta. It is suggested that the main driver of light-curve diversity is the extent of hydrogen envelopes retained before explosion. Finally, a new classification scheme is introduced where hydrogen-rich events are typed as simply 'SN II' with an 's 2 ' value giving the decline rate during the 'plateau' phase, indicating its morphological type. Subject headings: (stars:) supernovae: general * Based on observations obtained with the du-Pont and Swope telescopes at LCO, and the Steward Observatory's CTIO60, SO90 and CTIO36 telescopes.

We present ultraviolet through near-infrared (NIR) broadband photometry, and visual-wavelength and NIR spectroscopy of the Type Iax supernova (SN) 2012Z. The data set consists of both early-and late-time observations, including the first late phase NIR spectrum obtained for a spectroscopically classified SN Iax. Simple model calculations of its bolometric light curve suggest SN 2012Z produced ∼0.3 M of 56 Ni, ejected about a Chandrasekhar mass of material, and had an explosion energy of ∼10 51 erg, making it one of the brightest (M B = −18.3 mag) and most energetic SN Iax yet observed. The late phase (+269d) NIR spectrum of SN 2012Z is found to broadly resemble similar epoch spectra of normal SNe Ia; however, like other SNe Iax, corresponding visual-wavelength spectra differ substantially from all supernova types. Constraints from the distribution of intermediate mass elements, e.g., silicon and magnesium, indicate that the outer ejecta did not experience significant mixing during or after burning, and the late phase NIR line profiles suggests most of the 56 Ni is produced during high density burning. The various observational properties of SN 2012Z are found to be consistent with the theoretical expectations of a Chandrasekhar mass white dwarf progenitor that experiences a pulsational delayed detonation, which produced several tenths of a solar mass of 56 Ni during the deflagration burning phase and little (or no) 56 Ni during the detonation phase. Within this scenario only a moderate amount of Rayleigh-Taylor mixing occurs both during the deflagration and fallback phase of the pulsation, and the layered structure of the intermediate mass elements is a product of the subsequent denotation phase. The fact that the SNe Iax population does not follow a tight brightness-decline relation similar to SNe Ia can then be understood in the framework of variable amounts of mixing during pulsational rebound and variable amounts of 56 Ni production during the early subsonic phase of expansion.

This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts, and pseudo-equivalent widths (pW ). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW 2 (Si II 4130) and pW 6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of ≈0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a ≈2-3-σ correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.

The spectral energy distribution of the dark cloud LDN 1622, as measured by Finkbeiner using WMAP data, drops above 30 GHz and is suggestive of a Boltzmann cutoff in grain rotation frequencies, characteristic of spinning dust emission. LDN 1622 is conspicuous in the 31 GHz image we obtained with the Cosmic Background Imager, which is the first centimeter-wave resolved image of a dark cloud. The 31 GHz emission follows the emission traced by the four IRAS bands. The normalized cross-correlation of the 31 GHz image with the IRAS images is higher by 6.6 for the 12 and 25 m bands than for the 60 and 100 m bands: C 12þ25 ¼ 0:76 AE 0:02, and C 60þ100 ¼ 0:64 AE 0:01. The mid-IR-centimeter-wave correlation in LDN 1622 is evidence for very small grain (VSG) or continuum emission at 26-36 GHz from a hot molecular phase. In dark clouds and their photon-dominated regions (PDRs), the 12 and 25 m emission is attributed to stochastic heating of the VSGs. The mid-IR and centimeter-wave dust emissions arise in a limb-brightened shell coincident with the PDR of LDN 1622, where the incident UV radiation from the Ori OB 1b association heats and charges the grains, as is required for spinning dust.