Photometry of SN 2002ic and Implications for the Progenitor Mass-Loss History

We present new pre-maximum and late-time optical photometry of the Type Ia/IIn supernova 2002ic. These observations are combined with the published V-band magnitudes of Hamuy et al. (2003) and the VLT spectrophotometry of Wang et al. (2004) to construct the most extensive light curve to date of this unusual supernova. The observed flux at late time is significantly higher relative to the flux at maximum than that of any other observed Type Ia supernova and continues to fade very slowly a year after explosion. Our analysis of the light curve suggests that a non-Type Ia supernova component becomes prominent $\sim20$ days after explosion. Modeling of the non-Type Ia supernova component as heating from the shock interaction of the supernova ejecta with pre-existing circumstellar material suggests the presence of a $\sim1.7 10^{15}$ cm gap or trough between the progenitor system and the surrounding circumstellar material. This gap could be due to significantly lower mass-loss $\sim15 (v_w/10 km/s)^{-1}$ years prior to explosion or evacuation of the circumstellar material by a low-density fast wind. The latter is consistent with observed properties of proto-planetary nebulae and with models of white-dwarf + asymptotic giant branch star progenitor systems with the asymptotic giant branch star in the proto-planetary nebula phase.Comment: accepted for publication in Ap

Dark energy FRW cosmology - dynamical system reconstruction

We develop a simple method of dark energy reconstruction using a geometrical form of the luminosity-distance relation. In this method the FRW dynamical system with dark energy is reconstructed instead of the equation of state parameter. We give several examples which illustrate the usefulness of our method in fitting the redshift transition from the decelerating to accelerating phase as the value of the Hubble function at the transition.Comment: Talk presented at Spanish Relativity Meeting 2007, Puerto de la Cruz, Tenerife, Spain, 10-14 September 200

Environmental and correlative significance of a non-marine algal limestone (Westphalian D), Sydney Coalfield, Cape Breton Island, Nova Scotia

The occurrence of an algal limestone containing stromatolites within the Morien Group (Sydney Coalfield) is reported for the first time. Three distinct morphologic forms of stromatolite (pinnacle, mat and detached) and their stratigraphic variation are described. Variation in clast type and size, biota and elements within the algal limestone is interpreted as evidence for the growth of stromatolites on the shore of an ephemeral, fresh to brackish lake, subject to fluctuating water levels. Pinnacle and mat forms developed on substrate irregularities. A bivalve and ostracode fauna in mudatones and siltstones above and below the algal limestone indicates a correlation with the Anthraconauta tenuis chronozone of Britain (Westphalian D) and corroborates on age derived from associated macro- and microflora. RÉSUMÉ Four la première fols, on rapporte la présence de stromatolithes dans un calcaire à algues du groupe Morien (houillière de Sydney). Trois types morphologlques de stromatolithes (pinacle, paillasson, détache) et leur variation stratigraphique sont décrité. On interprète la variation dans la faune, la flore, les éléments, le type et la grosseur des fragment à au seln du calcaire à algues comme preuve de la croissance des stromatolithes sur les rives d'un lac éphemère, d'eau douce à saunâtre et sujet à des variations périodiques du niveau d'eau. Les formes en pinacle et en paillasson s'établirent sur les irrégularités du substrat. Une faune de bivalves et d'ostracodes dans lea roches arglleuses superposées et sous-jacentes au calcaire à algues est corrélative avec la zone chronologique Anthraconauta tenuis de Grande-Bretagne (Westphalien D) et confirme l'âge déduit de la macro et la micro flore. [Traduit par le journal

SweetSpot: Near-Infrared Observations of Thirteen Type Ia Supernovae from a New NOAO Survey Probing the Nearby Smooth Hubble Flow

We present 13 Type Ia supernovae (SNe Ia) observed in the restframe near-infrared (NIR) from 0.02 < z < 0.09 with the WIYN High-resolution Infrared Camera (WHIRC) on the WIYN 3.5-m telescope. With only 1-3 points per light curve and a prior on the time of maximum from the spectrum used to type the object we measure an H-band dispersion of spectroscopically normal SNe Ia of 0.164 mag. These observations continue to demonstrate the improved standard brightness of SNe Ia in H-band even with limited data. Our sample includes two SNe Ia at z ~ 0.09, which represent the most distant restframe NIR H-band observations published to date. This modest sample of 13 NIR SNe Ia represent the pilot sample for "SweetSpot" - a three-year NOAO Survey program that will observe 144 SNe Ia in the smooth Hubble flow. By the end of the survey we will have measured the relative distance to a redshift of z ~ 0.05 to 1%. Nearby Type Ia supernova (SN Ia) observations such as these will test the standard nature of SNe Ia in the restframe NIR, allow insight into the nature of dust, and provide a critical anchor for future cosmological SN Ia surveys at higher redshift.Comment: 36 pages, 8 figures, Submitted to Ap

Novae as a Mechanism for Producing Cavities around the Progenitors of SN 2002ic and Other SNe Ia

We propose that a nova shell ejected from a recurrent nova progenitor system created the evacuated region around the explosion center of SN 2002ic. In this picture, periodic shell ejections due to nova explosions on a white dwarf sweep up the slow wind from the binary companion, creating density variations and instabilities that lead to structure in the circumstellar medium (CSM). Our model naturally explains the observed gap between the supernova explosion center and the CSM in SN 2002ic, accounts for the density variations observed in the CSM, and resolves the coincidence problem of the timing of the explosion of SN 2002ic with respect to the apparent cessation of mass-loss in the progenitor system. We also consider such nova outburst sweeping as a generic feature of Type Ia supernovae with recurrent nova progenitors.Comment: Accepted to ApJL. 11 pages, 1 tabl

Dark Energy Accretion onto a Black Hole in an Expanding Universe

By using the solution describing a black hole embedded in the FLRW universe, we obtain the evolving equation of the black hole mass expressed in terms of the cosmological parameters. The evolving equation indicates that in the phantom dark energy universe the black hole mass becomes zero before the Big Rip is reached.Comment: 7 pages, no figures, errors is correcte

Time stability of asymmetric Fabry-Perot modulator based analog lightwave links

Lightwave links for analog signal transfer are being developed and evaluated for application in high-density interconnects. The reflective links are based on compact electro-optic intensity modulators connected by ribbons of single-mode fibres to remotely located transceivers (lasers and photoreceivers) and read-out electronics. For long-term characterization, four Asymmetric Fabry-Perot Modulator (AFPM) prototypes were continuously operated and monitored over a period of eight monthes. The collected data allow evaluation of the system time stability and simulation of the possible recalibration procedures. The recalibration requirements to achieve the desirable accuracy and reliability are inferred statistically