Extraordinary Late‐Time Infrared Emission of Type IIn Supernovae

Near-infrared observations are presented for five Type IIn supernovae (SN 1995N, SN 1997ab, SN 1998S, SN 1999Z, and SN 1999el) that exhibit strong infrared excesses at late times (t \u3e 100 days). H- and K-band emission from these objects is dominated by a continuum that rises toward longer wavelengths. The data are interpreted as thermal emission from dust, probably situated in a preexisting circumstellar nebula. The IR luminosities implied by single-temperature blackbody fits are quite large, \u3e1041-1042 ergs s-1, and the emission evolves slowly, lasting for years after maximum light. For SN 1995N, the integrated energy release via IR dust emission was ≈0.5-1 × 1050 ergs. A number of dust heating scenarios are considered, the most likely being an infrared echo powered by X-ray and UV emissions from the shock interaction with a dense circumstellar medium

Signature of Electron Capture in Iron‐rich Ejecta of SN 2003du

Late-time near-infrared and optical spectra of the normal-bright Type Ia supernova 2003du about 300 days after the explosion are presented. At this late epoch, the emission profiles of well-isolated [Fe II] lines (in particular that of the strong 1.644 μm feature) trace out the global kinematic distribution of radioactive material in the expanding supernova ejecta. In SN 2003du, the 1.644 μm [Fe II] line seems to show a flat-topped profile, indicative of a thick but hollow-centered expanding shell, rather than a strongly peaked profile that would be expected from a center-filled distribution. Based on detailed models for exploding Chandrasekhar-mass white dwarfs, we show that the feature is consistent with spherical explosion models. Our model predicts a central region of nonradioactive electron capture elements up to 2500-3000 km s-1 as a consequence of burning under high density and an extended region of radioactive 56Ni up to 9000-10,000 km s-1. Furthermore, our analysis indicates that the 1.644 μm [Fe II] line profile is not consistent with strong mixing between the regions of electron-capture isotopes and the 56Ni layers, as is predicted by detailed three-dimensional models for nuclear deflagration fronts. We discuss the possibility that the flat-topped profile could be produced as a result of an infrared catastrophe and conclude that such an explanation is unlikely. We discuss the limitations of our analysis and place our results into context by comparison with constraints on the distribution of radioactive 56Ni in other SNe Ia and briefly discuss the potential implications of our result for the use of SNe Ia as cosmological standard candles

Immunohistochemical Examination of a Resected Advanced Hilar Cholangiocarcinoma Arising in a 29-Year-Old Male without Primary Sclerosing Cholangitis

A 29-year-old man with advanced hilar cholangiocarcinoma was successfully treated with an extended right lobectomy. The carbohydrate antigen 19-9 (CA19-9) level was elevated to 939 IU/l, and the pathological findings revealed moderately differentiated tubular adenocarcinoma which involved almost the entire thickness of the hepatic duct and the adjacent liver tissue (T3) and which was associated with lymph node metastasis (N1). It was a stage IIB (T3N1M0) tubular adenocarcinoma according to UICC pathological staging. Immunohistochemical examination revealed that Ki-67, cyclin D1, and MMP-7 were positive, and 14-3-3σ and p27 were negative. The pathological and immunohistochemical findings indicated high malignant potential indicating poor prognosis. We administrated the postoperative adjunct gemcitabine combined with S-1 chemotherapy. The patient is alive without recurrence and doing well two years after surgery. We also review other reports of cholangiocarcinoma patients aged less than 30 years

A Wide Symbiotic Channel to Type Ia Supernovae

As a promising channel to Type Ia supernovae (SNe Ia), we have proposed a symbiotic binary system consisting of a white dwarf (WD) and a low mass red-giant (RG), where strong winds from the accreting WD play a key role to increase the WD mass to the Chandrasekhar mass limit. Here we propose two new evolutionary processes which make the symbiotic channel to SNe Ia much wider. (1) We first show that the WD + RG close binary can form from a wide binary even with such a large initial separation as $a_i \lesssim 40000 R_\odot$. Such a binary consists of an AGB star and a low mass main-sequence (MS) star, where the AGB star is undergoing superwind before becoming a WD. If the superwind at the end of AGB evolution is as fast as or slower than the orbital velocity, the wind outflowing from the system takes away the orbital angular momentum effectively. As a result the wide binary shrinks greatly to become a close binary. Therefore, the WD + RG binary can form from much wider binaries than our earlier estimate. (2) When the RG fills its inner critical Roche lobe, the WD undergoes rapid mass accretion and blows a strong optically thick wind. Our earlier analysis has shown that the mass transfer is stabilized by this wind only when the mass ratio of RG/WD is smaller than 1.15. Our new finding is that the WD wind can strip mass from the RG envelope, which could be efficient enough to stabilize the mass transfer even if the RG/WD mass ratio exceeds 1.15. With the above two new effects (1) and (2), the symbiotic channel can account for the inferred rate of SNe Ia in our Galaxy.Comment: 29 pages including 14 firgures, to be published in ApJ, 521, No.

Keck and ESO-VLT View of the Symmetry of the Ejecta of the XRF/SN 2006aj

Nebular-phase spectra of SN 2006aj, which was discovered in coincidence with X-ray flash 060218, were obtained with Keck in 2006 July and the Very Large Telescope in 2006 September. At the latter epoch spectropolarimetry was also attempted, yielding an upper limit of ~ 2% for the polarization. The spectra show strong emission lines of [OI] and MgI], as expected from a Type Ic supernova, but weak CaII lines. The [FeII] lines that were strong in the spectra of SN 1998bw are much weaker in SN 2006aj, consistent with the lower luminosity of this SN. The outer velocity of the line-emitting ejecta is ~ 8000 km/s in July and ~ 7400 km/s in September, consistent with the relatively low kinetic energy of expansion of SN 2006aj. All emission lines have similar width, and the profiles are symmetric, indicating that no major asymmetries are present in the ejecta at the velocities sampled by the nebular lines (v < 8000 km/s), except perhaps in the innermost part. The spectra were modelled with a non-LTE code. The mass of 56Ni required to power the emission spectrum is ~ 0.20 Msun, in excellent agreement with the results of early light curve modelling. The oxygen mass is ~ 1.5 Msun, again much less than in SN 1998bw but larger by ~ 0.7 Msun than the value derived from the early-time modelling. The total ejected mass is ~ 2 Msun below 8000 km/s. This confirms that SN 2006aj was only slightly more massive and energetic than the prototypical Type Ic SN 1994I, but also indicates the presence of a dense inner core, containing ~ 1 Msun of mostly oxygen and carbon. The presence of such a core is inferred for all broad-lined SNe Ic. This core may have the form of an equatorial oxygen-dominated region, but it is too deep to affect the early light curve and too small to affect the late polarization spectrum.Comment: 20 pages, 6 figures. Accepted for publication in the Astrophysical Journa