We present observations of the unusual optical transient SN 2010U, including spectra taken 1.03 days to 15.3 days after maximum light that identify it as a fast and luminous Fe II type nova. Our ...multi-band light curve traces the fast decline (t sub(2) = 3.5 + or - 0.3 days) from maximum light (M sub(v) = -10.2 + or - 0.1 mag), placing SN 2010U in the top 0.5% of the most luminous novae ever observed. We find typical ejecta velocities of asymptotically =1100 km s super(-1) and that SN 2010U shares many spectral and photometric characteristics with two other fast and luminous Fe II type novae, including Nova LMC 1991 and M31N-2007-11d. For the extreme luminosity of this nova, the maximum magnitude versus rate of decline relationship indicates a massive white dwarf (WD) progenitor with a low pre-outburst accretion rate. However, this prediction is in conflict with emerging theories of nova populations, which predict that luminous novae from massive WDs should preferentially exhibit an alternate spectral type (He/N) near maximum light.
Stellar winds of cool and pulsating asymptotic giant branch (AGB) stars enrich the interstellar medium with large amounts of processed elements and various types of dust. We present the first study ...on the influence of gas-to-dust drift on ab initio simulations of stellar winds of M-type stars driven by radiation pressure on forsterite particles. Our study is based on our radiation hydrodynamic model code T-800 that includes frequency-dependent radiative transfer, dust extinction based on Mie scattering, grain growth and ablation, gas-to-dust drift using one mean grain size, a piston that simulates stellar pulsations, and an accurate high spatial resolution numerical scheme. To enable this study, we calculated new gas opacities based on the E
XO
M
OL
database, and we extended the model code to handle the formation of minerals that may form in M-type stars. We determine the effects of drift by comparing drift models to our new and extant non-drift models. Three out of four new drift models show high drift velocities, 87–310 km s
−1
. Our new drift model mass-loss rates are 1.7–13 per cent of the corresponding values of our non-drift models, but compared to the results of two extant non-drift models that use the same stellar parameters, these same values are 0.33–1.5 per cent. Meanwhile, a comparison of other properties such as the expansion velocity and grain size show similar values. Our results, which are based on single-component forsterite particles, show that the inclusion of gas-to-drift is of fundamental importance in stellar wind models driven by such transparent grains. Assuming that the drift velocity is insignificant, properties such as the mass-loss rate may be off from more realistic values by a factor of 50 or more.
Context. We investigate iPTF13bvn, a core-collapse (CC) supernova (SN) in the nearby spiral galaxy NGC 5806. This object was discovered by the intermediate Palomar Transient Factory (iPTF) very close ...to the estimated explosion date and was classified as a stripped-envelope CC SN, likely of Type Ib. Furthermore, a possible progenitor detection in pre-explosion Hubble Space Telescope (HST) images was reported, making this the only SN Ib with such an identification. Based on the luminosity and color of the progenitor candidate, as well as on early-time spectra and photometry of the SN, it was argued that the progenitor candidate is consistent with a single, massive Wolf-Rayet (WR) star. Aims. We aim to confirm the progenitor detection, to robustly classify the SN using additional spectroscopy, and to investigate if our follow-up photometric and spectroscopic data on iPTF13bvn are consistent with a single-star WR progenitor scenario. Methods. We present a large set of observational data, consisting of multi-band light curves (UBVRI, g′r′i′z′) and optical spectra. We perform standard spectral line analysis to track the evolution of the SN ejecta. We also construct a bolometric light curve and perform hydrodynamical calculations to model this light curve to constrain the synthesized radioactive nickel mass and the total ejecta mass of the SN. Late-time photometry is analyzed to constrain the amount of oxygen. Furthermore, image registration of pre- and post-explosion HST images is performed. Results. Our HST astrometry confirms the location of the progenitor candidate of iPTF13bvn, and follow-up spectra securely classify this as a SN Ib. We use our hydrodynamical model to fit the observed bolometric light curve, estimating the total ejecta mass to be 1.9 M⊙ and the radioactive nickel mass to be 0.05 M⊙. The model fit requires the nickel synthesized in the explosion to be highly mixed out in the ejecta. We also find that the late-time nebular r′-band luminosity is not consistent with predictions based on the expected oxygen nucleosynthesis in very massive stars. Conclusions. We find that our bolometric light curve of iPTF13bvn is not consistent with the previously proposed single massive WR-star progenitor scenario. The total ejecta mass and, in particular, the late-time oxygen emission are both significantly lower than what would be expected from a single WR progenitor with a main-sequence mass of at least 30 M⊙.
We report extensive observational data for five of the lowest redshift Super-Luminous Type Ic Supernovae (SL-SNe Ic) discovered to date, namely, PTF10hgi, SN2011ke, PTF11rks, SN2011kf, and SN2012il. ...Photometric imaging of the transients at +50 to +230 days after peak combined with host galaxy subtraction reveals a luminous tail phase for four of these SL-SNe. A high-resolution, optical, and near-infrared spectrum from xshooter provides detection of a broad Hei X10830 emission line in the spectrum (+50 days) of SN2012il, revealing that at least some SL-SNe Ic are not completely helium-free. At first sight, the tail luminosity decline rates that we measure are consistent with the radioactive decay of super(56)Co, and would require 1-4 M sub(middot in circle) of super(56)Ni to produce the luminosity. These super(56)Ni masses cannot be made consistent with the short diffusion times at peak, and indeed are insufficient to power the peak luminosity. We instead favor energy deposition by newborn magnetars as the power source for these objects. A semi-analytical diffusion model with energy input from the spin-down of a magnetar reproduces the extensive light curve data well. The model predictions of ejecta velocities and temperatures which are required are in reasonable agreement with those determined from our observations. We derive magnetar energies of 0.4 <, ~ E(10 super(51) erg) <, ~ 6.9 and ejecta masses of 2.3 <, ~ M sub(ej)(M sub(middot in circle)) <, ~ 8.6. The sample of five SL-SNe Ic presented here, combined with SN 2010gx-the best sampled SL-SNe Ic so far-points toward an explosion driven by a magnetar as a viable explanation for all SL-SNe Ic.
Stellar winds of cool and pulsating asymptotic giant branch (AGB) stars enrich the interstellar medium with large amounts of processed elements and various types of dust. We present the first study ...on the influence of gas-to-dust drift on ab initio simulations of stellar winds of M-type stars driven by radiation pressure on forsterite particles. Our study is based on our radiation hydrodynamic model code T-800 that includes frequency-dependent radiative transfer, dust extinction based on Mie scattering, grain growth and ablation, gas-to-dust drift using one mean grain size, a piston that simulates stellar pulsations, and an accurate high spatial resolution numerical scheme. To enable this study, we calculated new gas opacities based on the EXOMOL database, and we extended the model code to handle the formation of minerals that may form in M-type stars. We determine the effects of drift by comparing drift models to our new and extant non-drift models. Three out of four new drift models show high drift velocities, 87–310 km s−1. Our new drift model mass-loss rates are 1.7–13 per cent of the corresponding values of our non-drift models, but compared to the results of two extant non-drift models that use the same stellar parameters, these same values are 0.33–1.5 per cent. Meanwhile, a comparison of other properties such as the expansion velocity and grain size show similar values. Our results, which are based on single-component forsterite particles, show that the inclusion of gas-to-drift is of fundamental importance in stellar wind models driven by such transparent grains. Assuming that the drift velocity is insignificant, properties such as the mass-loss rate may be off from more realistic values by a factor of 50 or more.
We report the results of a three-year-long dedicated monitoring campaign of a restless luminous blue variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and ...spectroscopically in the optical and near-infrared domains. In this paper, we present the full historical data set from 2009 to 2012 with multi-wavelength dense coverage of the two high-luminosity events between 2012 August and September. We construct bolometric light curves and measure the total luminosities of these eruptive or explosive events. We propose that the high intrinsic luminosity of the latest peak, the variability history of SN 2009ip, and the detection of broad spectral lines indicative of high-velocity ejecta are consistent with a pulsational pair-instability event, and that the star may have survived the last outburst. The question of the survival of the LBV progenitor star and its future fate remain open issues, only to be answered with future monitoring of this historically unique explosion.
Summary
Background. The role of Candida infections in the pathogenesis of chronic urticaria (CU) is debatable.
Objective. In this study, we investigated the role of Candida spp. colonization and ...infection in patients with CU.
Methods. In total, 38 patients with CU and a control group of 42 healthy individuals consented for inclusion in the study. Stool and oral specimens from all participants were cultured and evaluated quantitatively. Candida albicans ELISA IgG/IgM/IgA test kits were used for the detection of antibodies against C. albicans in the sera of patients and controls.
Results. Yeasts were isolated from the stools of 60.5% of the patients and 50.0% of the controls (P = 0.78, Student's t‐test) and from oral specimens in 47.4% and 42.9% (P = 0.85, Student's t‐test), respectively. Colony counts in the positive specimens of both groups were not significantly different. IgG, IgM and IgA antibodies were positive in 36.8%, 23.8% and 5.3% of the patients and in 42.9%, 19.1% and 4.8% of the controls, respectively. The qualitative and quantiative results of the antibodies were not significantly different between the two groups (χ2 test).
Conclusion. Intestinal and oral colonization of Candida spp. and serological evidence of Candida infections were not significantly different between patients with CU and controls. Claims of triggering of CU by Candida spp. should be explored in studies that measure allergic reactivity to Candida, and also in those that include eradication therapy.
Summary
Candida spp. has been the leading microorganism isolated from the urine specimens of patients hospitalized at the Anesthesiology and Reanimation intensive care unit (ICU) of Dokuz Eylul ...University Hospital, Izmir, since 1998. This study was undertaken to investigate the clonal relationship of Candida urine isolates in order to find the mode of spread among the patients. Epidemiological surveillance of 38 Candida albicans, 15 Candida tropicalis and 12 Candida glabrata recovered from the urine specimens of patients who were hospitalized in the ICU between June 11, 2000 and October 15, 2001 was carried out by antifungal susceptibility testing and randomly amplified polymorphic DNA (RAPD) analysis. Two short primers Cnd3 (5′‐CCAGATGCAC‐3′) and Cnd4 (5′‐ACGGTACACT‐3′) were used for RAPD. None of the isolates had high minimal inhibitory concentration (MIC) values (>1 μg ml−1) against amphotericin B with MIC50values of 0.5 μg ml−1, 0.5 μg ml−1 and 0.125 μg ml−1 for C. albicans, C. tropicalis and C. glabrata isolates, respectively. However, three C. glabrata isolates were resistant and one C. albicans and five C. glabrata isolates were dose‐dependent susceptible (D‐DS) to fluconazole. Among C. albicans isolates 19 and 20 patterns were detected with primers Cnd3 and Cnd4, respectively. When primers Cnd3 and Cnd4 were evaluated together, three and four genotypes were identified for C. tropicalis and C. glabrata isolates, respectively. Our results suggest that the source of C. albicans isolates was mostly endogenous. It is difficult to interpret the mode of spread of C. tropicalis and C. glabrata urine isolates as we obtained insufficient banding patterns for these species.
We perform hydrodynamical simulations of the interaction between supernova (SN) ejecta and circumstellar medium (CSM) for SN 1993J and SN 2011dh, and calculate the radio and X-ray emissions expected ...from the shocked gas at late epochs (t). Considering the ejecta structure from multi-group radiation hydrodynamics simulation, we find that the observed rapid drop in radio and X-ray light curves of SN 1993J at t > 3000 days may be due to a change in the mass-loss rate ((M)over dot) similar to 6500 yr prior to the explosion of the SN. The exact epoch scales inversely with the assumed wind velocity of nu(w) = 10 km s(-1). The progenitor of this SN very likely belonged to a binary system, where, during its evolution, the primary had transferred material to the secondary. It is argued in this paper that the change in (M)over dot can happen because of a change in the mass accretion efficiency (eta) of the companion star. It is possible that before similar to 6500. (nu(w)/10 km s(-1))(-1) yr prior to the explosion, eta was high, and thus the CSM was tenuous, which causes the late-time downturn in fluxes. In the case of SN. 2011dh, the late-time evolution is found to be consistent with a wind medium with (M)over dot/nu(w) = 4 x 10(-6) M-circle dot yr(-1)/10 km s(-1). It is difficult from our analysis to predict whether the progenitor of this SN had a binary companion; however, if future observations show a similar decrease in radio and X-ray fluxes, then this would give strong support to a scenario where both SNe had undergone a similar kind of binary evolution before explosion.
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