COMPLEX INVESTIGATION OF EN Ni-P METALLIC GLASSES HAVING ANOMALOUS BEHA VIOR DURING LONG TIME ISOTHERMAL HEAT-TREATMENT

An EN Ni-P layer consisting of two metallic glass components were examined after a short-time pre-heat treatment at 200°C, followed by a 5OOO-hour heat treatment at 160°C, then a 5-year relaxation at room temperature. X-ray diffraction, DSC, AES, and micro-hardness measurements were used in the study. Our only surprising experience was that the metallic glass recrystallized fully only during the room-temperature relaxation

The contact binary VW Cephei revisited: surface activity and period variation

Context. Despite the fact that VW Cephei is one of the well-studied contact binaries in the literature, there is no fully consistent model available that can explain every observed property of this system. Aims. Our motivation is to obtain new spectra along with photometric measurements, to analyze what kind of changes may have happened in the system in the past two decades, and to propose new ideas for explaining them. Methods. For the period analysis we determined 10 new times of minima from our light curves, and constructed a new O$-$C diagram of the system. Radial velocities of the components were determined using the cross-correlation technique. The light curves and radial velocities were modelled simultaneously with the PHOEBE code. All observed spectra were compared to synthetic spectra and equivalent widths of the H$\alpha$ line were measured on their differences. Results. We have re-determined the physical parameters of the system according to our new light curve and spectral models. We confirm that the primary component is more active than the secondary, and there is a correlation between spottedness and the chromospheric activity. We propose that flip-flop phenomenon occurring on the primary component could be a possible explanation of the observed nature of the activity. To explain the period variation of VW Cep, we test two previously suggested scenarios: presence of a fourth body in the system, and the Applegate-mechanism caused by periodic magnetic activity. We conclude that although none of these mechanisms can be ruled out entirely, the available data suggest that mass transfer with a slowly decreasing rate gives the most likely explanation for the period variation of VW Cep.Comment: 13 pages, 18 figures, 9 tables, accepted for publication in Astronomy and Astrophysic

Factorizations of Elements in Noncommutative Rings: A Survey

We survey results on factorizations of non zero-divisors into atoms (irreducible elements) in noncommutative rings. The point of view in this survey is motivated by the commutative theory of non-unique factorizations. Topics covered include unique factorization up to order and similarity, 2-firs, and modular LCM domains, as well as UFRs and UFDs in the sense of Chatters and Jordan and generalizations thereof. We recall arithmetical invariants for the study of non-unique factorizations, and give transfer results for arithmetical invariants in matrix rings, rings of triangular matrices, and classical maximal orders as well as classical hereditary orders in central simple algebras over global fields.Comment: 50 pages, comments welcom

Testing SNe Ia distance measurement methods with SN 2011fe

The nearby, bright, almost completely unreddened Type Ia supernova 2011fe in M101 provides a unique opportunity to test both the precision and the accuracy of the extragalactic distances derived from SNe Ia light curve fitters. We apply the current, public versions of the independent light curve fitting codes MLCS2k2 and SALT2 to compute the distance modulus of SN 2011fe from high-precision, multi-color (BVRI) light curves. The results from the two fitting codes confirm that 2011fe is a "normal" (not peculiar) and only slightly reddened SN Ia. New unreddened distance moduli are derived as 29.21 +/- 0.07 mag (D ~ 6.95 +/- 0.23$ Mpc, MLCS2k2), and 29.05 +/- 0.07 mag (6.46 +/- 0.21 Mpc, SALT2). Despite the very good fitting quality achieved with both light curve fitters, the resulting distance moduli are inconsistent by 2 sigma. Both are marginally consistent (at ~1 sigma) with the HST Key Project distance modulus for M101. The SALT2 distance is in good agreement with the recently revised Cepheid- and TRGB-distance to M101. Averaging all SN- and Cepheid-based estimates, the absolute distance to M101 is ~6.6 +/- 0.5 Mpc.Comment: 8 pages, 7 figures, accepted for publication in A&

The continuing story of SN IIb 2013df: new optical and IR observations and analysis

This work has been supported by the Hungarian Scientific Research Fund (OTKA) Grants NN107637, K104607, K83790, and K113117. TS is supported by the OTKA Postdoctoral Fellowship PD112325. JCW’s Supernova group at the UT Austin is supported by NSF Grant AST 11-09881 grant. JMS is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1302771. KS and AP are supported by the ‘Lend¨ulet-2009’ Young Researchers Program and the LP2012-31 grant of the Hungarian Academy of Sciences, respectively; KS is also supported by the ESA PECS Contract no. 4000110889/14/NL/NDe.SN 2013df is a nearby Type IIb supernova that seems to be the spectroscopic twin of the well-known SN 1993J. Previous studies revealed many, but not all interesting properties of this event. Our goal was to add new understanding of both the early- and late-time phases of SN 2013df. Our spectral analysis is based on six optical spectra obtained with the 9.2 m Hobby-Eberly Telescope during the first month after explosion, complemented by a near-infrared spectrum. We applied the SYNAPPS spectral synthesis code to constrain the chemical composition and physical properties of the ejecta. A principal result is the identification of 'high-velocity' He i lines in the early spectra of SN 2013df, manifest as the blue component of the double-troughed profile at ~5650 Å. This finding, together with the lack of clear separation of H and He lines in velocity space, indicates that both H and He features form at the outer envelope during the early phases. We also obtained ground-based BVRI and g'r'i'z' photometric data up to +45 d and unfiltered measurements with the ROTSE-IIIb telescope up to +168 d. From the modelling of the early-time quasi-bolometric light curve, we find Mej ~ 3.2-4.6 M⊙ and Ekin ~ 2.6-2.8 × 1051 erg for the initial ejecta mass and the initial kinetic energy, respectively, which agree well with the values derived from the separate modelling of the light-curve tail. Late-time mid-infrared excess indicates circumstellar interaction starting ~1 yr after explosion, in accordance with previously published optical, X-ray, and radio data.Publisher PDFPeer reviewe

A low-luminosity core-collapse supernova very similar to SN 2005cs

We present observations and analysis of PSN J17292918+7542390, a low-luminosity Type II-P supernova (LL SN IIP). The observed sample of such events is still low, and their nature is still under debate. Such supernovae are similar to SN 2005cs, a well-observed low-luminosity Type II-P event, having low expansion velocities, and small ejected $^{56}$Ni mass. We have developed a robust and relatively fast Monte-Carlo code that fits semi-analytic models to light curves of core collapse supernovae. This allows the estimation of the most important physical parameters, like the radius of the progenitor star, the mass of the ejected envelope, the mass of the radioactive nickel synthesized during the explosion, among others. PSN J17292918+7542390 has $R_0 = 91_{-70}^{+119} \cdot 10^{11} \;\text{cm}$, $M_\text{ej} = 9.89_{-1.00}^{+2.10} \; M_{\odot}$, $E_{\mathrm{kin}} = 0.65_{-0.18}^{+0.19} \;\text{foe}$, $v_{\mathrm{exp}} = 3332_{-347}^{+216}$ km s$^{-1}$, for its progenitor radius, ejecta mass, kinetic energy and expansion velocity, respectively. The initial nickel mass of the PSN J17292918+7542390 turned out to be $1.55_{-0.70}^{+0.75} \cdot 10^{-3} M_{\odot}$. The measured photospheric velocity at the earliest observed phase is 7000 km s$^{-1}$. As far as we can tell based on the small population of observed low-luminosity Type II-P supernovae, the determined values are typical for these events.Comment: 19 pages, 13 figure