We present new optical and near-infrared (NIR) photometry and spectroscopy of the Type IIP supernova (SN), SN 2004et. In combination with already published data, this provides one of the most ...complete studies of optical and NIR data for any Type IIP SN from just after explosion to +500 d. The contribution of the NIR flux to the bolometric light curve is estimated to increase from 15 per cent at explosion to around 50 per cent at the end of the plateau and then declines to 40 per cent at 300 d. SN 2004et is one of the most luminous IIP SNe which has been well studied and characterized, and with a luminosity of log L= 42.3 erg s−1 and a 56Ni mass of 0.06 ± 0.04 M⊙, it is two times brighter than SN 1999em. We provide parametrized bolometric corrections as a function of time since explosion for SN 2004et and three other IIP SNe that have extensive optical and NIR data. These can be used as templates for future events in optical and NIR surveys without full wavelength coverage. We compare the physical parameters of SN 2004et with those of other well-studied IIP SNe and find that the kinetic energies span a range of 1050–1051 erg. We compare the ejected masses calculated from hydrodynamic models with the progenitor masses and limits derived from pre-discovery images. Some of the ejected mass estimates are significantly higher than the progenitor mass estimates, with SN 2004et showing perhaps the most serious mass discrepancy. With the current models, it appears difficult to reconcile 100 d plateau lengths and high expansion velocities with the low ejected masses of 5–6 M⊙ implied from 7–8 M⊙ progenitors. The nebular phase is studied using very late-time Hubble Space Telescope photometry, along with optical and NIR spectroscopy. The light curve shows a clear flattening at 600 d in the optical and the NIR, which is likely due to the ejecta impacting on circumstellar material. We further show that the O i 6300, 6364 Å line strengths in the nebular spectra of four Type IIP SNe imply ejected oxygen masses of 0.5–1.5 M⊙.
ABSTRACT
We present optical photometric observations of SN 2018aoq from 2 to 100 d after explosion, and 7 spectra at epochs from 11 to 71 d. The light curves and spectra are typical for SNe II-P. As ...previously reported, SN 2018aoq appears to be of intermediate brightness between subluminous and normal SNe II-P. SN 2018aoq was discovered in Seyfert galaxy NGC 4151, for which the distance is uncertain. We utilized the expanding photosphere method using three sets of filter combinations and velocities derived from the absorption minima of Fe ii lines and obtained a distance of 20.0 ± 1.6 Mpc. The standard candle method applied to SN 2018aoq yields a distance of 16.6 ± 1.1 Mpc. Both values are consistent with the distance measurements for NGC 4151 based on geometric method.
We present the results of our
UBVRI
photometry for the type II-P supernova SN 2017eaw in NGC6946 obtained fromMay 14 to December 7, 2017, at several telescopes, including the 2.5-m telescope at the ...CaucasusHigh-Altitude Observatory of the SAIMSU. The dates andmagnitudes atmaximumlight and the light-curve parameters have been determined. The color evolution, extinction, and peak luminosity of SN 2017eaw are discussed. The results of our preliminary radiation–gasdynamic simulations of its light curves with the STELLA code describe satisfactorily the
UBVRI
observational data.
The distributions of supernovae of different types and subtypes along the radius and in
z
coordinate of galaxies have been studied. We show that among the type Ia supernovae (SNe Ia) in spiral ...galaxies, SNe Iax and Ia-norm have, respectively, the largest and smallest concentration to the center; the distributions of SNe Ia-91bg and Ia-91T are similar. A strong concentration of SNe Ib/c to the central regions has been confirmed. In spiral galaxies, the supernovae of all types strongly concentrate to the galactic plane; the slight differences in scale height correlate with the extent to which the classes of supernovae are associated with star formation.
We present photometric and spectrocsopic observations of supernovae carried out with the 2.5-m telescope of the Caucasus Mountain Observatory of SAI MSU. The light curves for the objects 2017egm, ...2017eaw, 2018cow, 2018aoq, 2018zd, 2019yvr, 2019vxm, 2020tlf, and 2020xtz were constructed and their basic parameters were determined. The observed light curves are compared to the theoretical calculations for SNe II-P 2017eaw and 2018aoq. The spectra of SNe 2019vxm, 2019yvr, 2020tlf, 2020xtz are presented. The profiles of emission lines are studied for SNe IIn 2019vxm and 2020tlf. Spectral modeling was carried out for SNe 2019yvr and 2020xtz. The results of the program of prompt SNe spectral classification for eight objects are reported.
The speed of implementation of electric vehicles depends on the level of development of the charging infrastructure, which is subject to ever new requirements, including increasing ease of use and ...reducing charging time. A solution to the problem could be an introduction of wireless charging of electric vehicles (inductive charging device – WPT). However, in order to produce an effective WPT (without preliminary calculation and modeling the efficiency of the device may not reach 10 %), it is necessary to select the parameters of the coils and simulate the frequency characteristics of the voltage. For this purpose, as part of the implementation of the project to create a mobile charging installation for electric vehicles, the problem of modeling the operation of the WPT has been solved. In accordance with the technical specifications, a coil has been built in Excel, which was used as geometry in Comsol to evaluate the distribution of magnetic fields. To study the frequency characteristics, the CST Studio program has been used. Using these programs, we simulated various methods for implementing the WPT with obtaining frequency characteristics. It has been confirmed that the coupling coefficient increases with decreasing distance between parts of the WPT. Calculations of resonant circuits and the expected efficiency for both types of resonant circuits have been carried out, and it has been concluded that decreasing the distance leads to a decrease in the resonant frequency of the system of connected circuits. The developed model allows us to obtain the values of the circuit capacitances for the formation of resonance, move on to practical implementation and verify the resulting models.
The TOAC-spin-labeled peptide Trichogin GA IV adsorbed on the TiO
2
surface is studied. It is shown that the continuous wave (CW) electron paramagnetic resonance (EPR) spectrum does not depend on ...temperature in a wide range of 77–300 K. A pulsed EPR method of electron spin echo (ESE) utilizing a two-pulse sequence (
π/2-τ-π
) is used to study temperature dependence of the phase relaxation time,
T
F
. The
T
F
values are found to change from 750 ns to 100 ns in the interval of 77–300 K. The pulsed electronelectron double resonance (PELDOR) measurements utilizing the pulse sequence((π/2)
A
,-T-π
B
,-(τ-
T
)-π
A
) show that the space distribution of spin labels on the surface remains uniform irrespective of the temperature, and provide the fractal dimension of the surface of 2.7±0.1. The obtained results testify that EPR pulse experiments can be used to study adsorbed spin-labeled molecules at room temperatures, i.e. not only at cryogenic temperatures.
The impact of pumping pulse duration on four-pulse pulsed electron–electron double resonance (PELDOR) data was experimentally studied. For biradicals with known distances between two spin labels, it ...is shown that refocused echo amplitude decreases with increasing the pumping pulse duration and decreasing the distance between spin labels. The effect becomes substantial when the pumping pulse duration is comparable or exceeds the inverse value of the dipole–dipole interaction between spin labels. This effect is essential for determination of distance distribution between labels in double-labeled molecules and for determination of the number of labels in clusters of spin-labeled molecules. PELDOR signal distortion was observed when the pumping pulse position in the time scale coincided with those of the detecting pulses. An approach of signal correction to eliminate this distortion is proposed.
The review considers the main propositions of PELDOR theory. It is shown how from the analysis of PELDOR time traces it is possible to find the parameters of a spin system such as the distance and ...the distance distribution (spectrum), number of spins in aggregates and complexes, exchange integral and how to separate for the following analysis the inter- and intramolecular contributions to the general dipole interaction. Examples of PELDOR application in the studies of the spatial distribution of nitroxyl radicals, the charge effect of dipolar interacting nitroxyls on their spatial distribution are given and the results of the determination of distances and the spectrum of distances for nitroxyl bi-, tri-, and tetraradicals are presented. The works on nitroxyl radicals in which the orientation selectivity effect, spin exchange, and conformational properties of the radicals are examined by the PELDOR method are analyzed. The studies of the structure of paramagnetic ion-nitroxyl radical pairs and the PELDOR data on nitroxyls at high frequencies (high fields) are considered. The last section of the review is devoted to the works examining the properties such as the molecular flexibility of oligomers and supramolecules contains nitroxyl radicals.
We present the results of a new stage of the long-term photometric study of FG Sge which is a quickly evolving central star of the planetary nebula Hen 1-5. Our new observations carried out on the ...SAI MSU telescopes in the optical (
) and infrared (IR) (
) regions in 2008–2021 and 2013–2021, respectively, allowed us to trace the evolution of the star’s brightness in recent years. The most significant observations were performed in 2019 when the star suffered a short clearing of the dust shell and became visible in
. Based on the spectral energy distribution of FG Sge in the 0.4–5
m wavelength range we derived the dust shell parameters: the size of dust grains
m, the inner radius temperature
K, optical depth
(
), the total mass of dust
. After the short-term clearing of the dust shell in 2019, another dust structure was ejected that resulted in the star fading in all the observed bands. Based on the IR brightness and color curves, we estimated the dust depth growth in 2019–2020.
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