The topicality is shown to improve the processing technology of complex polymetallic raw material containing a considerable amount of toxic impurities of arsenic and lead. Results on pressure ...leaching the mattes formed after reduction smelting the dusts of OAO Sredneural’skii Copper Smeltery (SUMZ) by solutions of copper sulfate are discussed. These mattes contain a considerable amount of lead and arsenic. According to the data of X-ray phase analysis of matte samples, phases of sulfides (PbS, PbS ⋅ As
2
S
3
, Cu
2
S, FeS, and (Zn,Fe)S) and arsenides (FeAs
2
, Cu
3
As, FeAs, and Cu
0.85
As
0.15
), as well as inclusions of metallic copper, are revealed in them. Optimal parameters of matte leaching by copper sulfate solutions are the temperature of 150–180°C, acidity from 5 to 30 g/dm
3
, and copper concentration of 14–32 g/dm
3
. This process made it possible to extract 85% As into the solution, while copper and lead remained in the cake in this case.
The results of the studies of the microstructure of the 08Kh18N10T austenitic steel irradiated in a BOR-60 reactor to a damaging dose of 36 dpa at a temperature of about 420°C have been presented. ...The results have been compared with previously published data on the effect of stresses on the development of vacancy porosity in austenitic steels irradiated in the BOR-60 reactor.
On the mass transfer in AE Aquarii Ikhsanov, N. R.; Neustroev, V. V.; Beskrovnaya, N. G.
Astronomy and astrophysics (Berlin),
07/2004, Letnik:
421, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The observed properties of the close binary AE Aqr indicate that the mass transfer in this system operates via the Roche lobe overflow mechanism, but the material transferred from the normal ...companion is neither accreted onto the surface of the white dwarf nor stored in a disk around its magnetosphere. As previously shown, such a situation can be realized if the white dwarf operates as a propeller. At the same time, the efficiency of the propeller action by the white dwarf is insufficient to explain the rapid braking of the white dwarf, which implies that the spin-down power is in excess of the bolometric luminosity of the system. To avoid this problem we have simulated the mass-transfer process in AE Aqr assuming that the observed braking of the white dwarf is governed by a pulsar-like spin-down mechanism. We show that the expected Hα Doppler tomogram in this case resembles the tomogram observed from the system. We find that the agreement between the simulated and the observed tomograms is rather good provided the mean value of the mass-transfer rate $\langle\dot{M}\rangle$ ~ 5 $\times$ $10^{16}~{\rm g~s^{-1}}$. Three spatially separated sources of Hα emission can be distinguished within this approach. The structure of the tomogram depends on the relative contributions of these sources to the Hα emission and is expected to vary from night to night.
Results are given for autoclave leaching of concentrates and mattes from polymetal semiproduct melts containing arsenic alongside copper. The possibility is demonstrated of selective copper and ...arsenic leaching into solution. It is confirmed that with autoclave leaching arsenides are broken down better than for natural arsenic-containing minerals.
Irradiated austenitic stainless steels removed from Russian water-cooled VVERs experience irradiation temperatures and He/dpa conditions that are very similar to steels to be used in ITER. Data are ...presented on the radiation hardening of the Russian analog of AISI 321 at 0.2–15
dpa in the range of 285–320
°C. The Russian variant of the ring-pull tensile test was used to obtain mechanical property data. Microhardness tests on the ring specimens provide useful information throughout the deformed regions, but at high hardening levels caution must be exercised before application of a widely accepted hardness-yield stress correlation to prediction of tensile properties. Low-nickel austenitic steels are very prone to form deformation martensite, a phase that increases strongly with the larger deformation levels characteristic of microhardness tests, especially when compared to the 0.2% deformation used to define yield stress.
Aims.We observed a new and poorly studied cataclysmic variable (CV) SDSS J123813.73-033933.0 to determine its classification and binary parameters.Methods.Simultaneous time-resolved photometric and ...spectroscopic observations were carried out to conduct period analysis and Doppler tomography mapping.Results.From radial velocity measurements of the Hα line we determined its orbital period to be $0.05592\pm0.00035$ days (80.53 min). This period is longer than the first estimate of 76 min by Szkody et al. (2003), but still at the very edge of the period limit for hydrogen-rich CVs. The spectrum shows double-peaked Balmer emission lines flanked by strong broad Balmer absorption, indicating a dominant contribution by the white dwarf primary star, and is similar to the spectra of short-period low-mass transfer WZ Sge-like systems. The photometric light curve shows complex variability. The system undergoes cyclic brightening up to 0.4 mag, which are of semi-periodic nature with periods of the order of 8–12 h. We also detect a 40.25 min variability of ${\sim}0.15$ mag corresponding to half of the orbital period. Amplitude of the latter increases with the cyclic brightening of the system. We discuss the variable accretion rate and its impact on the hot spot as the most probable reason for both observed processes.Conclusions.SDSS J123813.73-033933.0 is preliminary classified as a WZ Sge-like short period system with low and unstable accretion rate.
The mechanical test results and fractographic observations reported in Part 1 are discussed from the standpoint of possible fracture mechanisms in austenitic steels subjected to intensive neutron ...irradiation. We put forward the mechanisms that relate the γ →α-transformation to the occurrence of a ductile–brittle transition in the irradiated austenitic steels and presents a criterion that defines the irradiation conditions whereby the γ →α-transformation leads to the ductile–brittle transition. Some possible reasons for the deterioration of the material ultimate strength at a very high (above 20%) level of swelling are discussed.
We present a comparative analysis of photometric observations of the cataclysmic variable TT Ari in its bright state, obtained by the TESS orbital observatory in 2021 and 2023 and by ground-based ...amateur telescopes in 2022. The light curves from 2021 and 2022 are dominated by modulations with a period slightly shorter than the orbital one (negative superhumps), 0.13293 and 0.13273\(\,\)d respectively. In 2023, much stronger modulations appeared on a much longer time scale of a few days with an amplitude of up to 0.5 mag, compared to 0.2 mag in 2021. The negative superhump variability with the period of 0.13376\(\,\)d was also found in the first half of the 2023 observations, but then negative superhumps suddenly almost disappeared. Less significant additional modulations with a period exceeding the orbital one (positive superhumps) were detected in 2021 and 2022. Their periods were 0.15106 and 0.1523\(\,\)d, correspondingly. We also found a previously unnoticed periodic signal corresponding to the orbital period of 0.13755\(\,\)d in the TESS observations in 2021. Theoretical models of tidal precession of an elliptical disk predict a decrease in the precession period with increasing disk radius, which is consistent with the observed photometric behavior of the system. It enables us to estimate the mass ratio of the components in TT\(\,\)Ari to be \(q\approx 0.235\). The tilted disk precession model predicts a period of nodal precession whose value is in general agreement with observations.
Superhumps linked to X-ray emission Neustroev, V. V.; Page, K. L.; Kuulkers, E. ...
Astronomy and astrophysics (Berlin),
03/2018, Letnik:
611
Journal Article
Recenzirano
Context.
We present more than 4 years of
Swift
X-ray observations of the 2013 superoutburst, subsequent decline and quiescence of the WZ Sge-type dwarf nova SSS J122221.7−311525 (SSS J122222) from 6 ...days after discovery.
Aims.
Only a handful of WZ Sge-type dwarf novae have been observed in X-rays, and until recently GW Lib was the only binary of this type with complete coverage of an X-ray light curve throughout a superoutburst. We collected extensive X-ray data of a second such system to understand the extent to which the unexpected properties of GW Lib are common to the WZ Sge class.
Methods.
We collected 60
Swift
-XRT observations of SSS J122222 between 2013 January 6 and 2013 July 1. Four follow-up observations were performed in 2014, 2015, 2016 and 2017. The total exposure time of our observations is 86.6 ks. We analysed the X-ray light curve and compared it with the behaviour of superhumps which were detected in the optical light curve. We also performed spectral analysis of the data. The results were compared with the properties of GW Lib, for which new X-ray observations were also obtained.
Results.
SSS J122222 was variable and around five times brighter in 0.3–10 keV X-rays during the superoutburst than in quiescence, mainly because of a significant strengthening of a high-energy component of the X-ray spectrum. The post-outburst decline of the X-ray flux lasted at least 500 d. The data show no evidence of the expected optically thick boundary layer in the system during the outburst. SSS J122222 also exhibited a sudden X-ray flux change in the middle of the superoutburst, which occurred exactly at the time of the superhump stage transition. A similar X-ray behaviour was also detected in GW Lib.
Conclusions.
We show that the X-ray flux exhibits changes at the times of changes in the superhump behaviour of both SSS J122222 and GW Lib. This result demonstrates a relationship between the outer disc and the white dwarf boundary layer for the first time, and suggests that models for accretion discs in high mass ratio accreting binaries are currently incomplete. The very long decline to X-ray quiescence is also in strong contrast to the expectation of low viscosity in the disc after outburst.
We present multi-epoch, time-resolved optical spectroscopic observations of the dwarf nova HT Cas, which were obtained during 1986, 1992, 1995, and 2005 with the aim of studying the properties of ...emission structures in the system. We determined that the accretion disc radius, measured from the double-peaked emission-line profiles, is consistently large and lies within the range of 0.45–0.52a, where a is the binary separation. This is close to the tidal truncation radius rmax = 0.52a. However, this result is not consistent with previous radius measurements. An extensive set of Doppler maps reveals a very complex emission structure of the accretion disc. Apart from a ring of disc emission, the tomograms display at least three areas of enhanced emission: the hot spot from the area of interaction between the gas stream and the disc, which is superposed on the elongated spiral structure, and the extended bright region on the leading side of the disc, which is opposite to the location of the hotspot. The position of the hotspot in all the emission lines is consistent with the trajectory of the gas stream. However, the peaks of emission are located in the range of distances 0.22–0.30a, which are much closer to the white dwarf than the disc edge. This suggests that the outer disc regions have a very low density, allowing the gas stream to flow almost freely before it starts to be seen as an emission source. We have found that the extended emission region on the leading side of the disc is always observed at the very edge of the large disc. Observations of other cataclysmic variables, which show a similar emission structure in their tomograms, confirm this conclusion. We propose that the leading side bright region is caused by irradiation of tidally thickened sectors of the outer disc, by the white dwarf and/or hot inner disc regions.
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