Optical observations of PSR J0205+6449 Shearer, A.; Neustroev, V. V.
Monthly Notices of the Royal Astronomical Society,
10/2008, Letnik:
390, Številka:
1
Journal Article
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PSR J0205+6449 is an X-ray and radio pulsar in supernova (SN) remnant 3C 58. We report on observations of the central region of 3C 58 using the 4.2-m William Herschel Telescope at the Isaac Newton ...Group of Telescopes, La Palma, with the intention of identifying the optical counterpart of PSR J0205+6449 and characterizing its pulsar wind nebula (PWN). Around the pulsar position, we identified extended emission with a magnitude of B= 23.97 ± 0.10 mag, V= 22.95 ± 0.05 mag and R= 22.15 ± 0.03 mag consistent with a PWN. From the R-band image, we identified three knots with mR= 24.08 ± 0.07 mag (o1), 24.15 ± 0.07 mag (o2) and 24.24 ± 0.08 mag (o3). We confirm the presence of an optical PWN around PSR J0205+6449 and give an upper limit of mR≈ 24 for the optical magnitude of the pulsar. Furthermore, we make the tentative suggestion that our object o1, with an mR≈ 24.08, is the optical counterpart. If confirmed, the pulsar would have an LR/LX≈ 0.004 and an optical efficiency of about five per cent of the Crab pulsar. Such a low efficiency is more consistent with the characteristic age of the pulsar rather than that of SN 1181.
Aims. We observed a new cataclysmic variable (CV) SDSS J080434.20+510349.2 to study the origin of long-term variability found in its light curve. Methods. Multi-longitude, time-resolved, photometric ...observations were acquired to analyze this uncommon behavior, which has been found in two newly discovered CVs. Results. This study of SDSS J080434.20+510349.2 concerns primarily the understanding of the nature of the observed, double-humped, light curve and its relation to a cyclic brightening that occurs during quiescence. The observations were obtained early in 2007, when the object was at about $V\sim17.1$, about 0.4 mag brighter than the pre-outburst magnitude. The light curve shows a sinusoidal variability with an amplitude of about 0.07 mag and a periodicity of 42.48 min, which is half of the orbital period of the system. We observed in addition two “mini-outbursts” of the system of up to 0.6 mag, which have a duration of about 4 days each. The “mini-outburst” has a symmetric profile and is repeated in approximately every 32 days. Subsequent monitoring of the system shows a cyclical behavior of such “mini-outbursts” with a similar recurrence period. The origin of the double-humped light curve and the periodic brightening is discussed in the light of the evolutionary state of SDSS J080434.20+510349.2.
Cataclysmic variables (CVs) are close binary systems in which the primary, the more massive star, is a white dwarf. CVs usually exhibit a number of periodicities, most of which are now understood. ...However, recently a new phenomenon was discovered that does not fit the standard picture. Two objects have been found to show periods that are much longer than orbital and have no relation to it, either in light curves or in radial velocity variations measured from spectroscopy. Here we show that the precession of a fast-rotating magnetically accreting white dwarf can successfully explain these phenomena. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible to us.
We report simultaneous photometric and echelle-spectroscopic observations of the dwarf nova BZ UMa during which we were lucky to catch the system at the onset of an outburst, the development of which ...we traced in detail from quiescence to early decline. The outburst had a precursor, and was of a short duration (∼5 d) with a highly asymmetrical light curve. On the rise we observed a ‘jump’ during which the brightness almost doubled over the course of half an hour. Power spectra analysis revealed well-defined oscillations with period of ∼42 min. Using Doppler tomography we found that the unusual emission distribution detected in quiescence held during the outburst. After the maximum a new emission source arose, from the inner hemisphere of the secondary star, which became the brightest at that time. We analyse this outburst in terms of ‘inside-out’ and ‘outside-in’ types, in order to determine which of these types occurred in BZ UMa.
The highest void swelling level ever observed in an operating fast reactor component has been found after irradiation in BOR-60 with swelling in Kh18H10T (Fe–18Cr–10Ni–Ti) austenitic steel exceeding ...50%. At such high swelling levels the steel has reached a terminal swelling rate of ∼1%/dpa after a transient that depends on both dpa rate and irradiation temperature. The transient duration at the higher irradiation temperatures is as small as 10–13
dpa depending on which face was examined. When irradiated in a fast reactor such as BOR-60 with a rather low inlet temperature, most of the swelling occurs above the core center-plane and produces a highly asymmetric swelling loop when plotted vs. dpa. Voids initially harden the alloy but as the swelling level becomes significant the elastic moduli of the alloy decreases strongly with swelling, leading to the consequence that the steel actually softens with increasing swelling. This softening occurs even as the elongation decreases as a result of void linkage during deformation. Finally, the elongation decreases to zero with further increases of swelling. This very brittle failure is known to arise from segregation of nickel to void surfaces which induces a martensitic instability leading to a zero tearing modulus and zero deformation.
The black hole (BH) candidate SWIFT J1753.5−0127 has remained active since the onset of its 2005 outburst. Emission lines in the optical spectrum were observed at the very beginning of the outburst, ...but since then the spectrum has been featureless making a precise BH mass estimation impossible. Here we present results from our optical and ultraviolet (UV) observations of SWIFT J1753.5−0127 taken in 2012–2013. Our new observations show extremely broad, double-peaked emission lines in the optical and UV spectra. The optical data also show narrow absorption and emission features with nearly synchronous and significant Doppler motions. A radial velocity study of these lines which we associate with the secondary star, yields a semi-amplitude of K
2 = 382 km s−1. A time series analysis of the spectral and photometric data revealed a possible orbital periodicity of 2.85 h, significantly shorter than the reported 3.2 h periodic signal by Zurita et al. The observed variability properties argue against a low orbital inclination angle and we present several observational arguments in favour of the BH interpretation. However, the measured radial velocity semi-amplitude of the donor star and the short orbital period imply that SWIFT J1753.5−0127 has one of the lowest measured mass function for a BH in a low-mass X-ray binary. We show that the compact object mass in excess of 5 M⊙ is highly improbable. Thus, SWIFT J1753.5−0127 is a BH binary that has one of the shortest orbital period and hosts probably one of the smallest stellar mass BH found to date.
We present the analysis of high-speed photometric observations of FS Aurigae taken with the 4.2-m William Herschel Telescope and the high-speed camera ULTRACAM in late 2003. These observations were ...intended to determine whether there was any evidence of photometric variability with a period in the range 50–100 s. The discovery of such variations would help to explain the existence, in FS Aur, of the very coherent photometric period of 205.5 min that exceeds the spectroscopic period by 2.4 times. Such a discrepancy in the photometric and spectroscopic periods is unusual for a low-mass binary system that is unambiguously identified as a cataclysmic variable. Using various methods, including wavelet analysis, we found that with exception of the 205.5-min periodicity, the main characteristic of variability of FS Aur is usual flickering and quasi-periodic oscillations. However, we detected variability with a period of ∼101 and/or ∼105 s, seen for a short time every half of the orbital period. These oscillations may be associated with the spin period of the white dwarf (WD), not ruling out the possibility that we are observing a precessing rapidly rotating WD in FS Aur.
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.
Abstract
We report on our photometric observations of the 2016 superoutburst of ASASSN-16eg. This object showed a WZ Sge-type superoutburst with prominent early superhumps with a period of ...0.075478(8) d and a post-superoutburst rebrightening. During the superoutburst plateau, it showed ordinary superhumps with a period of 0.077880(3) d and a period derivative of 10.6(1.1) × 10−5 in stage B. The orbital period (Porb), which is almost identical with the period of the early superhumps, is exceptionally long for a WZ Sge-type dwarf nova. The mass ratio (q = M2/M1) estimated from the period of developing (stage A) superhumps is 0.166(2), which is also too large for a WZ Sge-type dwarf nova. This suggests that the 2 : 1 resonance can be reached in such high-q systems, contrary to our expectation. Such conditions are considered to be achieved if the mass-transfer rate is much lower than those in typical SU UMa-type dwarf novae that have comparable orbital periods to ASASSN-16eg, and a resultant accumulation of a large amount of matter on the disk is realized at the onset of an outburst. We examined other candidates for long-period WZ Sge-type dwarf novae for their supercycles, which are considered to reflect the mass-transfer rate, and found that V1251 Cyg and RZ Leo have longer supercycles than those of other WZ Sge-type dwarf novae. This result indicates that these long-period objects including ASASSN-16eg have a low mass-transfer rate in comparison to other WZ Sge-type dwarf novae.
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