Observations of Sy2 galaxy NGC 3281 by XMM-Newton and INTEGRAL satellites

We present here the results of our analysis of X-ray properties of Seyfert 2 galaxy NGC 3281, based on the observational data obtained by XMM-Newton and INTEGRAL within the energy ranges 0.2-12 keV and 20-150 keV, respectively. The XMM-Newton spectrum of this object is presented for the first time. We show that fitting the X-ray spectrum of this galaxy with models based on the reflection from the disc with infinite column density yields non-physical results. More appropriate fit takes into account both transmitted and reflected emission, passed through a gas-dusty torus-like structure. Keeping this in mind, to model the inhomogeneous clumpy torus, we used the MYTorus model. Hence, we propose that the torus of NGC 3281 is not continuous structure, but it consists of separate clouds, which is in a good agreement with the results of near-IR observations. Using this assumption, we found that the torus inclination angle and the hydrogen column density are 66.98^{+2.63}_{-1.34} degrees and 2.08^{+0.35}_{-0.18}x10^{24} cm^{-2}, respectively. Also, the emission of the hot diffuse gas with temperature ~590 eV and warm absorption were detected.Comment: 8 pages, 5 figures, 2 tables, accepted for publication in Advances in Astronomy and Space Physic

Is KPD 1930+2752 a good SN Ia progenitor?

We investigate the evolution of a binary system which initially has an orbital period of 2^h 17^m and contains a 0.5 M_sun helium star with a white dwarf companion of 0.97 M_sun, similarly to suggested SN Ia candidate progenitor KPD 1930+2752. We show that the helium star completes core helium burning and becomes a white dwarf before components merge. The most probable outcome of the merger of components is formation of a massive white dwarf, despite initially the total mass of the system is above the Chandrasekhar mass

Studying the long-time variability of the Seyfert 2 galaxy NGC 4388 with INTEGRAL and Swift

We present analysis results on the Seyfert 2 galaxy NGC 4388 based on 6 yr of INTEGRAL data combined with Swift/Burst Alert Telescope survey and Swift/X-Ray Telescope pointed observations. These data, taken from 2003 to 2009, allow us to study the broad-band properties of this active galactic nucleus in the 0.3-300 keV energy range. The continuum emission of NGC 4388 is well represented by an absorbed power-law model with exponential cut-off at high energies and an upper limit on the reflection component of R < 0.5. We find slow strong variations of the hard X-ray emission, indicating both flux and spectral slope changes on the 3-6 months time-scale. In comparison with previous results on NGC 4388, the source shows a complex variability behaviour, i.e. the spectral shape and the 20-60 keV flux vary independentl

High peak power sub-60 fs Yb:KGW laser

A high power sub-60 fs mode-locked diode-pumped Yb: KGW laser based on hybrid action of an InGaAs quantum-dot saturable absorber mirror and Kerr-lens mode locking was demonstrated. The laser delivered 56 fs pulses with 1.95 W of average power corresponding to 450 kW of peak power. The spectral bandwidth of the pulse was 20.5 nm, which was near the gain bandwidth limit of the Yb:KGW crystal. To the best of our knowledge, these are the shortest pulses generated from the monoclinic double tungstate crystals (and Yb:KGW laser crystal in particular) and the most powerful in the sub-60 fs regime. At the same time they are also the shortest pulses produced to date with the help of a quantum-dot-based saturable absorber

What the distribution of sperm size can tell about the stability of spermatogenesis in hybrid frogs Pelophylax esculentus

Interspecies hybrid frogs Pelophylax esculentus and one of its parental species Pelophylax ridibundus inhabit the Siversky Donets center of diversity of water frogs in Eastern Ukraine. These frogs can crossbreed and form progeny in population systems which are called hemiclonal (HPS). Such systems have their own exceptional features which make them interesting for studying. The Lower Dobrytskiy Pond, which is situated in the National Nature Park “Homilshansky lisy” and is a part of Siversky Donets river basin, is on focus. Current work is devoted to the combination of two methods of spermatogenesis investigation. First, using the method of Ag-staining we observed high variability of meiotic chromosomal plates in testes of 24 adult male water frogs P. esculentus (2n=26). Only one male had 100% of full meiotic plates with no aneuploid plates. A significant amount of studied males (21/24) produced aneuploid chromosomal plates (4-68% of the total amount of meiotic plates). This may lead to a decrease in their fertility or even to their entire sterility. Also, we have not observed any chromosomal meiotic plates in two of 24 males. Some males (8/24) even produced meiotic chromosomal plates with 26 bivalents (i.e. 4n germ cells) which may testify about the ability to produce diploid sperm. Further, the lengths of urinary sperm cells’ heads were measured. Finally, we performed an analysis of both meiotic chromosomes in testes and the distribution of sizes of urinary sperm cells’ heads of hybrid water frogs Pelophylax esculentus from Siversky Donets basin to find out if there is a link between these two features. No difference in sperm heads lengths was found between males producing moderate and low amounts of sperm. Based on the data of meiotic plates all males were assigned into five categories via PCA (principal component analysis). A significant difference in sperm heads lengths was found within the category I (males with mostly full meiotic plates). The analysed data shows that each male from the studied population has his own unique features. No direct link between sperm cells size and features of meiotic chromosomes in testes was found