Abstract.We present an analysis of new spectroscopic observations of the bright Be star κ Dra obtained at the Ondřejov observatory during 1992−2003 and UBV photometric observations secured at several observatories. General characteristics and a line identification of the spectrum of κ Dra are obtained in the regions 3730−5650 Å and 5850−7800 Å by a comparison with the theoretical spectrum. The fundamental stellar parameters have been obtained from a comparison with a grid of NLTE model atmospheres. The best fit was found for T eff = 14 000 K, log g = 3.5, and v sin i = 170 km s −1 . These values together with a Hipparcos parallax lead to a stellar mass M = 4.8 ± 0.8 M and radius R = 6.4 ± 0.5 R . It is encouraging to see that these values agree well with the expected evolutionary mass and radius for the effective temperature we derived. Long-term variations of κ Dra were analysed using measurements of equivalent widths, central intensities, peak intensities of emission lines and emission peak velocity differences for Hα, Hβ, Hγ, Hδ, and some helium, silicon, and iron lines. The previously reported period of 23 years in the variation of the emission strength is probably a cyclic, not a strictly periodic phenomenon. An attempt to find out a period from all available records of the Hβ emission strength led to a value of (8044 ± 167) days (22.0 years) but the phase plots show that each cycle has a different shape and length. The maximum strength of the emission lags behind the brightness maximum. This is a behaviour usually observed for long-term changes of Be stars with a positive correlation between the brightness and emission strength. Since there are obviously no published speckle observations of the star, we suggest these should be carried out. They could help to deny or confirm the possibility that the emission episodes are triggered by a periastron passage of a putative binary companion moving in an eccentric orbit with a 8044-d period, as it seems to be the case for some Be binaries. For the moment, the nature and origin of the disk around κ Dra remains unknown. From the comparison of the electronic spectra obtained at different phases of the long-term cycle and synthetic spectra it appears that there are no detectable changes in the photospheric part of the Balmer lines related to variations in the Balmer emission strength which could be attributed to an extended photosphere corresponding to inner parts of the disk, optically thick in continuum.

Abstract. The changes in the periods of the fundamental and first overtone pulsation of the variable V26 in the globular cluster M15 are studied. The analysis was based on published observations. The method of investigation was outlined in our previous paper (Paparó et al. 1998). The Fourier phase diagrams for both frequencies have been constructed. General guidelines concerning the cycle counting problems are discussed. In both periods a sudden increase took place around JD 2431500 (≈1945) and the changes were the same in sign but slightly different in magnitude. The period change behaviour of the fundamental mode was noticed for the first time. Before the abrupt change the fundamental and first overtone periods were P 0 = 0. d 538898 and P 1 = 0.d 402256 days and after it P 0 = 0. d 538979 and P 1 = 0. d 402273 days. Although the fundamental component is very weak, there is a remarkable concordance between our period after the abrupt change and the period derived by Clement & Walker (1991). The disagreement between the observed period changes and the expectation of stellar evolutionary theory strongly suggest that period changes are dominated by short term changes governed by the physics of the star. Fast changes in oscillation frequency such as in V26/M15 cannot take place without sudden changes in the stellar structure. The possible physical processes are the mixing events in a small part of the semiconvective zone (Sweigart & Renzini 1979) or the dredge up of a small amount of helium by occasional convection overshooting (Cox 1998).

Based on a new set of electronic spectra in a relatively wide spectral range (3500-8300Å) and using the methods of spectrum disentangling (code KOREL) and solution of RV curves (code FOTEL), we determined new orbital elements of the binary star κ Dra. The solution of the radial velocity curves for Balmer and some other strong metallic lines suggested a circular orbit and led to the following orbital elements: period P = 61.555 ± 0.029 days, epoch of periastron passage T periast = 49980.22 ± 0.59, RV semi-amplitude K 1 = 6.81 ± 0.24 km s −1 , and a mass function of f (m) = 0.002 M . Lines of the secondary were not detected. In addition, moving absorption bumps in the violet peaks of Hα and Hβ lines were found to be phase-locked with the orbital period. Their presence suggests some kind of interaction between the binary components.

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Vanillic acid (VA) exhibited antioxidant and neuroprotective properties in some neurodegenerative disorders. So, the current study examined the neuroprotective potential of VA as an antiepileptic agent in pentylenetetrazole (PTZ)-induced epileptic rats and the prospective role of Insulin like growth factor-1 (IGF-1) and nuclear factor-2 erythroid-related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) pathway in this respect. Thirty male albino rats were equally subdivided into 3 groups; (1) normal control (NC) group, (2) PTZ-group: received PTZ (50 mg/Kg, i.p. every other day) for 14 days, and (3) PTZ + VA group: received PTZ and VA (50 mg/Kg daily for 2 weeks). The seizure score and latency were evaluated a ter PTZ injection. Also, the markers of oxidative stress (malondialdehyde (MDA), catalase, and reduced glutathione (GSH)), histopathological examination, the expression of glial fibrillary acidic protein (GFAP) (a marker of astrocytes) IGF-1, Nrf2, and HO-1 were assessed in the brain tissues by the end of the experiment. PTZ caused significant decrease in seizure latency and significant increase in seizure score by the end of the experiment (p < 0.01). This was associated with significant increase in MDA and GFAP with significant decrease in GSH, total antioxidant capacity (TAC) and IGF-1 in brain tissues compared to normal group (p < 0.01). On the other hand, treatment with VA caused significant attenuation in PTZ-induced seizures which was associated with significant improvement in oxidative stress markers and downregulation in GFAP and upregulation of Nrf2, HO-1 and IGF-1 in CA3 hippocampal region (p < 0.01). VA showed neuroprotective and anti-epileptic e fects against PTZ-induced epilepsy which probably might be due to its antioxidant properties and upregulation of Nrf2/HO-1 pathway and IGF-1.

The development of astronomy and space science in Africa has grown significantly over the past few years. These advancements make the United Nations Sustainable Development Goals more achievable, and open up the possibility of new beneficial collaborations.

We investigated the luminosity function (LF) and initial mass function (IMF) of some open clusters having different ages. To calculate the LF, we followed the classical definition by van Rhijn (1936). Statistical investigation of the dispersion around a range of magnitudes concerning what is called Wielen dip revealed that the dip is unreal. To confirm the unreality of the dip, we computed the IMF for these open clusters, the statistical investigation of the IMF confirmed the results obtained using the LF, that is, there is no dip for these open clusters under study.

We carried out a spectroscopic survey of several B, Be, and shell stars in optical and near-infrared regions. Line profiles of the Hα line and of selected Fe ii and O i lines are presented.