In this paper, we continue our research on constructing the optimal fundamental plane (FP) of galaxy groups and clusters for measuring their distances. This work was carried out using archival data from the SDSS and 2MASX catalogs. We present the fundamental planes (scaling relations of dynamical and photometric parameters) of 205 galaxy groups and clusters ( $$z<0.15$$ ). We found that in the near infrared ( $$K$$ -filter), the distribution of galaxy clusters is well approximated by three-parameter planes of the form $$R_{e}\propto\sigma^{1.01\pm 0.05}\langle I_{e}\rangle{{}^{-0.32\pm 0.03}}$$ and $$R_{e}\propto N^{0.43\pm 0.01}\langle I_{e}\rangle^{-0.40\pm 0.02}$$ and a four-parameter plane of the form $$R_{e}\propto\sigma^{0.15\pm 0.06}\langle I_{e}\rangle^{-0.39\pm 0.02}N^{0.38\pm 0.02}$$ . The fundamental planes have logarithmic standard deviations of 0.060, 0.036, and 0.035. If we use the fundamental planes to measure distances of galaxy systems, these deviations correspond to 14 $$\%$$ and 8 $$\%$$ errors in the distance of a single cluster. Using the four-parameter fundamental plane, we obtained the scatter of the Hubble constant $$H_{0}=70\pm 5.6\text{ km s}^{-1}$$ Mpc $${}^{-1}$$ . Using three fundamental planes of galaxy clusters, it was found that the velocity of the average drift motion in the three-degree cosmic microwave background (CMB) system of five superclusters of galaxies from the SDSS region is $$\langle V_{\textrm{pec}}\rangle={+}241\pm 180\text{ km s}^{-1}$$ .

The atlas of the spectrum of the B[e] star CI Cam obtained with the 6-m BTA telescope of the SAO RAS applying the NES spectrograph in the wavelength range of 395–780 nm with a resolution of $$\lambda/\Delta\lambda\geq 60\,000$$ is presented. The atlas identifies about 400 spectral features and illustrates the diversity of spectral features of the unique star, forming in a complex circumstellar environment. The spectrum is dominated by forceful single-peaked H I, He I emissions and numerous double-peaked permitted and forbidden emission lines of ions of chemical elements starting from the CNO triad up to metals (Mg, Al, Ti, V, Cr, Fe) with ‘‘rectangular’’ profiles. The Fe II and [Fe II] emissions predominate in the spectrum. However, several double-peaked forbidden ion emissions were also detected: [V II], [Cr II], [Ni II]. The atlas is presented graphically, with a separate figure corresponding to each échelle order. A list of identified lines, including a number of known interstellar features is presented in table form. The supergiant status of CI Cam is confirmed by the richness of its spectrum with different features of nitrogen.

The paper studies the characteristics of optical emission formation and determines the fundamental parameters of the FL Psc dwarf nova for the epochs before and after its superoutburst in 2023. Moderate-resolution spectral sets were obtained in 2021, 2023 and 2024 with the BTA-6 telescope of the SAO RAS. Observations in all epochs are dominated by the continuous spectrum of the white dwarf (WD) with H I, He I, He II, C II, Mg I, Ca I, Ca II, Fe I emissions and Fe II from the accretion disk and a bright spot at its outer radius. Changes in emission intensities and their Doppler half-widths showed that during the transition from the relaxation stage to quiescence, the zone of maximum radiation shifted to the periphery of the disk, and the temperature in it decreased to $$T_{e}<8000$$ K. An analysis of the observed spectra for three epochs was performed using model flux (i.e. in flux units) and normalized spectra of the WD and a modified method for determining the parameters of their atmospheres. As a result, the following estimates of the accretor’s temperature were obtained for a single surface gravity value $$\log g=8.26\pm 0.13$$ : $$T_{\textrm{eff}}=17\,700\pm 1400$$ K, $$26\,700\pm 1900$$ K and $$19\,600\pm 1300$$ K in 2021, 2023 and 2024, respectively. It is shown that the observed systematic variations in the brightness of FL Psc after the end of the outburst are correctly explained by changes in the WD temperature, taking into account the additional contribution of emission lines. Based on the parameters found for the accretor’s atmosphere, the complete set of fundamental parameters of the system is refined. Its Doppler tomography showed that 1.3 years after the outburst, the accretion disk remained optically thick in the H I lines, but became optically thin in the lines of other elements. Analysis of the FL Psc maps suggests that the H I, He I and He II emissions are formed predominantly under thermalization conditions, while the Ca II and Fe II emissions are formed under the influence of the fluorescence effects of soft ultraviolet radiation from the WD in the accretion disk and the surrounding gaseous envelope.

Molecules in the interstellar medium form both in the gas phase and on dust particles. The chemical pathways for molecular formation are not yet well understood in detail, so the question of which pathway predominates for a particular molecule remains open. We analysed broadband emission spectra of a dense molecular clump in the RCW120 region, obtained with the APEX telescope in the 200–260 GHz range, to investigate molecular formation pathways in regions of massive star formation at an early evolutionary stage. The correlations between the derived molecular column densities, obtained under the LTE assumption, were investigated. An excess of methanol was found in the southern part of the dense clump compared to its northern part, while the abundance of other molecules, such as CH $${}_{3}$$ CN and CH $${}_{3}$$ CCH, remain comparable. The methanol abundance is also elevated relative to other oxygen-bearing molecules, such as OCS and SO. To identify possible causes of the enhanced methanol abundance in the southern part of the clump, we conducted simulations using the astrochemical model Presta in a two-phase approximation, accounting for chemical processes in both the gas phase and the mantles of dust grains. Modeling showed that the enhanced methanol abundance in the gas phase may be due to its photodesorption from icy mantles. At an $$A_{V}$$ value between $$4^{\textrm{m}}$$ and $$6^{\textrm{m}}$$ , methanol efficiently desorbs from ice mantles of dust grains upon interaction with photons, but it is not yet destroyed by UV radiation in the gas phase. A strong linear correlation between molecular column densities indicates that these molecules form in the same phase—either in the gas phase or on dust. However, integrated intensity maps of these molecules may differ, as seen for CCH and CH $${}_{3}$$ CN. If molecules form in different phases—one in the gas phase and the other in dust mantles—no correlation is observed, as in the case of CCH and CH $${}_{3}$$ OH. The weak correlation between methanol and oxygen-bearing molecules that form on dust suggests that only the upper part of the dust mantles, rich in CO ice, is being destroyed in the southern part of the clump.

In this paper we discuss the problems of classification of globular cluster systems (GCS), in particular, the problem of the auxiliary parameter. The simplest methods of their classification are proposed. The possibilities of classification by the degree of concentration of GCS to the center of the galaxy and the use of the velocity anisotropy parameter are studied. Empirical relationships between the initial value of the virial parameter and the physical characteristics of GCSs are found. It is shown that GCSs can be classified using the initial value of the virial parameter.

Four samples of open star clusters (OSCs) with average ages of 5.2, 18.6, 40, and 61 Myr have been analyzed. The selection of these OSCs was carried out from a narrow region inclined to the Galactic $$Y$$ axis at an angle of $$25^{\circ}$$ . Spectral analysis of the vertical positions and velocities of the selected clusters showed that the Radcliffe wave is associated with OSCs no older than 30 Myr. The following estimates of the Radcliffe wave characteristics were obtained for the OSCs with an average age of 5.2 Myr: $$z_{\textrm{max}}=117\pm 12$$ pc with the wavelength $$\lambda=4.55\pm 0.14$$ kpc, and the vertical velocity disturbance amplitude $$W_{\textrm{max}}=4.86\pm 0.19$$ km s $${}^{-1}$$ with the wavelength $$\lambda=1.74\pm 0.08$$ kpc. For the OSCs with an average age of 18.6 Myr, the estimates are as follows: $$z_{\textrm{max}}=54\pm 5$$ pc and $$\lambda=6.30\pm 0.12$$ kpc, and the vertical velocity disturbance amplitude $$W_{\textrm{max}}=7.90\pm 0.16$$ km s $${}^{-1}$$ and $$\lambda=0.83\pm 0.11$$ kpc. The radial motion of the Radcliffe wave away from the Galactic center has been confirmed. The velocity of such movement is 10 pc Myr $${}^{-1}$$ . In our opinion, the spatial distribution of OSCs younger than 30 Myr does not contradict the hypothesis of the association of the Radcliffe wave with the impact of shock waves from supernova explosions that arose on an extended front comparable in scale to the entire wave, that is, about 2 kpc in size.

An Erratum to this paper has been published: https://doi.org/10.1134/S1990341325550024

We present the results of spectroscopic observations of nine symbiotic star candidates in the 360–735 nm wavelength range carried out with the TDS spectrograph of the 2.5-m SAI MSU CMO telescope. Eight selected sample stars were classified as red giants of the M3–M6 spectral types. Light curve analysis revealed that all nine stars can be attributed to SRA- and SRB-type variables (based on the classification of the General Catalog of Variable Stars–GCVS). It is shown that one of the stars, V520 And, can be classified as a symbiotic star. Its spectrum reveals H I, He I, Fe II emission lines, weak lines of [O III] $$\lambda$$ 5007, [Ne III] $$\lambda$$ 3869, and He II $$\lambda$$ 4686, and a Balmer jump in emission. The emission spectrum is found to be variable on both the long and very short timescales. A high-resolution spectrum ( $$R=25000$$ ) obtained with the new CMO spectrograph showed the double-peaked shape of the H $$\alpha$$ line and the presence of an absorption component in it. The October 14, 2023 photometric monitoring revealed a flickering in the $$B$$ band with an amplitude of $$0\overset{\textrm{m}}{.}8$$ on a timescale of 10–15 minutes. The luminosity, effective temperature, and radius of the V520 And cool component were determined: $$L=1400{-}2200\;L_{\odot}$$ , $$T_{\textrm{eff}}=3200$$ K, and $$R=120{-}155\;R_{\odot}$$ , respectively. Evidence for the presence in the system of an accretion disk with the luminosity $$L<10\;L_{\odot}$$ was also found.

Based on data from the ‘‘TESIS’’ scientific instrumentation aboard the ‘‘CORONAS–Photon’’ satellite, collected during the solar activity minimum of 2009, the positions on the disk of 1014 solar flares were analyzed, with X-ray classes ranging from A0.003 to C2.7. A change in the spatial distribution was found in the region of class A events. As flare power decreases, a transition is observed from their localization within the activity belts to a more uniform latitudinal distribution. An estimate of the asymmetry in the positioning of the events on the solar disk was also obtained—0.009. Thus, it was established that the number of flares in the southern and northern hemispheres is almost identical.

The flux density spectra of cyclotron sources above the sunspots were obtained by observations with RATAN-600 in the range of 1.7–10 cm with high spectral ( $$\Delta f/f\sim 1{-}5\%$$ ) resolution and their spectral indices were estimated. The spectral index was then utilized to determine the magnitude of the magnetic field at the base of the transition region on the Sun. By analyzing the relationship between the emisson flux density of the sources and the magnetic field it was found that the observed characteristics of sunspot-associated sources did not align with predictions from a simplified radiation model commonly used for data interpretation. Specifically, there was an excess flux density in the spectrum of ordinary mode radiation compared to what was expected.