bluuebunny/crossref_metadata_2025 huggingface dataset:
Is the orientation of the galaxies in the Local Supercluster related to its Plane?
Authors: Dolgosheeva P. , Makarov D.
Published: December 2024

Modern cosmological models predict a close correlation between the angular momentum orientation of galaxies relative to the large-scale structure of the Universe. In the landmark 2004 paper, based on a sample of 30 galaxies, it was shown that the direction of the rotation axes of edge-on galaxies is predominantly in the plane of the Local Supercluster, supporting the theory of galaxy angular momentum formation by tidal forces. In the last two decades, the sample of known Local Supercluster galaxies has increased 7–8 times, giving us hope to estimate the correlation more accurately. We test the orientation of edge-on galaxies with respect to the Local Supercluster plane as a function of their redshift, position, luminosity, and color. We did not find a statistically significant correlation in any of the subsamples we examined. Most likely, the correlation found in the pioneering paper is due to the extremely small statistics.
Fundamental plane of groups and clusters of galaxies: distances and peculiar velocities of superclusters of galaxies on small scales
Authors: Kopylova F. , Kopylov A.
Published: December 2024

We have studied the relationships between the basic properties of 172 groups and clusters of galaxies based on archival data from the SDSS,
2MASX, and NED catalogs. The measured parameters ($\log R_e$, $<\log I_e>$ and $\log \sigma$ of the clusters of galaxies determine the fundamental plane (FP) in the near infrared: $\log R_e=0.98(\pm0.06)\,\log \sigma-0.56(\pm0.04)<\log \langle I_e \rangle>+3.57(\pm0.07)$, which can be used to determine the distances of the galaxy systems. The root-mean-square deviation of the FP zero-point is 0.07, which corresponds to an error of 16% in determining the distance of the group or cluster of galaxies. For the first time we have measured the peculiar velocities of the superclusters of galaxies. The mean peculiar velocity of the 5 superclusters of galaxies relative to the CMB is $+75\pm360$ km/s.
A strategy for wormhole search using observational astronomy
Authors: Moiseev Yu. , Sazhina O.
Published: December 2024

We present a promising strategy for wormhole (WH) search using astronomical observations. By identifying a net effect of anomalous gravitational acceleration may allow for assumptions regarding the hidden WH nature of a black hole (BH). We provide an upper estimate of this effect for several stars in known BH systems such as S2 and S62 orbiting around Sgr A*; along with modeling a synthetic system consisting of a traversable WH, a star on our side and a perturbing object on the other side of a WH. We also consider recently discovered objects from GAIA catalogue data – GAIA BH1, BH2 and BH3. We show that in the traversable WH model a perturbing object (star) located on the other side of the WH throat is capable of causing a significant anomalous acceleration of an object (star) on the observer’s side. This effect is observed to be more significant than other competing factors, including disturbances from nearby stars and the influence of the dark matter halo. The estimated magnitude of the anomalous acceleration varies from $10^{-4}$ to $10^{-2}$ cm$/$sec$^2$, which corresponds to the current accuracy of acceleration measurements. In the future, this may allow for a more precise estimation of the desired effect.
Cosmological interpretation of JWST observations
Authors: Raikov A. , Yershov V. , Lovyagin N.
Published: December 2024

Observational data from the James Webb Space Telescope (JWST) indicate a significant number of galaxies with redshifts $z > 10$. Galaxies with record-breaking redshifts exhibit luminosities comparable to those of galaxies in the local universe, and they are small in size, measuring hundreds of parsecs, as determined within the standard cosmological model, $\Lambda$CDM. Within this framework, a satisfactory explanation for their formation and evolution has not yet been found. So, most current research focuses on revising theories of galaxy formation and evolution to align with JWST observational data. In this talk, we discuss cosmological tests based on JWST observations, which could provide an alternative explanation. High-redshift galaxies detected by the JWST exhibit brightness and large masses, yet their sizes are over 10 times smaller than those of low-redshift galaxies with comparable masses. This leads to an increase in the gravitational potential $\phi$ and, consequently, an increase in the velocity dispersion, which in turn results in the broadening of galaxy spectral lines, including ${\rm Ly}_\alpha$. Thus, their spectral lines measured by the JWST must be widened. Checking galaxy spectral line widths constitutes a new physical cosmological test, which can be conduct using the current JWST data. The high rate of star formation in those galaxies implies a high number density of ionizing photons. This leads to a significant tension with the optical depth of reionization based on the cosmic microwave background (CMB). The previously known tensions of the $\Lambda$CDM model ($H_0$, $\sigma_8$), along with this new inconsistency, indicate that the method of using CMB to determine cosmological parameters and the concept of Planck precision cosmology may require further evaluation.
Analysis of the update sample of USS objects and search of candidates to GPS sources in the RZF survey
Authors: Temirova A. , Bursov N. , Kudryashova A.
Published: December 2024

A deep RATAN-600 Zenith Field (RZF) survey at wavelength ${\lambda}$ = 7.6 cm on the declination of the 3C84 radio source. In the center of the survey region, 448 objects were detected, and 73 of them have ultra-steep spectra (USS), which are the main indicator for finding possible candidates for distant galaxies. Optical identifications for 31 of the USS objects were made using the SDSS surveys have been used. It turns out that 23 objects are galaxies and 8 are star-forming objects. Photometric redshifts ($z_{\rm ph}$) and radio luminosities at 3.9 and 1.4 GHz ($L_{3.9}$ and $L_{1.4}$) are determined for 31 objects with spectral indices $\alpha < -1.1$, $S_{\rm \nu} \sim \nu^\alpha$ for objects with published photometric data. In the sample of USS objects, 15 galaxies have $z_{\rm ph}< 0.5$, and 8 of them have relatively high $L_{1.4} > 10^{26}$ W/Hz of type FR II. Seven galaxies at $z_{\rm ph} > 0.5$ are also of type FR II. Five sources are of intermediate type FR I-FR II. Only three radio galaxies at $z_{\rm ph}<0.5$ turned out to be a rare nearby galaxy with relatively low $L_{1.4}<10^{25}$ W/Hz (FR I). These radio sources are either located in the dense intergalactic medium of rich clusters or are confined within their host galaxies. Almost all of these sources can be observed with the SAO 6-m telescope. Galaxies with $L_{1.4} > 10^{26}$ W/Hz (FR II) have magnitudes $18<m_{\rm r}<23$. The search for Gigahertz Peaked-spectrum (GPS) candidates in the RZF survey was performed, and 29 objects were classified as GPS candidates. The most sensitive radio and optical catalogs, a new blazar candidate catalog, Blazar Radio and Optical Survey (BROS) were used. We propose 7 new candidates for GPS sources and 5 new Megahertz Peaked-spectrum (MPS) sources based on their spectral shape and variability characteristics.
Star formation in low brightness galaxies and in the extended gaseous disks of normal galaxies
Authors: Zasov Anatoly , Zaitseva N. , Saburova A.
Published: December 2024

We analyze the available observational data on the radial distribution of gas and young stellar populations in the disks of low surface brightness (LSB) galaxies and in the outer regions or the extended disks of normal brightness (HSB) galaxies. These cases involve star formation under special conditions of low volume and surface gas density. There is no well-defined boundary between these subgroups of galaxies that we consider, but in non-dwarf LSB galaxies the rate of current star formation within the wide range of radial distances appears to be higher compared to the outer disks of most of HSB galaxies at similar values of the surface gas density. The factors that could stimulate the compression of the rarefied gas at the periphery of galaxies are briefly discussed. Attention is drawn to the idea that the densities of LSB disks estimated from their brightness may be underestimated.
Formation of single stars and their planetary systems, typicality of the Solar system
Authors: Abdulmyanov T.
Published: December 2024

In this paper, we determine the dynamic viscosity for the case of pulsating disturbances in the density of gas-dust disks. The characteristic velocities of the disk dust particles are divided into separate classes of orbits with Keplerian and near-Keplerian motions. For these classes, we obtain formulas for the dynamic viscosity. We analyze the distributions of exoplanets by their masses, major semi-axes, and eccentricities of their orbits. We conclude that hot giant planets can be located on complex, unstable orbits of accretion onto the central star.
33 Lib is an analogue of Gamma Equulei?
Authors: Bychkov V. , Bychkova L. , Madey J.
Published: December 2024

In this paper we investigate the periodic variability of the magnetic field of the magnetic Ap star 33 Lib. The period of 83.5 years found by us earlier from the magnetic field estimates and 79.2 years determined later are close to the period of variability of the magnetic field of the known Ap star $\gamma$ Equ of 97 years. Such a slow rotation is also confirmed by a very small value of the projection of the equatorial velocity onto the line of sight $v_e \sin i = 0.6$ km/s.
Magnetic and photometric variability of the super-slowly rotating Ap star GY And (HD 9996)
Authors: Bychkov V. , Bychkova L. , Madey J. , Komissarova G. , Metlova N.
Published: December 2024

The star GY And (HD 9996) belongs to a very rare and poorly studied class of super-slowly rotating Ap (ssrAp) stars. The main difficulty in conducting studies of such stars is their unusually long periods, often amounting to tens or even hundreds of years. Based on long-term magnetic monitoring conducted at the 1-m telescope of the SAO RAS and photometric monitoring carried out at the 60-cm telescope of the Southern Station of the SAI, the period (which is just over 23 years) and the parameters of magnetic and photometric variability of GY And (HD 9996) have been clarified.
Interstellar medium of Galaxy in the optical range
Authors: Galazutdinov G.
Published: December 2024

The paper briefly presents the results of spectral studies of interstellar medium in the wavelength range from near-ultraviolet to near IR. Particular attention is paid to the mysterious diffuse interstellar bands (DIBs), which have remained unidentified since 1922. The connection between different components of the interstellar medium and possible candidates for the carriers of diffuse bands are discussed.
Frequency analysis of Gamma Doradus variables observed by TESS
Authors: Grigoriev S. , Dyachenko V.
Published: December 2024

We present a frequency analysis of $\gamma$ Dor variables based on the TESS photometric data: among 35 objects, period spacing patterns were found in five stars TIC 235680293, TIC 235682463, TIC 416401558, TIC 232620739 and TIC 406927322. We estimate their near-core rotation and make an assumption about the pulsation modes. Also three objects TIC 75784209, TIC 318837103, and TIC 309662501 show pulsations in $p$-modes and $g$-modes simultaneously, and we identify them as $\delta$ Sct–$\gamma$ Dor.
``Magnetospheric gate" in polars
Authors: Ikhsanov N. , Beskrovnaya N. , Kim V. , Korol'kova O.
Published: December 2024

The mass-exchange process in polars is discussed. We point out that the strong magnetic field of a white dwarf in these systems can under certain conditions prevent the material from flowing through the L1 point operating as a ``magnetospheric gate''. We show that the condition under which the ``magnetospheric gate'' is closed is satisfied in the majority of polars known to date. This finding opens the question about a possibility to realize an alternative mechanism of mass exchange in these systems. We briefly discuss application of this mechanism to the best studied polars.
Stellar wind velocity of the massive component in the high mass X-ray binary OAO 1657−415
Authors: Ikhsanov N. , Beskrovnaya N. , Kim V.
Published: December 2024

The parameters of the wind-fed accretion process in the massive X-ray binary OAO 1657−415 are discussed. We show that the X-ray luminosity of an accreting pulsar in this system can be explained only if the velocity of the stellar wind of the massive component in the orbital plane of the binary system is in the range of 200–500 km/s.
On the kinematic state of the atmosphere within IRAS 07430+1115 system
Authors: Klochkova V. , Zhuklevich G. , Panchuk V.
Published: December 2024

Having obtained high-resolution optical spectra with the NES spectrograph of the 6-m telescope BTA, we investigated the variability of the spectral features and radial velocity for a cold star which passed the asymptotic branch of giants and is associated with the IRAS 07430+1115 source. The optical spectrum of this post-AGB star with altered chemical composition is purely absorbtional, emissions and other peculiarities are absent in the spectrum. From the measurements of the positions of many metal absorbtions (mainly ions of heavy $s$-process metals) a weak variability of the radial velocity was revealed. The velocity varies with the average value $V_r=37.0$ km/s and the standard deviation $\Delta V_r \approx 0.8$ km/s, which may be a consequence of low-amplitude pulsations in the atmosphere of a far evolved star. The position of the H$\alpha$ line core varies within 40.5–43.8 km/s. Based on measurements of the positions of the rotational components of the (0;0), (1;0) and (2;0) Swan bands of the molecule C$_2$ origin in the circumstellar envelope, the average radial velocity $V_r{\rm (Swan)}=21$ km/s and the expansion velocity typical for post-AGB stars envelope $V_{\rm exp} \approx 16$ km/s are determinated. Using the intensity of the infrared triplet of oxygen, we estimated the luminosity of the central star of the IRAS 07430 system $\log L/L_{\odot} \approx 3.1$ which is within the range of values for post-AGB stars.
Evolution of non-spherical porous dust grains in galaxies
Authors: Kondratieva T.
Published: December 2024

Recent research has examined the evolution of interstellar dust grain size distribution over time scales of up to 10 Gyr, focusing on the primary grain growth and destruction mechanisms present in both the diffuse and dense interstellar medium. The grains were modeled as porous spheres, and for the first time, the porosity was considered to depend on the particle size and time. In this work, it is proposed in the first approximation that non-spherical dust grains have a comparable mass distribution to that of spherical ones. The use of porous spheroids facilitates the calculation of the time evolution of both the interstellar polarization curve and the interstellar extinction curve. As the polarization curve is known to be a critical test for porous dust grain models, the results obtained for spheroids are important for a further understanding of the dust grain evolution in galaxies.
Empirical isochrones for single and binary stars in open clusters
Authors: Mikhnevich V. , Plotnikova A. , Seleznev A. , Carraro G.
Published: December 2024

We compose systems of empirical isochrones for single and binary stars with various components' mass ratio $q=M_{2}/M_{1}$ ($M_{2}$ – mass of the secondary component, $M_{1}$ – mass of the primary component) in order to search for unresolved binaries and multiple stars in open star clusters.
We fit an empirical isochrone for single stars across the main sequence (MS) elements assigned using the HDBSCAN algorithm. Isochrones for binaries are obtained by shifting this empirical isochrone to values determined using PARSEC theoretical isochrones. We determine the parameter q for each source that lies within the corresponding intervals between the binary isochrones. We then plot a probability density distribution of the component mass ratio q and estimate the fraction of binaries in the cluster. This work is focuses on the study of close open star clusters with heliocentric distances less than 200 pc. We consider the color-magnitude diagrams (CMDs) in the Gaia photometric system and the two-index diagrams (TIDs) composed of bands in the visible and infrared wavelengths.
Study of clusters in the star forming region G174+2.5
Authors: Permyakova T. , Carraro G. , Kirsanova M. , Ladeyschikov D. , Seleznev A.
Published: December 2024

We study the structure, photometric diagrams and kinematics of four embedded clusters (S235North-West, S235A-B-C, S235Central and S235East1+East2) in the star-forming region associated with the giant molecular cloud G174+2.5. This research uses photometric data from the GPS UKIDSS catalog and astrometric data from the Gaia DR3 catalog. We determine the center positions, radii, and interstellar extinction for clusters in the region. An extinction was determined in two ways --- using the NICEST algorithm and the Q-method. The latter method gives a smaller scatter of the color indices on the extinction-corrected photometric diagrams. The membership probability of stars in the clusters, their masses and distances to clusters are also estimated. Additionally, we determine the average proper motions and study the kinematics of the clusters using data from the Gaia DR3 catalog. In all four regions, we estimate the mass of the gas component and the efficiency of star formation. Then, we apply the data obtained to evaluate the total energy of both the stellar and gas systems. It allows us to ascertain whether the clusters are gravitationally bound or not. The boundness of the systems depends on the size of the region where we estimate the mass of gas. If we take the mass of the entire cloud, all four cluster-gas systems appear to be gravitationally bound.
Stellar populations of extragalactic globular clusters
Authors: Sharina M. , Maricheva M. , Acharova I. , Shimansky V.
Published: December 2024

Globular clusters (GCs) are the oldest (ages up to 13.6 Gyr), but not the most metal-poor ( -2.9<[Fe/H]<0 dex) objects in the Universe. Studying properties of their stellar populations and comparing them with the properties of structural components of galaxies and stellar streams is necessary to understand the processes of nucleosynthesis and galaxy formation. We analyse integrated-light (IL) spectra of extragalactic GCs in order to determine the properties of their horizontal branch stars, ages and chemical composition. For this purpose, we compare the observed and synthetic spectra of clusters calculated using stellar atmosphere models. In this paper, we address the questions: 1) what signatures of multiple stellar populations can be inferred from the analysis of IL low-resolution spectra of GCs; and 2) what the origin of GCs is and their multiple stellar populations. For the second question, we consider only two sources of multiple stellar populations: asymptotic giant branch and rapidly rotating massive stars, and briefly consider the problems in this scientific area.
MHD-Modeling of the molecular filament evolution with numerical FLASH code
Authors: Sultanov I. , Khaibrakhmanov S.
Published: December 2024

We study numerically the gravitational fragmentation of a cylindrical molecular cloud with large-scale magnetic field. The simulations are performed with the help of the MHD code FLASH. We consider two cases: gravitational instability of the filament with initially deformed surface (model of Chandrasekhar and Fermi), and the instability of longitudinal compressible waves (model of Stodolkeiwicz). The simulations under typical parameters show that two types of the cores can be formed as a result of the fragmentation. Gravitational focusing leads to the formation of two massive clumps at the ends of filaments. Those cores move towards the cloud center with supersonic speeds. The instability of initial perturbations results in smaller evenly distributed cores inside the filament. The cores formed due to the instability of compressible waves have almost spherical shapes, while the cores resulted from the fragmentation of the filament with deformed surface are flattened. Typical sizes of the cores of 0.01–0.02 pc are in agreement with observations.
Study of a compact source with an enhanced NH$_2$D/NH$_3$ abundance ratio in the S187 region
Authors: Trofimova E. , Zinchenko I. , Zemlyanukha P. , Punanova A. , Henkel C.
Published: December 2024

When analyzing data obtained with the Onsala 20-m radio telescope (Sweden) in 2018, a compact peak of NH$_2$D emission with an enhanced ratio of NH$_2$D/NH$_3$ column densities was discovered in the S187 region. This peak is not associated with any known astronomical object from the SIMBAD database, but previously obtained dust emission maps have a peak in this region. Additional observations of this region were carried out in 2023 with the Onsala telescope. The kinetic temperature in the center of the source was determined using the rotational diagrams of the CH$_3$CN and CH$_3$CCH molecules, and it turned out to be quite high (according to various estimates, approximately from 30 K to 50 K). Based on the spectra of the C$^{18}$O molecule and dust emission, estimates of the column density of molecular hydrogen were obtained. Deuterated NH$_2$D and DCO$^+$ molecules were detected in this region, while no noticeable emission of the DCN molecule was detected. Estimates of the column densities at the center of the source were obtained by processing the spectra of NH$_2$D, DCO$^+$, HC$^{18}$O$^+$ and HC$_3$N molecules. Maps of the integral intensities of these molecules were also constructed. The ratio of the abundances of ortho- and para-NH$_2$D, as well as the ratio of NH$_2$D and the main isotopologue of NH$_3$ were found. The possible nature of the source is discussed.
Study of the high-mass star-forming region S255IR at various scales
Authors: Zinchenko Igor , Liu S. , Ojha D. , Su Y. , Zemlyanukha P.
Published: December 2024

The core of S255IR-SMA1 contains the protostar NIRS3 with a mass of about 20 $M_{\odot}$. A few years ago, the first burst of luminosity for massive protostars, caused by an episodic accretion event, was recorded here. We have been studying this object for a long time with various instruments, including ALMA. The general morphology and kinematics of this area have been investigated. Disk-shaped structures, jets and outflows have been identified and studied in detail. We have recently observed this object with ALMA at a resolution an order of magnitude higher than previously achieved―about 15 milliarcseconds, corresponding to about 25 AU. This paper presents new results from the analysis of these data together with observations in other bands. The new data show an inhomogeneous disk structure, an ionized region around the protostar, and the presence of a jet observed in the submillimeter continuum consisting of individual knots whose orientation differs markedly from that on large scales. The submillimeter emission from the jet most likely represents bremsstrahlung from ionized gas. Based on observations of the lines of some molecules, the kinematics and physical properties of this region are discussed. Methanol maser emission associated with the jet is observed.
Morphometric parameters of fresh lunar craters
Authors: Feoktistova E. , Rodionova Zh. , Shevchenko V.
Published: December 2024

We study the morphometric parameters of 111 lunar craters with a diameter of 10 km or more, the formation of which, according to some researchers, can be attributed to the Copernican period. These craters were selected by analyzing data from the Diviner spectrometer on board the LRO probe. The purpose of this work is to study the morphometric characteristics of such craters in order to identify their characteristic features. According to the results obtained, the morphometric parameters of the fresh lunar craters are significantly similar to the morphometric parameters of lunar craters of the 1st degree of degradation (well-preserved craters) according to the classification of the SAI MSU.
Longitudinal magnetic field gradients and vertical electric currents in active regions with different flare productivity levels
Authors: Fursyak Yu.
Published: December 2024

The purpose of the work performed was to search for parameters of longitudinal magnetic field gradients and vertical electric currents, and their values, which could serve as the basis for creating criteria for short-term forecasting of changes in the flare productivity of an active region (AR). In the course of the study, a threshold (critical) value of the average unsigned vertical electric current density ($
$) was identified, equal to 2.7 mA m$^{-2}$; it is shown that in all ARs with high flare activity, the value of $
$ is above the threshold; it is shown that a rapid increase in the parameter $
$ above the critical value, especially in ARs, in which additional ascent of the magnetic flux was recorded during their monitoring time, indicates an increase in AR flare activity in the time interval of 18-20 hours. A threshold value of the transverse component of the longitudinal magnetic field gradient between pairs of sunspots in the AR ($max(\nabla_{\perp}B_z)_{sp}$), equal to 0.118 G km$^{-1}$, was also found. In the AR NOAA 11283, a study of the dynamics of the value made it possible to detect a time delay of 19 hours between the beginning of its stable growth and the time of the beginning of the development of the first of a series of powerful solar flares.
Magnetic multipoles of the Sun from observations of the mean magnetic field
Authors: Haneychuk V.
Published: December 2024

The data of the mean magnetic field (MMF) of the Sun from the Wilcox Solar Observatory from 1975 to 2023 (49 years, number of daily measurements N=14516) were analyzed to identify the main periodicities over short time intervals. The wavelet-spectrum of these data shows that the MMF has significant rotational harmonics from the first to the third, although sometimes there are
higher orders up to the sixth harmonic inclusively. Each of these harmonics corresponds to its own multiplet of the magnetic field (dipole, quadrupole and higher components). Rotation harmonics were identified in the original data series and an approximated time series was built from them. In this case, wavelet-spectrum data and refined parameters of sinusoids obtained using the least squares method were used. The constructed approximated data series contains more than 90 % of the power of the original series.
The main components of the Sun's rotation change their amplitude, frequency and phase over time. Changes in the amplitude of oscillations occur depending on solar activity-they are usually maximal in the second half of the cycle. Rotational frequencies change over time, but do not show dependence on solar activity. The maximal amplitude of rotation component most often has a frequency of the main period of about $P\approx27$ day (55.4 % in time), as well as its half value $P/2\approx 13.5$ day (38.2 %); the share of periods $P/3\approx 9$ day is 6.1 %, the rest — no more than 0.3 %. This means that the Sun predominantly appears as a magnetic horizontal dipole ($\approx$55 % of the time), but the quadrupole component is also very significant and occupies 38 % of the time. In general, different multipoles are almost always present on the Sun, but the predominance of one or another component of the multipole does not reveal any patterns and is practically independent on solar activity.
Investigation of magnetic free energy dynamics in the M1.2-class complex solar flare of March 15, 2015 using the 135-second HMI vector magnetograms
Authors: Sharykin I. , Zimovets I. , Myshyakov I. , Anfinogentov S.
Published: December 2024

We investigate magnetic free energy (MFE) dynamics in the M1.2 solar flare occurred on March 15, 2015, 22:45 UT. We use the nonlinear force-free field (NLFFF) model of the coronal magnetic field on the basis of 135-second HMI vector magnetograms (standard magnetograms have a temporal resolution of 720 s) from the Heliosesmic and Magnetic Imager (HMI). Since we consider a rather long event (about 100 minutes) with several episodes of energy release of different temporal dynamics (pulsed or more gradual), we can find features of the MFE dynamics relative to the flare energy release stages using 135-second vector magnetograms. It is shown that the main MFE dissipation (approximately 30 % of the initial level) occurred during the two first subflare bursts seen in microwave hard X-ray ranges. These two bursts developed at low (less than 5 Mm) magnetic structures extremely elongated along the magnetic field polarity inversion line (PIL), while the other long-lasting bursts without appreciable MFE dissipation occurred in a growing flare arcade of magnetic loops. The obtained results are in favor of the fact that most of the MFE is localized in magnetic structures with a strong electric current at the PIL. It is possible that local monitoring of the preflare state around the PIL based on magnetic extrapolations with high temporal and spatial resolution will allow further improvement of methods for predicting solar flares. The dynamics of relative helicity are also studied in relation to the dynamics of the eruptions, and we found that the first impulsive subflares were accompanied by the most significant drop in helicity.
Peculiarities of Joule dissipation in the solar atmosphere
Authors: Stepanov A. , Zaitsev V. , Kupriyanova E.
Published: December 2024

The peculiarities of the electric current dissipation in the magnetic flux rope throughout the solar atmosphere from the photosphere to the corona are considered. It has been shown that the dissipation depends on both the magnitude of the electric current and the altitude. The dissipation rate reaches its maximum near an altitude of 2100 km and has a rather complex behaviour. The r745ns of predominance of Cowling and Spitzer resistances are determined. The consequences of these peculiarities in current problems of solar physics are discussed.
Exotic red flares on stars as the observational manifestation of the asteroids in exoplanet systems
Authors: Ibrahimov M.
Published: December 2024

The published data on exotic red flares (RFs) obtained using optical/IR photometry was for the first time gathered and discussed in this paper. To date, the RFs have been observed: (a) in IR space missions (1–2 yr long IR brightening observed using WISE/NEOWISE and Spitzer in NGC 2547-ID8, HD 166191, WD 0145+234, and some others systems); (b) in five optical systems with the normal stars (UU CrB, AZ Ori, FF Ori, IX Oph, CU Cnc; three of the five systems are binaries; seven single flares were observed in 1980–2009 having a 1-hour average duration, an amplitude up to $2^{\rm m}$, and an energy up to $10^{39}$ erg); (c) in three optical/hi-energy systems with a compact object (V404 Cyg, MAXI J1820+070, Swift J1858.6$-$0814; all the systems are binaries hosting a black hole or a neutron star as a component; a ``forest'' of tens of flares was observed, the flares having a subsecond duration, an amplitude up to $1\,.\!\!^{\rm m}6$, and an energy of the order of $10^{36}$ erg/s); (d) in the near-IR range in the 2MASS stars (hundreds of flares were found based on the statistical study of more then 1300 2MASS M dwarfs). The RFs are suggested to be produced by a collisional impact and destruction of asteroid-like bodies in exosystems. All the above data independently supports an idea that exotic red flares are actually a real and well-distributed phenomenon. Undoubtedly, the RFs serve more deeper and wider investigation, keeping in mind their direct connection to the manifestation of asteroids in exosystems.
The scientific potential of the Pulkovo velocity of GNSS-stations database: geodynamics of the East European Craton
Authors: Smirnov S. , Gorshkov V. , Scherbakova N. , Movsesyan P. , Petrov S.
Published: December 2024

A Velocities Data Base (VDB) for GNSS stations located on the territory of the Eastern European Platform (EEP) is being developed at Pulkovo Observatory. More than 70% of the stations belong to Russian GNSS networks. A comparison of the VDB velocities with a similar global database of the Nevada Geodetic Laboratory (NGL, USA) for common stations indicates the absence of systematic discrepancies between them, which made it possible to use the combined data from both databases for geodynamic studies in the EEP region. The kinematic parameters of the rotations of the main structural blocks of the EEP are determined and its deformation field is calculated.
Integer phase ambiguity resolution method for absolute GLONASS observations
Authors: Starikov K. , Petrov S.
Published: December 2024

With the help of modern navigation satellite systems it is possible to determine the coordinates of points with millimeter accuracy due to the precision measurement of the carrier phase of the navigation radio signal. However, in the course of achieving this accuracy, a nontrivial problem of resolving the integer phase ambiguity arises. The most difficult part is to determine the integer number of wavelengths between the phase centers of the transmitting antenna of the navigation satellite and the receiving antenna. An exact solution to this problem using the integer least squares method, although it exists in theory, is not applicable in practice due to the prohibitively high computational complexity. In this regard, a number of authors have developed various suboptimal methods for resolving integer phase ambiguity, which allow solving a problem with varying degrees of uncertainty. In this case, the problem can be considered satisfactorily solved for relative coordinate determinations from GPS (global positioning system) and GLONASS (global navigation satellite system) observations, as well as for absolute coordinate determinations from GPS. As for the absolute determinations of coordinates from GLONASS observations, the situation is complicated by the fact that GLONASS, unlike GPS, uses frequency-division multiple access. In other words, if all GPS navigation spacecraft broadcast navigation radio signals on a single frequency, then GLONASS satellites broadcast on different frequencies. This paper generalizes one of the modern and effective methods for resolving integer ambiguity for GPS observations, MLAMBDA, to the GLONASS system. The ultimate goal of the work is an independent algorithm for absolute determination of coordinates with millimeter accuracy using the GLONASS system. In the course of the work, the MLAMBDA formalism was generalized to navigation systems with frequency division of access, and the first results of independent coordinate determinations from GLONASS observations in absolute mode were obtained.
Study of the astroclimate at the Baikal Astrophysical Observatory
Authors: Bolbasova L. , Lukin V.
Published: December 2024

The atmospheric conditions are crucial for an astronomical observatory. Earth's atmosphere limits image quality in ground-based optical telescopes. The knowledge of the atmospheric turbulence vertical distribution above an astronomical site is significant for the design and operation of adaptive optics systems as well as for scheduling the observing time. The Baikal Astrophysical Observatory (latitude $51^\circ50'$ north, longitude $104^\circ55'$ east) is the site of the 1-meter Large Solar Vacuum Telescope (LSVT). In this study we estimate the vertical distribution of optical turbulence $C_{n}^{2}$, which determines all the integrated parameters for adaptive optics. A 5-year dataset (2019–2023) of temperature and wind speed at pressure levels from the National Centers for Environmental Prediction (NCEP) / National Centers for Atmospheric Research (NCAR) Reanalysis are used for the research.
Four-channel wide-field cluster for survey tasks and synchronous multicolor photometry
Authors: Ibrahimov M. , Nalivkin M. , Shugarov A.
Published: December 2024

A new wide-field optical instrument of the Institute of Astronomy of the Russian Academy of Sciences (INASAN) is described. It has been implemented under the bilateral Russia--Uzbekistan collaboration in astronomy in 2023–2025. The instrument comprises four identical wide-field 28-cm aperture telescopes on a common mount designed for all-sky surveys and photometry. For a single exposure, the cluster takes an image of a 7 square degree field in four photometric bands simultaneously with a 1.26 $''$/px scale. The technical and optoelectronic characteristics of the cluster are presented and discussed. The plan is to install the cluster at the Maidanak Astronomical Observatory, which has a large amount of clear night time (about 2500 hours per year) with a median seeing of $0\,.\!\!^{\prime\prime}7$. The INASAN cluster will become one of the most informative positional photometric multiband observing systems in Russia. It will also be useful in a global network of multiband wide-field optical instruments including the BRICS astronomical network.
A review of astroclimate conditions at possible locations for the Eurasian Submillimeter Telescopes (ESMT)
Authors: Khaikin V. , Shikhovtsev A. , Mironov A. , Kopylov E. , Khudchenko A. , Nazarov G. , Zemlyanukha P. , Makoev G. , Yao Y. , Qian X.
Published: December 2024

The paper presents the results of studying the astroclimate at possible locations for the Eurasian Submillimeter Telescopes (ESMT), including the sites of Kurapdag in the Agul district of Dagestan, Khunzundallbak (3676 m) in the Rutul district of Dagestan, Khulugaisha peak (Eastern Sayan), Tashanta checkpoint in the intermountain basin of the Altai Republic, Boguty (3350 m) in the foothills of the Altai Mountains near the border with Mongolia, the Suffa plateau (Aktashtau, 3282 m), and the Ali region in Tibet. The expected radio brightness temperatures of the clear and cloudy atmosphere at wavelengths of 2 and 3 mm and the characteristics of the 3-mm range radiometer for measuring the optical thickness of the atmosphere are presented.
Challenges of high-resolution spectroscopy in the Nasmyth focuses of the BTA
Authors: Panchuk V. , Klochkova V. , Yushkin M. , Zhuklevich G.
Published: December 2024

The article discusses the challenges and solutions associated with high-resolution spectroscopy on alt-azimuth mount telescopes, particularly focusing on the 6-meter BTA (Big Telescope Alt-Azimutal) and its Nasmyth focus. The main attention is given to the instability of spectra caused by the design features of the telescope and the equipment used. Special attention is paid to the issues of temperature non-uniformity and its impact on observation quality. Various stages of equipment development and testing are described along with the results of applying new technologies and methods to achieve high spectral resolution.
Fast implementation of coherent dispersion compensation
Authors: Sergeev S. , Kazakevich Yu.
Published: December 2024

The interstellar medium consists of gas and dust components, almost all of which are completely transparent at centimeter wavelengths. The main cause of radio wave scattering in the interstellar medium is ionized gas—plasma. The behavior of radio waves propagating through such a medium is described by the dispersion equation in a rarefied plasma. The plasma frequency is generally a function of position and time, because it depends on the electron density along the line of sight. The dispersion measure physically represents a column of free electrons between a pulsar and the Earth. Thus, the dispersion measure is a value that determines the delay of radiation pulses of cosmic objects. The delay of radio emission is due to the fact that the refractive index of the plasma depends on the wavelength. Long waves propagate more slowly than short ones, so a signal emitted simultaneously at different frequencies arrives to the observer at long waves later than at short ones. One type of astrophysical objects for which the pulse delay can be measured are pulsars. Since observations are always carried out in a certain wavelength band, the presence of a delay interferes with the study of the fine time structure of pulsar pulses. Without dispersion correction, pulsar observations in a wide frequency band become impossible. The presented work considers the implementation of the coherent dispersion compensation method on a heterogeneous computing structure. Processing in the spectral domain allows the simultaneous search for fast radio bursts (giant pulses), radio pulsars, and refinement of the dispersion measure of the found pulses. It is shown that the proposed implementation on modern computing accelerators allows real-time processing in a wide frequency band that meets modern requirements.
SODA: a system to detect	daytime asteroids of the ``Milky way'' project
Authors: Shugarov A. , Shustov B.
Published: December 2024

The ``Milky Way'' space safety program is under development in Russia. A part of the program implies the launch of a special spacecraft aimed to detect decameter asteroids coming from the day sky (from the sunward hemisphere) as well as to predict space weather and monitor the Sun's activity. The spacecraft will be launched to the Sun–Earth L1 point. The payload SODA (System for Observation of Daytime Asteroids) is under development at INASAN. The SODA concept is based on the results of the previous, conceptual, phase of the project. We present a general outline of SODA and give some new features in more detail. IKI RAS is responsible for the second part of the spacecraft payload related to space weather and solar activity.
Systematic effect in the standard processing of gravitational-wave signals
Authors: Yershov V. , Raikov A. , Popova E.
Published: December 2024

We analyze a systematic effect in the standard coordinate transformation of a gravitational-wave signal from the source to the detector reference frame. It is shown that, despite the mathematically correct application of the canonical Arnowitt–Deser–Misner transform (ADM formalism), the estimated characteristic mass of the source (a binary system of merging black holes) turns out to be affected by a systematic error if the mass estimation is based on the the time derivative of the signal frequency obtained in the detector reference frame, and not in the source reference frame. This systematic error leads to a significant overestimation of distances to gravitational wave sources, which reduces the probability that large ground-based telescopes detect possible electromagnetic afterglows associated with gravitational wave sources.
Interactive multi-instrumental database of solar activity observations
Authors: Berezin I. , Illarionov E. , Tlatov A.
Published: December 2024

The project of creating a center of access to solar activity data on the basis of domestic ground-based observations is presented. The center uses a complex of automated systems for recognition of solar activity objects. The observational data are based on the continuous synoptic observations at the Kislovodsk Mountain Astronomical Station (KMAS) of the Central Astronomical Observatory of the Russian Academy of Sciences. The KMAS data we are considering are images of the solar photosphere, chromosphere, corona, and observations of the magnetic fields on the Sun. The creation of the system will allow users to find the data on individual events as well as to conduct statistical studies of a large number of events using an interactive database interface. The concept behind the operation of our computer vision system is that the data will be analyzed almost in real time as soon as they arrive to the KMAS operations center and undergo basic processing. This will allow the system to issue space weather alerts in due time as well as to create images and videos for quick viewing and to archive the solar activity data. The complex and a unique data processing pipeline consisting of hardware and control software that has been created at the KMAS is described. We build software modules that detect, track, and analyze numerous phenomena in real data streams, including flares, filaments, sunspots, active regions, coronal holes, coronal mass ejections (CMEs), coronal oscillations, and jets. Detections of CMEs and filaments are made based on the continuous data from the Solar Patrol Optical Telescopes (SPOT).
Improving the Quasar VLBI Network for data transfer with the National Research Computer Network of Russia
Authors: Bezrukov I. , Salnikov A. , Vasiliev V. , Plotnikov R. , Evseev A. , Abramov A.
Published: December 2024

This article presents the results of the phased integration of the VLBI complex ``Quasar'' into the National Research Computer Network of Russia (NIKS). The VLBI complex ``Quasar'' has implemented e-VLBI technology in Russia, enabling near real-time radio interferometric observations. This technology is critical for high-precision determination of Universal Time, which is essential for fundamental and applied space research, particularly for the GLONASS system. The complex consists of three observatories: ``Badary'' (Republic of Buryatia), ``Zelenchukskaya'' (Karachay-Cherkess Republic), and ``Svetloe'' (Leningrad Region), with a fourth under construction in Primorsky Krai. Each observatory can register data at speeds up to 16 Gbit/s, while the correlator in St. Petersburg can receive data at up to 96 Gbit/s. The current data transmission from ``Badary'' and ``Zelenchukskaya'' is limited to 2 Gbit/s, restricting the complex’s functionality. Increasing the transfer speed to 8 Gbit/s or more would significantly improve capabilities. This article details the results of the data transfer speed tests conducted during hourly sessions to the Center for Correlation Processing of RAS in the NIKS network. Additionally, the article explores options for connecting the nearby academic organizations of the IAA RAS to the NIKS network via fiber-optic cable, enhancing the overall data transmission efficiency and reliability of the VLBI complex. The integration of these observatories into NIKS is expected to enhance the ``Quasar'' VLBI complex, enabling more robust and rapid data processing for various scientific applications.
Creation and development of domestic scientific and educational space infrastructure and its use as a tool for ground-based and space astronomy
Authors: Starikov K.
Published: December 2024

An overview of current advances in the use of small spacecraft for astronomical research and space education is provided. Existing projects, their goals, achievements and plans for implementation are reviewed. The current results of the authors in creating a scientific and educational digital platform for research and educational space activities are presented.
Boron Buckminsterfullerene
Authors: Choi Hyun Wook , Zhang Yang-Yang , Kahraman Deniz , Xu Cong-Qiao , Li Jun , Wang Lai-Sheng
Published: December 2024

Fullerenes, spherical molecules made entirely of carbon atoms, have played a foundational role in the birth of nanoscience. Despite extensive research, however, comparable structures composed of other elements remain elusive, highlighting the unique bonding properties of carbon that enable the formation of such remarkable nanoscale architectures. Here, we report the discovery of a fullerene-like 80-atom boron cluster using photoelectron spectroscopy and quantum-chemical calculations. The photoelectron spectrum of B80– reveals a surprisingly simple spectral pattern, suggesting a high symmetry B80 cluster with a large energy gap. Following extensive structural searches and high-level ab initio calculations, we find that a spherical B80– represents the global minimum with only its simulated spectrum agreeing with the experimental result. We show that the electronic structure and chemical bonding of B80 closely mimic those of the C60 buckminsterfullerene. The discovery of the B80 buckminsterfullerene will stimulate its bulk synthesis and pave the way for the development of boron-fullerene chemistry.