Based on the Doppler observations from the FFOREST spectrograph of the 6-meter telescope (BTA) and on the photometric observations from the TESS spacecraft, we provide an updated analysis for TOI-1408, an F-type main sequence star, located 140 pc away, that hosts exoplanet TOI-1408.01. We confirm the qualitative conclusions from our initial paper: (1) a grazing transit geometry such that the planet obscures its host star by only a portion of the visible disc,(2) unreliably fitted planet radius, (3) which nonetheless has a lower bound constraint of $\sim\!1~R_{\rm Jup}$, (4) unexpectedly large planet mass of $\simeq\!1.7~M_{\rm Jup}$, and (5) significant evidence in favor of a moderately eccentric orbit with $e\simeq0.27$. This solution may suggest that the planet is likely to experience a high tidal eccentricity migration at the stage of intense orbital rounding or may indicate the possible presence of other unseen companions in the system, yet to be detected.

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.

The light curves for almost 50 thousand stars with magnitudes m∈[11m.5,19m.5] have been obtained over 2.5 years at SAO RAS in the process of conducting an exoplanet survey in roughly 1∘.5 -sized fields around the white dwarfs WD 0009 + 501 and GRW + 708247. In this paper we present a catalog of variable stars that have been found in the considered regions. Periodogram analysis was used as the main variation search method. The catalog includes 150 periodic variable stars: 113 of them have been known previously, and for the remaining 37 variations have been discovered for the first time. These stars were classified according to the nature of the variations into four eclipsing variable and three pulsating types, as well as rotating stars. We present the periods and variation amplitudes in the range of P∈[0d.036,32d.14] and Δ m∈[0m.0064,1m.45] , determined from the investigated data.

ABSTRACT This paper describes the specific profile of the diffuse interstellar band (DIB) 6196 Å in objects belonging to the Sco OB2 association. The investigated feature is the narrowest known strong diffuse band. Reddened Sco OB2 association objects show slightly broadened and split (W-shaped) 6196 DIB profiles. The split cannot be explained by the presence of two (or more) clouds of different radial velocities along the line of sight because it is not observed in the much narrower identified atomic/molecular features. The observed DIB profile may (in some cases) be a composition of the band centre and its head of a still unknown molecule. Our estimation of the rotational temperature of C2 exhibits systematically higher values for objects with the observed split effect (Sco OB2 members). These split profiles are observed in both ζ and σ types of clouds, although in Sco OB2 objects only, suggesting that the phenomenon originates in some specific and currently unclear physical/chemical conditions inside the Sco OB2 association. It could be that a lower amount of small dust particles in Sco OB2 affects the flux of ultraviolet photons, providing a higher rotational temperature of DIB 6196 carriers, which is seen as a profile split.

We present a brief description of a joint Russian-Korean project abbreviated as EXPLANATION (EXoPLANet And Transient events InvestigatiON). The project is aimed at a massive photometric, speckle-interferometric, spectral, and radio bolometric search for non-stationary events in the Universe, as well as the study of exoplanets. The core of the project consists of several 0.07–2.5-m optical telescopes, 6-m telescope BTA and a six-hundred-meter radio telescope RATAN-600 of the Special Astrophysical Observatory of RAS (Russia), Moscow State University observatory (Russia), Kourovka Observatory (Russia), Crimean Astrophysical Observatory (Crimea), Korea Astronomy and Space Science Institute (Republic of Korea). We discuss the philosophy of the project and its instrumentation, as well as the first obtained results. In this paper we report the results related to the detection of several types of transient events and the study of exoplanets.

We report an independent Doppler confirmation of the TESS planet candidate orbiting an F-type main-sequence star TOI-1408 located 140 pc away. We present a set of radial velocities obtained with a high-resolution fibre-optic spectrograph FFOREST mounted at the SAO RAS 6-m telescope (BTA-6). Our self-consistent analysis of these Doppler data and TESS photometry suggests a grazing transit such that the planet obscures its host star by only a portion of the visible disc. Because of this degeneracy, the radius of TOI-1408.01 appears ill-determined with lower limit about similar to 1 R-Jup, significantly larger than in the current TESS solution. We also derive the planet mass of 1.69 +/- 0.20 M-Jup and the orbital period similar to 4.425 d, thus making this object a typical hot Jupiter, but with a significant orbital eccentricity of 0.259 +/- 0.026. Our solution may suggest that the planet is likely to experience a high tidal eccentricity migration at the stage of intense orbital rounding, or may indicate possible presence of other unseen companions in the system, yet to be detected.

We measured the equivalent widths ( EW s) of interstellar Ti II absorption lines at λ 3383.759 for about 250 reddened objects and found a good correlation of the EW s with distances to the background stars, estimated using Gaia DR3 parallaxes. Hipparcos trigonometric parallaxes were used for very bright objects which were not observed by Gaia. The Ti II based distance estimation procedure is similar to the well known Ca II-method (Megier et al., 2005, 2009). However, there are at least 3 advantages of the Ti II method: in contrast to interstellar Ca II H and K lines, blending of Ti II with stellar lines is not an issue even for late B stars; Ti II is to a much less extent influenced by the saturation effect; only a single line must be measured, i.e. there is only a single measurement error to be taken into account. The relation of between Ti II EW and distance is given by simple equation d≈ 30EW , where d is the distance in pc and EW is the equivalent width of the Ti II λ 3383.759 line in mÅ.

The article provides a brief description of the software package DECH for processing and analysis of astronomical spectra. DECH supports all stages of processing and analysis of spectral data, including image preprocessing, spectra extraction (including those with a variable tilted slit), wavelength calibration by a two-dimensional polynomial, continuum normalization (manual or automatic), measurement of equivalent widths and radial velocities in various ways, cross-correlation analysis, etc. The DECH software package is actively used by astronomers from different countries and continues to be improved. In particular, utilities for processing and analysis of data from the high-resolution fiber-feed echelle spectrograph installed at 6-m telescope of Special Astrophysical Observatory of Russian Academy of Sciences were added in the latest version. Software provides high-precision measurements of radial velocities, including those for detection of extraterrestrial planets.

We report eight new exoplanet candidates discovered at the SpecialAstrophysical Observatory of the Russian Academy of Sciences usingthe transit technique. Photometric observations were performedwith a 50-cm robotic telescope during the second half of 2020.Transits with depths of $$\Delta m=0\overset{\textrm{m}}{.}056{-}0\overset{\textrm{m}}{.}173$$ andperiods $$P=18\overset{\textrm{h}}{.}8{-}8\overset{\textrm{d}}{.}3$$ weredetected in $$m=14\overset{\textrm{m}}{.}3$$ – $$18\overset{\textrm{m}}{.}8$$ stars. All the stars considered are dwarfs with radii $$R_{*}=0.4{-}0.6R_{\odot}$$ (with an uncertainty of up to $$1.1 R_{\odot}$$ for a single star). We use simulations to estimatethe candidate radii (all are greater than 1.4 times the Jovianradius), semi-major axes of their orbits (0.012–0.035 AU), andother orbital parameters. We report the transit light curves fortwo stars obtained in 2022 based on individual observations.

We present a study of the influence of magnetically induced control of external convection in stars of different types, in particular white dwarfs, on their thermal evolution. In the work preceding this study, we argued that for the cooling down white dwarf stars that have exhausted the sources of thermonuclear combustion, cessation of convection by a magnetic field significantly slows down their cooling. To test this asertion, we performed an observational program to search for new highly magnetized white dwarfs. The program is described in detail in the same issue of the journal. Our observations, together with the observations of other researchers, allowed us to construct the observed luminosity function of strongly magnetized white dwarfs with stopped convection and compare it with the well-known similar luminosity function of white dwarfs with weak fields that allow effective convective heat removal from their insides. As a result of the model analysis of these functions, the hypothesis that strongly magnetized white dwarfs cool down slower than weakly magnetic ones is confirmed. The article also qualitatively examines the effect of magnetic braking of convection in solar-type stars and cool M-dwarf stars of the Main Sequence on the periodicity of their radiation activity. The geophysical aspect of the problem and the practical application of magnetic field control of the heat removal in electrically conductive media are discussed.

We present the results of observations within the program for the search for new highly magnetized white dwarfs among evolutionary old stars of this class. The program was carried out for two years at the 1-m telescope of the SAO RAS. As a result, new white dwarf candidates of different ages with super-strong (several megagauss, tens, hundreds of megagauss) magnetic fields were discovered. These observations, along with the observations of other authors made it possible to make a new estimate of the frequency of occurrence of magnetic white dwarfs among old stars. Our results confirm our earlier assumptions that the frequency of occurrence of far-evolved magnetic white dwarfs with magnetic fields of several megagauss or higher and with the temperatures of less than 10 000 K is at the level of 15% or higher, while the frequency of occurrence of such stars among young white dwarfs does not exceed 4–6%. This fact means that the thermal evolution of the physical properties of magnetic white dwarfs differs from the thermal evolution of their weakly magnetic counterparts.

We study, for the first time, the relations of two strong diffuse bands (DIBs) at 9633 and 9577 angstrom, commonly attributed to C-60(+), to other interstellar features seen in optical and UV spectra including H i, Ca i, Fe ii, Na i, Ti ii, CN, CH, CH+, and C-2 and DIBs 5780, 5797, 6196, 6269, 6284, and 6614. We analyzed 62 lines of sight where the stellar contamination by Mg ii was corrected or found negligible for DIB 9633. Equivalent widths of DIB 9577 were measured in 62 lines of sight. Poor mutual correlation between the strengths of the above features and the major diffuse bands (5780 and 5797) as well as with other DIBs (with some exceptions) were revealed. The considered DIBs are also poorly correlated with the features of neutral hydrogen, molecular carbon, and those of simple interstellar radicals. Perhaps this phenomenon can be explained if the diffuse band 9577 is an unresolved blend of two or more interstellar features. There are indications that 9633 and 9577 diffuse bands are stronger in sigma-type clouds, i.e., these features resemble the behavior of reasonably broad DIBs, which are strong in the lines of sight where the UV flux from the very hot nearby stars plays an important role.

The paper describes profile broadening and peak wavelength variation of diffuse interstellar bands (DIBs) measured for 46 lines of sight, probably caused by the physical properties of intervening clouds. The full width at half-maximum of four studied DIBs (5780, 5797, 6196 and 6614 angstrom) demonstrates strong variability, sometimes doubling the widths of the features. Despite the high magnitude of the effect, our current analysis is restricted to the strongest DIBs because the weaker ones require a much higher signal-to-noise ratio. The profile broadening in the studied DIBs moves the profile's centres towards longer wavelengths, probably due to the excitation of higher levels of the P branch of the unknown molecular carrier. Moreover, DIBs are broader in clouds with abundantly populated vibrationally excited states of hydrogen molecules; that is, the broadening of DIBs correlates with the rotational temperature estimated on the H-2 nu = 2 vibrational level. However, objects that demonstrate extremely broadened profiles of DIBs are scarce. The extreme peculiarity of the DIB profiles was detected in Herschel 36. Here we show the gradual growths of the widths of DIBs, confirmed in spectra from different instruments.

Using many spectra of the star AE Aur (HD 34078), covering the period 1997–2019, we demonstrate temporal variations of the intensities of spectral features carried by simple interstellar radicals. The drop of the CH + and CH line intensities was demonstrated by Krełowski et al. (2016)—Paper I. More recent data suggest that the CH + interstellar lines reach the minimum of intensity in 2015–2016 being then followed by the evident rise, which continues. The intensities of CH lines show a similar drop to CH + . However, the further (after 2016) rise seems marginal if any. Thus, the CH + features grow since 2016 while those of CH remain almost constant, likely due to the fact that both species are formed in different environments. No variations in the radial velocities of the observed interstellar features were detected during the whole covered time period.

The precise characteristics of clouds and the nature of dust in the diffuse interstellar medium can only be extracted by inspecting the rare cases of single-cloud sightlines. In our nomenclature such objects are identified by interstellar lines, such as KI, that show at a resolving power of lambda/Delta lambda similar to 75 000 one dominating Doppler component that accounts for more than half of the observed column density. We searched for such sightlines using high-resolution spectroscopy towards reddened OB stars for which far-UV extinction curves are known. We compiled a sample of 186 spectra, 100 of which were obtained specifically for this project with UVES. In our sample we identified 65 single-cloud sightlines, about half of which were previously unknown. We used the CH/CH+ line ratio of our targets to establish whether the sightlines are dominated by warm or cold clouds. We found that CN is detected in all cold (CH/CH+ > 1) clouds, but is frequently absent in warm clouds. We inspected the WISE (3-22 mu m) observed emission morphology around our sightlines and excluded a circumstellar nature for the observed dust extinction. We found that most sightlines are dominated by cold clouds that are located far away from the heating source. For 132 stars, we derived the spectral type and the associated spectral type-luminosity distance. We also applied the interstellar CaII distance scale, and compared these two distance estimates with Gaia parallaxes. These distance estimates scatter by similar to 40%. By comparing spectral type-luminosity distances with those of Gaia, we detected a hidden dust component that amounts to a few mag of extinction for eight sightlines. This dark dust is populated by greater than or similar to 1 mu m large grains and predominately appears in the field of the cold interstellar medium.

We discuss possible relations between different constituents of interstellar clouds, such as gas atoms (Fe i), simple molecular species (CH, CN), and the carriers of the puzzling diffuse interstellar bands (DIBs 5780, 5797, 5850 Å) as well as dust grains. We exemplify that abundances of carriers of these spectral features, revealed by the Doppler components, may be astonishingly poorly related to each other. Spectra of interstellar clouds seem to be sensitive to the changes of the environmental parameters such as density, temperature, and irradiation from nearby stars. The diffuse bands’ carriers likely do not occupy the same volumes with CH, CN, or Fe i and/or are much less sensitive to the processes related to the formation/destruction of these species.