More than 95% of the known exoplanets were discovered by the transit- and radial velocity techniques. However, the observed distributions of planets by their masses and by their orbital periods are significantly distorted by numerous observational selections, different for these techniques and different surveys.We found and studied the de-biased statistical distributions of exoplanets by masses and by orbital periods for three groups of exoplanets: I. transiting planets discovered by Kepler ST, whose masses were measured by the follow-up radial velocity technique, II. transiting planets discovered by ground-based surveys (SuperWASP, HATNet, NGTS, XO, KELT, etc.), III. planets discovered by the radial velocity technique. The synthetic projective-mass distribution of RV planets obeys the piecewise power law with the breakpoints at ~0.14MJ and ~1.7MJ. The distribution of RV-planets with m = (0.011-0.087)MJ (or (3.5-28)ME) accurately obeys the power law with an exponent of -2, dN/dm ∝ m^-2. The distribution of RV planets with m = (0.21-1.7)MJ follows the power law with an exponent ranging from -0.7 to -0.8, dN/dm ∝ m^(-0.7…-0.8). The distribution of RV planets with m = (1.7-13)MJ is fitted by a power law with an exponent ranging from -1.7 to -2.0, dN/dm ∝ m^(-1.7…-2.0). In general, the synthetic projective-mass distribution of RV planets well agrees with the predictions of the population synthesis theory (Mordasini, 2018) and includes more detailed features to be discussed.The exoplanets distribution by periods generally follows a power law with an exponent of -0.75 and indicates a predominant (averaged) structuring of the planetary systems.De-biased mass distribution of RV-planets with orbital periods of 2-58 days is well consistent with a similar distribution of the Kepler planets. The mass distribution of the transit exoplanets detected by ground-based surveys is consistent with the similar distribution of RV planets with periods of 1-20 days.

This article presents a novel approach to actively compensate wavefront errors in both phase and amplitude using a Liquid Crystal Spatial Light Modulator (LC-SLM) for direct exoplanet imaging. This method involves controlling the wavefront to address challenges posed by stellar coronagraphy. Experimental results demonstrate successful wavefront error compensation in both phase and amplitude components. This technique shows promise for direct exoplanet imaging and may be applied onboard orbital telescopes in the future.

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.

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 propose and investigate a precise wavefront correction method for the astronomical observation of exoplanets in the diffraction stellar vicinity. We show the applicability of the method for measuring and correcting the wavefront in the scheme of a telescope and an interferometric coronagraph without applying any Hartmann wavefront sensors. In our laboratory experiment we achieved a correction accuracy ~λ/50 and a coronagraphic contrast better than 10 5 . We outline the prospects for increasing the correction accuracy to a target value of λ/500 to visualize the Earth in the vicinity of the Sun observed from a distance of 10 pc (in the immediate neighborhood of the Solar System) through an additional amplitude correction and the inclusion of non-common-path aberrations.

We implemented the common-path achromatic interfero-coronagraph both for the wavefront sensing and the on-axis image component suppression, aiming for the stellar coronagraphy. A common-path achromatic interfero-coronagraph has its optical scheme based on a nulling rotational-shear interferometer. The angle of rotational shear can be chosen at a small angular extent of about 10 deg. Such a small angular shear maintains the coronagraphic contrast degradation known as the stellar leakage effect, caused by a finite stellar size. We study the phase and amplitude wavefront control by a liquid crystal spatial light modulator of reflection type which is used as the pixilated active adaptive optics unit. Therefore, adaptive optics perform a wavefront-correcting input toward a stellar interfero-coronagraph aiming at the direct exoplanet imaging. Presented here are both the numeric evaluations and the lab experiment stand to prove the declared functionality output.

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.

When studying the statistics of exoplanets, it is necessary to take into account the effects of observational selection and the inhomogeneity of the data in the exoplanets databases. When considering exoplanets discovered by the radial velocity technique (RV), we propose an algorithm to account for major inhomogeneities. We show that the de-biased mass distribution of the RV exoplanets approximately follows to a piecewise power law with the breaks at ~0.14 and ~1.7 MJ. FGK host stars planets group shows an additional break at 0.02 MJ. The distribution of RV planets follows the power laws of: dN/dm α m−3 (masses of 0.011–0.087 MJ), dN/dm α m−0.8…−1 (0.21–1.7 MJ), dN/dm ∝ m−1.7…−2 (0.087–0.21 MJ). There is a minimum of exoplanets in the range of 0.087–0.21 MJ. Overall, the corrected RV distribution of the planets over the minimum masses is in good agreement with the predictions of population fusion theory in the range (0.14–13 MJ) and the new population fusion theory in the range (0.02–0.14 MJ). The distributions of planets of small masses (0.011–0.14 MJ), medium masses (0.14–1.7 MJ), and large masses (1.7–13 MJ) versus orbital period indicate a preferential structure of planetary systems, in which the most massive planets are in wide orbits, as analogous to the Solar system.

We used the 0.5-m robotic telescope located at the Special Astrophysical Observatory of the Russian Academy of Sciences for monitoring two square degrees of the sky with the aim of detecting new exoplanets. A dimming of the visible brightness is expected due to the exoplanets transiting their host stars. We analyzed about 25,000 raw images of stars taken in the period between August 2020 and January 2021 and plotted the light curves for about 30,000 stars on a half-year timescale. Five newly discovered exoplanet candidates are being investigated to determine their transit event parameters. We also present the light curves for dozens of binary stars.

Over the past decades, the achievements in astronomical instrumentation have given rise to a number of novel advanced studies related to the analysis of large arrays of observational data. One of the most famous of these studies is a study of transient events in the near and far space and a search for exoplanets. The main requirements for such kinds of projects are a simultaneous coverage of the largest possible field of view with the highest possible detection limits and temporal resolution. In this study, we present a similar project aimed at creating an extensive, continuously updated survey of transient events and exoplanets. To date, the core of the project incorporates several 0.07–2.5 m optical telescopes and the 6-m BTA telescope of the Special Astrophysical Observatory of RAS (Russia), a number of other Russian observatories and the Bonhyunsan observatory of the Korea Astronomy and Space Science Institute (South Korea). Our attention is mainly focused on the description of two groups of small, wide-angle optical telescopes for primary detection. All the telescopes are originally designed for the goals of the project and may be of interest to the scientific community. A description is also given for a new, high-precision optical spectrograph for the Doppler studies of transient and exoplanet events detected within the project. We present here the philosophy, expectations and first results obtained during the first year of running the project.

Statistical distributions of exoplanets obtained by both ground-based and satellite telescopes are heavily distorted by observational selection. It is easier to detect massive planets orbiting close to the star, rather than planets of small masses and planets with large orbital periods. Low-mass planets with orbital periods of about a year or more, falling in the habitable zone of sun-like stars, cannot be detected by modern means. To account for this factor, we proposed and investigated the method of correcting the observational selection. It has been shown that the corrected mass distributions of exoplanets are well described by a piecewise power law. The result is in agreement with the conclusions of cosmogony and demonstrates a number of new features.

Many Earth-sized planets have been discovered and some of them are potentially in the habitable zone. In addition, several Earth-sized planets have been detected around low temperature stars near our solar system. However, it is difficult to characterize them as Earth-like or Venus-like, even though they are relatively very close to our solar system. We performed a conceptual design of an Ultraviolet Spectrograph for Exoplanet (UVSPEX) for World Space Observatory Ultraviolet (WSO-UV), which is 1.7-m UV space telescope being prepared by Russia. The spectral range is to exceed wavelengths from 115 nm to 135 nm to detect at least H Lyman alpha 121.6nm to O I 130 nm. The throughput is >4%. UVSPEX is planned to be a part of a Field Camera Unit (FCU). This additional instrument would enable us to observe ~20 Earth-like exoplanets and detect an oxygen exosphere if some of them have an Earth-like atmosphere.

We analyse the causes of a discrepancy between the earlier obtained samples of the mass distributions of exoplanets detected by the transit method and the radial velocity (RV) one and corrected for some observational selection effects. It is found that this discrepancy can be removed by introducing the following restrictions into the procedures forming the samples: (i) to consider, among transit exoplanets, only those which masses were determined by the RV method (i.e. excluding the transit time variation method); (ii) to take into account exoplanets with orbital periods P ∈ [1, 100] days and masses M ∈ [0.02, 13]MJ (Jupiter masses). In addition, we compare here the distributions by projective masses (which is Msin i, where i is the orbital inclination of an exoplanet). For this, the mass distribution of transit exoplanets is transformed into the projective mass distribution. Due to these three changes in the procedure, the obtained RV and transit distributions exhibit a similar behaviour in an interval of M ∈ [0.02, Mmid]MJ and coincide at M ∈ [Mmid, 13]MJ, where Mmid ≈ 0.17MJ.

Abstract—We present the results of observations of radial velocity variability in stars with exoplanets. Observations of a number of stars with characteristic stellar magnitudes from 8.54m to 10.5m were carried out using a new high-resolution (R = 35 000–120 000) fiber-fed spectrograph mounted at the foundation of the 6-m BTA telescope, in the mode of resolutions from R = 45 000 to R = 65 000 with a simultaneous registration of the calibration spectrum of a thorium–argon hollow cathode lamp. The achieved characteristic measurement accuracies ranged from a few to several tens of m s−1. In the future, the thorium-argon lamp will be supplemented with a Fabri–Perot etalon to reach the radial velocity measurement accuracy in stars up to 1 m s−1.

A method of correcting the statistical data of the exoplanets discovered through radial velocity measurements is proposed. The statistical regularities of the mass and orbital period distributions of exoplanets have been analyzed.

Abstract—A general description is given of the international (with Russia as the key contributor) project World Space Observatory–Ultraviolet (WSO–UV; in Russian named SPEKTR–UF). The project is aimed at creating a large space observatory for observation in the UV part of the spectrum (110–310 nm). The project has been underway for quite a long time. There are no outstanding engineering issues. Because of several factors not related to technology, the launch of the observatory has been postponed to 2025. The cushion of time allows for a possibility of improvements in the project scheme. The scientific program has been refined; a new design of the field camera has been prepared; a new spectrograph will be installed according to the cooperation agreement between Roscosmos and JAXA (Japan); a new, more optimal orbit has been selected; a system for collecting proposals has been developed and an experimental call for proposals has been launched, etc. Thus, the overall picture of the project has acquired new touches. This paper briefly describes the current status of the project, focusing on these new touches.

Предложен метод коррекции статистических данных по экзопланетам, открытым по измерениям лучевых скоростей. Исследованы статистические закономерности распределений экзопланет по их массам и по орбитальным периодам.