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We review the stellar magnetism studies published in 2022. We analyzed a total of 75 papers, which focus mostly on the study of magnetic fields in chemically peculiar and active cool stars. In the latter, migration of magnetic spots and change of their configuration is observed. Projects of spectrographs and spectropolarimeters for new big telescopes are also presented. [ABSTRACT FROM AUTHOR]

We explain the details of the photometric operation mode of the ASTRONICAM near-IR spectrograph camera mounted on the 2.5-m telescope of the Caucasian Mountain Observatory of the Sternberg Astronomical Institute and describe algorithms used for primary correction and overall pipeline reduction of the acquired data. We present the transformation equations from the 2MASS photometric system to the instrumental -band system. We derive color transformation coefficients between the instrumental photometric system and standard MKO-NIR (Mauna Kea Observatories Near-Infrared) system for the , , and -band filters and show that the camera system is close to the standard photometric system. We found that in the case of observations at zenith, average background brightness level, and seeing the stars with , , can be measured with a 3000-s exposure at the signal-to-noise ratio . [ABSTRACT FROM AUTHOR]

We performed photometric observations of the S 255, S 257, S 140, NGC 7358, and the Orion Bar photo-dissociation regions (PDRs) at 2 m using narrow-band filters centered on the Br , H , and [Fe II] lines, as well as the narrow-band and the broad-band filters for continuum subtraction. The observations were done with the 2.5-m telescope of the SAI Caucasian Mountain Observatory and the near-infrared camera and spectrograph ASTRONIRCAM. We find several high-density arc-like structures in the Br and [Fe II] images of the ionized gas in NGC 7538 and extended shells and arcs visible through the H emission. The H ionization front and H dissociation front are merged in NGC 7538. In S 255 and S 257 we detected only Br emission from the H II regions and bright H emission from the PDRs. The projected distance between the H ionization and H dissociation fronts is approximately 0.3–0.4 pc, which cannot be explained using models of a uniform medium. Most probably, the ionized and neutral gas in these PDRs is clumpy. The H I-to-H transitions in the NGC 7538, S 255, S 257 and S 140 PDRs are gradual with no sharp borders. This conclusion also agrees with the suggestion of a clumpy medium. [ABSTRACT FROM AUTHOR]

The results of the analysis of photometric and spectral monitorings of the recurrent symbiotic nova T CrB, carried out using the low-resolution spectrograph TDS of the 2.5-m telescope and the CCD photometer of the 0.6-m telescope of the CMO SAI, are presented. It is shown that the fluxes in the emission lines H , H , He I 5876 change by 6–16 , and in the emission line He II 4686 by about 60 on timescales of 20–60 minutes. The line flux curves on August 25, 2020 are similar to the light curve of T CrB, but with a time delay of up to 600 s for different lines. The observed spectrum is approximated by the radiation of the system components with the following parameters: a red giant of spectral type M4 III, a nebula with K and emission measure of cm , and the accretion disk with , (at inclination ). [ABSTRACT FROM AUTHOR]

The nonlinearity of the transfer function of photon detection by a CCD receiver of an echelle fiber-optic spectrograph of high spectral resolution at the BTA SAO RAS is studied. Local analysis of signals in the image of the emission spectrum and correction of data are carried out. [ABSTRACT FROM AUTHOR]

This paper presents a description of the pipeline reduction of low and medium resolution spectral data obtained in the long-slit mode of the multi-functional Robert Stobie Spectrograph (RSS), mounted on the Southern African Large Telescope (SALT). The paper describes features of RSS that result in the creation of the pipeline. The main ideas of the developed pipeline are presented together with a general description of the pipeline and detailed description of its steps. The flow diagrams of all the pipeline steps are shown as well. [ABSTRACT FROM AUTHOR]

Abstract—Two modifications of the Fabry–Perot interferometer were developed that use oblique incidence planar fronts from the source: Fabry–Perot interferometer with an open beam input and Fabry–Perot interferometer with an open beam output. The modifications differ only in the direction of the rays. The first modification has already been used as a basic element of the solar interference spectrograph layout (Kulagin, 1980) and the stellar interference spectrograph layout (Kulagin and Panchuk, 2017). The second modification has no analogues. Estimates of the increase in the illumination of interference patterns in the modifications are given. The same formula describes the dependence of the intensity of the outgoing radiation on the interference phase in both devices. However, the properties of the modifications differ dramatically. Possible applications of the two modifications combined with a diffraction grating are described. [ABSTRACT FROM AUTHOR]

Abstract—The paper provides complete measurement results of the effective longitudinal magnetic field and the radial velocity for 107 targets that are mainly Main-Sequence chemically peculiar stars and standard stars. The spectropolarmetric data were obtained in 2013 with the Main Stellar Spectrograph (MSS) at the 6-m BTA telescope of SAO RAS. Seven new magnetic stars were discovered during the year: HD 16545, HD 34736, HD 36997, HD 37633, HD 128220, HD 220846, and BD +37°431. During 11 observation nights, 296 circularly polarized spectra were obtained. Radial velocities were measured for all the objects, for sixty-four of them—for the first time. Observations of standard magnetic and non-magnetic stars confirm the absence of any significant systematic errors capable of distorting the measurement results. The paper presents comments for measurement results for all the observed stars. [ABSTRACT FROM AUTHOR]

Abstract—Over the past two decades NES spectrograph attached to the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences was used to perform spectroscopy of stars at advanced stages of evolution spanning a wide range of masses. The studies cover a variety of star types with high mass-loss rates during the preceding and current stages of evolution. All these stars have extended atmospheres and structured circumstellar envelopes produced by strong stellar winds. We have studied luminous blue variables (LBVs) near the Eddington limit; hot supergiants exhibiting B[e] phenomenon, which are very likely intermediate-mass binary systems soon after the fast mass exchange stage; a group of yellow hypergiants, as well as an extensive sample of low-mass post-AGB supergiants. The diverse nature of the types of these stars whose common feature is the presence of a envelope makes the spectroscopy of such objects a comprehensive task. Such studies consist of many etapes, which include not only determining the specifics of the chemical composition and understanding the role of supergiants in the enrichment of the interstellar medium with freshly synthesized elements, but also the determination of the evolutionary stage of the objects considered, as well as search for and analysis of spectroscopic manifestations of kinematic processes in their extended and unstable atmospheres and gas-dust envelopes. We spectroscopically monitored selected objects to study in detail the instability of the kinematic state of the atmospheres of the stars considered. Studies of stars at neighboring evolutionary stages have been initiated. This review reports the most significant observational obtained within the framework of the – programs. [ABSTRACT FROM AUTHOR]

Absctract—The present study continues the investigation of the super-fast variability of line profiles in the spectra of stars of early spectral types. We studied the line-profile variability in the spectrum of the binary (O9.7Ib+B0III) star Ori A using the MSS spectrograph of the 6-m BTA telescope based on observations carried out on February 19, 2019. Short-period regular variations of the hydrogen Balmer lines and He I lines with periods from 89 to 295 minutes were found. The presence of short-period variations in the period interval of 10–20 minutes is also possible. An analysis of the stellar brightness variations from observations by the TESS satellite showed the presence of seven regular components, one of which is probably the second harmonic of the rotation period of the main component of the Aa star Ori A. The magnetic field of the star was determined for the whole series of observations. The longitudinal component of the root-mean-square magnetic field measured by the regression method over the whole observation period is G. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract—We briefly discuss the stages of the development of high-resolution spectroscopy methods used with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, which are related to the problem considered. We consider the possibility of the multiple increase of the stellar spectroscopy efficiency as a result of application of state-of-the-art solutions in the field of adaptive optics. At the first stage, we plan to perform tasks involving the image control and correction based on the central star. This stage should be naturally started with a spectrograph with the highest spectral resolution where the relatively bright star studied can serve as the reference source in the method of adaptive optics. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents complete results of measurements of the magnetic-field longitudinal component Be and radial velocities VR for 163 objects, mainly main-sequence chemically peculiar stars and standards. Observations were carried out in 2012 at the 6-m BTA telescope using the Main Stellar Spectrograph (MSS) equipped with a Zeeman analyzer. Six new chemically peculiar magnetic stars were discovered: HD84 882, HD109 030, HD170 054, HD189 775, HD341 037, and BD + 61°2436. The observations were carried out during 18 nights, 560 circularly-polarizedspectra were detected. New data were obtained for 120 magnetic stars (including 5 standard stars) and 43 non-magnetic stars (including nine standard stars). The radial velocities of all objects were measured; for 46 stars, they were obtained for the first time. Observations of standard magnetic and non-magnetic stars confirm the absence of any significant systematic errors capable of introducing distortions into the measurement results of Be. The paper provides comments on the research results for each of 163 stars. [ABSTRACT FROM AUTHOR]

Abstract—This work is a continuation of the studies of the ultrafast variability of line profiles in the spectra of early-type stars. Line profile variations in the spectrum a chemically peculiar A0Vp star α2 CVn are investigated using the January 6, 2020 observations carried out with the 6-meter BTA telescope at SAO RAS equipped with the MSS spectrograph. Regular short-term periodic variations of the Hβ, FeII, and CrII lines were detected with periods ranging from 4 to 140 minutes. The magnetic field of the star was determined for all observations. The average measured longitudinal magnetic field component over the entire duration of observations is about 600 G, which is close to the value expected from the well-known magnetic field phase curve. [ABSTRACT FROM AUTHOR]

Abstract—We report the results of laboratory tests of the first version of the high-resolution fiber-fed spectrograph designed for the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS). During laboratory tests a spectral resolution of about 70 000 was achieved. The peak efficiency of the entire optical path of the spectrograph (without light losses at the CCD, primary mirror of the 6-m telescope, and in the atmosphere) at 620 nm and with the equivalent slit widths of the 1″.5 and 0″.75 are equal to 8% and 4%, respectively. The resolving power R = 70 000 and 100 000 can be reached with the sky aperture 0″.75 and 0″.4 respectively. In the current version of the spectrograph these regimes of operation are implemented by mechanic aperturing of the slit. A dedicated projecting camera has been developed and is currently manufactured to operate with a collimated 200-mm diameter beam, which will make it possible to increase the spectral resolution up to 100 000. A two-beam image slicer will be used to maintain the luminous efficiency of the instrument at least at the 6% level. [ABSTRACT FROM AUTHOR]

A technique for computing the spectrograph for astrophysical studies based on the basic input and output parameters of the optical system. In the framework of the proposed technique, it is possible to determine the main properties of the spectrograph components: the focal length of the collimator, the focal length of the projection camera, the blaze angle of the grating, the frequency of the grating. The following parameters are used as the basic ones: the required spectral resolution, the spectral range studied, the spectrograph entrance aperture, the height of the detector in the direction of dispersion, and the available length of the diffraction grating. Recommendations are proposed on the choice of the schematic of the spectrograph based on the computed magnification in the optical system of the device inferred from the basic parameters. [ABSTRACT FROM AUTHOR]

We briefly describe the large observational project MAGIC aimed at mass spectroscopic studies of stars of different subsystems of our Galaxy. The project was carried out on the Southern African Large Telescope (hereafter referred to as SALT) with efficient use of its capabilities, site's climate, and spectroscopic instruments. We discuss in detail the issues of high-resolution spectroscopy when studying the chemical composition of Galactic Cepheids. Observations of these objects with HRS echelle spectrograph of SALT telescope started in 2016 and currently the number of such observations exceeds one hundred. Spectra were acquired in the medium-resolution mode (R ~36 500–39 000)with a high signalto-noise ratio (S/N ~50–220). All obtained echelle images acquired were reduced with a package that we developed based on standard MIDAS system. We describe standard reduction steps using the Cepheid RSNor as a test object. Based on the data of spectroscopic observations we determined the atmospheric parameters and the abundances of 31 chemical elements (36 neutral atoms and ions) whose absorption lines are observed in the spectrum of RSNor. We performed all computations using two methods and showed that echelle spectra acquired in the medium-resolution mode of HRS can be used to study the chemical composition of Cepheids with good accuracy and that the results agree with the results of other studies within the quoted errors. [ABSTRACT FROM AUTHOR]

We have studied the interstellar lines and diffuse bands in the spectrum of the supergiant κ Cas using the CCD spectra obtained with the Echelle spectrograph of the 2 meter telescope at the peak Terskol observatory. A synthetic stellar spectrum was used to correctly reveal the interstellar features, computed for a model atmosphere with Teff = 21 500 K, log g = 2.60, v sin i = 83 kms-1, [M/H] = 0.0, ξ = 15 kms-1 and with partial selection of main chemical element abundances. Eleven interstellar bands and 91 diffuse interstellar bands were identified. A further 14 absorption features were revealed, possibly also diffuse bands. The spectrophotometric diffuse band parameters and their accuracies were tabulated. We present maps of observed and synthetic spectral regions containing interstellar diffuse bands. [ABSTRACT FROM AUTHOR]

The paper presents the results of determination of fundamental parameters (effective temperature, surface gravity, luminosity, mass, radius, rotation velocity, and radial velocity) for 146 stars observed at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the Main Stellar Spectrograph during 2009–2011; 124 of the stars are magnetic or potentially magnetic objects. We obtained and analyzed at least 500 pairs of circularly-polarized-emission spectra. Various methods and approaches were used in estimating the fundamental parameters. [ABSTRACT FROM AUTHOR]

The paper presents results of measurements of magnetic-field longitudinal components Be, radial velocities Vr, and projections of the rotation velocity in the line of sight ve sin i for 74 objects, mainly main-sequence chemically peculiar stars and standard stars. Observations were carried out in 2011 at the 6-m BTA telescope using the Main Stellar Spectrograph (MSS) with a Zeeman analyzer. Seven new magnetic stars were discovered: HD38129, HD47152, HD50341, HD63347, HD188501, HD191287, and HD260858. Three more stars were suspected to have magnetic fields. Observations of magnetic standard stars and non-magnetic stars confirm the absence of any systematic errors capable of introducing distortions into the Be longitudinal-field measurement results. The paper gives comments on the research results for each of the 74 stars. [ABSTRACT FROM AUTHOR]

We present LTE analysis of high resolution optical spectra for B-type hot PAGB stars LS IV-04 1 and LB3116 (LSE 237). The spectra of these high Galactic latitude stars were obtained with the 3.9-m Anglo-Australian Telescope (AAT) and the UCLES spectrograph. The standard 1D LTE analysis with line-blanketed LTE model atmospheres and spectral synthesis provided fundamental atmospheric parameters of Teff= 15 000±1000 K, log g= 2.5±0.2, ξ = 5.0±1.0 km s−1, [M/H] = −1.81 dex, and v sin i= 5 km s−1 for LSIV-04 1 and Teff= 16 000±1000 K, log g= 2.5±0.1, v sin i= 25 km s−1, and [Fe/H] = −0.93 dex for LB 3116. Chemical abundances of ten different elements were obtained. For LS IV-04 1, its derived model temperature contradicts with previous analysis results. The upper limits for its nitrogen and oxygen abundances were reported for the first time. The magnesium, silicon and calcium were overabundant (i.e. [Mg/Fe] = 0.8 dex, [Si/Fe] = 0.5 dex, [Ca/Fe] = 0.9 dex). With its metal-poor photosphere and VLSR ≈ 96 km s−1, LSIV-04 1 is likely a population II star and most probably a PAGB star. LTE abundances of LB 3116 were reported for the first time. The spectrum of this helium rich star shows 0.9 dex enhancement in the nitrogen. The photosphere of the star is slightly deficient in Mg, Si, and S. (i.e. [Mg/Fe] = −0.2 dex, [Si/Fe] = −0.4 dex, [S/Fe] = −0.2 dex). The Al is slightly enhanced. The phosphorus is overabundant, i.e. [P/Fe] ≈ 1.7 ± 0.47 dex, hence LB3116 may be the first example of a PAGB star which is rich in phosphorus. With its high radial velocity (i.e.VLSR = 73 km s−1), and the deficiencies observed in C, Mg, Si, and S indicate that LB 3116 is likely a hot PAGB star at high galactic latitude. [ABSTRACT FROM AUTHOR]

We have designed and produced a speed camera lens for fiber-optic magnetometer of the prime focus of the 6-m Russian telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. Resolution of the developed lens obtained during test observations corresponds to the calculated value. The transmission of the lens was measured at three wavelength ranges. It is equal to 78% at a wavelength of 6328 Å, 80% at λ 5320 Å, and 19% at λ 4050 Å. A transmission cutoff for wavelengths shorter than 430 nm is outside the operational range of the spectrograph of the fiber-optic magnetometer which is 430-690 nm. [ABSTRACT FROM AUTHOR]

ASTRONIRCAM is a cryogenic-cooled slit camera-spectrograph for the spectral range 1-2.5 μm installed at the Nasmyth focus of the 2.5-meter telescope of the Caucasian observatory of the Sternberg Astronomical Institute of Lomonosov Moscow State University. The instrument is equipped with a HAWAII-2RG 2048×2048 HgCdTe array. Grisms are used as dispersive elements. In the photometric mode ASTRONIRCAM allows for extended astronomical object imaging in a 4.′6 × 4.′6 field of view with a 0.269 arcsec/pixel scale in standard photometric bands J, H, K, and K as well as in the narrow-band filters centered on the lines CH, [Fe II], H v=1-0 S(1), Br, and CO. In the spectroscopic mode, ASTRONIRCAM takes spectra of extended or point-like sources with a spectral resolution of R = λ/Δ λ ≤ 1200. The general design, optical system, detector electronics and readout, amplification and digitization schemes are considered. The GAIN conversion factor measurement results are described as well as its dependence on the accumulated signal (nonlinearity). The full transmission of the atmosphere-to-detector train ranges from 40 to 50% in the wide-band photometry mode. The ASTRONIRCAMsensitivity at the 2.5-m telescope is characterized by the limiting J = 20, K = 19 stellar magnitudes measured with a 10% precision and 15 minute integration for 1″ atmospheric seeing conditions. References to the first results based on ASTRONIRCAM observations are given. [ABSTRACT FROM AUTHOR]

We present first results of spectroscopic observations of transiting exoplanets in the Special Astrophysical Observatory of the Russian Academy of Sciences with the Main Stellar Spectrograph of the 6-m BTA telescope. For the exoplanetWASP-32b, we detected a significant variation of intensity and equivalent width in the Hα spectral line of the parent star at the time of a transit. The equivalent width of the line during transit is by 8-10% larger than outside the planet passage. Residual intensity in the core of the line reveals the following tendency: the line is by 10-15% deeper inside transit than outside it. Observations with the long-slit spectrograph of the Crimean Astrophysical Observatory at the 2.6-m ZTSh telescope also showed a transit event in the Hα line, although, with a smaller amplitude and shape inverted in relation to the data from the 6-m telescope. While in the observations with the BTA the Hα line becomes deeper during the transit, in the ZTSh observations, the residual intensity of the Hα line decreases during the transit. Reducing and analysis of the archive data of WASP-32b observations with the HARPS spectrograph also confirm the Hα line modulation at the time of the transit. The observed data give evidence of the envelope in WASP-32b filling the Roche lobe and a comet-like tail of changing geometry and orientation relative to the observer. These changes determine different depths and shapes of the Hα spectral line at the time of transits. [ABSTRACT FROM AUTHOR]

We describe the design of a suspended low- and medium-resolution spectrograph ( R ≈ 300-1300) designed and made at the Special Astrophysical Observatory of the Russian Academy of Sciences for the 1.6-m AZT-33IK telescope of Sayan Observatory of the Institute of Solar-Terrestrial Physics of the Siberian Branch of the Russian Academy of Sciences. We report the results of laboratory measurements of the parameters of the instrument and tests performed on the 1-m Zeiss-1000 telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. We measured the total quantum efficiency of the 'spectrograph + telescope + detector' system on AZT-33IK telescope, which at its maximum reaches 56%. Such a hight transparency of the spectrograph allows it to be used with the 1.6-m telescope to determine the types and redshifts of objects with integrated magnitudes m ≈ 20-21, and this result was confirmed by actual observations. [ABSTRACT FROM AUTHOR]

We present the technique and algorithm of numerical modeling of high-resolution spectroscopic equipment. The software is implemented in C++ using nVidia CUDA technology. We report the results of currently developedmodeling of new-generation echelle spectrographs. To validate the algorithms used to construct the mathematical model, we present the results of modeling of NES spectrograph of the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. A comparison of simulated and real images of the spectra acquired with NES spectrograph demonstrates good agreement between the model constructed and experimental data. [ABSTRACT FROM AUTHOR]

We present the results of measuring longitudinal magnetic fields ( B ), rotation velocities ( v sin i), and radial velocities ( V ) of 44 stars observed with the Main Stellar Spectrograph (MSS) of the 6-m BTA telescope of the Special Astrophysical Observatory in 2009. For the first time, magnetic fields were detected for the stars HD5441, HD199180, HD225627, and BD+00° 4535. We show that for the same stars, the longitudinal fields B measured from the H β hydrogen line core and from metal lines can differ by 10% and up to a factor of 2-3. Except in rare cases, magnetic fields measured from the metal lines are stronger. We believe that this phenomenon is of a physical nature and depends on the magnetic field topology and the physical conditions inside a specific star. Observations of standard stars without magnetic fields confirm the absence of systematic errors capable of introducing distortions into the longitudinal-field measurement results. In this work we comment on the results for each of the stars. [ABSTRACT FROM AUTHOR]

We present a new scheme of a moderate-resolution spectrograph based on a cascade of serial holographic gratings each of which produces an individual spectrum with a resolution of about 6000 and a bandwidth of 80 nm. The gratings ensure centering of each part of the spectrum they produce so as to provide uniform coverage of the broadest possible wavelength interval. In this study we manage to simultaneously cover the 430-680 nm interval without gaps using three gratings. Efficiency of the spectrograph optical system itself from the entrance slit to the CCD detector is typically of about 60% with a maximum of 75%. We discuss the advantages and drawbacks of the new spectrograph scheme as well as the astrophysical tasks for which the instrument can be used. [ABSTRACT FROM AUTHOR]

We report the computation of the design of a polarimetric unit for the optical scheme of the fiberfed high-resolution spectrograph for the 6-m Russian telescope.We discuss a variant of its integration into the design of conversion optics at the input of the fiber path if the instrument and estimate the efficiency of the entire pre-fiber optical system. The luminous efficiency of the assembly is equal to 80 and 90% when operated in the polarimetry and normal spectroscopic modes, respectively.We estimate the lower limit for the distorting instrumental effects of the polarimetric unit. [ABSTRACT FROM AUTHOR]

Based on the material of multiple high-resolution R = 60 000 observations conducted on the 6-m telescope (BTA) of the Special Astrophysical Observatory in combination with the Nasmyth Echelle Spectrograph (NES), we closely studied the features of the optical spectrum of the star MWC17 with the B[e] phenomenon. In the wavelength interval of 4050-6750 Å, we identified numerous permitted and forbidden emissions, interstellar Na I lines, and diffuse interstellar bands (DIBs). Radial velocities were estimated from lines of different origin. As the systemic velocity, V, the velocity of the forbidden emissions can be accepted: −47 kms (relative to the local standard V = −42 kms). Comparison of the obtained data with the earlier measurements allows us to conclude on the absence of considerable variability of spectral details. [ABSTRACT FROM AUTHOR]

We designed a cross-dispersion fiber-fed spectrograph for moderate-diameter telescopes. The instrument can simultaneously record the wavelength interval spanning from 3850 to 10 850 Å at a spectral resolution of R = 45 000 with the maximum diameter of the input star image of $$3''_ \cdot 3$$. The instrument allows the spectrum of the star to be recorded simultaneously with the comparison spectrum. Spectra can also be acquired with the use of linear and circular polarization analyzers. The instrument is oriented toward high-precision monitoring of line properties in stellar spectra. [ABSTRACT FROM AUTHOR]

Long-slit medium-resolution spectra of the Galactic globular clusters (GCs) NGC6229 and NGC6779, obtained with the CARELEC spectrograph at the 1.93-m telescope of the Haute-Provence observatory, have been used to determine the age, helium abundance (Y), and metallicity [Fe/H] as well as the first estimate of the abundances of C, N, O, Mg, Ca, Ti, and Cr for these objects. We solved this task by comparing the observed spectra and the integrated synthetic spectra, calculated with the use of the stellar atmosphere models with the parameters preset for the stars from these clusters. The model mass estimates, T, and log g were derived by comparing the observed 'color-magnitude' diagrams and the theoretical isochrones. The summing-up of the synthetic blanketed stellar spectra was conducted according to the Chabrier mass function. To test the accuracy of the results, we estimated the chemical abundances, [Fe/H], log t, and Y for the NGC5904 and NGC6254 clusters, which, according to the literature, are considered to be the closest analogues of the two GCs of our study. Using the medium-resolution spectra from the library of Schiavon et al., we obtained for these two clusters a satisfactory agreement with the reported estimates for all the parameters within the errors. We derived the following cluster parameters. NGC6229: [Fe/H] = −1.65 dex, t = 12.6 Gyr, Y = 0.26, [ α/Fe] = 0.28 dex; NGC6779: [Fe/H] = −1.9 dex, t = 12.6 Gyr, Y = 0.23, [ α/Fe] = 0.08 dex; NGC5904: [Fe/H] = −1.6 dex, t = 12.6 Gyr, Y = 0.30, [ α/Fe] = 0.35 dex; NGC6254: [Fe/H] = −1.52 dex, t = 11.2 Gyr, Y = 0.30, [ α/Fe] = 0.025 dex. The value [ α/Fe] denotes the average of the Ca and Mg abundances. [ABSTRACT FROM AUTHOR]

This paper presents the results of magnetic field measurements for 39 chemically peculiar and 3 normal main sequence stars used as standard stars. Observations were carried out with the Main Stellar Spectrograph of the Russian 6-m telescope during 2007. Zeeman measurements for 8 stars were performed for the first time. The accuracy analysis for the longitudinal magnetic field measurements of the stars confirms that the systematic errors do not exceed 10-20 G and are within the quoted limits. The absence of significant instrumental deviations follows from the measurements of the CP stars with well-known B variation curves. [ABSTRACT FROM AUTHOR]

We report the results of testing the high-resolution fiber-fed spectrograph of Kourovka Astronomical Observatory of the Ural Federal University in 2010-2012 and the corresponding operation experience, and demonstrate the need for an upgrade of the instrument. We also describe the modifications that were made to the design of the spectrograph during the start of its regular operation in 2010 and the refurbishment of its suspended part carried out in 2013, which allowed to expand the capabilities of the instrument. [ABSTRACT FROM AUTHOR]

We propose a project of a high-resolution ( R = 100 000) fiber-fed spectrograph for comprehensive studies of stellar atmospheres, exoplanet searches, asteroseismological studies, studies of stellar magnetism, active nuclei of bright galaxies, interstellar medium, etc. We present the optical scheme of the instrument. The operating wavelength region spans from 4000 to 7500 Å. We also present the optical scheme of the pre-fiber optic unit of the spectrograph. The unit supports four main modes of spectroscopic observations: the mode of traditional spectroscopy with the spectrum of the studied object taken along with the background spectrum in the immediate vicinity of the object; the mode of the simultaneous recording of the spectrum of the object and that of the wavelength standard; the mode of high-precision spectroscopy with an iodine cell, and the mode of spectropolarimetric observations with the measurement of all the Stokes parameters. [ABSTRACT FROM AUTHOR]

We analyze the properties of high-resolution spectrographs fed from the telescope through optical fiber links. We report the results of tests performed with the fiber-fed spectrograph that we developed for 1-2 m telescopes. [ABSTRACT FROM AUTHOR]