We have carried out a detailed investigation of eclipsing binary star NT Aps using high cadence photometric observations from the TESS satellite and time-series spectra from EFOSC2 at ESO's New Technology Telescope.a We have, for the first time, determined precise system parameters for this W UMa-type late-type contact binary. Our analysis indicates that the system is composed of two solar-like stars with mass ratio of q=0.31 and orbital period of 0.29475540 +/- 0.00000035 days. These values are typical for common envelope contact binaries. However, the system does not exhibit strong magnetic activity in the form of frequent flaring and large starspots, even if large flare rates have been earlier predicted for this system. This lack of strong magnetic activity further strengthens the earlier indications that the contact binaries are less magnetically active than those of detached chromospherically active binaries with similar parameters.

Context. Around half of the heavy elements in the Universe are formed through the slow neutron capture (s-) process, which takes place in thermally pulsing asymptotic giant branch (AGB) stars with masses of 1 - 6 M-circle dot. The nucleosynthetic imprint of the s-process can be studied by observing the material on the surface of binary barium (Ba), carbon (C), CH, and carbon-enhanced metal-poor (CEMP) stars. Aims. We study the s-process by observing the luminous components of binary systems polluted by a previous AGB companion. Our radial velocity (RV) monitoring program establishes an ongoing collection of binary stars exhibiting enrichment in s-process material for the study of elemental abundances, the production of s-process material, and binary mass transfer. Methods. From high-resolution optical spectra, we measured RVs for 350 stars and derived stellar parameters for approximately 150 stars using ATHOS. For a subsample of 24 chemically interesting stars, we refined our atmospheric parameters using ionization and excitation balance with the Xiru program. We used the MOOG code to compute one-dimensional local thermodynamic equilibrium (1D-LTE) abundances of carbon, magnesium, s-process elements (Sr, Y, Zr, Mo, Ba, La, Ce, Nd, Pb), and Eu to investigate neutron capture events and stellar chemical composition. We estimated dynamical stellar masses via orbital optimization using Markov chain Monte Carlo techniques in the ELC program, and we compared our results with low-mass AGB models in the FUll-Network Repository of Updated Isotopic Tables & Yields (FRUITY) database. Results. In our abundance subsample, we find enhancements in s-process material in spectroscopic binaries, a signature of AGB mass transfer. We add the element Mo to the abundance patterns, and for 12 stars we add Pb detections or upper limits, as these are not known in the literature. Computed abundances are in general agreement with the literature. Comparing our abundances to dilution-modified FRUITY yields, we find correlations in s-process enrichment and AGB mass, which are supported by dynamical modeling from RVs. Conclusions. From our high-resolution observations, we expand heavy element abundance patterns and highlight binarity in our chemically interesting systems. We find trends in s-process element enhancement from AGB stars, and agreement between theoretical and dynamically modeled masses. We investigate evolutionary stages for a small subset of our stars.

We present the results of a systematic search of the Transiting Exoplanet Survey Satellite (TESS) 2-min cadence data for new rapidly oscillating Ap (roAp) stars observed during the Cycle 2 phase of its mission. We find seven new roAp stars previously unreported as such and present the analysis of a further 25 roAp stars that are already known. Three of the new stars show multiperiodic pulsations, while all new members are rotationally variable stars, leading to almost 70 per cent (22) of the roAp stars presented being alpha(2) CVn-type variable stars. We show that targeted observations of known chemically peculiar stars are likely to overlook many new roAp stars, and demonstrate that multiepoch observations are necessary to see pulsational behaviour changes. We find a lack of roAp stars close to the blue edge of the theoretical roAp instability strip, and reaffirm that mode instability is observed more frequently with precise, space-based observations. In addition to the Cycle 2 observations, we analyse TESS data for all-known roAp stars. This amounts to 18 further roAp stars observed by TESS. Finally, we list six known roAp stars that TESS is yet to observe. We deduce that the incidence of roAp stars amongst the Ap star population is just 5.5 per cent, raising fundamental questions about the conditions required to excite pulsations in Ap stars. This work, coupled with our previous work on roAp stars in Cycle 1 observations, presents the most comprehensive, homogeneous study of the roAp stars in the TESS nominal mission, with a collection of 112 confirmed roAp stars in total.

Here we analyze high-resolution spectra of the Nova V392 Per obtained during the 2018 outburst. The H$\alpha$ and H$\beta$ emission lines show a triple-peak structure with radial velocities of about -2000 km/s, -250 km/s and 1900 km/s respectively. The near infrared spectrum is dominated by the narrow and single-peaked Paschen lines of hydrogen and the OI $\lambda$8446 and OI $\lambda$7773 emission lines. Using DIBs and the KI line, we estimate the interstellar excess towards V392 Per. Based on AAVSO and ASAS-SN photometry data, we calculate that the t$_2$ and t$_3$ decline times are $\sim$ 3 d and $\sim$ 11 d respectively, which classifies V392 Per as a very fast nova. We also briefly discuss the similarity between V392 Per and other very fast novae and the possible future evolution of the system in terms of the hibernation model.

Photometric and spectral observations of the W UMa binaries FI Lyn, UV Lyn, and NSVS 781878 with periods of around 9.5-10 hr were carried out in order to determine their global parameters by simultaneous light curve and radial velocity curve solutions. We found that the three targets have shallow-contact configurations with close in mass and radius components. UV Lyn is of W-subtype, NSVS 781878 is of A-subtype, while FI Lyn may be considered as binary in thermal contact. Our data show evidences of photospheric activity of the targets but not of emission in the H(alpha)line. The surface inhomogeneity of UV Lyn is stable during the last several decades. ItsO-Cdiagram implies presence of third body with a period of 24 years. The distances of FI Lyn, UV Lyn, and NSVS 781878 calculated from the derived luminosities coincide with those obtained byGAIAastrometrically.

Photometric and spectral observations of the W UMa binaries FI Lyn, UV Lyn, and NSVS 781878 with periods of around 9.5–10 hr were carried out in order to determine their global parameters by simultaneous light curve and radial velocity curve solutions. We found that the three targets have shallow-contact configurations with close in mass and radius components. UV Lyn is of W-subtype, NSVS 781878 is of A-subtype, while FI Lyn may be considered as binary in thermal contact. Our data show evidences of photospheric activity of the targets but not of emission in the H α line. The surface inhomogeneity of UV Lyn is stable during the last several decades. Its O–C diagram implies presence of third body with a period of 24 years. The distances of FI Lyn, UV Lyn, and NSVS 781878 calculated from the derived luminosities coincide with those obtained by GAIA astrometrically.

We present new photometric and spectroscopic observations and analyses for the eclipsing binary systems V1241 Tau and GQ Dra. Our photometric light and radial velocity curves analyses combining with the TESS light curves show that both are conventional semi-detached binary systems. Their absolute parameters are also derived. We present the $O-C$ analyses of the systems and we propose the most possible orbital period modulating mechanisms. Furthermore, Fourier analyses are applied to the photometric residual data of the systems to check for the pulsational behavior of the components. We conclude that the primary component of the system GQ Dra is a $δ$ Sct type pulsator with a dominant pulsation frequency of 18.58 d$^{-1}$ based on our $B$ filter residual light curve although it can not be justified by 30-minute cadence TESS data. No satisfactory evidence of pulsational behaviour for V1241 Tau was verified. Finally, the evolutionary tracks of the components of both systems are calculated, while their locations within evolutionary diagrams are compared with other Algol-type systems.

The original paper can be found online at https://doi.org/10.1134/S1990341318030094. The affiliation of the J. Zverko in the original paper was erroneous and need to be corrected. The correct affiliation is: 1Tatranská Lomnica, 05960 Slovakia

Photometric and spectral observations of the W UMa binaries NSVS 4161544 and 1SWASP J034501.24+493659.9 with periods of around 8 hr are presented. The simultaneous light-curve and radial-velocity-curve solutions revealed that the two targets have over-contact configurations, and their components undergo partial eclipses. The derived parameters of NSVS 4161544 are: mass ratio q = 3.377, orbital inclination i = 65.0(0), temperatures T-1 = 6016 K and T-2 = 5726 K, masses M-1 = 0.43 M-circle dot and M-2 = 1.47 M-circle dot, radii R-1 = 0.74 R-circle dot and R-2 = 1.28 R-circle dot, luminosities L-1 = 0.64 L-circle dot and L-2 = 1.51 L-circle dot. The derived parameters of 1SWASP J034501.24+493659.9 are: mass ratio q = 2.378, orbital inclination i = 60.3(0), temperatures T-1 = 6514 K and T-2 = 6494 K, masses M-1 = 0.275 M-circle dot and M-2 = 0.654 M-circle dot, radii R-1 = 0.693 R-circle dot and R-2 = 1.012 R-circle dot, luminosities L-1 = 0.775 L-circle dot and L-2 = 1.632 L-circle dot. Hence, the masses of the 1SWASP J034501.24+493659.9 components are quite small for the rest global parameters, and their sum of 0.93 M-circle dot is slightly below the lower mass limit of 1.0-1.2 M-circle dot for the contact binaries. The calculated distance of NSVS 4161544 almost coincides with that determined by GALA. The calculated distance of 1SWASP J034501.24+493659.9 is considerably smaller than the GALA value that is most likely due to overestimation of the interstellar extinction to this star from the Galactic disk.

We present the first results from the Transiting Exoplanet Survey Satellite (TESS) on the rotational and pulsational variability of magnetic chemically peculiar A-type stars. We analyse TESS 2-min cadence data from sectors 1 and 2 on a sample of 83 stars. Five new rapidly oscillating Ap (roAp) stars are announced. One of these pulsates with periods around 4.7 min, making it the shortest period roAp star known to date. Four out of the five new roAp stars are multiperiodic. Three of these, and the singly-periodic one show the presence of rotational mode splitting. Individual frequencies are provided in all cases. In addition, seven previously known roAp stars are analysed. Additional modes of oscillation are found in some stars, while in others we are able to distinguish the true pulsations from possible aliases present in the ground-based data. We find that the pulsation amplitude in the TESS filter is typically a factor 6 smaller than that in the B filter which is usually used for ground-based observations. For four roAp stars we set constraints on the inclination angle and magnetic obliquity, through the application of the oblique pulsator model. We also confirm the absence of roAp-type pulsations down to amplitude limits of 6 and 13 micromag, respectively, in two of the best characterised non-oscillating Ap (noAp) stars. We announce 27 new rotational variables along with their rotation periods, and provide different rotation periods for seven other stars. Finally, we discuss how these results challenge state-of-the-art pulsation models for roAp stars.

We present the first asteroseismic results for δ Scuti and γ Doradus stars observed in Sectors 1 and 2 of the TESS mission. We utilize the 2-min cadence TESS data for a sample of 117 stars to classify their behaviour regarding variability and place them in the Hertzsprung–Russell diagram using Gaia DR2 data. Included within our sample are the eponymous members of two pulsator classes, γ Doradus and SX Phoenicis. Our sample of pulsating intermediate-mass stars observed by TESS also allows us to confront theoretical models of pulsation driving in the classical instability strip for the first time and show that mixing processes in the outer envelope play an important role. We derive an empirical estimate of 74 per cent for the relative amplitude suppression factor as a result of the redder TESS passband compared to the Kepler mission using a pulsating eclipsing binary system. Furthermore, our sample contains many high-frequency pulsators, allowing us to probe the frequency variability of hot young δ Scuti stars, which were lacking in the Kepler mission data set, and identify promising targets for future asteroseismic modelling. The TESS data also allow us to refine the stellar parameters of SX Phoenicis, which is believed to be a blue straggler.

We present results of a study of variability of the marginal Am star HD 176843 observed in the Kepler field. Kepler photometry and ground-based spectroscopy are used to investigate the light variations of the star. HD 176843 is classified as a marginal Am star that shows delta Sct type pulsations. From an analysis of the Kepler time series, we find that the light curve of HD 176843 is dominated by three modes with frequencies f(1) = 0.1145, f(2) = 0.0162 and ,f(3) = 0.1078 d(-1). The amplitude of the radial velocity variations of about 10 km/s is much more than the radial velocity errors and allows us to conclude clear radial velocity variations. Using the radial velocity data and the adopted spectra, the orbital solution of HD 176843 is also obtained with an orbital period of 34.14 days. However, the available photometric data show no significant evidence for any possible motion in the binary system.

We report the discovery of two massive eccentric systems with BRITE data, τ Ori and τ Lib, showing heartbeat effects close to the periastron passage. τ Lib exhibits shallow eclipses that will soon vanish due to the apsidal motion in the system. In neither system, tidally excited oscillations were detected.

We report the discovery of two massive eccentric systems with BRITE data, tau Ori and tau Lib, showing heartbeat effects close to the periastron passage. tau Lib exhibits shallow eclipses that will soon vanish due to the apsidal motion in the system. In neither system, tidally excited oscillations were detected.

We present the analysis of the variability of the SPB-type star 53 Per based on space photometry from BRITE-Constellation nano-satellites and SMEI-Coriolis experiment. The two photometries allowed us to detect 17 independent sinusoidal terms in the range 0.2-1.4 d(-1) plus one combination, and one harmonic. The independent terms can be attributed to g modes excited in this star. Only three of these modes have been known earlier. In addition, we gathered almost 3500 new mid- and high-resolution spectra of 53 Per, which were used to calculate radial velocities. The frequency spectrum of the time-series radial-velocity data revealed four independent terms and one combination, all consistent with the frequencies detected in BRITE and SMEI photometry. The high-resolution and high signal-to-noise averaged spectrum was used to obtain atmospheric parameters of 53 Per, T-eff = 15600 +/- 400 K and log(g/(cms(-2)))= 3.85 +/- 0.10.

A new investigation of the variability of the SPB-type star 53 Per is presented. The analysis of the BRITE photometry allowed us to determine eight independent frequencies and the combination one. Five of these frequencies and the combination one were not known before. In addition, we gathered more than 1800 new moderate and high-resolution spectra of 53 Per spread over approximately six months. Their frequency analysis revealed four independent frequencies and the combination one, all consistent with the BRITE results.

The high precision data obtained by the Kepler satellite allows us to detect hybrid-type pulsator candidates more accurately than the data obtained by ground–based observations. In this study, we present preliminary results on the new analysis of the Kepler light curve and high-resolution spectroscopic observations of the pulsating Am star KIC 9204718. Our tentative analysis shows that the star has hybrid-type pulsational characteristics.

We analyzed the spectra of a well known SB1 binary HD199892 for which the projected rotational velocity v sin i, introduced in the literature, significantly differs when determined from the lines of Ca II at 3933 Å and ofMg II at 4481 Å. Contrary to the former findings, we discovered the signs of spectral lines of a companion star in the profile of Hβ as well as weak metallic lines in the high resolution high S/N spectra covering the most of the visual region. We estimated the secondary star to be a main sequence A4V star with a mass of 2.2M ⊙ and derived its radial velocity which resulted in the mass of the primary M = 4.6M ⊙. Short sections of the spectra in the Mg II 4481 Å and Ca II 3933 Å regions are analyzed as well.

The axial rotation of a star plays an important role in its evolution, the physical conditions in its atmosphere and the appearance of its spectrum.We analyzed the CCD spectra of two stars for which their projected rotational velocity differs remarkably when derived from Ca II λ3933 Å and Mg II λ4481 Å lines. We estimated the projected rotational velocity of HD182255 to be 15.5 kms −1 , although in various spectra of this star the line widths correspond to values as high as 28.5 km s −1 . We found the HeI λ4471.498 Å line to be shifted to longer wavelengths by 0.046 Å, thus indicating a presence of the 3 He I isotope in the atmosphere of this star with the 3 He : 4 He ratio from 0.2 to 0.6.We also found an absorption feature at the position of the forbidden line He I λ4470.02Å. We found the lines ofMg II and CII originating from higher excited levels to be missing in the spectra of HD 182255. For HD 214923 we determined the projected rotational velocity v sin i = 165km s −1 from the profiles of the metallic lines and Ca II λ3933Å, whereas for helium lines v sin i ≈ 130km s −1 is more appropriate. Radial velocity analysis results in three long periods of ≈ 105, 34, and 15 days, and a short period of ≈ 22 hours, close to the pulsational one mentioned earlier in the literature.