We present a detailed analysis of the binary modeling and pulsation properties of TIC 197757000, an eclipsing binary system hosting a delta Scuti component, based on photometric data from the Transiting Exoplanet Survey Satellite (TESS) and Photometric Auxiliary Telescope-17, and spectroscopic data from the Beijing Faint Object Spectrograph and Camera equipment of the 2.16 m telescope. The primary star temperature of 7782(150) K from spectroscopic observations is consistent with the temperature of 7895(-271)(+243 )K, determined by spectral energy distribution fitting within the respective uncertainties. The Fourier transform (FT) of the TESS light curve for TIC 197757000 reveals seven independent frequencies associated with its light variations, which are detected in the typical frequency range of delta Scuti stars and identified as pressure modes. Among these, the ratios F0/F1 and F0/F2 are measured as 0.77095 and 0.62203, where F0, F1, and F2 correspond to the fundamental frequency, the first overtone, and the second overtone respectively. Furthermore, through analyses of the FT, histogram of frequency differences, autocorrelation function, and & eacute;chelle diagram, a large frequency separation of Delta nu = 33.45 +/- 0.50 mu Hz has been derived. The short orbital period and distinctive light curve morphology are both consistent with the properties of a tidally locked system.

We report a significant nonperiodic amplitude modulation in the delta Scuti star KIC 8712760. In this study, we conduct a long-term, multimission analysis of KIC 8712760, using uniformly processed light curves from the Wide Angle Search for Planets (WASP), Kepler, and Transiting Exoplanet Survey Satellite (TESS) missions, all placed on a common Barycentric Julian Date timescale. The amplitude of the primary mode at f1 = 16.331 day-1 decreases over time. It changes from 5.2 +/- 0.2 mmag observed in the WASP data to 0.929 +/- 0.005 mmag in the Kepler data. However, in the TESS data, it shows an upward trend. Meanwhile, the amplitude of f2 = 17.648 day-1 increases during the Kepler observation period. It later overtakes f1 as the dominant frequency for part of the TESS baseline. The relative amplitude ranking further confirms this behavior. The observations may be related to two physical mechanisms that suggest a complex interaction in the pulsational dynamics of low-amplitude delta Scuti stars.

We present a photometric and spectroscopic analysis of the long-period Algol-type eclipsing binary 2MASS J06281154+164439.3 (J0628), based on 1082days of TESS full-frame photometry and 21 LAMOST spectra. The radial-velocity modeling supports a semidetached configuration with a Roche-lobe-filling donor and a mass ratio q similar or equal to 0.37, adopting the TESS photometric ephemeris (P = 21.556 days). The H alpha line exhibits persistent double-peaked emission whose peak separation is nearly constant (Delta V = 334.8 +/- 16.2 km s-1) but with variable V/R, indicating a disk-dominated origin with modest nonaxisymmetry. Interpreting Delta V as Keplerian rotation implies an outer emitting radius Rout approximate to 21.4 +/- 2.2 R circle dot(approximate to 0.79 RL,1). To ensure physical self-consistency, we perform a joint forward modeling of the TESS light curve and a representative H alpha profile using ShellSpec. This unified model uses a physically consistent stream-impact hot spot at the outer edge of the accretion disk to reproduce the out-of-eclipse asymmetry, yielding global parameters of i = 62 .degrees 86, a = 57.60 R circle dot, Teff,1 = 10,096 K, and Teff,2 = 4569 K. The joint fit firmly constrains the disk properties to log10 rho disk=-13.37 (cgs), Tdisk = 6021 K, Rin = 3.48 R circle dot, Rout = 26.56 R circle dot, and vturb = 49.7 km s-1, confirming a stable Roche-lobe-contained Keplerian disk. J0628 is therefore a valuable laboratory for connecting precise binary parameters with phase-resolved disk diagnostics.

We report the discovery and detailed analysis of three new high-amplitude δ Scuti (HADS) stars, TIC 408074920, TIC 189714989, and TIC 34137913, identified from Transiting Exoplanet Survey Satellite short-cadence observations. Fourier analysis reveals dominant radial modes accompanied by rich harmonic structures in all three stars, confirming their HADS classification. In addition, TIC 189714989 exhibits clear symmetric side peaks around the radial harmonics, indicative of amplitude and/or phase modulation. Broadband spectral energy distribution (SED) fitting constrained by Gaia DR3 parallaxes provides independent estimates of the stellar effective temperatures and radii. These are compared with results from stellar evolutionary and seismic modeling based on MESA and GYRE . For two targets, the SED-derived and seismic radii are mutually consistent, while TIC 408074920 displays a significant discrepancy, plausibly attributable to the different sensitivities of the two methods and additional systematic effects. These findings highlight the diversity of amplitude variability among classical HADS and emphasize the importance of the long-term monitoring that future missions such as PLATO will allow in order to explore the underlying physical mechanisms of this variability.

We present a detailed analysis of a double-lined spectroscopic binary system, Bo Gem, using data obtained from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and the Transiting Exoplanet Survey Satellite (TESS). By applying spectral disentangling techniques to the LAMOST Medium Resolution Spectra, we determine the orbital parameters, including the orbital period of P = 4.0689 days, and semimajor axis of a = 14.90 +/- 0.04 R-circle dot. The mass ratio between the two components is found to be q = 0.198 +/- 0.006, with an inclination of i = 823 +/- 013. The photometric data from TESS revealed periodic light variations due to the eclipsing nature of the system, allowing for the determination of the primary star's radius as R-1 = 1.68 +/- 0.03 R-circle dot and the secondary star's radius as R-2 = 3.68 +/- 0.04 R-circle dot. The effective temperatures of the primary and secondary stars are measured to be T-eff,T-1 = 9705 +/- 50 K and T-eff,T-2 = 5830 +/- 22 K, respectively. By analyzing the disentangled spectra, we determined the stellar atmospheric parameters-including surface gravity and metallicity of both stars. These results not only confirm the double-lined spectroscopic binary status of Bo Gem, but also underscore its value as an important system for testing and refining stellar evolution models.

KOI-1755 (KIC 5302006) was initially identified by the Kepler mission as a candidate exoplanet host but subsequently classified as a false positive due to suspected background contamination. The target star itself exhibits intrinsic stellar pulsations, accompanied by transit-like dimming events, complicating a straightforward identification of the signal source. In this study, we carried out a detailed pixel-level reanalysis of KOI-1755 using the Kepler Target Pixel Files (TPFs) to clarify the origin of these transit-like signals. Through careful pixel-level flux modeling, centroid shift measurements, and cross-matching with the Gaia DR3 catalog, we conclusively determined that the dimming signals originate from a faint background eclipsing binary (EB), rather than KOI-1755 itself. We then developed a specialized photometric method to effectively remove contamination from nearby stars, allowing us to reliably extract the EB's uncontaminated light curve directly from the TPFs data. Analysis of this extracted light curve confirmed the contaminating source to be an EB system composed of two dwarf stars with a clear eclipse period of approximately 6.14 days. Our study provides a concrete example of how background EBs can mimic planetary transit signals, highlighting the importance of detailed pixel-level analyses for correctly identifying astrophysical false positives. Furthermore, our method demonstrates significant potential for uncovering previously hidden variable-star information within archival Kepler data, thus emphasizing the continuing scientific value of mining and reanalyzing existing data sets.

The preliminary results of searching and study for variable stars using TESS photometry in the intermediate age open star cluster King 18 are presented. We have investigated the light curves and frequency spectra of different types of variable stars located in the open cluster area. The results obtained together with prospects of study of this open cluster are briefly discussed.

We investigated the pulsating behavior of KIC 10855535 using Kepler 4 yr long-cadence data. Two independent frequencies were detected: a pulsation frequency F0 = 17.733260(5) day-1 and a low frequency f 8 = 0.412643(8) day-1. We identify F0 as the fundamental frequency, at which an equidistant quintuplet is centered, suggesting that the star orbits in a binary system. The fitted orbital parameters align well with those reported in previous literature. Long-term phase modulation caused by binarity has been confirmed by considering the light curve from the Transiting Exoplanet Survey Satellite. By removing the light-time effect, we measured a linear change in period of order P/P similar or equal to 1.44x10-7yr-1 , a value that could be indicative of stellar evolution. The star also exhibits a gradual and stable amplitude growth, thereby raising the possibility of structural changes during its evolution. We attributed f 8 and its two harmonics to rotation and surface spots, with further analysis suggesting characteristics evolving over time. Based on this hypothesis, KIC 10855535 may rotate slowly for its type, with a speed of 37(2) km s-1. Overall, KIC 10855535 presents an exceptionally clean spectrum and a relatively slow rotation as a delta Sct pulsator, exhibiting a single pulsation mode that undergoes both amplitude and phase modulation.

We report a delta Scuti star, KIC 10407873, exhibiting significant amplitude modulation. Fourier analysis of Kepler long-cadence data (i.e., Q0-Q17, spanning 1471 days) reveals two distinct features: harmonic series of frequencies in the low-frequency region and the frequencies of the split triplet lines in the high-frequency region. Using the Hilbert transform method, we separated the amplitude modulation signals, obtaining precise parameters for the two modulation frequencies. For the harmonic series of frequencies in the low-frequency region, we isolated them through a prewhitening process. Based on the residual segmented spectrum and the phase-folding diagram, we propose that these harmonic series of frequencies may be caused by temperature inhomogeneity on the stellar surface and stellar rotation. The subsequent phase evolution diagrams we generated, combined with LAMOST's vsini data, further support this hypothesis. Consequently, this suggests that the cause of amplitude modulation in the high-frequency region is unrelated to stellar rotation. Finally, we discussed the information potentially carried by the isolated modulation signals, as well as the similarities between the star's dual-amplitude modulation and the periodically modulated Tseraskaya-Blazhko effect.

We report seven newly identified high-amplitude δ Scuti (HADS) stars. Among them, two stars (TIC 30977864 and TIC 387379145) exhibit pure radial pulsation without the excitation of non-radial modes. TIC 30977864 is classified as a double-mode HADS star, while the other four stars potentially show triple-mode HADS behavior. TIC 112682462 and TIC 255603395 closely resemble RR Lyrae stars based on their light curves, position in the period–luminosity diagram, and the period ratio diagram. However, without spectral observations, it is challenging to ascertain whether these two stars are HADS or RR Lyrae stars. TIC 281695001 exhibits a fundamental frequency amplitude smaller than that of the first overtone, suggesting the presence of intriguing phenomena that necessitate further analysis. We analyzed the relationship between metallicity and period using data provided by Netzel & Smolec. The metallicities of the 176 stars display a broad distribution ranging from −2.0 dex to 0.5 dex, with periods spanning 0.05 to 0.20 days. This random distribution of metallicities may contribute to the dispersion observed in the P1/P0 ratio. To derive more accurate conclusions, future spectroscopic observations of a larger sample of HADS stars are crucial. These observations will provide precise rotational velocities and more accurate determinations of metallicities.

The Stellar Abundances and Galactic Evolution Survey (SAGES) of the northern sky is a specifically designed multiband photometric survey aiming to provide reliable stellar parameters with accuracy comparable to those from low-resolution optical spectra. It was carried out with the 2.3 m Bok telescope of Steward Observatory and three other telescopes. The observations in the u s and v s passband produced over 36,092 frames of images in total, covering a sky area of ∼9960 deg 2 . The median survey completenesses of all observing fields for the two bands are u s = 20.4 mag and v s = 20.3 mag, respectively, while the limiting magnitudes with signal-to-noise ratio of 100 are u s ∼ 17 mag and v s ∼ 18 mag, correspondingly. We combined our catalog with the data release 1 (DR1) of the first Panoramic Survey Telescope And Rapid Response System (Pan-STARRS, PS1) catalog, and obtained a total of 48,553,987 sources that have at least one photometric measurement in each of the SAGES u s and v s and PS1 grizy passbands. This is the DR1 of SAGES, released in this paper. We compared our gri point-source photometry with those of PS1 and found an rms scatter of ∼2% difference between PS1 and SAGES for the same band. We estimated an internal photometric precision of SAGES to be of the order of ∼1%. Astrometric precision is better than 0.″2 based on comparison with DR1 of the Gaia mission. In this paper, we also describe the final end-user database, and provide some science applications.

We present 43 times of minima for the W Ursae Majoris type eclipsing binary V0674 Lyr. The observations were obtained using the Zeiss-600 telescope at the Maidanak astronomical observatory in Uzbekistan from 2018 to 2020.

In this paper, we study the pulsation properties of KIC 3440495 using Kepler and TESS data. A Fourier analysis of the light curve reveals 24 pulsation modes as well as 29 frequencies associated with rotation. The rotation frequency is derived to be f (rot) = 2.322909(2) day(-1), and the rotational modulation is determined to be caused by starspots. A large frequency separation of Delta nu = 54.5 mu Hz is found by using a Fourier transform, the autocorrelation function, a histogram of frequency differences, and an echelle diagram. We use the large separation to estimate the refined stellar parameters of the star to be v = [239, 279] km s(-1), M = [1.5, 1.65] M (circle dot), R (equator) = [2.03, 2.30] R (circle dot), R (polar) = [1.72, 1.78] R (circle dot), and omega = [0.61, 0.77]. The phase modulations of the pulsating frequencies show a long-term trend which may be attributed to an orbital effect of a binary system; hence, the star may be a fast rotating pulsator in a binary system. KIC 3440495 has an amplitude spectrum similar to Altair, and is identified as a potential sister of Altair. Based on studies of Altair, KIC 3330495 is presumably a young star at a similar evolutionary stage.

We describe here the formulation of our search for additional bodies in fifteen short period eclipsing binary stars and some results obtained by now. We intended to use two methods: transits across the surface of one or both stars (in order to detect planets) in the binary and a timing of eclipses of central binary stars (that can indicate the presence of a stellar mass body in the system). Observations were carried out using ground based photometry with 50-60 cm telescopes in 2013-2017. Until now no transits had been detected in our data. But at the same time we found several candidates for additional bodies in four systems. Further data processing will be performed.

We homogeneously analyse similar to 3.2 x 10(5) photometric measurements for similar to 1100 transit light curves belonging to 17 exoplanet hosts. The photometric data cover 16 years (2004-2019) and include amateur and professional observations. Old archival light curves were reprocessed using up-to-date exoplanetary parameters and empirically debiased limb-darkening models. We also derive self-consistent transit and radial-velocity fits for 13 targets. We confirm the non-linear transit timing variation (TTV) trend in the WASP-12 data at a high significance, and with a consistent magnitude. However, Doppler data reveal hints of a radial acceleration of about -7.5 +/- 2.2 ms(-1) yr(-1), indicating the presence of unseen distant companions, and suggesting that roughly 10 per cent of the observed TTV was induced via the light-travel (or Roemer) effect. For WASP-4, a similar TTV trend suspected after the recent TESS observations appears controversial and model dependent. It is not supported by our homogeneous TTV sample, including 10 ground-based EXPANSION light curves obtained in 2018 simultaneously with TESS. Even if the TTV trend itself does exist in WASP-4, its magnitude and tidal nature are uncertain. Doppler data cannot entirely rule out the Roemer effect induced by possible distant companions.

The article presents the latest status of the Maidanak 1 m telescope, instruments and the related facilities of the Observatory as well as the science projects. The renovation of the 1 m telescope of Carl Zeiss (Germany) at the Maidanak observatory of the Ulug Bek Astronomical Institute (UBAI) AS of Uzbekistan has been made. All systems of the telescope were completely modernized based on modern standards, the main results of modernization are also described. All modernization works, as well as scientific research on this project are carried out in close cooperation of UBAI with the National Astronomical Observatories of the Academy of Sciences of the PRC in framework of the Agreement on cooperation between these organizations. The FOV has been enlarged and new CCD camera is mounted. The related facilities, like the observing circumstance monitoring system and the photovoltaic station, are also built for the observing support. The telescope and new camera will be tested and used for the science projects of the 1 m telescope. According to the collaboration agreement, a large-scale scientific project on a full survey of the northern sky in special photometric system - Stellar Abundance and Galactic Evolution (SAGE) survey will be carried out with the upgraded 1 m telescope. The main goal of the project is to measure the stellar atmospheric parameters for more than 500 million FGK stars. As other projects, the time domain science, like GRB, SNe searching, variable stars, also will be performed.

This study aims timing the eclipses of the short period low mass binary star AB And. The times of minima are taken from the literature and from our observations in October 2013 (22 times of minima) and in August 2014 (23 times of minima). We find and discuss an inaccuracy in the determination of the types of minima in the previous investigation by Li et al. (2014). We study the secular evolution of the central binary’s orbital period and the possibility of the existence of third and fourth companions in the system.

This study aims timing the eclipses of the short period low mass binary star AB And. The times of minima are taken from the literature and from our observations in October 2013 (22 times of minima) and in August 2014 (23 times of minima). We find and discuss an inaccuracy in the determination of the types of minima in the previous investigation by Li et al. (2014). We study the secular evolution of the central binary's orbital period and the possibility of the existence of third and fourth companions in the system. (C) 2017 Elsevier B.V. All rights reserved.