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Highlights • We analyzed the time series of R Sct light curve from 1970 to 2017. • Behavior of the light curve and period evolution were also reviewed and investigated. • We have shown the amplitude variation of two modes as time progresses. • An estimated value of seasonal variations is approximately 10 years, and hence, we suggested a magnetic field cycle for this system. Abstract The observation of R Scuti star has a long history. This unique characteristic of light curve allows us to search for evidence of period evolution. The behavior of R Sct is complex and has not been understood well. In the present work, we reviewed and analyzed the time series of light curve observations to search for period evolution. The irregular behavior of the light curve was investigated by power spectral density (PSD) and fast Fourier transform (FFT) techniques. A time-frequency technique was performed to show frequency evolution. Additionally, we studied the amplitude and frequency variations of the main and the second mode. The characteristics of the amplitude variation of two modes as time progresses are presented. An estimated value of the seasonal variations is approximately 10 years. The results suggest a magnetic field cycle for this system. [ABSTRACT FROM AUTHOR]

The article focuses on a study on period of variable star R Scuti with spectral variations linked to its brightness. Topics discussed include reflection of RV Tauri luminous blue variables, type behaviour by variable throughout 20th century with periodic figures similar to earlier research's forecast, presence of a chaotic phase attractor, and use of global flow reconstruction method to recognize nature of attractor.

In the faint star KIC 9700322 observed by the Kepler satellite, 76 frequencies with amplitudes from 14 to 29 000 ppm were detected. The two dominant frequencies at 9.79 and 12.57 d (113.3 and 145.5 μHz), interpreted to be radial modes, are accompanied by a large number of combination frequencies. A small additional modulation with a 0.16 d frequency is also seen; this is interpreted to be the rotation frequency of the star. The corresponding prediction of slow rotation is confirmed by a spectrum from which km s is obtained. The analysis of the spectrum shows that the star is one of the coolest δ Sct variables. We also determine T = 6700 ± 100 K and = 3.7 ± 0.1, compatible with the observed frequencies of the radial modes. Normal solar abundances are found. An frequency quintuplet is also detected with a frequency separation consistent with predictions from the measured rotation rate. A remarkable result is the absence of additional independent frequencies down to an amplitude limit near 14 ppm, suggesting that the star is stable against most forms of non-radial pulsation. A low-frequency peak at 2.7763 d in KIC 9700322 is the frequency difference between the two dominant modes and is repeated over and over in various frequency combinations involving the two dominant modes. The relative phases of the combination frequencies show a strong correlation with frequency, but the physical significance of this result is not clear. [ABSTRACT FROM AUTHOR]

Pulsation frequencies of acoustic modes are calculated for realistic rotating stellar models using both a perturbative and a two-dimensional approach. A comparison between the two yields validity domains which are similar to those previously obtained in Reese et al. for polytropic models. One can also construct validity domains based on polynomial fits to the frequencies from the two-dimensional approach, and these also turn out to be similar, thus further confirming the agreement between the perturbative and the two-dimensional approaches at low rotation rates. Furthermore, as was previously shown in Espinosa et al., adjacent frequencies in multiplets come close together, thus forming pairs. This phenomenon, exclusive to two-dimensional calculations, is shown to be an unlikely explanation of the close frequency pairs observed in δ Scuti stars. A systematic search for all close frequency pairs in the calculated spectrum is also carried out. The number of close frequency pairs is shown to agree with what is expected based on a Poisson distribution, but does not match the number or distribution of close pairs in stars such as FG Vir. Furthermore, a lack of close frequency pairs appears at low rotation rates, where frequency multiplets do not overlap. δ Scuti stars currently reported as having close frequency pairs do not fall in this interval. [ABSTRACT FROM AUTHOR]

In the course of a program to digitize the astronomical plates of the Sternberg Astronomical Institute's plate stacks, we are developing algorithms for searching for new variable stars and studying them using digitized photographic plates. We have discovered and studied 480 new variable stars in a 10° × 10° field of view centered on 66 Ophiuchi. The digitized plate negatives used are from the 40-cm astrograph, and are 30 × 30 cm in size. These stars include three new Cepheids of the Galaxy's spherical component, 157 eclipsing binaries, 11 high-amplitude δ Scuti stars (HADSs), 144 RR Lyrae stars, 110 irregular variables (109 LB and one white star), and 55 semi-regular red variables. New important information has been obtained for 43 known variables, which we have classified and derived or improved their light elements; an erroneous identification of the Mira V404 Oph has been corrected. We have also identified more than 50 suspect brightness variables; a program of CCD observations of these suspected variables has been initiated. Our discoveries of new variable stars were performed in a star field with a large number of known variables, detected earlier photographically or using CCD techniques. The discovery of hundreds of new variables in a well-studied region of sky demonstrates that archive photographs possess a large information potential that has remained unrealized. [ABSTRACT FROM AUTHOR]

We comment on the recent results of a temporal analysis of R Scuti, a star of RV Tauri type, presented by Buchler et al. As an alternative approach, we apply the technique of linear state space analysis to describe the irregular temporal behaviour with a linear stochastic process. We find evidence that the variability of R Scuti can be explained by the superposition of two stochastically driven damped oscillators. [ABSTRACT FROM AUTHOR]

The article offers spectroscopic observations and analysis for the R Scuti (Sct), a star in constellation Scutum and variable of RV Tauri, a star in constellation Taurus. It discusses the visual magnitude ranges, hydrogen emission lines, and titanium oxide (TiO) molecules content of R Sct. Also mentioned the role of Lick Observatory in California and University of Michigan Observatory for studying the stars.

The article offers information on R Scuti which considered as the brightest of the RV Tauri class of variables. It is consist of a small but interesting class of pulsating luminous yellow supergiants. Such stars are generally found among the older Population II-type stars and are seen to congregrate in the galactic halo or disc. It is known as a member of the still-mysterious class of "RV Tauri stars," which are pulsating variables, but are characterized by alternating deep and shallow minima.