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971. P Cyg H{alpha} squared visibility
ID:
ivo://CDS.VizieR/J/AJ/139/2269
Title:
P Cyg H{alpha} squared visibility
Short Name:
J/AJ/139/2269
Date:
21 Oct 2021
Publisher:
CDS
Description:
High spatial resolution observations of the H{alpha}-emitting wind structure associated with the luminous blue variable star P Cygni were obtained with the Navy Prototype Optical Interferometer. These observations represent the most comprehensive interferometric data set on P Cyg to date. We demonstrate how the apparent size of the H{alpha}-emitting region of the wind structure of P Cyg compares between the 2005, 2007, and 2008 observing seasons and how this relates to the H{alpha} line spectroscopy. Using the data sets from 2005, 2007, and 2008 observing seasons, we fit a circularly symmetric Gaussian model to the interferometric signature from the H#-emitting wind structure of P Cyg.
972. P Cygni H{alpha} measurements
ID:
ivo://CDS.VizieR/J/AJ/141/120
Title:
P Cygni H{alpha} measurements
Short Name:
J/AJ/141/120
Date:
21 Oct 2021
Publisher:
CDS
Description:
P Cygni is a prototype of the luminous blue variables (or S Doradus variables), and the star displays photometric and emission line variability on a timescale of years (known as the "short S Doradus-phase" variations). Here we present new high-resolution H{alpha} spectroscopy of P Cyg that we combine with earlier spectra and concurrent V-band photometry to document the emission and continuum flux variations over a 24 year time span.
973. Period analysis of 7 field RRab stars
ID:
ivo://CDS.VizieR/J/ApJ/863/151
Title:
Period analysis of 7 field RRab stars
Short Name:
J/ApJ/863/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the times of light maximum collected from the GEOS RR Lyrae database and determined from sky surveys, we utilize the O-C method to study the period variations of seven field ab-type RR Lyrae stars. The time coverage of data for most stars is more than 100 years, allowing us to investigate period changes over a large time span. We find that the O-C diagrams for most stars can be described by a combination of cyclic variations and long-term period changes. Assuming the former were caused by the light-travel-time effect, the pulsation and orbital parameters are obtained by the nonlinear fitting. We find that the orbital periods in our sample range from 33 to 78 years, and the eccentricities are relatively higher than the results for other candidates (e>0.6). The minimal masses of the potential companions of XX And, BK Dra, and RY Psc are less than one solar mass, and those of SV Eri, AR Her, and RU Scl are 3.3, 2.1, and 3.4M_{sun}_, respectively. Moreover, we suggest that the companion of AR Her may be a blue straggler that experienced mass transfer or a merger of two stars. The O-C diagram for ST Vir also shows distinct long- term period decrease, and in the O-C residuals, additional quasi-periodic variations that can be described by damped oscillation are found. Combining the data from the literature and our analysis, we plot the log P-AO-C diagram. The distribution of our binary candidates suggests that their period variations are not caused by the Blazhko effect.
974. Period change for 143 SuperWASP eclipsing binaries
ID:
ivo://CDS.VizieR/J/A+A/549/A86
Title:
Period change for 143 SuperWASP eclipsing binaries
Short Name:
J/A+A/549/A86
Date:
21 Oct 2021
Publisher:
CDS
Description:
Building on previous work, a new search of the SuperWASP archive was carried out to identify eclipsing binary systems near the short-period limit. 143 candidate objects were detected with orbital periods between 16000 and 20000s, of which 97 are new discoveries. Period changes significant at 1{sigma} or more were detected in 74 of these objects, and in 38 the changes were significant at 3{sigma} or more. The significant period changes observed followed an approximately normal distribution with a half-width at half-maximum of ~0.1s/yr. There was no apparent relationship between period length and magnitude or direction of period change. Amongst several interesting individual objects studied, 1SWASP J093010.78+533859.5 is presented as a new doubly eclipsing quadruple system, consisting of a contact binary with a 19674.575s period and an Algol-type binary with a 112799.109s period, separated by 66.1AU, being the sixth known system of this type.
975. Period changes in RT Lac
ID:
ivo://CDS.VizieR/J/A+A/287/817
Title:
Period changes in RT Lac
Short Name:
J/A+A/287/817
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
976. Period changes in SuperWASP eclipsing binaries
ID:
ivo://CDS.VizieR/J/A+A/578/A136
Title:
Period changes in SuperWASP eclipsing binaries
Short Name:
J/A+A/578/A136
Date:
21 Oct 2021
Publisher:
CDS
Description:
Orbital period changes of binary stars may be caused by the presence of a third massive body in the system. Here we have searched the archive of the Wide Angle Search for Planets (SuperWASP) project for evidence of period variations in 13927 eclipsing binary candidates. Sinusoidal period changes, strongly suggestive of third bodies, were detected in 2% of cases; however, linear period changes were observed in a further 22% of systems. We argue on distributional grounds that the majority of these apparently linear changes are likely to reflect longer-term sinusoidal period variations caused by third bodies, and thus estimate a higher-order multiplicity fraction of 24% for SuperWASP binaries, in good agreement with other recent figures for the fraction of triple systems amongst binary stars in general.
977. Period changes of 148 Galactic Cepheids
ID:
ivo://CDS.VizieR/J/MNRAS/511/2125
Title:
Period changes of 148 Galactic Cepheids
Short Name:
J/MNRAS/511/2125
Date:
14 Feb 2022 13:42:07
Publisher:
CDS
Description:
Investigating period changes of classical Cepheids through the framework of O-C diagrams provides a unique insight to the evolution and nature of these variable stars. In this catalogue, we present the O-C diagrams and period change rates derived for 148 Galactic Classical Cepheids variables, along with the exact period values of these stars for a given date as determined by the O-C diagrams. The catalogue also contains photometric data adopted from Gaia EDR3 and the David Dunlap Observatory Cepheid Database, which were used for the study, and the results obtained from the statistical modelling of the individual O-C diagrams. We find that a significant fraction of the Cepheids show period fluctuations, which appear on the O-C diagrams as quasi-periodic waves, which could be modelled and described through the statistical framework. For completeness, we also included all photometric data collected from various previous publications and survey that were used for the research.
978. Periodicities in KIC 3527751 from 3yr Kepler data
ID:
ivo://CDS.VizieR/J/ApJ/805/94
Title:
Periodicities in KIC 3527751 from 3yr Kepler data
Short Name:
J/ApJ/805/94
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze 3yr of nearly continuous Kepler spacecraft short cadence observations of the pulsating subdwarf B (sdB) star KIC 3527751. We detect a total of 251 periodicities, most in the g-mode domain, but some where p-modes occur, confirming that KIC3527751 is a hybrid pulsator. We apply seismic tools to the periodicities to characterize the properties of KIC3527751. Techniques to identify modes include asymptotic period spacing relationships, frequency multiplets, and the separation of multiplet splittings. These techniques allow for 189 (75%) of the 251 periods to be associated with pulsation modes. Included in these are three sets of l=4 multiplets and possibly an l=9 multiplet. Period spacing sequences indicate l=1 and 2 overtone spacings of 266.4+/-0.2 and 153.2+/-0.2s, respectively. We also calculate reduced periods, from which we find evidence of trapped pulsations. Such mode trappings can be used to constrain the core/atmosphere transition layers. Interestingly, frequency multiplets in the g-mode region, which sample deep into the star, indicate a rotation period of 42.6+/-3.4days while p-mode multiplets, which sample the outer envelope, indicate a rotation period of 15.3+/-0.7days. We interpret this as differential rotation in the radial direction with the core rotating more slowly. This is the first example of differential rotation for a sdB star.
979. Periodic variables in Catalina and LINEAR
ID:
ivo://CDS.VizieR/J/other/Ap/64.27
Title:
Periodic variables in Catalina and LINEAR
Short Name:
J/other/Ap/64.27
Date:
22 Feb 2022
Publisher:
CDS
Description:
In this study we continue spectral class determinations for large number of optically faint periodic variables taken from the Catalina Surveys Data Release 1 (CSDR1)and LINEAR data sets. Spectral classes and physical parameters are presented for 1184 periodic variables with periods P>=10 days, taken from modern large sky area spectroscopic and photometric databases, including LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope), SDSS(Sloan Digital Sky Survey), the Hamburg Quasar Survey(HQS)m the Hamburg /ESO Survey (HES), and Gaia Data Release 2 (DR2). In Gaia DR2 catalogue, luminosities are presented for 276 objects and radial velocities (RV) for 108. Spectral classes were confirmed for more than 650 objects. The majority of the variables are found to be F, G, K, M dwarfs and giants, a few dozen carbon (C) stars (N-type Asymptotic Giant Branch (AGB) stars), and a few S stars. Some periodic variables are blue objects, such as B and A stars. The periods are in the range 10<=P<=1504 days and Catalina magnitudes in range 11.5<=V<=20.0mag. Finding new and faint evolved AGB stars in the halo of our Galaxy is the first priority. A catalogue containing multi-parameter data for 1184 periodic variables from modern astronomical databases has been generated.
980. Periodic variables in NGC 3766
ID:
ivo://CDS.VizieR/J/A+A/554/A108
Title:
Periodic variables in NGC 3766
Short Name:
J/A+A/554/A108
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze the population of periodic variable stars in the open cluster NGC3766 based on a 7-year multiband monitoring campaign conducted on the 1.2m Swiss Euler telescope at La Silla, Chili. The data reduction, light curve cleaning, and period search procedures, combined with the long observation time line, allowed us to detect variability amplitudes down to the mmag level. The variability properties were complemented with the positions in the color-magnitude and color-color diagrams to classify periodic variable stars into distinct variability types. We find a large population (36 stars) of new variable stars between the red edge of slowly pulsating B (SPB) stars and the blue edge of delta Sct stars, a region in the Hertzsprung-Russell (HR) diagram where no pulsation is predicted to occur based on standard stellar models. The bulk of their periods ranges from 0.1 to 0.7d, with amplitudes between 1 and 4mmag for the majority of them. About 20% of stars in that region of the HR diagram are found to be variable, but the number of members of this new group is expected to be higher, with amplitudes below our mmag detection limit. The properties of this new group of variable stars are summarized and arguments set forth in favor of a pulsation origin of the variability, with g-modes sustained by stellar rotation. Potential members of this new class of low-amplitude periodic (most probably pulsating) A and late-B variables in the literature are discussed. We additionally identify 16 eclipsing binary, 13 SPB, 14 delta Sct, and 12 gamma Dor candidates, as well as 72 fainter periodic variables. All are new discoveries. We encourage searching for this new class of variables in other young open clusters, especially in those hosting a rich population of Be stars.