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- 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.
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/PASP/121/1188
- Title:
- Periodic variables in NGC 2301
- Short Name:
- J/PASP/121/1188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for periodic variables within 4078 time-series light curves and an analysis of the period-color plane for stars in the field of the open cluster NGC 2301. One hundred thirty-eight periodic variables were discovered, of which five are eclipsing binary candidates with unequal minima. The remaining 133 periodic variables appear to consist mainly of late-type stars whose variation is due to rotation modulated by star spot activity. The determined periods range from less than a day to over 14 days and have nearly unreddened B-R colors in the range of 0.8 to 2.8. The Barnes (2003ApJ...586..464B) interpretation of the period-color plane of late type stars is tested with our data. Our data did not show distinct I and C sequences, likely due to nonmember field stars contaminating in the background, as we estimate the total contamination to be 43%. Using different assumptions, the gyrochronological age of the cluster is calculated to be 210+/-25Myr, which falls in the range of age values (164-250Myr) determined by previous studies. Finally, we present evidence which nullifies the earlier suggestion that two of the variable stars in NGC 2301 might be white dwarfs.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A38
- Title:
- Period-mass-loss rate relation of Miras
- Short Name:
- J/A+A/556/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery that Mira variables with and without absorption lines of the element technetium (Tc) occupy two different regions in a diagram of near- to mid-IR colour versus pulsation period. Tc is an indicator of a recent or ongoing mixing event called the third dredge-up (3DUP), and the near- to mid-IR colour, such as the (K-[22]) colour where [22] is the the 22um band of the WISE space observatory, is an indicator of the dust mass-loss rate of a star. We collected data from the literature about the Tc content, pulsation period, and near- and mid-IR magnitudes of more than 190 variable stars on the asymptotic giant branch (AGB) to which Miras belong. The sample is naturally biased towards optical AGB stars, which have low to intermediate (dust) mass-loss rates.
- ID:
- ivo://CDS.VizieR/J/ApJ/591/L111
- Title:
- Period of Cepheids in M 83
- Short Name:
- J/ApJ/591/L111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We apply the image-subtraction method in order to reanalyze the ESO Very Large Telescope data on M83 (NGC 5236), obtained and analyzed by Thim et al. (2003ApJ...590..256T). Whereas Thim et al. (2003ApJ...590..256T) found 12 Cepheids with periods between 12 and 55 days, we find 112 Cepheids with periods ranging from 7 to 91 days as well as 60 other variables. These include two candidate eclipsing binaries, which, if confirmed, would be the first optically discovered outside the Local Group. We thus demonstrate that the image-subtraction method is much more powerful for detecting variability, especially in crowded fields. However, Hubble Space Telescope observations are necessary to obtain a Cepheid period-luminosity distance not dominated by blending and crowding. We propose a "hybrid" approach, in which numerous Cepheids are discovered and characterized using large ground-based telescopes and then followed up with the Hubble Space Telescope to obtain precise distances.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1459
- Title:
- Period of M15 variable stars
- Short Name:
- J/AJ/135/1459
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new BVI CCD photometry for variables in the globular cluster M15. Our photometry was obtained using both the image subtraction package ISIS and DAOPHOT/ALLFRAME. The data were acquired in 2001 on two observing runs on 11 observing nights using the 2m telescope of the Bulgarian National Astronomical Observatory "Rozhen" with a Photometrics CCD camera. For 39 previously known variables, we present a period for the first time, and improved periods were obtained for many previously known variables. Fourteen new variables are reported. We present updated Bailey diagrams for the cluster, and discuss its Oosterhoff classification. Although many of M15's RRab pulsators fall at an intermediate locus between Oosterhoff types I and II (OoII) in the Bailey diagram, we argue that M15 is indeed a bona fide OoII globular cluster.
