- 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.
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Search Results
- 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/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/584/A17
- Title:
- phi Dra BVRI light curves
- Short Name:
- J/A+A/584/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The presence of heavier chemical elements in stellar atmospheres influences the spectral energy distribution of stars. An uneven surface distribution of these elements, together with flux redistribution and stellar rotation, are commonly believed to be the primary causes of the variability of chemically peculiar (CP) stars. We aim to model the photometric variability of the CP star phi Dra based on the assumption of inhomogeneous surface distribution of heavier elements and compare it to the observed variability of the star. We also intend to identify the processes that contribute most significantly to its photometric variability. We use a grid of TLUSTY model atmospheres and the SYNSPEC code to model the radiative flux emerging from the individual surface elements of phi Dra with different chemical compositions. We integrate the emerging flux over the visible surface of the star at different phases throughout the entire rotational period to synthesise theoretical light curves of the star in several spectral bands.
- ID:
- ivo://CDS.VizieR/J/AJ/143/129
- Title:
- Photometric and Spectroscopic observations of BF Dra
- Short Name:
- J/AJ/143/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BF Dra is now known to be an eccentric double-lined F6+F6 binary star with relatively deep (0.7mag) partial eclipses. Previous studies of the system are improved with 7494 differential photometric observations from the URSA WebScope and 9700 from the NFO WebScope, 106 high-resolution spectroscopic observations from the Tennessee State University 2m automatic spectroscopic telescope and the 1m coude-feed spectrometer at Kitt Peak National Observatory, and 31 accurate radial velocities from the CfA. Very accurate (better than 0.6%) masses and radii are determined from analysis of the two new light curves and four radial velocity curves. Theoretical models match the absolute properties of the stars at an age of about 2.72Gyr and [Fe/H]=-0.17, and tidal theory correctly confirms that the orbit should still be eccentric. Our observations of BF Dra constrain the convective core overshooting parameter to be larger than about 0.13H_p_. We find, however, that standard tidal theory is unable to match the observed slow rotation rates of the components' surface layers.
- ID:
- ivo://CDS.VizieR/J/A+AS/122/409
- Title:
- Photometric catalogue of Coma
- Short Name:
- J/A+AS/122/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a CCD catalogue of 7023 galaxies and 4096 stars in the region of the Coma cluster containing positions, central surface brightnesses and V magnitudes (isophote 26.5). We estimate that data is complete up to isophotal V magnitude 22.5 and the surface brightness limiting detection value is approximately 24 mag/arcsec2.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/345.133
- Title:
- Photometric variability of WR 103
- Short Name:
- J/other/ApSS/345
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss a collection of archival multi-colour photometric data of the variable WC9-type Wolf-Rayet star WR103=HD164270 observed over a time interval of eleven years. The photometric systems used are Walraven VBLUW, Bessel UBV and Stromgren uvby. The purpose is to search for periodicity and to disentangle continuum and line emission variations.
- ID:
- ivo://CDS.VizieR/J/PASP/106/281
- Title:
- Photometry and radial velocities in NGC752
- Short Name:
- J/PASP/106/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using all available proper-motion and radial-velocity data, including new radial-velocity observations obtained for this investigation, probable members of the open cluster NGC 752 have been identified. Photoelectric data on six systems have been transformed and collated to form an internally consistent sample on the BV system. Binaries have been identified using photometric and radial-velocity data, including a photographic survey for variability and the radial-velocity observations of this study. Analysis of the data leads to the following cluster parameters and their probable errors: E(B-V) = 0.035+/-0.005mag, Fe/H = -0.15+/-0.05dex, and (m-M) = 8.25+/-0.10mag. The spread in color among stars in the color-magnitude diagram (CMD) along the main sequence from the turnoff to the unevolved main sequence is the consequence of a rich population of binaries. Due to its age and the comprehensive data available for the cluster, NGC 752 provides an ideal test of a variety of evolutionary phenomena. Comparison with theoretical isochrones normalized in an internally consistent manner leads to the conclusion that the morphology and distribution of stars in the CMD can best be matched using models that include convective overshoot, particularly those of Schaller et al. (1992A&AS...96..269S). Despite their differences, the traditional and the overshoot isochrones both imply very similar ages, 1.9+/-0.2Gyr and 1.7+/-0.1Gyr, respectively, for the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/154/226
- Title:
- Photometry and radial velocities of K2-131
- Short Name:
- J/AJ/154/226
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a new ultra-short-period planet and summarize the properties of all such planets for which the mass and radius have been measured. The new planet, K2-131b, was discovered in K2 Campaign 10. It has a radius of 1.81_-0.12_^+0.16^ R_{Earth}_ and orbits a G dwarf with a period of 8.9 hr. Radial velocities obtained with Magellan/PFS and TNG/HARPS-N show evidence for stellar activity along with orbital motion. We determined the planetary mass using two different methods: (1) the "floating chunk offset" method, based only on changes in velocity observed on the same night; and (2) a Gaussian process regression based on both the radial velocity and photometric time series. The results are consistent and lead to a mass measurement of 6.5+/-1.6 M_{Earth}_ and a mean density of 6.0_-2.7_^+3.0^ g/cm^3^.
