- ID:
- ivo://CDS.VizieR/J/AJ/152/104
- Title:
- New photometrically variable magnetic CP stars
- Short Name:
- J/AJ/152/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The magnetic Ap or CP2 stars are natural atomic and magnetic laboratories. Strictly periodic changes are observed in the spectra and brightness of these stars, which allow the derivation of rotational periods. Related to this group of objects are the He-weak (CP4) and He-rich stars, some of which also undergo brightness changes due to rotational modulation. Increasing the sample size of known rotational periods among CP2/4 stars is important and will contribute to our understanding of these objects and their evolution in time. We have compiled an extensive target list of CP2/4 stars from the General Catalog of Ap, HgMn, and Am stars, including several early-type (spectral types B/A) variables of undetermined type from the International Variable Star Index. We investigated our sample stars using publicly available observations from the ASAS-3 archive. Our previous efforts in this respect led to the discovery of 323 variable stars. Using a refined analysis approach, we were able to identify another 360 stars exhibiting photometric variability in ASAS-3 data. Summary data, folded light curves and, if available, information from the literature are presented for our final sample, which is composed of 334 bona-fide {alpha}^2^ Canum Venaticorum (ACV) variables, 23 ACV candidates, and 3 eclipsing binary systems. Interesting and unusual objects are discussed in detail. In particular, we call attention to HD66051 (V414 Pup), which is an eclipsing binary system showing obvious rotational modulation of the light curve due to the presence of an ACV variable in the system.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/578/A3
- Title:
- New survey of supergiants in the MCs
- Short Name:
- J/A+A/578/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this study, we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership to the clouds. Around two hundred new RSGs have been detected, hinting at a yet to be observed large population. Using near and mid infrared photometry we study the brightness distribution of these stars, the onset of mass-loss and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid and near infrared photometry to improve the observational efficiency of similar programs as this.
- ID:
- ivo://CDS.VizieR/J/other/JAD/16.2
- Title:
- New times of maximum of CY Aqr
- Short Name:
- J/other/JAD/16.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a collection of 102 new times of maximum of the SX Phoenicis star CY Aquarii. These times, together with 20 times of maximum taken from the literature, lead to a new local linear ephemeris for 2003-2009 with a formally slightly shorter period than the one for 1996-2002. It will require at least another half decade of additional monitoring before any significant update to any model can be considered. Such monitoring should preferably occur at regular intervals, be done in a consistent photometric band, and at high time resolution. A set of 114 new times of maximum obtained since 2002 leads to a new local linear ephemeris for 2003-2009: Tmax=2426159.512(+/-0.001)+0.061038349E(+/-0.000000002).
- ID:
- ivo://CDS.VizieR/J/A+AS/133/1
- Title:
- New variable chemically peculiar stars
- Short Name:
- J/A+AS/133/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since variability of chemically peculiar (CP) stars plays an important role for the astrophysical explanation of their outstanding behaviour, we have identified new variable CP stars listed in Renson's catalogue using the extensive Hipparcos Variability Annex. From the 293 objects found, 33 were excluded because they are not CP stars and/or have no period listed, half of the remaining stars are newly identified and half had been already included in the catalogue of variable CP stars by Catalano & Renson (1997, Cat. <J/A+AS/121/57>). Most of the newly identified variability is due to an apparent magnetic field coupled with stellar rotation (oblique rotator model). The constraints of this model are fulfilled for all but three CP2 stars. Variations of bona fide Am-Fm stars are exclusively explained by eclipses of binary systems. Furthermore eight candidates of the gamma Doradus group (pulsating Am-Fm stars) were detected. Table 1 (table1.dat) presents the newly identified chemically peculiar stars.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A116
- Title:
- New variables and 2 delta Scuti pulsations
- Short Name:
- J/A+A/619/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dome C in Antarctica is a promising site for photometric observations thanks to the continuous night during the Antarctic winter and favorable weather conditions. We developed instruments to assess the quality of this site for photometry in the visible and to detect and characterize variable objects through the Antarctic Search for Transiting ExoPlanets (ASTEP) project. Here, we present the full analysis of four winters of data collected with ASTEP South, a 10cm refractor pointing continuously toward the celestial south pole. We achieved nearly continuous observations over the winters. We improved the instrument over the years and developed specific data reduction methods. We measure an average sky background of 20mag/arcsec^2^ in the 579-642nm bandpass. We built the lightcurves of 6000 stars and developed a model to infer the photometric quality of Dome C from the lightcurves themselves. The weather is photometric 67.1+/-4.2% of the time and veiled 21.8+/-2.0% of the time. The remaining time corresponds to poor quality data or winter storms.We analyzed the lightcurves of Oct and HD 184465 and find that the amplitude of their main frequency varies by a factor of 3.5 and 6.7 over the four years, respectively. We also identify 34 new variable stars and eight new eclipsing binaries with periods ranging from 0.17 to 81 days. The phase coverage that we achieved with ASTEP South is exceptional for a ground-based instrument and the data quality enables the detection and study of variable objects. These results demonstrate the high quality of Dome C for photometry in the visible and for time series observations in general.
- ID:
- ivo://CDS.VizieR/J/other/PZ/27.2
- Title:
- 86 new variables in Andromed
- Short Name:
- J/other/PZ/27.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the most extensive sky surveys in the recent years is the Northern Sky Variability Survey (NSVS, Wozniak et al., 2004AJ....127.2436W). Light curves of about 14000000 objects with instrumental magnitudes between 8 and 15.5 are included in the database of that survey, for the period April 1999 - March 2000, covering all of the Northern hemisphere and reaching DE=-38{deg} in the South. To look for different types of variables, we rely only upon internal NSVS data. We select an area on the sky and check for variability in the NSVS database. Our test area covers 46 deg in Andromeda, its coordinates are: 23:00<=RA<=23:45 and 43:30<=DE<=29:30 (2000.0). The galactic latitude is in the -10{deg} - -20{deg} range. The total number of NSVS light curves in this area is and every star has between 1 and 4 light curves, the mean value being 1.875 light curves per star.
- ID:
- ivo://CDS.VizieR/J/other/NewA/49.50
- Title:
- New Variables in 3 Galactic open clusters
- Short Name:
- J/other/NewA/49.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This project is a massive near-infrared (NIR) search for variable stars in highly reddened and obscured open cluster (OC) fields projected on regions of the Galactic bulge and disk. The search is performed using photometric NIR data in the J-, H- and Ks - bands obtained from the Vista Variables in the Via Lactea (VVV) Survey. We performed in each cluster field a variability search using Stetson's variability statistics to select the variable candidates. Later, those candidates were subjected to a frequency analysis using the Generalized Lomb-Scargle and the Phase Dispersion Minimization algorithms. The number of independent observations range between 63 and 73. The newly discovered variables in this study, 157 in total in three different known OCs, are classified based on their light curve shapes, periods, amplitudes and their location in the corresponding color-magnitude (J-Ks,Ks)(J-Ks,Ks) and color-color (H-Ks,J-H)(H-Ks,J-H) diagrams. We found 5 possible Cepheid stars which, based on the period-luminosity relation, are very likely type II Cepheids located behind the bulge. Among the newly discovered variables, there are eclipsing binaries, {delta} Scuti, as well as background RR Lyrae stars. Using the new version of the Wilson & Devinney code as well as the "Physics Of Eclipsing Binaries" (PHOEBE) code, we analyzed some of the best eclipsing binaries we discovered. Our results show that these studied systems turn out to be ranging from detached to double-contact binaries, with low eccentricities and high inclinations of approximately 80{deg}. Their surface temperatures range between 3500K and 8000K.
- ID:
- ivo://CDS.VizieR/J/A+A/373/899
- Title:
- New variables in M22 globular cluster
- Short Name:
- J/A+A/373/899
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1 contains equatorial coordinates for 36 newly identified variables from the central field of the globular cluster M22. File table2 contains basic photometric data for SX Phe stars reported in the paper. File table3 contains magnitudes and colors for selected sample of new variables. Files table4-39 contain V-band time-series photometry for 36 newly identified variables from the central field of the globular cluster M22. Individual finding charts for new variables are in fig directory; each chart is 33arcsec on a side with north up and east to the left.
- ID:
- ivo://CDS.VizieR/J/other/IBVS/6137
- Title:
- New variables in M5 (NGC 5904)
- Short Name:
- J/other/IBVS/613
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report twelve variables not previously detected in the globular cluster M5 (NGC 5904); one SX Phe and eleven semi-regular variables (SR). Their identifications, equatorial coordinates, ephemerides, and light curves are given. Furthermore, we have explored the light curves of a group of stars whose variability has not been confirmed and that are marked as probable non-variables in the CVSGC. Finally, we offer detailed identifications for some of the known variables in crowded regions that were misidentified in previous studies. We shall also address the cases of the cataclysmic variable or U Gem type V101 and of the variable blue straggler V159.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/337
- Title:
- New variables in NGC 288
- Short Name:
- J/A+AS/125/337
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report discovery of 3 new faint variables in the globular cluster NGC 288: 2 SX Phe stars and 1 contact binary. Both SX Phe variables are blue stragglers. The contact binary is located below cluster turnoff, slightly to the red of the main sequence. New photometry of 6 previously known variables is also presented. We note that 26 out of a total 43 SX Phe stars identified recently in {omega} Cen and NGC 288 exhibit V-band light curves with full amplitudes smaller than 0.10mag. The sample of known SX Phe stars is likely to be significantly incomplete in regard to the low amplitude variables.
