- ID:
- ivo://CDS.VizieR/J/MNRAS/372/69
- Title:
- VR light curves of M2 variables
- Short Name:
- J/MNRAS/372/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of CCD V and R photometry of the RR Lyrae stars in M2. The periodicities of most variables are revised and new ephemerides are calculated. Light-curve decomposition of the RR Lyrae stars was carried out and the corresponding mean physical parameters [Fe/H]=-1.47, Teff=6276K, logL=1.63L_{sun}_ and M_V_=0.71 from nine RRab and [Fe/H]=-1.61, M=0.54M_{sun}_, Teff=7215K, logL=1.74L_{sun}_ and M_V_=0.71 from two RRc stars were calculated. A comparison of the radii obtained from the above luminosity and temperature with predicted radii from non-linear convective models is discussed. The estimated mean distance to the cluster is 10.49+/-0.15kpc. These results place M2 correctly in the general globular cluster sequences for Oosterhoff type, mass, luminosity and temperature, all as a function of the metallicity. Mean relationships for M, logL/L_{sun}_, Teff and MV as a function of [Fe/H] for a family of globular clusters are offered. These trends are consistent with evolutionary and structural notions on the horizontal branch. Eight new variables are reported.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/40.209
- Title:
- VR light curves of 15 RR Lyrae in NGC 4147
- Short Name:
- J/other/RMxAA/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of CCD V and R photometry of the RR Lyrae stars known in NGC 4147. The periodicities of most variables are revised and new ephemerides are calculated. The Blazhko effect has been detected in V2 and V6. Three previously reported variables; V5, V9, and V15 are found to be non-variable. A new variable V18 was discovered with a period of 0.49205-days and an amplitude of 0.15mag. Using the approach of Fourier decomposition of the light curves, the physical parameters of the RRab and RRc variables were estimated. The cluster is of the Oosterhoff type I. With the newly values [Fe/H]=-1.22+/-0.31 and 16.8+/-1.3kpc, the cluster fits very well into the Oosterhoff type-metallicity and metallicity-temperature sequence found in globular clusters. A comparison with ZAHB models indicates that the RRab stars have not yet evolved off the horizontal branch, a result consistent with the mean period of the RRab variables and with the metallicity of the cluster derived in this work.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1748
- Title:
- VR photometry of type II Cepheids
- Short Name:
- J/AJ/128/1748
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 1256 new photometric observations of 36 Cepheids with periods longer than 8 days. The majority are likely type II Cepheids, but we have included about a dozen classical Cepheids for comparison purposes, a few stars of uncertain type, and one putative RV Tauri star. We discuss the appearance of the light curves, the Fourier parameters, and the light-curve stability in terms of differentiation between type I and type II Cepheids. Although we encounter the same difficulties as previous investigators in using these parameters for this purpose, we are able to identify some stars of particular interest, including several likely type I Cepheids at large distances from the Galactic plane. Six stars with especially large period changes are identified and discussed.
- ID:
- ivo://CDS.VizieR/J/AJ/130/832
- Title:
- VR photometry of type II Cepheids. III
- Short Name:
- J/AJ/130/832
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 741 new photometric observations for 22 Cepheids with periods between 3 and 8 days. Many of the stars are probable type II Cepheids, but we have included some type I Cepheids for comparison.
- ID:
- ivo://CDS.VizieR/J/AJ/149/99
- Title:
- VVV globulars. I. 2MASS-GC 02, Terzan 10
- Short Name:
- J/AJ/149/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VISTA Variables in the Via Lactea (VVV) ESO Public Survey is opening a new window to study inner Galactic globular clusters (GCs) using their variable stars. These GCs have been neglected in the past due to the difficulties caused by the presence of elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RR Lyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the questions raised by the intriguing Oosterhoff dichotomy in the Galactic GC system. In a series of papers we plan to explore variable stars in the GCs falling inside the field of the VVV survey. In this first paper, we search for and study the variables present in two highly reddened, moderately metal-poor, faint, inner Galactic GCs: 2MASS-GC 02 and Terzan 10. We report the discovery of sizable populations of RR Lyrae stars in both GCs. We use near-infrared period-luminosity relations to determine the color excess of each RR Lyrae star, from which we obtain both accurate distances to the GCs and the ratios of the selective-to-total extinction in their directions. We find the extinction toward both clusters to be elevated, non-standard, and highly differential. We also find both clusters to be closer to the Galactic center than previously thought, with Terzan 10 being on the far side of the Galactic bulge. Finally, we discuss their Oosterhoff properties, and conclude that both clusters stand out from the dichotomy followed by most Galactic GCs.
- ID:
- ivo://CDS.VizieR/J/A+A/605/A100
- Title:
- VVV survey Galactic Bulge Pop. II Cepheids
- Short Name:
- J/A+A/605/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the near-infrared observations of population II Cepheids in the Galactic bulge from VVV survey. We identify 340 population II Cepheids in the Galactic bulge from VVV survey based on their match with OGLE-III Catalogue. The single-epoch JH and multi-epoch Ks observations complement the accurate periods and optical (VI) mean-magnitudes from OGLE. The sample consisting of BL Herculis and W Virginis subtypes is used to derive period-luminosity relations after correcting mean-magnitudes for the extinction. The absolute magnitudes for population II Cepheids and RR Lyraes calibrated using Gaia and Hubble Space Telescope parallaxes, together with calibrated magnitudes for Large Magellanic Cloud population II Cepheids, are used to obtain a distance to the Galactic center. The number density for population II Cepheids is more limited as compared to abundant RR Lyraes but they are bright and exhibit a wide range in period that provides a robust period-luminosity relation for an accurate estimate of the distance to the Galactic center.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A169
- Title:
- VVV survey near-infrared colour catalogue
- Short Name:
- J/A+A/647/A169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Vista Variables in the Via Lactea (VVV) near-infrared (IR) variability survey explores some of the most complicated regions of the Milky Way bulge and disk in terms of high extinction and high crowding. We add a new wavelength dimension to the optical information available at the American Association of Variable Star Observers International Variable Star Index (VSX-AAVSO) catalogue to test the VVV survey near-IR photometry to better characterise these objects. We cross-match the VVV and the VSX-AAVSO catalogues along with Gaia Data Release 2 photometry and parallax. We present a catalogue that includes accurate individual coordinates, near-IR magnitudes (ZYJHKs), extinctions AKs, and distances based on Gaia parallaxes. We also show the near-IR CMDs and spatial distributions for the different VSX types of variable stars, including important distance indicators, such as RR Lyrae, Cepheids and Miras. By analysing the photometric flags in our catalogue, we found that around 20% of the stars with measured and verified variability are flagged as "non-stellar source", even when they are outside of the saturation and/or noise regimes. Additionally, we pair-matched our sample with the VIVA catalogue and found that more than half of our sources are missing from the VVV variability list, mostly due to low signal-to-noise observations or photometric problems with a small percentage due to failures in the selection process. Conclusions. Our results suggest that the current knowledge about variability in the Galaxy is biased to the nearby, low extincted stars. The present catalogue also provides the groundwork to characterise the results of future large variability surveys like the Vera C. Rubin Observatory's Legacy Survey of Space and Time in the heavily crowded and reddened regions of the Galactic plane, as wellas follow-up campaigns to characterise specific types of variables. The analysis of the miss-flagged stars can be used to improve the photometric classification of the VVV data allowing to expand the amount of data considered useful for science purposes. Besides, we provide an additional list of stars missed by the VIVA procedures for which the observations are actually good and they were missed due to some failure in the VIVA selection process.
- ID:
- ivo://CDS.VizieR/J/A+A/591/A145
- Title:
- VVV Survey outer bulge RRab stars
- Short Name:
- J/A+A/591/A145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VISTA Variables in the Via Lactea (VVV) is a near-IR time-domain survey of the Galactic bulge and southern plane. One of the main goals of this survey is to reveal the 3D structure of the Milky Way through their variable stars. In particular, enormous numbers of RR Lyrae stars have been discovered in the inner regions of the bulge (-8{deg}<~b<~-1{deg}) by optical surveys such as OGLE and MACHO, but leaving an unexplored window of more than ~47 sq deg (-10.0{deg}<~l<~+10.7{deg} and -10.3{deg}<~b<~-8.0{deg}) observed by the VVV Survey. Our goal is to characterize the RR Lyrae stars in the outer bulge in terms of their periods, amplitudes, Fourier coefficients, and distances in order to evaluate the 3D structure of the bulge in this area. The distance distribution of RR Lyrae stars will be compared to that of red clump stars, which is known to trace a X-shaped structure, in order to determine whether these two different stellar populations share the same Galactic distribution. A search for RR Lyrae stars was performed in more than ~47 sq deg at low Galactic latitudes (-10.3{deg}<~b<~-8.0{deg}). In the procedure the {chi}^2^ value and analysis of variance (AoV) statistic methods were used to determine the variability and periodic features of the light curves, respectively. To prevent misclassifications, the analysis was performed only on the fundamental mode RR Lyrae stars (RRab) owing to similarities found in the near-IR light curve shapes of contact eclipsing binaries (W UMa) and first overtone RR Lyrae stars (RRc). On the other hand, the red clump stars of the same analyzed tiles were selected, and cuts in the color-magnitude diagram were applied and the maximum distance restricted to ~20kpc in order to construct a similar catalog in terms of distances and covered area compared to the RR Lyrae stars. We report the detection of more than 1000 RR Lyrae ab-type stars in the VVV Survey located in the outskirts of the Galactic bulge. A few of them are possibly associated with the Sagittarius Dwarf Spheroidal Galaxy. We calculated colours, reddening, extinction, and distances of the detected RR Lyrae stars in order to determine the outer bulge 3D structure. Our main result is that, at the low galactic latitudes mapped here, the RR Lyrae stars trace a centrally concentrated spheroidal distribution. This is a noticeably different spatial distribution to the one traced by red clump stars known to follow a bar and X-shaped structure. We estimate the completeness of our sample at 80% for K_s_<=15mag.
- ID:
- ivo://CDS.VizieR/J/AJ/153/179
- Title:
- VVV Survey RR Lyr stars in Southern Galactic plane
- Short Name:
- J/AJ/153/179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep near-IR images from the VISTA Variables in the Via Lactea (VVV) Survey were used to search for RR Lyrae stars in the Southern Galactic plane. A sizable sample of 404 RR Lyrae of type ab stars was identified across a thin slice of the fourth Galactic quadrant (295{deg}<l<350{deg}, -2.24{deg}<b<-1.05{deg}). The sample's distance distribution exhibits a maximum density that occurs at the bulge tangent point, which implies that this primarily Oosterhoff type I population of RRab stars does not trace the bar delineated by their red clump counterparts. The bulge RR Lyrae population does not extend beyond l~340{deg}, and the sample's spatial distribution presents evidence of density enhancements and substructure that warrants further investigation. Indeed, the sample may be employed to evaluate Galactic evolution models, and is particularly lucrative since half of the discovered RR Lyrae are within reach of Gaia astrometric observations.
- ID:
- ivo://CDS.VizieR/J/A+A/445/423
- Title:
- WeCAPP Survey. M31 variables
- Short Name:
- J/A+A/445/423
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observations in the WeCAPP microlensing survey towards the Andromeda galaxy (M31) for a period of three years (2000-2003) resulted in a database with unprecedented time coverage for an extragalactic variable star study. We have monitored a 16.1' x 16.6' field centered on the nucleus of M31 in two optical bands (R and I) using the 0.8-m telescope at Wendelstein, Germany and the 1.2-m telescope at Calar Alto, Spain. Using the difference imaging method we detected 23781 variable sources for which we calculated the periods and variation amplitudes. We classified the variables according to their position in the R-band period-amplitude plane. Three groups can be distinguished; while the first two groups can be mainly associated with Cepheid-like variables (population I Cepheids in group I; type II Cepheids and RV Tauri stars in group II), the third one consists of Long Period Variables (LPVs). We detected 37 RV Tauri stars and 11 RV Tauri candidates, which makes this catalogue one of the largest collections of this class of stars to date. The classification scheme is supported by Fourier decomposition of the light curves. The catalogue of variable stars contains the positions, the periods in R and I, the significance of the assigned periods, and the variation amplitudes in the R and I bands.
