- ID:
- ivo://CDS.VizieR/J/A+A/464/373
- Title:
- VRIZJHK photometry around Alpha Cen
- Short Name:
- J/A+A/464/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Thanks to its proximity, alpha Centauri is an outstanding target for an imaging search for extrasolar planets. We searched for faint comoving companions to alpha Cen located at angular distances of a few tens of arcseconds, up to 2-3 arcmin. We obtained CCD images from the NTT-SUSI2 instrument in the Bessel V, R, I, and Z bands, and archive data from 2MASS.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/489/571
- Title:
- VRizK photometry of RDCSJ0910+54 cluster
- Short Name:
- J/A+A/489/571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the environmental dependence of properties of galaxies around the RDCSJ0910+54 cluster at z=1.1. We obtained multi-band wide-field images of the cluster with Suprime-Cam and MOIRCS on Subaru and WFCAM on UKIRT. Also, an intensive spectroscopic campaign was carried out using LRIS on Keck and FOCAS on Subaru. We collected 161 spectra with secure redshifts, with which we calibrated a larger sample of photometric redshifts.
- ID:
- ivo://CDS.VizieR/J/MNRAS/365/1392
- Title:
- VRi'z' phot. & redshifts around RX J0152.7-1352
- Short Name:
- J/MNRAS/365/1392
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a discovery of definitive large-scale structures around RX J0152.7-1352 at z=0.83 based on spectroscopic redshifts. In our previous papers, we reported a photometric identification of the large-scale structures at z~0.8. A spectroscopic follow-up observation was carried out on eight selected regions covering the most prominent structures to confirm their association to the main cluster. In six out of the eight fields, a well-isolated peak is identified in the distribution of spectroscopic redshifts at or near the cluster redshift. This is strong evidence for the presence of large-scale structures associated to the main cluster at z=0.83.
- ID:
- ivo://CDS.VizieR/J/AJ/137/4598
- Title:
- VR light curve of ASAS-North Cepheids
- Short Name:
- J/AJ/137/4598
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained VR photometry of 282 Cepheid variable star candidates from the northern part of the All Sky Automated Survey (ASAS). These together with data from the ASAS and the Northern Sky Variability Survey (NSVS) were used to redetermine the periods of the stars.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A77
- Title:
- VR light curves of AA Tau in 2007-2013
- Short Name:
- J/A+A/557/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AA Tau has been monitored for more than 20 years since 1987, exhibiting a nearly constant brightness level of V=12.5mag. We report here that in 2011 it suddenly faded away, becoming 2 magnitudes fainter in the V-band, and has remained in this deep state since then. We investigate the origin of the sudden dimming of the AA Tau system. We report new optical and near-IR photometry and spectroscopy obtained during the fading event.
21176. VR light curves of CK Boo
- ID:
- ivo://CDS.VizieR/J/AJ/143/122
- Title:
- VR light curves of CK Boo
- Short Name:
- J/AJ/143/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present precision CCD photometry, a period study, and a two-color simultaneous Wilson code solution of the short-period contact binary CK Bootis. The asymmetric light curves were modeled by a dark spot on the primary component. The result identifies that CK Boo is an A-type W UMa binary with a high fillout of f=71.7(+/-4.4)%. From the O-C curve, it is found that the orbital period changes in a complicated mode, i.e., a long-term increase with two sinusoidal variations. One cyclic oscillation with a period of 10.67(+/-0.20)yr may result from magnetic activity cycles, which are identified by the variability of Max. I-Max. II. Another sinusoidal variation (i.e., A=0.0131days(+/-0.0009days) and P3=24.16(+/-0.64)yr) may be attributed to the light-time effect due to a third body. This kind of additional companion can extract angular momentum from the central binary system. The orbital period secularly increases at a rate of dP/dt=+9.79(+/-0.80)*10^-8days/yr, which may be interpreted by conservative mass transfer from the secondary to the primary. This kind of deep, low-mass ratio overcontact binaries may evolve into a rapid-rotating single star, only if the contact configuration do not break down at J_spin_>(1/3)J_orb_.
21177. VR light curves of EI CVn
- ID:
- ivo://CDS.VizieR/J/other/RAA/11.181
- Title:
- VR light curves of EI CVn
- Short Name:
- J/other/RAA/11.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present charge-coupled device (CCD) photometry for the short-period K-type binary EI CVn, observed on 2009 February 28 at the Xinglong Station of National Astronomical Observatories, Chinese Academy of Sciences. By using the Wilson-Devinney program, the photometric solution was first deduced from our VR observations.
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/1444
- Title:
- Vr light curves of NGC 5466 RR Lyrae
- Short Name:
- J/MNRAS/384/1444
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of CCD V and r photometry of the globular cluster NGC 5466. The difference image analysis technique adopted in this work has resulted in accurate time series photometry even in crowded regions of the cluster enabling us to discover five probably semi-regular variables. We present new photometry of three previously known eclipsing binaries and six SX Phe stars. The light curves of the RR Lyrae stars have been decomposed in their Fourier harmonics and their fundamental physical parameters have been estimated using semi-empirical calibrations. The zero points of the metallicity, luminosity and temperature scales are discussed and our Fourier results are transformed accordingly. The average iron abundance and distance to the Sun derived from individual RR Lyrae stars, indicate values of [Fe/H]=-1.91+/-0.19 and D=16.0+/-0.6kpc, or a true distance modulus of 16.02+/-0.09mag, for the parent cluster. These values are respectively in the Zinn & West metallicity scale and in agreement with recent luminosity determinations for the RR Lyrae stars in the LMC. The M_V_-[Fe/H] relation has been recalibrated as M_V_=+(0.18+/-0.03)[Fe/H]+(0.85+/-0.05) using the mean values derived by the Fourier technique on RR Lyrae s tars in a family of clusters. This equation predicts M_V_=0.58mag for [Fe/H]=-1.5, in agreement with the average absolute magnitude of RR Lyrae stars calculated from several independent methods. The M_V-[Fe/H] relationship and the value of [Fe/H] have implications on the age of the globular clusters when determined from the magnitude difference between the horizontal branch and the turn off point (HB-TO method). The above results however would not imply a change in the age of NGC 5466, of 12.5+/-0.9Gyr, estimated from recent isochrone fitting.
- 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.
