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7811. Vi' LCs and RVs of the EB star TYC 5227-1023-1
ID:
ivo://CDS.VizieR/J/ApJ/839/52
Title:
Vi' LCs and RVs of the EB star TYC 5227-1023-1
Short Name:
J/ApJ/839/52
Date:
21 Oct 2021
Publisher:
CDS
Description:
The orbit and physical parameters of the previously unsolved double-lined eclipsing binary Tyc 5227-1023-1, discovered during the search for RR Lyr variable candidate members of the Aquarius stream, are derived using high-resolution echelle spectroscopy and V,i' photometry. A synthetic spectral analysis of both components has been performed, yielding metallicity [M/H]=-0.63+/-0.11 for both stars and a temperature for the secondary that is in close agreement with the one from the orbital solution, while the temperature of the primary is determined from photometry (T_1_=6350K). The masses and radii (M_1_=0.96+/-0.02, M_2_=0.84+/-0.01M_{sun}_, R_1_=1.39+/-0.01, R_2_=0.98+/-0.01R_{sun}_) reveal that both stars have already slightly evolved away from the main-sequence band, having an age of about 7Gyr, and the results of the synthetic spectral analysis support the claim of corotation with the orbital motion. The radial velocity of the system is -60+/-2km/s, while its distance, computed from orbital parameters and the derived reddening E_B-V_=0.053, is 496+/-35pc. Even though Tyc 5227-1023-1 was initially treated as a possible member of the Aquarius stream, the results presented here disagree with reported values for this ancient structure and suggest a likely membership of the thick disk.
7812. VI light curves and spectra of V479 And
ID:
ivo://CDS.VizieR/J/A+A/553/A28
Title:
VI light curves and spectra of V479 And
Short Name:
J/A+A/553/A28
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted a multi-wavelength study to unveil the properties of the extremely long-period cataclysmic variable V479 And. We performed series of observations, including moderate to high spectral resolution optical spectrophotometry, X-ray observations with Swift, linear polarimetry and near-IR photometry. This binary system is a low-inclination ~17{deg} system with a 0.594093(4) day orbital period. The absorption line complex in the spectra indicate a G8-K0 spectral type for the donor star, which has departed from the zero-age main sequence. This implies a distance to the object of about 4kpc. The primary is probably a massive 1.1-1.4M_{sun}_ magnetic white dwarf, accreting matter at a rate dM/dt>10^-10^M_{sun}_/yr. This rate can be achieved if the donor star fills its corresponding Roche lobe, but there is little observational evidence for a mass-transfer stream in this system. An alternative explanation is a stellar wind from the donor star, although such a high rate mass loss is not anticipated from a subgiant. If the strongly magnetic white dwarf in V479 And is confirmed by future observations, the system the polar with the longest observed orbital period. We also discuss the evolutionary state of V479 And.
7813. VI light curves of NGC 247 Cepheids
ID:
ivo://CDS.VizieR/J/AJ/136/1770
Title:
VI light curves of NGC 247 Cepheids
Short Name:
J/AJ/136/1770
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the discovery of a Cepheid population in the Sculptor Group spiral galaxy NGC 247 for the first time. On the basis of wide-field images collected in photometric surveys in V and I bands that were conducted with three different telescopes and cameras, 23 Cepheid variables were discovered with periods ranging from 17 to 131 days.
7814. VI light curves of NGC 1039 solar-type stars
ID:
ivo://CDS.VizieR/J/A+A/515/A100
Title:
VI light curves of NGC 1039 solar-type stars
Short Name:
J/A+A/515/A100
Date:
21 Oct 2021
Publisher:
CDS
Description:
Employing photometric rotation periods for solar-type stars in NGC 1039 [M 34], a young, nearby open cluster, we use its mass-dependent rotation period distribution to derive the cluster's age in a distance independent way, i.e., the so-called gyrochronology method. We present an analysis of 55 new rotation periods, using light curves derived from differential photometry, for solar type stars in the open cluster NGC 1039 [M 34]. We also exploit the results of a recently-completed, standardized, homogeneous BVIc CCD survey of the cluster, performed by the Indiana Group of the WIYN open cluster survey, in order to establish photometric cluster membership and assign B-V colours to each photometric variable. We describe a methodology for establishing the gyrochronology age for an ensemble of solar-type stars. Empirical relations between rotation period, photometric colour and stellar age (gyrochronology) are used to determine the age of M 34.
7815. Vi light curves of NGC6333 variables
ID:
ivo://CDS.VizieR/J/MNRAS/434/1220
Title:
Vi light curves of NGC6333 variables
Short Name:
J/MNRAS/434/1220
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report CCD V and I time series photometry of the globular cluster NGC 6333 (M9). The technique of difference image analysis has been used, which enables photometric precision better than 0.05mag for stars brighter than V~19.0mag, even in the crowded central regions of the cluster. The high photometric precision has resulted in the discovery of two new RRc stars, three eclipsing binaries, seven long-term variables and one field RRab star behind the cluster. A detailed identification chart and equatorial coordinates are given for all the variable stars in the field of our images of the cluster. Our data together with the literature V-data obtained in 1994 and 1995 allowed us to refine considerably the periods for all RR Lyrae stars. The nature of the new variables is discussed. We argue that variable V12 is a cluster member and an Anomalous Cepheid. Secular period variations, double-mode pulsations and/or the Blazhko-like modulations in some RRc variables are addressed. Through the light-curve Fourier decomposition of 12 RR Lyrae stars we have calculated a mean metallicity of [Fe/H]_ZW_=-1.70+/-0.01(statistical)+/-0.14(systematic) or [Fe/H]_UVES_=-1.67+/-0.01(statistical)+/-0.19(systematic). Absolute magnitudes, radii and masses are also estimated for the RR Lyrae stars. A detailed search for SX Phe stars in the Blue Straggler region was conducted but none were discovered. If SX Phe exist in the cluster then their amplitudes must be smaller than the detection limit of our photometry. The colour-magnitude diagram has been corrected for heavy differential reddening using the detailed extinction map of the cluster of Alonso-Garcia et al. (2012, Cat. J/AJ/143/70). This has allowed us to set the mean cluster distance from two independent estimates; from the RRab and RRc absolute magnitudes, we find 8.04+/-0.19 and 7.88+/-0.30kpc, respectively.
7816. VI light curves of NGC4590 variables
ID:
ivo://CDS.VizieR/J/A+A/578/A128
Title:
VI light curves of NGC4590 variables
Short Name:
J/A+A/578/A128
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyse 20 nights of CCD observations in the V and I bands of the globular cluster M68 (NGC 4590), using these to detect variable objects. We also obtained electron-multiplying CCD (EMCCD) observations for this cluster in order to explore its core with unprecedented spatial resolution from the ground. We reduced our data using difference image analysis, in order to achieve the best possible photometry in the crowded field of the cluster. In doing so, we showed that when dealing with identical networked telescopes, a reference image from any telescope may be used to reduce data from any other telescope, which facilitates the analysis significantly. We then used our light curves to estimate the properties of the RR Lyrae (RRL) stars in M68 through Fourier decomposition and empirical relations. The variable star properties then allowed us to derive the cluster's metallicity and distance. M68 had 45 previously confirmed variables, including 42 RRL and 2 SX Phoenicis (SX Phe) stars. In this paper we determine new periods, and search for new variables, especially in the core of the cluster where our method performs particularly well. We detect an additional 4 SX Phe stars, and confirm the variability of another star, bringing the total number of confirmed variable stars in this cluster to 50. We also used archival data stretching back to 1951 in order to derive period changes for some of the single-mode RRL stars, and analyse the significant number of double-mode RRL stars in M68. Furthermore, we find evidence for double-mode pulsation in one of the SX Phe stars in this cluster. Using the different classes of variables, we derived values for the metallicity of the cluster of [Fe/H]=-2.07+/-0.06 on the ZW scale, or -2.20+/-0.10 on the UVES scale, and found true distance moduli 15.00 +/- 0.11 mag (using RR0 stars), 15.00+/-0.05mag (using RR1 stars), 14.97+/-0.11mag (using SX Phe stars), and 15.00+/-0.07mag (using the M_V_-[Fe/H] relation for RRL stars), corresponding to physical distances of 10.00+/-0.49, 9.99+/-0.21, 9.84+/-0.50 and 10.00+/-0.30kpc, respectively. Thanks to the first use of difference image analysis on time-series observations of M68, we are now confident that we have a complete census of the RRL stars in this cluster.
7817. VI light curves of RRL stars in M31
ID:
ivo://CDS.VizieR/J/ApJ/765/71
Title:
VI light curves of RRL stars in M31
Short Name:
J/ApJ/765/71
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first evidence that Oosterhoff type II globular clusters exist in the Andromeda galaxy (M31). On the basis of time-series photometry of the moderately metal-poor ([Fe/H]~-1.6dex) M31 globular cluster G11, obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope, we detected and derived periods for 14 RR Lyrae stars, of which five are found to lie inside the cluster tidal radius. They include three fundamental-mode (RRab) and two first-overtone (RRc) pulsators, with average periods <P_ab_>=0.70 days, and <P_c_>=0.40 days, respectively. These mean periods and the position of the cluster variable stars in the period-amplitude and period-metallicity diagrams all suggest that G11 is likely to be an Oosterhoff type II globular cluster. This appears to be in agreement with the general behavior of Milky Way globular clusters with similar metallicity and horizontal branch morphology.
7818. VI light curves of Sand 986 in M67
ID:
ivo://CDS.VizieR/J/AJ/126/2954
Title:
VI light curves of Sand 986 in M67
Short Name:
J/AJ/126/2954
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have discovered that the star S986 in the old open cluster M67 has detectable total eclipses of depth 0.08mag for the primary eclipse and 0.011mag for the secondary eclipse (in I only). We confirm the detection of a third star in spectra contributing (11.5+/-1.5)% of the total light in V band. The radial velocity of the third star indicates that it is a cluster member, but it is unclear whether it is physically associated with the eclipsing binary.
7819. VI light curves of the variable stars in M92
ID:
ivo://CDS.VizieR/J/A+A/369/862
Title:
VI light curves of the variable stars in M92
Short Name:
J/A+A/369/862
Date:
21 Oct 2021
Publisher:
CDS
Description:
Results of a search for variable stars in the central region of the Oosterhoff II type globular cluster M 92 are presented. Out of the 28 variable and suspected variable stars listed in the Catalogue of Variable Stars in Globular Clusters (Clement, 1997, Cat. <V/97>) only two were not observed. Surprisingly, almost half of the observed suspected variables did not show any evidence of variability. Only one out of the 11 candidate RR Lyrae variables of Kadla et al. (1983PZ.....21..827K) appeared to be variable. Moreover, variable V7, until now classified as an RR Lyrae star with a period of about 0.515d, turned out to be of the BL Herculis type, with the period approximately twice that long. In addition, six new variables were found in the very core of the cluster: four of the RR Lyrae and the remaining two of the SX Phoenicis type. RRc variable V11 shows changes in the light curve shape. Due to the aliasing problems, however, we can state only that this star is biperiodic. There is a possibility that V11 belongs to the new group of recently discovered double-period RRc variables pulsating in non-radial mode. Altogether, light curves were obtained for 20 variable stars. The total number of known RR Lyrae stars in M92 equals now 17, 11 of type RRab and the remaining 6, RRc. The CCD observations presented here were carried out at the Bialkow station of the Wroclaw University Observatory with the same equipment as that described by Kopacki & Pigulski (1995AcA....45..753K). Two 6x4arcmin^2^ fields of view, one centred approximately on the core of M92 and the other shifted about 2.5arcmin north and 2.6arcmin east, were observed through V and I_c_ filters of the Johnson-Kron-Cousins UBV(RI)_c_ system. The observations were carried out in two seasons: on 9 nights between 1998 July 20 and September 1, and on 17 nights between 2000 May 4 and June 20. During the 1998 season only a few frames of the second field were taken. The main field, centred on the core of the cluster, was observed during both seasons.
7820. VI light-curves of the variable stars in M13
ID:
ivo://CDS.VizieR/J/A+A/398/541
Title:
VI light-curves of the variable stars in M13
Short Name:
J/A+A/398/541
Date:
21 Oct 2021
Publisher:
CDS
Description:
VI light-curves of variable stars in the globular cluster M13 are presented. They are based on the CCD observations carried out at the Bialkow station of the Wroclaw University Observatory using 60-cm reflecting telescope and the CCD camera. A 6x4 arcmin-squared field of view covering the core of the cluster was observed through V and I_C filters of the Johnson-Kron-Cousins UBV(RI)_C system. About 300 frames in both filters were taken during 23 nights between 2001 February 27 and August 1. The CCD images were analyzed with the DAOPHOT profile-fitting software and Image Subtraction Method. The main result of this study is discovery of five RR Lyrae and one SX Poenicis stars. Moreover we detect non-radial pulsations in RRc star v36. We also comment the variability of all observed suspected variable stars in M13.