- ID:
- ivo://CDS.VizieR/J/ApJ/563/629
- Title:
- VIK' photometry and redshifts of galaxy clusters
- Short Name:
- J/ApJ/563/629
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze photometry and spectroscopy of a sample of 63 clusters at 0.3<=z<=0.9 drawn from the Las Campanas Distant Cluster Survey to empirically constrain models of cluster galaxy evolution. Our data originate from a variety of telescopes and instruments. The candidate galaxy clusters are identified using drift-scan images and techniques described briefly below for context but in full detail by Gonzalez et al. (2001, Cat. <J/ApJS/137/117>).
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/566/103
- Title:
- VIK' photometry and redshifts of galaxy clusters
- Short Name:
- J/ApJ/566/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the influence of environment on brightest cluster galaxy (BCG) evolution using a sample of 63 clusters at 0.3<=z<=0.9 drawn primarily from the Las Campanas Distant Cluster Survey and follow-up V, I, and K' photometry. Our data originate from a variety of telescopes and instruments. The cluster sample and observations used here stem from deep optical and infrared follow-up imaging of a small subset of the full catalog that was obtained to aid in the classification of candidates and to develop photometric redshift indicators.
- ID:
- ivo://CDS.VizieR/J/ApJ/475/445
- Title:
- VIK photometry of faint field galaxies
- Short Name:
- J/ApJ/475/445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine deep K-band (W. M. Keck Telescope) with V- and I-band (New Technology Telescope) observations of two "blank" high Galactic latitude fields, surveying a total of ~2arcmin^2^. The K-band number-magnitude counts continue to rise above K~22mag, reaching surface densities of few x10^5^deg^-2^. The slope for the galaxy counts is approximately [dlog(N)/dmag].deg^-2^=0.23+/-0.02 over the range 18-23mag. While this slope is consistent with other recent deep K-band surveys, there is a definite scatter in the normalisations by about a factor of 2. In particular, our normalisation is ~2x greater than the galaxy counts reported by Djorgovski et al. in 1995 (1995ApJ...438L..13D). Optical near-infrared color-magnitude and color-color diagrams for all objects detected in the V+I+K image are plotted and discussed in the context of grids of Bruzual-Charlot isochrone synthesis galaxy evolutionary models. The colors of most of the observed galaxies are consistent with a population drawn from a broad redshift distribution. A few galaxies at K~19-20 are red in both colors (V-I>3; I-K>2, consistent with being early-type galaxies having undergone a burst of star formation at z>5 and viewed at z~1. At K>20, we find several (approximately eight) "red outlier" galaxies with I-K>4 and V-I<2.5, whose colors are difficult to mimic by a single evolving or nonevolving stellar population at any redshift unless they either have quite low metallicity or are highly reddened. We compare the data against the evolutionary tracks of second-burst ellipticals and against a grid of models that does not constrain galaxy ages to a particular formation redshift. The red outliers' surface density is several per square arcminute, which is so high that they are probably common objects of low luminosity L<L*. Whether these are low-metallicity, dusty dwarf galaxies, or old galaxies at high redshift, they are curious and merit spectroscopic follow-up.
- ID:
- ivo://CDS.VizieR/J/A+A/443/413
- Title:
- VIKs photometry of NGC4365 globular clusters
- Short Name:
- J/A+A/443/413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table lists VIKs photometry for compact objects in the giant Virgo elliptical NGC 4365. The majority of these objects are globular clusters. V and I magnitudes are measured on images taken with the FORS1 instrument on the ESO Very Large Telescope, while the K magnitudes are from the SOFI imager on the ESO New Technology Telescope. No correction for foreground extinction has been applied to the photometry in the table.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
