- 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.
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- ID:
- ivo://CDS.VizieR/J/AJ/158/51
- Title:
- VR CCD photometry of variable stars in the GC NGC 4147
- Short Name:
- J/AJ/158/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a search for variable stars in a region of the globular cluster NGC 4147 based on photometric observations with a 4Kx4K CCD imager mounted at the axial port of the recently installed 3.6 m Devasthal optical telescope (DOT) at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, India. We performed time series photometry of NGC 4147 in the V and R bands, and identified 42 periodic variables in the region of NGC 4147, 28 of which have been detected for the first time. Seventeen variable stars are located within the half-light radius ~<0.48', of which 10 stars are newly identified variables. Two of the 10 variables are located within the core radius ~<0.09'. Based on their location in the V/(V-R) color-magnitude diagram and variability characteristics, seven, eight, five, and one newly identified probable member variables are classified as RRc, EA/E, EW, and SX Phe, respectively. The metallicity of NGC 4147 estimated from the light curves of RRab and RRc stars with the help of Fourier decomposition is found to be characteristic of Oosterhoff II. The distance derived using the light curves of RRab stars is consistent with that obtained from the observed V/(V-R) color-magnitude diagram.
- ID:
- ivo://CDS.VizieR/J/AJ/127/840
- Title:
- VRI photometry of Fornax red giants
- Short Name:
- J/AJ/127/840
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared spectra were obtained for 117 red giants in the Fornax dwarf spheroidal galaxy with the FORS1 spectrograph on the VLT, in order to study the metallicity distribution of the stars and to lift the age-metallicity degeneracy of the red giant branch (RGB) in the color-magnitude diagram (CMD). Metallicities are derived from the equivalent widths of the infrared calcium triplet lines at 8498, 8542, and 8662{AA} calibrated with data from globular clusters, the open cluster M67, and the LMC. For a substantial portion of the sample, the strength of the calcium triplet is unexpectedly high, clearly indicating that the main stellar population of Fornax is significantly more metal-rich than could be inferred from the position of its RGB in the CMD.
- 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/627/A138
- Title:
- XSL atmospheric parameters
- Short Name:
- J/A+A/627/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The X-shooter Spectral Library (XSL) is an empirical stellar library at medium spectral resolution covering the wavelength range from 3000 to 24800 angstrom. This library aims to provide a benchmark for stellar population studies. In this work, we present a uniform set of stellar atmospheric parameters, effective temperatures, surface gravities, and iron abundances for 754 spectra of 616 XSL stars. We used the full-spectrum fitting package ULySS with the empirical MILES library as reference to fit the ultraviolet-blue (UVB) and visible (VIS) spectra. We tested the internal consistency and we compared our results with compilations from the literature. The stars cover a range of effective temperature 2900<Teff<38000K, surface gravity 0<logg<5.7, and iron abundance -2.5<[Fe/H]<+1.0, with a couple of stars extending down to [Fe/H]=-3.9. The precisions of the measurements for the G- and K-type stars are 0.9%, 0.14, and 0.06 in Teff, log g and [Fe/H], respectively. For the cool giants with logg<1, the precisions are 2.1%, 0.21, and 0.22, and for the other cool stars these values are 1%, 0.14, and 0.10. For the hotter stars (Teff>6500K), these values are 2.6%, 0.20, and 0.10 for the three parameters.
- ID:
- ivo://CDS.VizieR/J/ApJ/832/121
- Title:
- 4-yr RV survey of red giant in eclipsing binaries
- Short Name:
- J/ApJ/832/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Given the potential of ensemble asteroseismology for understanding fundamental properties of large numbers of stars, it is critical to determine the accuracy of the scaling relations on which these measurements are based. From several powerful validation techniques, all indications so far show that stellar radius estimates from the asteroseismic scaling relations are accurate to within a few percent. Eclipsing binary systems hosting at least one star with detectable solar-like oscillations constitute the ideal test objects for validating asteroseismic radius and mass inferences. By combining radial velocity (RV) measurements and photometric time series of eclipses, it is possible to determine the masses and radii of each component of a double-lined spectroscopic binary. We report the results of a four-year RV survey performed with the echelle spectrometer of the Astrophysical Research Consortium's 3.5m telescope and the APOGEE spectrometer at Apache Point Observatory. We compare the masses and radii of 10 red giants (RGs) obtained by combining radial velocities and eclipse photometry with the estimates from the asteroseismic scaling relations. We find that the asteroseismic scaling relations overestimate RG radii by about 5% on average and masses by about 15% for stars at various stages of RG evolution. Systematic overestimation of mass leads to underestimation of stellar age, which can have important implications for ensemble asteroseismology used for Galactic studies. As part of a second objective, where asteroseismology is used for understanding binary systems, we confirm that oscillations of RGs in close binaries can be suppressed enough to be undetectable, a hypothesis that was proposed in a previous work.
