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16971. VI photometry of new M53 variables
ID:
ivo://CDS.VizieR/J/A+A/507/803
Title:
VI photometry of new M53 variables
Short Name:
J/A+A/507/803
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the variable star content of the globular cluster M53 to compute the physical parameters of the constituting stars and the distance of the cluster. Covering two adjacent seasons in 2007 and 2008, new photometric data are gathered for 3048 objects in the field of M53. By using the OIS (optimal image subtraction) method and subsequently TFA (trend filtering algorithm), we search for variables in the full sample by using discrete Fourier transformation and box-fitting least squares method. We select variables based on the statistics related to these methods combined with visual inspection. We identified 12 new variables (2 RR Lyrae stars, 7 short periodic stars - 3 of them are SX Phe stars - and 3 long-period variables). No eclipsing binaries were found in the present sample. Except for the 3 (hitherto unknown) Blazhko RR Lyrae (two RRab and an RRc) stars, no multiperiodic variables were found. We showed that after proper period shift, the PLC (period-luminosity-color) relation for the first overtone RR Lyrae sample tightly follows the one spanned by the fundamental stars. Furthermore, the slope is in agreement with that derived from other clusters. Based on the earlier Baade-Wesselink calibration of the PLC relations, the derived reddening-free distance modulus of M53 is 16.31+/-0.04mag, corresponding to a distance modulus of 18.5mag for the Large Magellanic Cloud. From the Fourier parameters of the RRab stars we obtained an average iron abundance of -1.58+/-0.03 (error of the mean). This is ~0.5dex higher than the overall abundance of the giants as given in the literature and derived in this paper from the three-color photometry of giants. We suspect that the source of this discrepancy (observable also in other, low-metallicity clusters) is the lack of a sufficient number of low-metallicity objects in the calibrating sample of the Fourier method.
16972. VI photometry of NGC 5634
ID:
ivo://CDS.VizieR/J/AJ/124/915
Title:
VI photometry of NGC 5634
Short Name:
J/AJ/124/915
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first (V, V-I) color-magnitude diagram (CMD) for the poorly studied globular cluster NGC 5634. The CMD shows a steep red giant branch (RGB) and a predominantly blue horizontal branch (HB): both these characteristics suggest a low metal content for this cluster. The data were obtained at the 3.52 m Italian Telescopio Nazionale Galileo (Roque de los Muchachos, La Palma, Canary Islands, Spain), using the LSR DoLoRes Camera equipped with a 2048x2048 pixel thinned and back-illuminated Loral CCD array.
16973. VI photometry of NGC 6293 and NGC 6541
ID:
ivo://CDS.VizieR/J/AJ/132/2171
Title:
VI photometry of NGC 6293 and NGC 6541
Short Name:
J/AJ/132/2171
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present VI photometry of the metal-poor inner halo globular clusters NGC 6293 and NGC 6541 using the WFPC2 on board the Hubble Space Telescope (HST). Our color-magnitude diagrams of the clusters show well-defined blue horizontal-branch populations, consistent with their low metallicities and old ages. NGC 6293 appears to have blue straggler stars in the cluster's central region. We discuss the interstellar reddening and the distance modulus of NGC 6293 and NGC 6541 and obtain E(B-V)=0.40 and (m-M)_0_=14.61 for NGC 6293 and E(B-V)=0.14 and (m-M)_0_=14.19 for NGC 6541. Our results confirm that NGC 6293 and NGC 6541 are clearly located in the Galaxy's central regions (R_GC_<=3kpc).
16974. VI photometry of 5 open clusters
ID:
ivo://CDS.VizieR/J/A+A/464/573
Title:
VI photometry of 5 open clusters
Short Name:
J/A+A/464/573
Date:
21 Oct 2021
Publisher:
CDS
Description:
The stellar populations in the outer Galactic disk are a subject of wide interest nowadays. To contribute to a better picture of this part of the Galaxy, we have studied the nature of five marginally investigated star clusters (Collinder 74, Berkeley 27, Haffner 8, NGC 2509, and VdB-Hagen4) by means of accurate CCD photometry in the V and I passbands. These clusters are in fact located in the third Galactic quadrant. We aim to obtain the basic parameters of these objects, which in some cases are still disputed in the literature. In the case of VdB-Hagen 4 we provide the first estimate of its fundamental parameters, while for Haffner 8 we present the first CCD photometry. The analysis is based on the comparison between field star decontaminated color-magnitude diagrams and stellar models. Particular care is devoted to the the assessment of the data quality and the statistical field star decontamination. The Padova library of stellar isochrones is adopted in this study. The analysis we carried out allowed us to solve a few inconsistencies in the literature regarding Haffner 8 and NGC 2509. Collinder 74 is found to be significantly older than reported before. VdB-Hagen 4 is a young open cluster located more than 20kpc from the Galactic center. Such an extreme distance is compatible with the cluster belonging to the Norma-Cygnus arm.
16975. VI photometry of Sombrero globular clusters
ID:
ivo://CDS.VizieR/J/MNRAS/327/1116
Title:
VI photometry of Sombrero globular clusters
Short Name:
J/MNRAS/327/1116
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explore the rich globular cluster (GC) system of the nearby Sa galaxy M104, the "Sombrero" (NGC 4594), using archive Wide Field Planetary Camera 2 data. The GC colour distribution is found to be bimodal at the >99 per cent confidence level, with peaks at (V-I)0=0.96+/-0.03 and 1,21+/-0.03. The inferred metallicities are very similar to those of GCs in our Galaxy and M31. However, the Sombrero reveals a much enhanced number of red (metal-rich) GCs compared to other well-studied spirals. Because the Sombrero is dominated by a huge bulge and only has a modest disc, we associate the two subpopulations with the halo and bulge components, respectively. Thus our analysis supports the view that the metal-rich GCs in spirals are associated with the bulge rather than with the disc. The Sombrero GCs have typical effective (half-light) radii of ~2pc with the red ones being ~30 per cent smaller than the blue ones. We identify many similarities between the GC system of the Sombrero and those of both late-type spirals and early-type galaxies. Thus both the GC system and the Hubble type of the Sombrero galaxy appear to be intermediate in their nature.
16976. VI photometry of sources in the halo of NGC253
ID:
ivo://CDS.VizieR/J/ApJ/736/24
Title:
VI photometry of sources in the halo of NGC253
Short Name:
J/ApJ/736/24
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained Magellan/IMACS and HST/ACS imaging data that resolve red giant branch stars in the stellar halo of the starburst galaxy NGC 253. The HST data cover a small area, and allow us to accurately interpret the ground-based data, which cover 30% of the halo to a distance of 30kpc, allowing us to make detailed quantitative measurements of the global properties and structure of a stellar halo outside of the Local Group. The geometry of the halo is significantly flattened in the same sense as the disk, with a projected axis ratio of b/a~0.35+/-0.1. The total stellar mass of the halo is estimated to be M_halo ~2.5+/-1.5x10^9^M_{sun}_, or 6% of the total stellar mass of the galaxy, and has a projected radial dependence that follows a power law of index -2.8+/-0.6, corresponding to a three-dimensional power law index of ~-4. The total luminosity and profile shape that we measure for NGC 253 are somewhat larger and steeper than the equivalent values for the Milky Way and M31, but are well within the scatter of model predictions for the properties of stellar halos built up in a cosmological context. Structure within the halo is seen at a variety of scales: there is small kpc-scale density variation and a large shelf-like feature near the middle of the field. The techniques that have been developed will be essential for quantitatively comparing our upcoming larger sample of observed stellar halos to models of halo formation.
16977. VI photometry of the Leo II galaxy
ID:
ivo://CDS.VizieR/J/MNRAS/360/185
Title:
VI photometry of the Leo II galaxy
Short Name:
J/MNRAS/360/185
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present V and I photometry of a 9.4'x9.4' field centered on the dwarf spheroidal galaxy Leo II. The Tip of the Red Giant Branch is identified at I^TRGB^=17.83+/-0.03 and adopting <[M/H]>=-1.53+/-0.2 from the comparison of RGB stars with Galactic templates, we obtain a distance modulus (m-M)_0=21.84+/-0.13, corresponding to a distance D=233+/-15kpc. Two significant bumps have been detected in the Luminosity Function of the Red Giant Branch. The fainter bump (B1, at V=21.79+/-0.05) is the RGB bump of the dominant stellar population while the brightest one (B2, at V=21.36+/-0.05) may be identified as the Asymptotic Giant Branch Clump of the same population. The luminosity of the main RGB bump (B1) suggest that the majority of RGB stars in Leo II belongs to a population that is >~4Gyr younger than the classical Galactic globular clusters. The stars belonging to the He-burning Red Clump are shown to be significantly more centrally concentrated than RR Lyrae and Blue Horizontal Branch stars, probing the existence of an age/metallicity radial gradient in this remote dwarf spheroidal.
16978. VI photometry of variable stars in Fornax
ID:
ivo://CDS.VizieR/J/AJ/123/840
Title:
VI photometry of variable stars in Fornax
Short Name:
J/AJ/123/840
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a search for variable stars in the Fornax dwarf galaxy covering an area of half a square degree. We have ~30 epochs of VI data. We found and determined periods for more than 500 RR Lyrae, 17 anomalous Cepheids, and six Population II Cepheids. In addition we have 85 candidate long-period variables, the majority of which were previously unknown. We estimate that the average metal abundance of RR Lyrae stars is [Fe/H]~=-1.6dex.
16979. VIRAC. The VVV Infrared Astrometric Catalogue
ID:
ivo://CDS.VizieR/II/364
Title:
VIRAC. The VVV Infrared Astrometric Catalogue
Short Name:
II/364
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present VIRAC version 1, a near-infrared proper motion and parallax catalogue of the VISTA Variables in the Via Lactea (VVV) survey for 312587642 unique sources averaged across all overlapping pawprint and tile images covering 560deg^2^ of the bulge of the Milky Way and southern disc. The catalogue includes 119 million high-quality proper motion measurements, of which 47 million have statistical uncertainties below 1mas/yr. In the 11<K_s_<14 magnitude range, the high-quality motions have a median uncertainty of 0.67mas/yr. The catalogue also includes 6935 sources with quality-controlled 5{sigma} parallaxes with a median uncertainty of 1.1mas. The parallaxes show reasonable agreement with the Tycho-Gaia Astrometric Solution, though caution is advised for data with modest significance. The SQL data base housing the data is made available via the web. We give example applications for studies of Galactic structure, nearby objects (low-mass stars and brown dwarfs, subdwarfs, white dwarfs) and kinematic distance measurements of young stellar objects. Nearby objects discovered include LTT 7251 B, an L7 benchmark companion to a G dwarf with over 20 published elemental abundances, a bright L subdwarf, VVV 1256-6202, with extremely blue colours and nine new members of the 25pc sample. We also demonstrate why this catalogue remains useful in the era of Gaia. Future versions will be based on profile fitting photometry, use the Gaia absolute reference frame and incorporate the longer time baseline of the VVV extended survey.
16980. Virgo cluster ETGs: GC and galaxy diffuse light
ID:
ivo://CDS.VizieR/J/ApJ/806/133
Title:
Virgo cluster ETGs: GC and galaxy diffuse light
Short Name:
J/ApJ/806/133
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a kinematic analysis of the globular cluster (GC) systems and diffuse stellar light of four intermediate luminosity (sub-L*) early-type galaxies in the Virgo cluster based on Gemini Multi-Object Spectrographs (GMOS) data. Our galaxy sample is fainter (-23.8<M_K_<-22.7) than most previous studies, nearly doubling the number of galaxies in this magnitude range that now have GC kinematics. The data for the diffuse light extends to 4R_e_, and the data for the GCs reaches 8-12R_e_. We find that the kinematics in these outer regions are all different despite the fact that these four galaxies have similar photometric properties, and are uniformly classified as "fast rotators" from their stellar kinematics within 1R_e_. The GC systems exhibit a wide range of kinematic morphology. The rotation axis and amplitude can change between the inner and outer regions, including a case of counter-rotation. This difference shows the importance of wide-field kinematic studies, and shows that stellar and GC kinematics can change significantly as one moves beyond the inner regions of galaxies. Moreover, the kinematics of the GC systems can differ from that of the stars, suggesting that the formation of the two populations are also distinct.

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