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16981. 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.
16982. 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.
16983. 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.
16984. 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.
16985. 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.
16986. 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.
16987. Virgo cluster radio luminosity function. I.
ID:
ivo://CDS.VizieR/J/A+A/343/86
Title:
Virgo cluster radio luminosity function. I.
Short Name:
J/A+A/343/86
Date:
21 Oct 2021
Publisher:
CDS
Description:
We cross-correlate the galaxies brighter than m_B_=18 in the Virgo cluster with the radio sources in the NVSS survey (1.4GHz), resulting in 180 radio-optical identifications. We determine the radio luminosity function of the Virgo galaxies, separately for the early- and late-types. Late-type galaxies develop radio sources with a probability proportional to their optical luminosity. In fact their radio/optical (R_B_) distribution is gaussian, centered at log R_B_~-0.5, i.e. the radio luminosity is ~0.3 of the optical one. The probability of late-type galaxies to develop radio sources is almost independent of their detailed Hubble type, except for Sa (and S0+S0a) which are a factor of ~5 less frequent than later types at any R_B_. Giant elliptical galaxies feed "monster" radio sources with a probability strongly increasing with mass. However the frequency of fainter radio sources is progressively less sensitive on the system mass. The faintest giant E galaxies (M_B_=-17) have a probability of feeding low power radio sources similar to that of dwarf E galaxies as faint as M_B_=-13.
16988. Virgo cluster ultraviolet sources
ID:
ivo://CDS.VizieR/J/ApJS/111/143
Title:
Virgo cluster ultraviolet sources
Short Name:
J/ApJS/111/143
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze three UV images covering a ~100 square degree field toward the Virgo cluster, obtained by the FAUST space experiment. We detect 191 sources to a signal-to-noise ratio of 4.4 and identify 94% of them. Most sources have optical counterparts in existing catalogs, and about half are identified as galaxies. Some sources with no listed counterpart were observed at the Wise Observatory. We present the results of low-resolution visible spectrophotometry and discuss the foreground 101 stellar sources and the 76 detected galaxies, both in the cluster and in the foreground or background. We derive conclusions on star formation properties of galaxies and on the total UV flux from discrete and diffuse sources in the cluster. We test for the presence of intracluster dust, determine the clustering properties of UV emitting galaxies, and derive the UV luminosity function of Virgo galaxies.
16989. Virgo early-type galaxies optical properties
ID:
ivo://CDS.VizieR/J/A+A/538/A69
Title:
Virgo early-type galaxies optical properties
Short Name:
J/A+A/538/A69
Date:
21 Oct 2021
Publisher:
CDS
Description:
Studies of dwarf spheroidal (dSph) galaxies with statistically significant sample sizes are still rare beyond the Local Group, since these low surface brightness objects can only be identified with deep imaging data. In galaxy clusters, where they constitute the dominant population in terms of number, they represent the faint end slope of the galaxy luminosity function and provide important insight on the interplay between galaxy mass and environment. In this study we investigate the optical photometric properties of early-type galaxies (dwarf ellipticals (dEs) and dSphs) in the Virgo cluster core region, by analysing their location on the colour magnitude relation (CMR) and the structural scaling relations down to faint magnitudes, and by constructing the luminosity function to compare it with theoretical expectations.
16990. Virgo Filaments. I. CO and HI data
ID:
ivo://CDS.VizieR/J/A+A/657/A9
Title:
Virgo Filaments. I. CO and HI data
Short Name:
J/A+A/657/A9
Date:
21 Mar 2022 09:21:25
Publisher:
CDS
Description:
It is now well established that galaxies have different morphology, gas content and star formation rate in dense environments like galaxy clusters. The impact of environmental density extends to several virial radii, and galaxies appear to be pre-processed in filaments and groups, before falling into the cluster. Our goal is to quantify this pre-processing, in terms of gas content, and star formation rate, as a function of density in cosmic filaments. We have observed the two first CO transitions in 163 galaxies with the IRAM-30m telescope, and added 82 more measurements from the literature, for a sample of 245 galaxies in the filaments around Virgo cluster. We gathered HI-21cm measurements from the literature, and observed 69 galaxies with the Nancay telescope, to complete our sample. We compare our filament galaxies with comparable samples from the Virgo cluster and with the isolated galaxies of the AMIGA sample. We find a clear progression from field galaxies to filament and cluster ones for decreasing star formation rate, increasing fraction of galaxies in the quenching phase, increasing proportion of early-type galaxies and decreasing gas content. Galaxies in the quenching phase, defined as having star formation rate below one third of the main sequence rate, are only between 0-20% in the isolated sample, according to local galaxy density, while they are 20-60% in the filaments and 30-80% in the Virgo cluster. Processes that lead to star formation quenching are already at play in filaments. They depend mostly on the local galaxy density, while the distance to the filament spine is a secondary parameter. While the HI to stellar mass ratio decreases with local density by an order of magnitude in the filaments, and two orders of magnitude in the Virgo cluster with respect to the field, the decrease is much less for the H2 to stellar mass ratio. As the environmental density increases, the gas depletion time decreases, since the gas content decreases faster than the star formation rate. This suggests that gas depletion significantly precedes star formation quenching.

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