- 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.
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Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/A+AS/120/153
- Title:
- VI photometry of Ton 2 cluster
- Short Name:
- J/A+AS/120/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ton 2 is among the less-known Galactic globular clusters. We present for the first time colour magnitude diagrams in the V, I bands. We used the ESO NTT telescope under an excellent seeing of 0.6". The horizontal branch is red and close to the red giant branch, tilted by some differential reddening. The horizontal branch morphology and the red giant branch curvature suggest a metallicity similar to that of 47 Tucanae. We derive a reddening of E(B-V)=1.26 and a distance d_{sun}_=6.4kpc. Therefore, Ton 2 is =~2.0kpc from the Galactic center, and it appears to belong to the bulge population, being however only moderately metal rich.
- ID:
- ivo://CDS.VizieR/J/A+AS/118/303
- Title:
- VI Photometry of variables in NGC 2243
- Short Name:
- J/A+AS/118/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tables 3-13 contain V and I band light curves for 6 variables reported in the paper. Tables 14 and 15 contain VI photometry presented in Figs. 5 and 9, respectively.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/423
- Title:
- VI photometry of Westerlund 1 and 2
- Short Name:
- J/A+AS/127/423
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out CCD observations of stars in the region of the open cluster Westerlund 1 through the V and I passbands. The direct images were obtained with the 24-inch telescope of the University of Toronto Southern Observatory situated at Las Campanas Observatory, Chile. After cross-correlating all independent V, (V-I) tables we have obtained a improved set of colour and magnitude values as compared to those based on a single measure.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/108/1598
- Title:
- Virgo cluster ellipticals. III.
- Short Name:
- J/AJ/108/1598
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Planetary Camera on the Hubble Space Telescope to study the morphology and surface brightness parameters of a luminosity- limited sample of fourteen elliptical galaxies in the Virgo cluster. The total apparent blue magnitudes of the galaxies range between 9.4 and 13.4. In this paper, the core brightness profiles are presented, while the overall morphology and the isophotal shapes are discussed in two companion papers [Jaffe et al. AJ, 108, 1567 (1994); van den Bosch et al. AJ, 108, 1579 (1994)]. We show that, in spite of the spherical aberration affecting the HST primary mirror, deconvolution techniques allow recovery of the brightness profile up to 0.2arcsec from the center of the galaxies. We find that none of the galaxies has an isothermal core. On the basis of their morphological and photometrical properties, the galaxies can be divided in two physically distinct groups, referred to as Type I and Type II. All of the Type I galaxies are classified as E1 to E3 in the Revised Shapley Ames Catalog (Sandage & Tammann 1981), while Type II galaxies are classified as E5 to E7. The characteristics of Type II galaxies are explained by the presence of disks component on both the 1 arcsec and the 10 arcsec scales, while Type I galaxies correspond to the classical disk-free ellipticals.
- 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.
- 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.
