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- ID:
- ivo://CDS.VizieR/J/AJ/128/1684
- Title:
- NGC 2264: VRIH{alpha} photometry
- Short Name:
- J/AJ/128/1684
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The young open cluster NGC 2264 was observed on 2002 January 67 with the CFH12K mosaic CCD on the 3.6m Canada-France-Hawaii Telescope to investigate the shape of the initial mass function (IMF). In order to select the pre-main-sequence (PMS) members more completely, Chandra X-Ray Observatory archival data were retrieved and used for the identification of X-ray-emitting weak-line T Tauri stars. In addition, the (R-I, V-I) diagram was used to exclude background late-type giants, and a statistical approach was applied to estimate the number of contaminating foreground main-sequence stars.
2033. NGC 3503 YSO candidates
- ID:
- ivo://CDS.VizieR/J/A+A/565/A30
- Title:
- NGC 3503 YSO candidates
- Short Name:
- J/A+A/565/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here a follow-up study of the molecular gas and dust in the environs of the star forming region NGC 3503. This study aims at dealing with the interaction of the HII region NGC 3503 with its parental molecular cloud, and also with the star formation in the region, that was possibly triggered by the expansion of the ionization front against the parental cloud. To analyze the molecular gas we use CO(J=2-->1), ^13^CO(J=2-->1), C^18^O(J=2-->1), and HCN(J=3-->2) line data obtained with the on-the-fly technique from the APEX telescope. To study the distribution of the dust, we make use of unpublished images at 870um from the ATLASGAL survey and IRAC-GLIMPSE archival images. We use public 2MASS and WISE data to search for infrared candidate young stellar objects (YSOs) in the region.
- ID:
- ivo://CDS.VizieR/J/ApJ/802/30
- Title:
- NGVS VI. Ultra-compact dwarfs in M87
- Short Name:
- J/ApJ/802/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The origin of ultra-compact dwarfs (UCDs; r_h_>~10pc) --objects larger and more massive than typical globular clusters (GCs), but more compact than typical dwarf galaxies-- has been hotly debated in the 15yrs since their discovery. Even whether UCDs should be considered galactic in origin, or simply the most extreme star clusters, is not yet settled. We present the dynamical properties of 97 spectroscopically confirmed UCDs and 911 GCs associated with the central cD galaxy of the Virgo cluster, M87. Our UCDs, of which 89% have M_*_>~2x10^6^M_{sun}_ and 92% are as blue as the classic blue GCs, nearly triple the confirmed sample of Virgo UCDs, providing by far the best opportunity for studying global dynamics of a UCD system. We found that (1) UCDs have a surface number density profile that is shallower than that of blue GCs in the inner ~70kpc and as steep as that of red GCs at larger radii; (2) UCDs exhibit a significantly stronger rotation than GCs, and blue GCs seem to have a velocity field that is more consistent with that of the surrounding dwarf ellipticals than with that of UCDs; (3) UCDs have an orbital anisotropy profile that is tangentially biased at radii <~40kpc and radially biased farther out, whereas blue GCs become more tangentially biased at larger radii beyond ~40kpc; (4) GCs with M_*_>~2x10^6^M_{sun}_ have rotational properties indistinguishable from the less massive ones, suggesting that it is the size, instead of mass, that differentiates UCDs from GCs as kinematically distinct populations. We conclude that most UCDs in M87 are not consistent with being merely the most luminous and extended examples of otherwise normal GCs. The radially biased orbital structure of UCDs at large radii is in general agreement with the "tidally threshed dwarf galaxy" scenario.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/128
- Title:
- NGVS. XIV. Bona fide Virgo cluster members
- Short Name:
- J/ApJ/890/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Next Generation Virgo Cluster Survey (NGVS) was designed to provide a deep census of baryonic structures in the Virgo cluster. The survey covers the 104deg^2^ area from the core of Virgo out to one virial radius, in the u*griz bandpasses, to a point-source depth of g~25.9mag (10{sigma}) and a single pixel surface brightness limit of {mu}_g_~29mag/arcsec^2^ (2{sigma} above the sky). Here we present the final catalog of 404 Virgo galaxies located within a 3.71deg^2^ (0.3Mpc^2^) region centered on M87, Virgo's dominant galaxy. Of these, 154 were previously uncataloged and span the range 17.8mag<g<23.7mag (-13.4mag<M_g_{<}-7.4mag at the 16.5Mpc distance of Virgo). Extensive simulations show that the NGVS catalog is complete down to g=18.6mag (M_g_=-12.5mag, corresponding to a stellar mass M~1.6x10^7^M_{sun}_ for an old stellar population), and 50% complete at g=22.0mag (M_g_=-9.1mag, M~6.2x10^5^M_{sun}_). The NGVS 50% completeness limit is 3mag deeper than that of the Virgo Cluster Catalog (VCC), which has served as Virgo's reference standard for over a quarter century, and 2mag deeper than the VCC detection limit. We discuss the procedure adopted for the identification of objects and the criteria used to assess cluster membership. For each of the 404 galaxies in the NGVS Virgo Cluster core catalog, we present photometric and structural parameters based on a nonparametric curve-of-growth and isophotal analysis, as well as parametric (Sersic, double-Sersic, and/or core-Sersic) fits to the one-dimensional surface brightness profiles and two-dimensional light distributions.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/18
- Title:
- NGVS. XXIII. Nuclear star clusters
- Short Name:
- J/ApJ/878/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using deep, high-resolution optical imaging from the Next Generation Virgo Cluster Survey, we study the properties of nuclear star clusters (NSCs) in a sample of nearly 400 quiescent galaxies in the core of Virgo with stellar masses 10^5^<~M*/M_{sun}_<~10^12^. The nucleation fraction reaches a peak value f_n_~90% for M*~10^9^M_{sun}_ galaxies and declines for both higher and lower masses, but nuclei populate galaxies as small as M*~5x10^5^M_{sun}_. Comparison with literature data for nearby groups and clusters shows that at the low-mass end nucleation is more frequent in denser environments. The NSC mass function peaks at M_NSC_~7x10^5^M_{sun}_, a factor 3-4 times larger than the turnover mass for globular clusters (GCs). We find a nonlinear relation between the stellar masses of NSCs and those of their host galaxies, with a mean nucleus-to-galaxy mass ratio that drops to M_NSC_/M*~3.6x10^-3^ for M*~5x10^9^M_{sun}_ galaxies. Nuclei in both more and less massive galaxies are much more prominent: M_NSC_{propto}M_*_^0.46^ at the low-mass end, where nuclei are nearly 50% as massive as their hosts. We measure an intrinsic scatter in NSC masses at a fixed galaxy stellar mass of 0.4dex, which we interpret as evidence that the process of NSC growth is significantly stochastic. At low galaxy masses we find a close connection between NSCs and GC systems, including very similar occupation distributions and comparable total masses. We discuss these results in the context of current dissipative and dissipationless models of NSC formation.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/12
- Title:
- NGVS XXV. Virgo globular clusters photometry
- Short Name:
- J/ApJS/227/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central region of the Virgo cluster of galaxies contains thousands of globular clusters (GCs), an order of magnitude more than the numbers found in the Local Group. Relics of early star formation epochs in the universe, these GCs also provide ideal targets to test our understanding of the Spectral Energy Distributions (SEDs) of old stellar populations. Based on photometric data from the Next Generation Virgo cluster Survey (NGVS) and its near-infrared counterpart NGVS-IR, we select a robust sample of ~2000 GCs with excellent photometry and spanning the full range of colors present in the Virgo core. The selection exploits the well defined locus of GCs in the uiK diagram and the fact that the globular clusters are marginally resolved in the images. We show that the GCs define a narrow sequence in 5-dimensional color space, with limited but real dispersion around the mean sequence. The comparison of these SEDs with the predictions of eleven widely used population synthesis models highlights differences between models, and also shows that no single model adequately matches the data in all colors. We discuss possible causes for some of these discrepancies. Forthcoming papers of this series will examine how best to estimate photometric metallicities in this context, and compare the Virgo globular cluster colors with those in other environments.
- ID:
- ivo://CDS.VizieR/J/ApJS/250/17
- Title:
- NGVS. XXXIV. Ultracompact dwarf galaxies in Virgo
- Short Name:
- J/ApJS/250/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of ultracompact dwarf (UCD) galaxies in the Virgo cluster based mainly on imaging from the Next Generation Virgo Cluster Survey (NGVS). Using ~100deg^2^ of u*giz imaging, we have identified more than 600 candidate UCDs, from the core of Virgo out to its virial radius. Candidates have been selected through a combination of magnitudes, ellipticities, colors, surface brightnesses, half-light radii, and, when available, radial velocities. Candidates were also visually validated from deep NGVS images. Subsamples of varying completeness and purity have been defined to explore the properties of UCDs and compare to those of globular clusters and the nuclei of dwarf galaxies with the aim of delineating the nature and origins of UCDs. From a surface density map, we find the UCDs to be mostly concentrated within Virgo's main subclusters, around its brightest galaxies. We identify several subsamples of UCDs-i.e., the brightest, largest, and those with the most pronounced and/or asymmetric envelopes-that could hold clues to the origin of UCDs and possible evolutionary links with dwarf nuclei. We find some evidence for such a connection from the existence of diffuse envelopes around some UCDs and comparisons of radial distributions of UCDs and nucleated galaxies within the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/546/694
- Title:
- NICMOS star formation history
- Short Name:
- J/ApJ/546/694
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an extensive analysis of the star formation rates determined from the NICMOS deep images of the northern Hubble Deep Field. We use SED template fitting photometric techniques to determine both the redshift and the extinction for each galaxy in our field. Measurement of the individual extinctions provides a correction for star formation hidden by dust obscuration. We determine star formation rates for each galaxy based on the 1500{AA} UV flux and add the rates in redshift bins of width 1.0 centered on integer redshift values.
- ID:
- ivo://CDS.VizieR/J/ApJ/610/128
- Title:
- NIR colors of hard X-ray-selected AGN
- Short Name:
- J/ApJ/610/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of near-infrared photometry (J, H, K_s_) for a hard X-ray-selected sample of active galactic nuclei (AGNs) obtained from optical identification of the sources detected in ASCA surveys (total ~75deg^2^) with a flux limit of (1-3)x10^-13^erg/s/cm^2^ (2-10keV). The sample covers the AGNs at 0.1<~z<~1 with L_2-10keV_=10^42^-10^46^erg/s with very high completeness. The near-infrared photometric data of the sample are obtained from the Two Micron All Sky Survey (2MASS, Cat. <II/246>) and observations with Kitt Peak National Observatory 2.1m telescope and the University of Hawaii 2.2m telescope.
