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4671. Old passively evolving galaxies at z=1
ID:
ivo://CDS.VizieR/J/ApJ/634/861
Title:
Old passively evolving galaxies at z=1
Short Name:
J/ApJ/634/861
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtained the number counts and the rest-frame B-band luminosity function of color-selected old passively evolving galaxies (OPEGs) at z=1 with very high statistical accuracy using a large and homogeneous sample of about 4000 such objects with z'<25 detected in an area of 1.03deg^2^ in the Subaru/XMM-Newton Deep Survey (SXDS) field. Our selection criteria are defined on the i'-z' and R-z' color-magnitude plane so that OPEGs at z=0.9-1.1 with formation redshift z_f_=2-10 are properly sampled with minimum contamination by other populations. The limiting magnitude corresponds to the luminosity of galaxies with M*+3 at z=0 (where M* is the characteristic absolute magnitude of the Schechter galaxy luminosity function). We made pilot redshift observations for 99 OPEG candidates with 19<z'<22 and found that at least 78% (73 of 93) of the entire sample, or 95% (73 of 77) of those whose redshifts were obtained, indeed lie between z=0.87 and 1.12, and most of their spectra show a continuum break and strong Ca H and K lines, indicating that these objects are indeed dominated by the old stellar populations.
4672. Old star clusters in M101 from HST
ID:
ivo://CDS.VizieR/J/ApJ/805/160
Title:
Old star clusters in M101 from HST
Short Name:
J/ApJ/805/160
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new photometric catalog of 326 candidate globular clusters (GCs) in the nearby spiral galaxy M101, selected from B, V, and I Hubble Space Telescope Advanced Camera for Surveys images. The luminosity function (LF) of these clusters has an unusually large number of faint sources compared with GCLFs in many other spiral galaxies. Accordingly, we separate and compare the properties of "bright" (M_v_<-6.5) versus "faint" (M_v_>-6.5; one magnitude fainter than the expected GC peak) clusters within our sample. The LF of the bright clusters is well fit by a peaked distribution similar to those observed in the Milky Way (MW) and other galaxies. These bright clusters also have similar size (r_eff_) and spatial distributions as MW GCs. The LF of the faint clusters, on the other hand, is well described by a power law, dN(L_v_)/dL_v_{propto}L_v_^{alpha}^ with {alpha}=2.6+/-0.3, similar to those observed for young and intermediate-age cluster systems in star forming galaxies. We find that the faint clusters have larger typical r_eff_ than the bright clusters, and have a flatter surface density profile, being more evenly distributed, as we would expect for clusters associated with the disk. We use the shape of the LF and predictions for mass-loss driven by two-body relaxation to constrain the ages of the faint clusters. Our results are consistent with two populations of old star clusters in M101: a bright population of halo clusters and a fainter, possibly younger, population of old disk clusters.
4673. Old star clusters in NGC 4449 from HST imaging
ID:
ivo://CDS.VizieR/J/AJ/143/52
Title:
Old star clusters in NGC 4449 from HST imaging
Short Name:
J/AJ/143/52
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use Hubble Space Telescope imaging to show that the nearby dwarf starburst galaxy NGC 4449 (=UGC 7592) has an unusual abundance of luminous red star clusters. Joint constraints from integrated photometry, low-resolution spectroscopy, dynamical mass-to-light ratios, and resolved color-magnitude diagrams provide evidence that some of these clusters are old globular clusters (GCs). Spectroscopic data for two massive clusters suggest intermediate metallicities ([Fe/H]~-1) and subsolar Mg enhancement ([Mg/Fe]~-0.1 to -0.2). One of these clusters may be the nucleus of a tidally disrupting dwarf galaxy; the other is very massive (~3*10^6^M_{sun}_). We have also identified a population of remote halo GCs. NGC 4449 is consistent with an emerging picture of the ubiquity of stellar halos among dwarf galaxies, and study of its GCs may help distinguish between accretion and in situ scenarios for such halos.
4674. Old stellar systems (globulars to ellipticals)
ID:
ivo://CDS.VizieR/J/MNRAS/389/1924
Title:
Old stellar systems (globulars to ellipticals)
Short Name:
J/MNRAS/389/1924
Date:
21 Oct 2021
Publisher:
CDS
Description:
Elliptical galaxies and globular clusters (GCs) have traditionally been regarded as physically distinct entities due to their discontinuous distribution in key scaling diagrams involving size, luminosity and velocity dispersion. Recently this distinctness has been challenged by the discovery of stellar systems with mass intermediate between those of GCs and dwarf ellipticals (such as ultracompact dwarfs and dwarf galaxy transition objects). Here we examine the relationship between the virial and stellar mass for a range of old stellar systems, from GCs to giant ellipticals, and including such intermediate-mass objects (IMOs). Improvements on previous work in this area include the use of (i) near-infrared magnitudes from the Two Micron All Sky Survey (2MASS), (ii) aperture corrections to velocity dispersions, (iii) homogeneous half-light radii and (iv) accounting for the effects of non-homology in galaxies.
4675. Omega Cen FUV photometry
ID:
ivo://CDS.VizieR/J/AJ/108/1350
Title:
Omega Cen FUV photometry
Short Name:
J/AJ/108/1350
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present far-ultraviolet images of the globular cluster {omega} Centauri obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 mission. A total of 1957 sources are detected at 1620{AA} to a limiting UV magnitude of 16.4 in the central 24' diameter region of the field and a limit of 15.6 over the remainder of the 40' diameter field. Over 1400 of these sources are matched with stars on a Stroemgren u band CCD frame obtained with the CTIO 0.9m telescope to produce a (far-UV, u) color-magnitude diagram. Completeness of the sample and error estimates are determined by photometry of artificial stars added to the images. The horizontal branch (HB) of the CMD is heavily populated hotter than 9000K. A large number of "extreme HB" stars are found hotter than a conspicuous break in the HB at Te~16000K. There is also a significant population of stars above the HB, the brightest of which is 4mag brighter than the HB. Most of the hotter of these appear to be "AGB-manque" or "Post-Early Asymptotic Giant Branch" stars. We compare the observations to recent theoretical evolutionary tracks for the zero-age HB and subsequent phases. The tracks match the data well, with the exception of the hotter HB stars, many of which fall below the zero-age horizontal branch. It is unclear as yet whether these are a special population or an artifact of errors in the models or photometry. We identify 33 stars with Te>~50000K, which are hotter than zero-age HB stars with envelope masses of 0.003M_{sun}_.
4676. omega Cen RR Lyrae and SX Phoenicis stars
ID:
ivo://CDS.VizieR/J/A+A/604/A120
Title:
omega Cen RR Lyrae and SX Phoenicis stars
Short Name:
J/A+A/604/A120
Date:
21 Oct 2021
Publisher:
CDS
Description:
The globular cluster {omega} Centauri (NGC 5139) hosts hundreds of pulsating variable stars of different types, thus representing a treasure trove for studies of their corresponding period-luminosity (PL) relations. Our goal in this study is to obtain the PL relations for RR Lyrae and SX Phoenicis stars in the field of the cluster, based on high-quality, well-sampled light curves in the near-infrared (IR). Observations were carried out using the VISTA InfraRed CAMera (VIRCAM) mounted on the Visible and Infrared Survey Telescope for Astronomy (VISTA). A total of 42 epochs in J and 100 epochs in K_S_ were obtained, spanning 352 days. Point-spread function photometry was performed using DoPhot and DAOPHOT crowded-field photometry packages in the outer and inner regions of the cluster, respectively. Based on the comprehensive catalog of near-IR light curves thus secured, PL relations were obtained for the different types of pulsators in the cluster, both in the J and K_S_ bands. This includes the first PL relations in the near-IR for fundamental-mode SX Phoenicis stars. The near-IR magnitudes and periods of Type II Cepheids and RR Lyrae stars were used to derive an updated true distance modulus to the cluster, with a resulting value of (m-M)_0_=13.708+/-0.035+/-0.10mag, where the error bars correspond to the adopted statistical and systematic errors, respectively. Adding the errors in quadrature, this is equivalent to a heliocentric distance of 5.52+/-0.27kpc.
4677. omega Cen Spitzer photometry
ID:
ivo://CDS.VizieR/J/AJ/135/1395
Title:
omega Cen Spitzer photometry
Short Name:
J/AJ/135/1395
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a Spitzer Space Telescope imaging survey of the most massive Galactic globular cluster, {omega} Centauri, and investigate stellar mass loss at low metallicity and the intracluster medium (ICM). The survey covers approximately 3.2x the cluster half-mass radius at 3.6, 4.5, 5.8, 8, and 24um, resulting in a catalog of over 40000 point sources in the cluster.
4678. OmegaWINGS BV photometry of galaxy clusters
ID:
ivo://CDS.VizieR/J/A+A/581/A41
Title:
OmegaWINGS BV photometry of galaxy clusters
Short Name:
J/A+A/581/A41
Date:
21 Oct 2021
Publisher:
CDS
Description:
The WIde-field Nearby Galaxy-cluster Survey (WINGS) is a wide-field and multiwavelength survey of 76 galaxy clusters in the local Universe. The sample consists of all clusters at 0.04<z<0.07 in both hemispheres at Galactic latitude |b|>20 selected from the ROSAT X-ray-Brightest Abell-type Cluster Sample, the Brightest Cluster Sample, and its extension. The original WINGS survey is based on B and V imaging for the 76 clusters over a 34 by 34 arcminute field of view taken with the Wide Field Cameras on the INT and the 2.2m MPG/ESO telescopes. With the aim to cover the virial region and extend out into the infall region, we have obtained GTO OmegaCAM imaging in the B, and V bands over 1 by 1 degree for 45 fields covering 46 WINGS clusters. We present the Johnson B- and V-band OmegaCAM photometry of 46 WINGS clusters. With a median seeing of 1 arcsecond in both B- and V-bands, our 25-minutes exposures in each band typically reach the 50% completeness level at V=23.1mag.
4679. O-M stars model atmospheres
ID:
ivo://CDS.VizieR/J/A+A/333/231
Title:
O-M stars model atmospheres
Short Name:
J/A+A/333/231
Date:
21 Oct 2021
Publisher:
CDS
Description:
Broad band colors and bolometric corrections in the Johnson-Cousins-Glass system (Bessell, 1990PASP..102.1181B; Bessell & Brett, 1988PASP..100.1134B) have been computed from synthetic spectra from new model atmospheres of Kurucz (1995a, priv. comm.), Castelli (1997, priv. comm.), Plez, Brett & Nordlund (1992A&A...256..551P), Plez (1995-97, priv. comm.), and Brett (1995A&A...295..736B, 1995A&AS..109..263B). These atmospheres are representative of larger grids that are currently being completed. We discuss differences between the different grids and compare theoretical color-temperature relations and the fundamental color temperature relations derived from: (a) the infrared-flux method (IRFM) for A-K stars (Blackwell & Lynas-Gray 1994A&A...282..899B; Alonso et al. 1996A&AS..117..227A) and M dwarfs (Tsuji et al. 1996A&A...305L...1T); (b) lunar occultations (Ridgway et al. 1980ApJ...235..126R) and (c) Michelson interferometry (Di Benedetto & Rabbia 1987A&A...188..114D; Dyck et al. 1996AJ....111.1705D; Perrin et al. 1998A&A...331..619P) for K-M giants, and (d) eclipsing binaries for M dwarfs. We also compare color-color relations and color-bolometric correction relations and find good agreement except for a few colors. The more realistic fluxes and spectra of the new model grids should enable accurate population synthesis models to be derived and permit the ready calibration of non-standard photometric passbands. As well, the theoretical bolometric corrections and temperature-color relations will permit reliable transformation from observed color magnitude diagrams to theoretical HR diagrams.
4680. ONC low-mass stars photometry
ID:
ivo://CDS.VizieR/J/AJ/121/1676
Title:
ONC low-mass stars photometry
Short Name:
J/AJ/121/1676
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have photometrically monitored ~3600 young, low-mass stars in four 45'x45' fields in the outer Orion Nebula cluster, surrounding but not including the Trapezium region.