Search

Start Over Subject galaxies Validation Level 2
3881. U-band photometry of 17 WINGS clusters
ID:
ivo://CDS.VizieR/J/A+A/561/A111
Title:
U-band photometry of 17 WINGS clusters
Short Name:
J/A+A/561/A111
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper belongs to a series presenting the WIde Field Nearby Galaxy-cluster Survey (WINGS). The WINGS project has collected wide-field, optical (B,V), and near-infrared (J,K) imaging as well as medium resolution spectroscopy of galaxies in a sample of 76 X-ray selected nearby clusters (0.04<z<0.07) with the aim of establishing a reference sample for evolutionary studies of galaxies and galaxy clusters. We present the U-band photometry of galaxies and stars in the fields of 17 clusters of the WINGS sample. We also extend the original B- and V-band photometry (WINGS-OPT) for 9 and 6 WINGS clusters to a larger field of view. We used both the new and already existing B-band photometry to obtain reliable (U-B) colors of galaxies within three fixed apertures in kpc. To this aim, we particular care the astrometric precision in the reduction procedure. Since not all the observations were taken in good transparency conditions, the photometric calibration was partly obtained by relying on the SDSS and WINGS-OPT photometry for the U- and optical bands, respectively. We provide U-band (also B- and V-band, where possible) total magnitudes of stars and galaxies in the fields of clusters. For galaxies only, the catalogs also provide geometrical parameters and carefully centered aperture magnitudes. The internal consistency of magnitudes was checked for clusters imaged with different cameras, while the external photometric consistency was obtained by comparison with the WINGS-OPT and SDSS surveys. The photometric catalogs presented here add the U-band information to the WINGS database for extending the spectral energy distribution (SED) of the galaxies, in particular in the ultraviolet (UV) wavelengths which are fundamental for deriving the star formation rate (SFR) properties.
3882. UBgRIJKs photometry in the FORS Deep Field
ID:
ivo://CDS.VizieR/J/A+A/398/49
Title:
UBgRIJKs photometry in the FORS Deep Field
Short Name:
J/A+A/398/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
The FORS Deep Field project is a multi-colour, multi-object spectroscopic investigation of a 7' times 7' region near the south galactic pole based mostly on observations carried out with the FORS instruments attached to the VLT telescopes. It includes the QSO Q0103-260 (z=3.36). The goal of this study is to improve our understanding of the formation and evolution of galaxies in the young Universe. In this paper the field selection, the photometric observations, and the data reduction are described. The source detection and photometry of objects in the FORS Deep Field is discussed in detail. A combined B and I selected UBgRIJKs photometric catalog of 8753 objects in the FDF is presented and its properties are briefly discussed. The formal 50% completeness limits for point sources, derived from the coadded images, are 25.64, 27.69, 26.86, 26.68, 26.37, 23.60 and 21.57 in U, B, g, R, I, J and Ks (Vega-system), respectively. A comparison of the number counts in the FORS Deep Field to those derived in other deep field surveys shows very good agreement.
3883. UBIc photometry of ACO2390 early-type galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/358/233
Title:
UBIc photometry of ACO2390 early-type galaxies
Short Name:
J/MNRAS/358/233
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate a spectroscopic sample of 48 early-type galaxies in the rich cluster Abell 2390 at z=0.23 and 48 early-type galaxies from a previously published survey of Abell 2218 at z=0.18. The spectroscopic data of A2390 are based on multi-object spectroscopy using the multi-object spectrograph for Calar Alto at the 3.5-m telescope on Calar Alto Observatory and are complemented by ground-based imaging using the 5.1-m Hale telescope and Hubble Space Telescope (HST) observations in the F555W and F814W filters.
3884. UBRI photometry of radio galaxies
ID:
ivo://CDS.VizieR/J/AJ/121/2381
Title:
UBRI photometry of radio galaxies
Short Name:
J/AJ/121/2381
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe a new estimate of the radio galaxy 1.4 GHz luminosity function and its evolution at intermediate redshifts (z~0.4). Photometric redshifts and color selection have been used to select B_J_<23.5 early-type galaxies from the Panoramic Deep Fields, a multicolor survey of two 25deg^2^ fields. Approximately 230 radio galaxies have then been selected by matching early-type galaxies with NVSS radio sources brighter than 5mJy. Estimates of the 1.4GHz luminosity function of radio galaxies measure significant evolution over the observed redshift range. For an {Omega}_M_=1 cosmology the evolution of the radio power is consistent with luminosity evolution where P(z)~P(0)(1+z)^K_L_^ and 3<K_L_<5. The observed evolution is similar to that observed for UVX and X-ray selected active galactic nuclei and is consistent with the same physical process being responsible for the optical and radio luminosity evolution of active galactic nuclei.
3885. UBR photometry of 39 elliptical galaxies
ID:
ivo://CDS.VizieR/J/AJ/100/1091
Title:
UBR photometry of 39 elliptical galaxies
Short Name:
J/AJ/100/1091
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained U,B, and R CCD surface photometry for a sample of 39 elliptical galaxies. For each galaxy we have determined the surface brightness profile, U-R and B-R color profiles, and the ellipticity and position angle profiles, all as function of major axis radius, using a two-dimensional ellipse fitting program. In addition, we have derived the sin and cos(3.theta) and 4.theta terms that describe the high-order deviations of the B and R isophotes from ellipses. While it is very common for ellipticals to display measurable 3.theta and 4.theta terms, the amplitudes of these terms rarely exceed 0.5%. The isophotes of elliptical galaxies are very well characterized by ellipses. The surface brightness and color profiles are given to radii at which the error in the profile reaches 0.1 mag from the uncertainty in the brightness of the night sky. We have carried out a series of simulations of the effects of seeing on luminosity and ellipticity profiles, to determine the radius beyond which the errors in our data from seeing are less than 0.05 mag and 0.02 in ellipticity. Measurable effects of seeing extend to surprisingly large radii, as much as 5-10 seeing radii, depending upon the ellipticity of the galaxy and the form of the surface brightness profile. Ellipticity and position angle profiles are usually the same in all passbands with no indication that the contours of constant color are more or less flattened than the isophotes, i.e., the isochromes and isophotes have the same shapes, but the insensitivity of the ellipticity to differences between these properties makes this a weak argument. The high-order terms, particularly the 3.theta terms, appear to be sensitive diagnostics for the existence of dust in ellipticals. We find that all the galaxies in this sample either become bluer in B-R and U-R with increasing radius or are of constant color. Mean values for the logarithmic gradients in color are -0.09 mag/arcsec2 per dex in radius in B-R, and -0.20 mag/arcsec2 per dex in radius in U-R. These color changes are consistent with a decrease in the [Fe/H] of approximately 0.20 per decade in radius. Surprisingly, there is no correlation of color gradient with luminosity. It is striking, however, that the lowest luminosity galaxies in the sample (i.e., those with M(B) > -20) do not show any color gradients. They have boxy isophotes, and are also rotationally flattened. While these properties may be related to the fact that they are companions of larger ellipsoidal systems, it could provide an important clue to the formation of ellipticals. Low luminosity ellipticals that are not close companions to giant ellipticals need to be studied.
3886. UBVI and HST photometry of young stellar clusters
ID:
ivo://CDS.VizieR/J/A+A/416/537
Title:
UBVI and HST photometry of young stellar clusters
Short Name:
J/A+A/416/537
Date:
21 Oct 2021
Publisher:
CDS
Description:
These tables contain a combination of ground-based and HST archive data for stellar clusters in 18 nearby spiral galaxies. Structural parameters for each cluster are measured on HST images, while UBVI photometry is from ground-based data obtained with the Danish 1.54m telescope at ESO La Silla, the 2.56m Nordic Optical Telescope in La Palma, Canary Islands, and the 3m Shane Telescope at Lick Observatory, California. Photometry in the STMAG system based on the HST data is also given (table 7) for each cluster for the available bandpasses.
3887. UBVI CCD photometry of Carina region stars
ID:
ivo://CDS.VizieR/J/A+A/592/A149
Title:
UBVI CCD photometry of Carina region stars
Short Name:
J/A+A/592/A149
Date:
21 Oct 2021
Publisher:
CDS
Description:
Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. However, in many cases, these studies only concentrated on the central region (Trumpler 14/16) or were not homogeneous. This latter aspect, in particular is crucial because very different ages and distances for key clusters have been claimed in recent years. The aim of this work is to study in detail an area of the Galactic plane in Carina, east ward Carina. We analyze the properties of different stellar populations and focus on a sample of open clusters and their population of young stellar objects and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. We obtained deep and homogeneous photometric data (UBVIKC) for six young open clusters: NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11, and 12, located in Carina at l~291, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional information from the literature, which includes stellar spectral classifications and near-infrared photometry from 2MASS. We finally developed a numerical code that allowed us to perform a homogeneous and systematic analysis of the data. Our results provide more reliable estimates of distances, color excesses, masses, and ages of the stellar populations in this direction. We estimate the basic parameters of the studied clusters and find that they identify two overdensities of young stellar populations located at about 1.8kpc and 2.8kpc, with E_(B-V)_~0.1-0.6. We find evidence of pre-main-sequence populations inside them, with an apparent coeval stellar formation in the most conspicuous clusters. We also discuss apparent age and distance gradients in the direction NW-SE. We study the mass distributions of the covered clusters and several others in the region (which we took form the literature). They consistently show a canonical IMF slope (the Salpeter one). We discover and characterise an abnormally reddened massive stellar population, scattered between 6.6 and 11kpc. Spectroscopic observations of ten stars of this latter population show that all selected targets were massive OB stars. Their location is consistent with the position of the Carina-Sagittarius spiral arm.
3888. UBVIc photometry of NGC 3077 center
ID:
ivo://CDS.VizieR/J/AN/325/307
Title:
UBVIc photometry of NGC 3077 center
Short Name:
J/AN/325/307
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present UBVIc photometry of starlike objects in the central region of NGC 3077. The colour-colour and colour-magnitude diagrams of the objects are discussed. Many of the objects under consideration, starlike from the ground, are probably dense young star clusters (super star clusters, SSC). Ages spreading over ~4 to ~150Myr are estimated for most of these objects. Sakai and Madore (2001ApJ...555..280S) found enhanced star formation ~30-125Myr ago also in the halo of this galaxy; thus, high star forming activity has occurred within the entire galaxy (centre and halo) since ~130..150Myr. Having ended in the outer regions about 30Myr ago, it is going on near the centre with full vigour.
3889. UBV imaging of irregular galaxies
ID:
ivo://CDS.VizieR/J/ApJS/162/49
Title:
UBV imaging of irregular galaxies
Short Name:
J/ApJS/162/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of UBV imaging of a large sample of irregular galaxies: 94 Im systems, 24 blue compact dwarfs (BCDs), and 18 Sm galaxies. We also include JHK imaging of 42 of these galaxies. The sample spans a large range in galactic parameters. Ellipse fit axial ratios, inclinations, and position angles are derived, integrated photometry and azimuthally averaged surface photometry profiles are determined, and exponential fits give the central surface brightnesses, scale lengths, and isophotal and half-power radii.
3890. UBVI photometry of NGC 7252
ID:
ivo://CDS.VizieR/J/AJ/114/2381
Title:
UBVI photometry of NGC 7252
Short Name:
J/AJ/114/2381
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new U, B, V, and I images of the prototypical merger remnant NGC 7252 obtained with the WFPC2 instrument of the Hubble Space Telescope. The photometry reaches about 3 mag deeper than the previous observations with WF/PCI and we detect 499 cluster candidates, most of them previously undiscovered. We can distinguish three populations of star clusters. We confirm the existence of a very luminous, blue population of clusters with a narrow range in color. Comparisons with Bruzual & Charlot (1996, in preparation) models incorporating a Salpeter stellar IMF show that the mean ages of these clusters are 650Myr for [Fe/H]=0.0 and 750 Myr if [Fe/H]=-0.3. Therefore, these are the clusters that formed during the merger event. The upper limit to the effective radii of these objects is 4.8+/-0.4pc (for D=64.4Mpc, H_0_=75), suggesting that they have physical properties like Galactic globular clusters. The second population of clusters is associated with the inner disk. Their (U-B) colors and reddening-free Q values indicate that their light is dominated by O stars and that they have ages less than 10Myr. However, with <R_eff_>=8.3+/-0.6pc, these objects may be more like stellar associations and they may not survive for a significant time. Finally, there is also evidence for the presence of the most luminous of the old, metal-poor globular clusters that belonged to the progenitor galaxies. The cluster luminosity function is a single power law with slope {alpha}~-1.8 down to a limiting magnitude of V=26. The current specific cluster frequency is S_N_=0.6+/-0.3 for old clusters and young clusters with M>10^5^M_{sun}_, but after the remnant has faded for about 15Gyr S_N_ will have increased to about 2.5. The central disk is now resolved into much finer detail than in earlier WF/PCI observations and the light profile of the nuclear region is consistent with a single power law with slope {gamma}=-1.26+/-0.03. After both the main body and the cluster system of NGC 7252 have aged, for several Gyr it may have the properties of a field elliptical.

Limit your search

more »

more »

more »

more »