- ID:
- ivo://CDS.VizieR/J/A+A/415/63
- Title:
- UBVRI surface brightness of 26 bright galaxies
- Short Name:
- J/A+A/415/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBVRI images of 26 bright spiral galaxies were decomposed in disks and bulges. Correlations of the resulting structural parameters are investigated, giving clues to the formation history of the bulges. We confirm that the large and bright bulges of early-type spirals are similar to elliptical galaxies. They were probably formed prior to the disks in a monolithic collapse or via early mergers. Late-type spirals have tiny and faint bulges with disk-like profiles. These bulges were probably formed after the disk in secular evolution processes, e.g. from a disk instability. The comparison of the color indices of corresponding spirals and bulges with population synthesis computations support above formation scenarios.
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- ID:
- ivo://CDS.VizieR/J/AJ/126/632
- Title:
- UBVRIz'HK' photometry of 2Ms CDFN X-ray sources
- Short Name:
- J/AJ/126/632
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical and near-infrared catalog for the X-ray sources in the 2Ms Chandra observation of the Hubble Deep Field North region. We have high-quality multicolor imaging data for all 503 X-ray point sources in the X-ray-selected catalog and reliable spectroscopic redshifts for 284. We spectroscopically identify six high-redshift (z>1) type II quasars (L_2-8keV_>10^44^ergs/s) in our sample. Our spectroscopic completeness for the R<=24 sources is 87%. The spectroscopic redshift distribution shows two broad redshift spikes that have clearly grown over those originally seen in the 1Ms exposure. The spectroscopically identified extragalactic sources already comprise 75% of the measured 2-8keV light. Redshift slices versus 2-8keV flux show that an impressive 54% of the measured 2-8keV light arises from sources at z<1 and 68% from sources at z<2.
- ID:
- ivo://CDS.VizieR/J/AJ/151/33
- Title:
- UBVRIz light curves of 51 Type II supernovae
- Short Name:
- J/AJ/151/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986-2003: the Cerro Tololo Supernova Survey, the Calan/Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.
- ID:
- ivo://CDS.VizieR/J/A+A/479/827
- Title:
- UBVR light curves of weak-line T Tauri stars
- Short Name:
- J/A+A/479/827
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- T Tauri stars exhibit variability on all timescales, whose origin is still debated. On WTTS the variability is fairly simple and attributed to long-lived, ubiquitous cool spots. We investigate the long term variability of WTTS, extending up to 20 years in some cases, characterize it statistically and discuss its implications for our understanding of these stars. We have obtained a unique, homogeneous database of photometric measurements for WTTS extending up to 20-years. It contains more than 9000 UBVR observations of 48 WTTS. All the data were collected at Mount Maidanak Observatory (Uzbekistan) and they constitute the longest homogeneous record of accurate WTTS photometry ever assembled. Definitive rotation periods for 35 of the 48 stars are obtained. Phased light curves over 5 to 20 seasons are now available for analysis. Light curve shapes, amplitudes and colour variations are obtained for this sample and various behaviors exhibited, discussed and interpreted. Our main conclusion is that most WTTS have very stable long term variability with relatively small changes of amplitude or mean light level. The long term variability seen reflects modulation in the cold spot distributions. Photometric periods are stable over many years, and the phase of minimum light can be stable as well for several years. On the long term, spot properties do change in subtle ways, leading to secular variations in the shape and amplitudes of the light curves.
- ID:
- ivo://CDS.VizieR/J/ApJ/630/784
- Title:
- UBVR observations of nearby galaxies
- Short Name:
- J/ApJ/630/784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce a data set of 142 mostly late-type spiral, irregular, and peculiar (interacting or merging) nearby galaxies observed in UBVR at the Vatican Advanced Technology Telescope (VATT), and we present an analysis of their radial color gradients.
- ID:
- ivo://CDS.VizieR/J/AN/316/225
- Title:
- UBVR photoelectric survey
- Short Name:
- J/AN/316/225
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of photoelectric stellar magnitudes and colours in the UBVR Johnson system in 47 sky areas with galaxies near the Main Galactic Meridian is presented. The catalogue includes 1141 stars within the V magnitude interval 4.5-15.5mag. The rms errors are +/-0.014, +/-0.026, +/-0.012, +/-0.016mag for stellar magnitudes V and colours (U-B), (B-V), (V-R), respectively. The catalogue contains accurate equatorial coordinates (alpha, delta)_1950.0_, too.
- ID:
- ivo://CDS.VizieR/J/other/KFNT/22.231
- Title:
- UBVR photometry in NGC 6913
- Short Name:
- J/other/KFNT/22.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CCD observations of a sky area in the NGC 6913 cluster were performed with the 2-meter telescope of the Terskol Peak Observatory (Northern Caucasus, Russian Federation). The magnitudes and coordinates of stars down to V=20mag were determined for a 7'x5' field. The equatorial coordinates of stars were obtained in the reference system of the USNO A2.0 catalog (Cat. <I/252>) with an accuracy of 0.35". The relationship between the instrumental photometric system and the Johnson UBVR system was derived.
- ID:
- ivo://CDS.VizieR/J/AJ/121/3114
- Title:
- UBVR photometry of NGC 6712 with VLT
- Short Name:
- J/AJ/121/3114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present extensive UBVR photometry of the Galactic globular cluster (GGC) NGC 6712 obtained with the ESO Very Large Telescope (VLT) which reaches down to 2 mag below the main-sequence turn-off and allows us for the first time to determine the age of this cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/240/262
- Title:
- UBVR photometry of the open cluster King 2
- Short Name:
- J/A+A/240/262
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present the Johnson-Cousins UBVR CCD photometry of the stars in King 2, an old open cluster towards the galactic anticenter. We have obtained the colour-magnitude diagram, the colour excess, the reddening, an estimate of the metallicity, and the distance modulus. The comparison of the observational colour-magnitude diagram with the theoretical simulations based on stellar models with convective overshoot shows that a major revision of the model structure is required. To this aim, we explore the possibility that the formulation of convective overshoot for stars in the mass range 1 to 2M_{sun}_ ought to be different from the one currently in use. The point of major uncertainty that we see to affect the stars in this domain is whether or not convective overshoot may erode the gradient in molecular weight in the regions surrounding the convective core. We find that models, in which this is not allowed to occur, better fit the overall morphology of the colour-magnitude diagram of King 2. In addition to this, analyzing the width of the main sequence band we suggest that a significant fraction of the stars are members of binary systems, and evaluate the range spanned by their mass ratios. Finally, we derive the luminosity function and the mass function for the main sequence stars of the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1632
- Title:
- UBVR(UIT) photometry of O and OB stars in SMC
- Short Name:
- J/AJ/127/1632
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of N*, the number of OB stars per association or cluster, appears to follow a universal power-law form (N*)^-2^ in the local universe. We evaluate the distribution of N* in the Small Magellanic Cloud using recent broadband optical and space-ultraviolet data, with special attention to the lowest values of N*. We find that the power-law distribution in N* continues smoothly down to N*=1. This strongly suggests that the formation of field massive stars is a continuous process with those in associations and that the field stars do not originate from a different star formation mode.
