- ID:
- ivo://CDS.VizieR/J/A+A/464/495
- Title:
- UBVI photometry of NGC 45 star clusters
- Short Name:
- J/A+A/464/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Star clusters are present in almost all types of galaxies. Here we investigate the star cluster population in the low-luminosity, unperturbed spiral galaxy NGC 45, which is located in the nearby Sculptor group. Both the old (globular) and young star-cluster populations are studied. Previous ground-based observations have suggested that NGC 45 has few if any "massive" young star clusters. We aim to study the population of lower-mass "open" star clusters and also identify old globular clusters that could not be distinguished from foreground stars in the ground-based data. Star clusters were identified using UBVI imaging from the Advanced Camera for Surveys (ACS) and the Wide Field Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope. From broad band colors and comparison with simple stellar population (SSP) models assuming a fixed metallicity, we derived the age, mass, and extinction. We also measured the radius for each star cluster candidate.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/408/1147
- Title:
- UBVI photometry of 4 open clusters
- Short Name:
- J/MNRAS/408/1147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry in the Johnson UBV and Kron-Cousins I systems down to V~22.0 for the open clusters NGC 2311, Trumpler 6, NGC 2432 and BH 54 and their surrounding fields. Trumpler 6 and BH 54 have never been studied before and so we provide, for the first time, estimates of their fundamental parameters. We obtained colour-magnitude diagrams (CMDs) and colour-colour diagrams cleaned from field star contamination by statistically subtracting stars in terms of spatial density, magnitude and colour distributions. Cluster angular radii were estimated from star counts in appropriate-sized boxes distributed throughout the entire observed fields. Using the cleaned CMDs and colour-colour diagrams, we applied sound photometric membership criteria to discriminate cluster members from interloper field stars. The interstellar extinction across the cluster fields derived from the 100-{mu}m dust emission full-sky maps can be considered uniform within the quoted uncertainties. The E(B-V) and E(V-I) colour excesses and the apparent distance moduli of the clusters were estimated from the fit of the zero-age main-sequence to the colour-colour diagrams and CMDs, respectively. Cluster ages were determined from the comparison of the four clusters' CMDs with solar metallicity theoretical isochrones of the Geneva group. All the clusters were found to be moderately young objects, their ages ranging between 60 and 250Myr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/2720
- Title:
- UBVI photometry of 5 open clusters
- Short Name:
- J/MNRAS/402/2720
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained CCD UBVI_KC_ photometry down to V~21.0 for the open clusters Berkeley 26, Czernik 27, Melotte 72, NGC 2479 and BH 37. The latter has never been studied before. Cluster stellar density profiles were obtained from star counts in appropriate-sized boxes distributed throughout the entire observed fields. Based on different measured indices, we estimate the ages of Berkeley 26, Melotte 72 and NGC 2479. On the other hand, we indicate possible solutions for the cluster fundamental parameters by matching theoretical isochrones which reasonably reproduce the main cluster features in their colour-magnitude diagrams. In the case of NGC 2479, the cluster E(BV) and E(VI) colour excesses and apparent distance modulus were estimated from the fit of the zero-age main sequence to the colour-colour and colour-magnitude diagrams, respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/502
- Title:
- UBVI photometry of 7 open clusters
- Short Name:
- J/MNRAS/428/502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New photometric material is presented for six outer disc supposedly old, Galactic star clusters: Berkeley 76, Haffner 4, Ruprecht 10, Haffner 7, Haffner 11 and Haffner 15, which are projected against the rich and complex Canis Major overdensity at 225{deg}<=l<=248{deg}, -7{deg}b<=-2{deg}. This CCD data set, in the UBVI passbands, is used to derive their fundamental parameters, in particular age and distance. Four of the program clusters turn out to be older than 1Gyr. This fact makes them ideal targets for future spectroscopic campaigns aiming at deriving their metal abundances. This, in turn, contributes to increase the number of well-studied outer disc old open clusters. Only Haffner 15, previously considered an old cluster, is found to be a young, significantly reddened cluster, member of the Perseus arm in the third Galactic quadrant. As for Haffner 4, we suggest an age of about half a Gyr. The most interesting result we found is that Berkeley 76 is probably located at more than 17kpc from the Galactic centre, and therefore is among the most peripherical old open clusters so far detected. Besides, for Ruprecht 10 and Haffner 7, which were never studied before, we propose ages larger than 1Gyr. All the old clusters of this sample are scarcely populated and show evidence of tidal interaction with the Milky Way, and are therefore most probably in advanced stages of dynamical dissolution.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A101
- Title:
- UBVI photometry towards (l=314,b=0)
- Short Name:
- J/A+A/536/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spiral structure of the Milky Way is nowadays receiving renewed attention thanks to the combined efforts of observational campaigns in different wavelength regimes, from the optical to the radio. We start in the paper the exploration of a number of key sectors (line of sights) in the inner Milky Way, where the spiral structure is still poorly known. We search for density enhancements of young stars that might plausibly be associated with spiral structure. To this aim we collect sufficiently wide-field UBVI photometry to allow us to probe in statistical sense the distribution in reddening and distance of young stars in the field. The intensive usage of U-band photometry - although heavily demanding in terms of observational efforts - ensures robust determination of reddening and hence distance for stars of spectral type earlier than A0, which are well-known spiral arm tracers, even though no spectroscopic information are available. The fields we use are large enough to include in most cases well-studied Galactic clusters, which we use as bench-marks to assess the quality and standardisation of the data, and to validate our method. We focus in this paper on the line of sight to the Galactic longitude l=314{deg}, where previous surveys already detected H{alpha} emitters at different standard of rest velocities, and hence distances. The difficulty, however, to translate velocity into distance make predictions on the spiral structure quite vague. First of all, we made exhaustive tests to show that our data-set is in the standard system, and calibrated our method using the two open clusters NGC 5617 and Pismis 19 which happen to be in the field, and for which we found estimates of the basic parameters in full agreement with the literature. We then applied the method to the general field stars and detected signatures of three different groups of stars, evenly distributed across the field of view, at 1.5^+0.5^_-0.2_, 2.5^+0.3^_-0.5_, and 5.1^+1.5^_-1.1_kpc, respectively. These distances are compatible with the location of the nowadays commonly accepted description of the Carina-Sagittarius and Scutum-Crux arms, at heliocentric distance of ~2 an 5kpc, respectively. As a consequence, we consider these groups to be good candidates to trace the location of these two inner arms. In line with previous studies, this investigation demonstrates once again how powerful the use of U-band photometry is to characterize ensembles of young stars, and make predictions on the spiral structure of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/AZh/71/618
- Title:
- UBVJHKLM Photometry of Nova Cygni 1992
- Short Name:
- J/AZh/71/618
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of photometric UBVJHKLM observations of Nova Cygni 1992 performed from the 83d until the 290th day after the nova outburst are presented. The accuracy of the brightness estimate was better than 0.03mag for UBVJHK, 0.05mag for L, and 0.1mag for M bands.
- ID:
- ivo://CDS.VizieR/J/A+A/394/617
- Title:
- UBVJHKLM photometry of R Corona Borealis
- Short Name:
- J/A+A/394/617
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of UBVJHKLM photometry of R CrB spanning the period from 1976 to 2001.
- ID:
- ivo://CDS.VizieR/J/A+A/457/637
- Title:
- UBVJHK synthetic photometry of Galactic O stars
- Short Name:
- J/A+A/457/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The development of powerful infrared observational techniques enables the study of very extincted objects and young embedded star-forming regions. This is especially interesting in the context of massive stars that form and spend a non negligible fraction of their life still enshrouded in their parental molecular cloud. Spectrophotometric calibrations are thus necessary to constrain the physical properties of heavily extincted objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/841/48
- Title:
- UBVR and IR photometry of SN 2011fe (Ia)
- Short Name:
- J/ApJ/841/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Hubble Space Telescope (HST) and the Large Binocular Telescope, we followed the evolution of the Type Ia supernova (SN Ia) 2011fe for an unprecedented 1840 days past B-band maximum light and over a factor of 7 million in flux. At 1840 days, the 4000-17000{AA} quasi-bolometric luminosity is just (420+/-20)L_{sun}_. By measuring the late-time quasi-bolometric light curve, we present the first confident detection of ^57^Co decay in a SN Ia light curve and estimate a mass ratio of log(^57^Co/^56^Co)=-1.59_-0.07_^+0.06^. We do not have a clean detection of ^55^Fe, but find a limit of ^55^Fe/^57^Co<0.22 with 99% confidence. These abundance ratios provide unique constraints on the progenitor system because the central density of the exploding white dwarf(s) dictates these nucleosynthetic yields. The observed ratios strongly prefer the lower central densities of double-degenerate models (^55^Fe/^57^Co=0.27) over the higher central densities of near-Chandrasekhar-mass single-degenerate models (^55^Fe/^57^Co=0.68). However, additional theoretical studies predicting isotopic yields from a broader range of progenitor systems are motivated by these unique observations. We will continue to observe SN 2011fe for another ~600 days with HST and possibly beyond.
- ID:
- ivo://CDS.VizieR/J/AZh/79/309
- Title:
- UBVR and spectroscopic observations of CI Cam
- Short Name:
- J/AZh/79/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric (UBVR) observations in 1998-2001 and medium-resolution spectroscopy obtained in the SAO in the same period for the B[e]/X-ray transient CI Cam display cyclic variations with a period of 1100 days.
