- ID:
- ivo://CDS.VizieR/J/MNRAS/339/44
- Title:
- UBVRI photometry of Tr 14, Tr 15 and Tr 16
- Short Name:
- J/MNRAS/339/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a large-scale imaging photometric study of the stellar population in the northern part of NGC 3372 in the UBVRIJHK bands with a wavelength coverage from 0.33 to 2.5{mu}m. The observations were made at Las Campanas Observatory. The optical CCD mosaics cover an area approximately of 32x22arcmin^2^ centred between the Tr 14 and Tr 16 clusters. The survey was extended to cover 12x12arcmin^2^ at the location of Tr 15. Near-infrared NICMOS3 mosaics covering the areas occupied by these clusters were obtained in the JHK photometric bands. By means of star counts in V, the centres and sizes of each cluster were redetermined yielding: Tr 14 (r=264"), Tr 15 (r=320") and Tr 16 (r=320"). It was confirmed that Cr 232 is not a true cluster. Multicolour optical photometry was obtained for 4152 stars. Two colour and colour-magnitude diagrams are presented and analysed for each individual cluster and compared to those of the field. We confirm the widespread variations in the dust density and also in the dust size distribution leading to widely different values of A_V_and reddening laws towards Tr 14 and Tr 16. No spatial patterns were found for these variations. Spectroscopic parallaxes were computed and the results are consistent with all three clusters being at a similar distance from the Sun (<d>=2.7kpc) but the data have shown very large scatter in both A_V_and d. Analyses of the extinction-corrected colour-magnitude diagrams suggest ages between 3 and 60 million years for the stars in Tr 15 and between less than 1 and 6 million years for Tr 14 and Tr 16. A small number of infrared-excess stars were found in Tr 16 and Tr 14 but not in Tr 15. The distribution of stars in Tr 14 seen in the near-infrared suggests that this cluster is partially embedded in a molecular cloud. This molecular cloud extends towards the west reaching its highest density, marked by a CO peak emission, some three arcmin to the south-west of the nucleus of Tr 14. The rich ultraviolet field created by the Tr 14 stars ionizes most of the visible HII region in its vicinity and most of the radio HII region Car I. Evidence is found of ionization fronts leading into the molecular cloud, which appears to be "wrapping" the Tr 14 cluster. Deep JHK images of the Car I region reveal the presence of an embedded stellar population illuminating a large infrared reflection nebula. It includes at least one O9-B0 star associated with an ultracompact HII region. Nebulous 2.2{mu}m emission from three of the mid-infrared sources in the Tr 14 region is also found.
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- ID:
- ivo://CDS.VizieR/J/A+A/379/136
- Title:
- UBVRI photometry of 3 young open clusters
- Short Name:
- J/A+A/379/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present and analyze CCD UBVRI photometry in the region of the three young open clusters NGC 3114, Collinder 228, and vdB-Hagen 99, located in the Carina spiral feature. NGC 3114 lies in the outskirts of the Carina nebula. We found 7 star members in a severely contaminated field, and obtain a distance of 950pc and an age less than 3x10^8^yrs. Collinder 228 is a younger cluster (8x10^6^yrs), located in front of the Carina nebula complex, for which we identify 11 new members and suggest that 30% of the stars are probably binaries. As for vdB-Hagen 99, we add 4 new members, confirming that it is a nearby cluster located at 500pc from the Sun and projected toward the direction of the Carina spiral arm. Observations were conducted at La Silla on April 13-16, 1996, with the 0.92m ESO-Dutch telescope.
- 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.
- 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/A+A/426/827
- Title:
- ubvyH{beta} photometry in NGC 1817 / 1807
- Short Name:
- J/A+A/426/827
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue of accurate uvby-H{beta} and J2000 coordinates for 7842 stars in an area of 65'x40' around NGC 1817. We mark the selection of probable members of NGC 1817, combining this photometric study with the previous astrometric analysis (Balaguer-Nunez et al. 2004, Cat. <J/A+A/426/819>). Also given is the cross-identification of stars in common with the astrometry (Balaguer-Nunez et al. 2004, Cat. <J/A+A/426/819>), WEBDA (http://obswww.unige.ch/WEBDA), Hipparcos (ESA, 1997, Cat. <I/239>), Tycho-2 (Hog et al., 2000, Cat. <I/250>) and USNO-A2 (Monet et al., 1998, Cat. <I/252>) catalogues.
- ID:
- ivo://CDS.VizieR/J/A+A/364/455
- Title:
- ubvy photometry of LMC/SMC B stars
- Short Name:
- J/A+A/364/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The individual reddenings for B stars in two fields in the Small Magellanic Cloud (SMC) and two fields in the Large Magellanic Cloud (LMC) are determined by means of Stroemgren uvby CCD photometry. In both LMC fields we find a foreground reddening of E(B-V)=0.085+/-0.02, and for the SMC fields we find E(B-V)=0.070+/-0.02. In addition to the foreground reddening we find contributions from reddening intrinsically in the Clouds up to E(B-V)~0.21. The intrinsic contribution is not correlated with position within our ~6'x4.5' CCD fields but varies in an essentially random way. Unless the reddening is measured for a particular object, it will be uncertain by +/-0.035 (best case, far from the central bars) to more than +/-0.10 (close to the central bars). The Stroemgren uvby photometry has been used to derive metallicities for GK giant stars in the observed fields. Adopting average reddenings we obtain mean metallicities which are consistent with those found from spectroscopic studies of F and G supergiants (Westerlund, 1997, The Magellanic Clouds, Cambridge University Press), but with a considerable scatter in the derived metallicities, from [Fe/H]=~-2.0 to [Fe/H]>0. A significant fraction of the scatter is, however, due to reddening variations rather than being intrinsic. The possible existence of high metallicity stars should be investigated further using spectroscopic methods.
- ID:
- ivo://CDS.VizieR/J/ApJS/127/1
- Title:
- UGRK Photometry in the Hubble Deep field region
- Short Name:
- J/ApJS/127/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detection and photometry of sources in the U_n_, G, {R}, and K_s_ bands in a 9x9 arcmin^2^ region of the sky, centered on the Hubble Deep Field, are described. The data permit construction of complete photometric catalogs to roughly U_n_=25, G=26, {R}=25.5, K_s_=20 mag and significant photometric measurements somewhat fainter. Galaxy catalogs selected in the {R} and K_s_ bands are presented, containing 3607 and 488 sources in field areas of 74.8 and 59.4arcmin^2^, to {R}=25.5 and K_s_=20mag.
- ID:
- ivo://CDS.VizieR/J/A+A/394/479
- Title:
- uvby{beta} photometry of h and chi Per
- Short Name:
- J/A+A/394/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD uvby{beta} photometry for stars in the nuclei of the young double cluster {h} and {chi} Persei. We find that the reddening is highly variable through the {h} Per nucleus, increasing from west to east, with values ranging from E(b-y)=0.328+/-0.022 in the western part to E(b-y)=0.465+/-0.025 in the south-east. Towards {chi} Persei the reddening is fairly constant, with E(b-y)=0.398+/-0.025. Both clusters share a common distance modulus of 11.7+/-0.1mag, and an age of logt=7.10+/-0.05 years.
- ID:
- ivo://CDS.VizieR/J/MNRAS/358/66
- Title:
- uvby{beta} photometry of NGC 663
- Short Name:
- J/MNRAS/358/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD uvby{beta} photometry for stars in the central area of the young open cluster NGC 663. We find that the reddening is highly variable, with values ranging from E(b-y)=0.639+/-0.032 in the central part to E(b-y)=0.555+/-0.038 in the south-east. The distance modulus is found to be 11.6+/-0.1mag. (2.1kpc), and the age logt=7.25+/-0.1 years (25+7/-5Myr).
- ID:
- ivo://CDS.VizieR/J/AJ/150/134
- Title:
- uvbyCaH{beta} photometry of NGC 752
- Short Name:
- J/AJ/150/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precision uvbyCaH{beta} photometry of the nearby old open cluster, NGC752, is presented. The mosaic of CCD fields covers an area ~42' on a side with internal precision at the 0.005-0.010mag level for the majority of stars down to V~15. The CCD photometry is tied to the standard system using an extensive set of published photoelectric observations adopted as secondary standards within the cluster. Multicolor indices are used to eliminate as nonmembers a large fraction of the low probability proper-motion members near the faint end of the main sequence, while identifying 24 potential dwarf members between V=15.0 and 16.5, eight of which have been noted before from Vilnius photometry. From 68 highly probable F dwarf members, we derive a reddening estimate of E(b-y)=0.025+/-0.003 (E(B-V)=0.034+/-0.004), where the error includes the internal photometric uncertainty and the systematic error arising from the choice of the standard (b-y,H{beta}) relation. With reddening fixed, [Fe/H] is derived from the F dwarf members using both m_1_ and hk, leading to [Fe/H]=-0.071+/-0.014(sem) and -0.017+/-0.008(sem), respectively. Taking the internal precision and possible systematics in the standard relations into account, [Fe/H] for NGC 752 becomes -0.03+/-0.02. With the reddening and metallicity defined, we use the Victoria-Regina isochrones on the Stromgren system and find an excellent match for (m-M)=8.30+/-0.05 and an age of 1.45+/-0.05Gyr at the appropriate metallicity.
