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- ID:
- ivo://CDS.VizieR/J/A+A/404/927
- Title:
- UBVRI photometry of NGC 2422
- Short Name:
- J/A+A/404/927
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVRI photometry of the open cluster NGC 2422 (age~10^8^yr) down to a limiting magnitude V=~19. These data are used to derive the Luminosity and Mass Functions and to study the cluster spatial distribution. By considering the color-magnitude diagram data and adopting a representative cluster main sequence, we obtained a list of candidate cluster members based on a photometric criterion.
- ID:
- ivo://CDS.VizieR/J/other/NewA/17.160
- Title:
- UBVRI photometry of Stock 18
- Short Name:
- J/other/NewA/17.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out deep (V~21mag) UBVRI photometric study of the star cluster Stock 18. These along with archival Infrared data have been used to derive the basic cluster parameters and also to derive the basic cluster parameters and also to study the star for formation processes in and around the cluster region. The distance to the cluster is derived as 2.8+/-0.2kpc while its age is estimated as 6.0+/-2.0Myr. Present study indicates that interstellar reddening is normal in the direction of the cluster. The mass function slope is found to be -1.37+/-0.27 for the mass range 1<M/M_{sun}_<11.9. There is no evidence found for the effect of mass segregation in main-sequence stars of the cluster. A young stellar population with age between 1-2Myr have been found in and around the cluster region. The presence of IRAS and AKARI sources with MSX intensity map also show the youth of the Sh2-170 region.
- 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.
- 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/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/MNRAS/349/641
- Title:
- VIc, CT1 magnitudes in Trumpler 5
- Short Name:
- J/MNRAS/349/641
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations in the Johnson V, Kron-Cousins I and the Washington system C and T_1_ passbands have been used to generate colour-magnitude diagrams (CMDs) reaching down to V~21.0mag and T_1_~19.0 for Trumpler 5, an old open cluster located towards the Galactic anticentre. Our data analysis confirms the existence of non-uniform extinction over the face of the cluster, the mean E(V-I) and E(C-T_1_) values being 0.80+/-0.05 and 1.17+/-0.15, respectively. Through comparison of the cluster CMDs with theoretical isochrones of the Geneva group, Washington Standard Giant Branches and measures of V and T_1_ indices, we derive the following values for the cluster apparent distance modulus, age, and metallicity: V-M_V_=13.80+/-0.30 (corresponding to a distance from the Sun of 2.4+/-0.5 kpc and 0.04kpc above the Galactic plane), t=5.0+/-0.5Gyr and [Fe/H]=-0.30+/-0.15. We estimate the cluster angular radius to be about 7.7 arcmin (=5.4pc) from star counts carried out within and outside the cluster field.
- ID:
- ivo://CDS.VizieR/J/MNRAS/340/1249
- Title:
- VIc magnitudes in NGC 2194
- Short Name:
- J/MNRAS/340/1249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD VI_KC_ photometry down to V~21mag in the field of the rich open cluster NGC 2194, which is projected towards the Galactic anticentre direction. We measured V magnitudes and V-I colours for a total of 2515 stars in a field of 13.6x13.6arcmin^2^, supplemented with CCD photometry in the C, M and T_1_ filters of the Washington system and photoelectric CMT_1_T_2_ photometry of 20 red giant candidates, using the 0.9-m telescope at the Cerro Tololo Inter-American Observatory (CTIO), Chile, on 1997 December 23-24.
- ID:
- ivo://CDS.VizieR/J/A+A/410/879
- Title:
- VRI CCD photometry of NGC 2126
- Short Name:
- J/A+A/410/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first CCD photometric observations of the northern open cluster NGC 2126. Data were taken on eight nights in February and December 2002 with a total time span of ~57 hours. Almost 1000 individual V-band frames were examined to find short-period variable stars. We discovered six new variable stars, of which one is a promising candidate for an eclipsing binary with a pulsating component. Here we present single-epoch colours and magnitudes for ~800 stars in the field and the light curve data for the six variables. Note that the coordinates in ngc2126.dat are not particularly accurate because of the applied crude astrometry (errors up to +/-1-2arcsec are quite likely close to the edge). For variable star identification, consult table3.dat.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A63
- Title:
- W51 OB stars NIR spectroscopy
- Short Name:
- J/A+A/624/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The interplay between the formation of stars, stellar feedback and cloud properties strongly influences the star formation history of giant molecular clouds. The formation of massive stars leads to a variety of stellar clusters, ranging from low stellar density OB associations to dense, gravitationally bound starburst clusters. We aimed at identifying the massive stellar content and reconstructing the star formation history of the W51 giant molecular cloud. We performed near-infrared imaging and K-band spectroscopy of the massive stars in W51. We analysed the stellar populations using colour-magnitude and colour-colour diagrams and compared the properties of the spectroscopically identified stars with stellar evolution models. We derive the ages of the different sub-clusters in W51 and, based on our spectroscopy derive an age for W51 of 3Myrs or less. The age of the P Cygni star LS1 and the presence of two still forming proto- clusters suggests that the star formation history of W51 is more complex than a single burst. We did not find evidence for triggered star formation and we concluded that the star formation in W51 is multi seeded. We finally concluded that W51 is a OB association where different sub-clusters form over a time span of at least 3-5Myrs.