- ID:
- ivo://CDS.VizieR/J/AcA/59/349
- Title:
- NGC 1502 UBVIc photometry
- Short Name:
- J/AcA/59/349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of variability search in the field of the young open cluster NGC 1502. Eight variable stars were discovered. Of six other stars in the observed field that were suspected for variability, we confirm variability of two, including one beta Cep star, NGC 1502-26. The remaining four suspects were found to be constant in our photometry. In addition, UBVIc photometry of the well-known massive eclipsing binary SZ Cam was obtained.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/309/739
- Title:
- NGC 2660 UBVIc photometry
- Short Name:
- J/MNRAS/309/739
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD UBVI photometry of the intermediate old open cluster NGC 2660, covering from the red giant region to about seven magnitudes below the main sequence turn-off. Using the synthetic colour-magnitude diagram method, we estimate in a self-consistent way values for distance modulus [(m-M)_0_~12.2], reddening [E(B-V)~0.40], metallicity ([Fe/H] about solar) and age (t<=1Gyr). A 30 per cent population of binary stars turns out to be probably present.
- ID:
- ivo://CDS.VizieR/J/AJ/115/734
- Title:
- NGC 6231 UBVRI and H{alpha} photometry
- Short Name:
- J/AJ/115/734
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI and H{alpha} CCD photometry has been obtained for the young open cluster NGC 6231. From the R-H{alpha} color, a measure of the H{alpha} emission, we find 12 pre-main-sequence (PMS) members and seven possible PMS members in the cluster. Applying recent stellar evolutionary tracks and PMS evolutionary tracks, we derive the age, age spread, and initial mass function of the cluster. The initial mass function of NGC 6231 is a Gaussian with a turnover at logm~0.4 (m~2.5M_{Sun}_) and shows an abrupt decrease in the number of low-mass stars. Possible reasons for the suppression of low-mass star formation and star formation processes are discussed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/1095
- Title:
- NGC 6866 UBVRI photometry
- Short Name:
- J/MNRAS/453/1095
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD UBVRI photometry of the field of the open cluster NGC 6866. Structural parameters of the cluster are determined utilizing the stellar density profile of the stars in the field. We calculate the probabilities of the stars being physical members of the cluster, using their astrometric data, and perform further analyses using only the most probable members. The reddening and metallicity of the cluster were determined by independent methods. The LAMOST spectra and the ultraviolet excess of the F- and G-type main-sequence stars in the cluster indicate that the metallicity of the cluster is about the solar value. We estimated the reddening E(B-V)=0.074+/-0.050mag using the U-B versus B-V two-colour diagram. The distance modula, the distance and the age of NGC 6866 were derived as {mu}=10.60+/-0.10mag, d=1189+/-75pc and t=813+/-50Myr, respectively, by fitting colour-magnitude diagrams of the cluster with the PARSEC isochrones. The Galactic orbit of NGC 6866 indicates that the cluster is orbiting in a slightly eccentric orbit with e=0.12. The mass function slope x=1.35+/-0.08 was derived by using the most probable members of the cluster.
1775. NGC 3105 UBVR photometry
- ID:
- ivo://CDS.VizieR/J/A+A/616/A124
- Title:
- NGC 3105 UBVR photometry
- Short Name:
- J/A+A/616/A124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 3105 is a young open cluster hosting blue, yellow, and red supergiants. This rare combination makes it an excellent laboratory for constraining evolutionary models of high-mass stars. It has been poorly studied, and the fundamental parameters such as its age or distance are not well defined. We intend to characterise in an accurate way the cluster and its evolved stars, for which we derive for the first time atmospheric parameters and chemical abundances. We performed a complete analysis combining UBVR photometry with spectroscopy. We obtained spectra with classification purposes for 14 blue stars and high-resolution spectroscopy for an in-depth analysis of the six other evolved stars. We identify 126 B-type likely members within a radius of 2.7+/-0.6arcmin, which implies an initial mass, Mcl~=4100M_{sun}_. We find a distance of 7.2+/-0.7kpc for NGC 3105, placing it at R_GC_=10.0+/-1.2kpc. Isochrone fitting supports an age of 28+/-6Ma, implying masses around 9.5M_{aun}_ for the supergiants. A high fraction of Be stars (~25%) is found at the top of the main sequence down to spectral type b3. From the spectral analysis we estimate for the cluster an average v_rad_=+46.9+/-0.9km/s and a low metallicity, [Fe/H]=-0.29+/-0.22. We also have determined, for the first time, chemical abundances for Li, O, Na, Mg, Si, Ca, Ti, Ni, Rb, Y, and Ba for the evolved stars. The chemical composition of the cluster is consistent with that of the Galactic thin disc. An overabundance of Ba is found, supporting the enhanced s-process. NGC 3105 has a low metallicity for its Galactocentric distance, comparable to typical LMC stars. It is a valuable spiral tracer in a very distant region of the Carina-Sagittarius spiral arm, a poorly known part of the Galaxy. As one of the few Galactic clusters containing blue, yellow, and red supergiants, it is massive enough to serve as a test bed for theoretical evolutionary models close to the boundary between intermediate- and high-mass stars.
- ID:
- ivo://CDS.VizieR/J/A+A/372/95
- Title:
- NGC 2439 ubvy{beta} photometry
- Short Name:
- J/A+A/372/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The structure of the field surrounding the Galactic cluster NGC 2439 is studied utilizing uvby{beta} photometry of bright OB stars. We collate all photometric and kinematic data available to identify possible groupings. The stars of our sample show a large scatter in their distances, radial velocities, proper motions and reddenings. We conclude that they do not belong to a single stellar association. We find evidence of the existence of three coherent structures at distances of 370pc, 1kpc, and 2.6-3.2kpc. The high stellar density toward NGC 2439 is very likely due to a decreased absorption in this direction, which poses some doubt on the reality of the cluster. A comprehensive uvby{beta} study of NGC 2439 is required to clarify its nature. The spatial distribution of the stars and their reddening are used to characterise the spatial distribution of the visual extinction in the region. The results obtained confirm previously determined constraints on the formation mechanism of interstellar CH^+^ towards the NGC 2439 field.
- ID:
- ivo://CDS.VizieR/J/A+A/437/457
- Title:
- NGC 2548 uvbyH{beta} and proper motions
- Short Name:
- J/A+A/437/457
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep CCD photometry in the uvby-H{beta} intermediate-band system is presented for the cluster NGC 2548 (M 48). A complete membership analysis based on astrometric and photometric criteria is applied.
- ID:
- ivo://CDS.VizieR/J/A+A/470/585
- Title:
- NGC 2682 uvby-Hbeta photometry
- Short Name:
- J/A+A/470/585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following deep astrometric and photometric study of the cluster NGC 2682 (M 67), we are able to accurately determine its fundamental parameters. Being an old and rich cluster, M 67 is relevant for the analysis of the Galactic disk evolution. M 67 is well studied but lacks a wide and deep Stroemgren photometric study. The brightest stars of the open cluster M 67 were used as uvby-Hbeta standard stars in our studies of NGC 1817 and NGC 2548, and the extension of the field covered, as well as the number of observations, allowed us to obtain the best set of Stroemgren data ever published for this cluster. We discuss the results of our CCD uvby-Hbeta intermediate-band photometry, covering an area of about 50'x50' down to V~19. Moreover, a complete membership segregation based on astrometric and photometric criteria is obtained. The photometric analysis of a selected sample of stars yields a reddening value of E(b-y)=0.03+/-0.03, a distance modulus of V_0_-M_V_=9.7+/-0.2 and [Fe/H]=0.01+/-0.14. Through isochrone fitting we found an age of logt=9.6+/-0.1 (4.2+/-0.2Gyr). A clump of approximately 60 stars around V=16, (b-y)=0.4 could be interpreted as a population of pre-cataclysmic variable stars (if members), or as a stream of field G-type stars placed at twice the distance of the cluster (if non-members).
- ID:
- ivo://CDS.VizieR/J/AJ/141/81
- Title:
- NGC 2419 variable star population
- Short Name:
- J/AJ/141/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B, V, and I CCD light curves for 101 variable stars belonging to the globular cluster NGC 2419, 60 of which are new discoveries, based on data sets obtained at the Telescopio Nazionale Galileo, the Subaru telescope, and the Hubble Space Telescope. The sample includes 75 RR Lyrae stars (38 RRab, 36 RRc, and one RRd), one Population II Cepheid, 12 SX Phoenicis variables, two delta Scuti stars, three binary systems, five long-period variables, and three variables of uncertain classification.
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/1996
- Title:
- NGC 6712 variable stars VI light curves
- Short Name:
- J/MNRAS/493/1996
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of VI CCD time-series photometry of globular cluster NGC 6712. Our main goal is to study the variable star population as indicators of the cluster mean physical parameters. We employed the Fourier decomposition of RR Lyrae light curves to confirm that [Fe/H]_UVES_=-1.0+/-0.05 is a solid estimate. We estimated the reddening to the cluster as E(B-V)=0.35+/-0.04 from the RRab stars colour curves. The distance to the cluster was estimated using three independent methods which yielded a weighted mean distance <d>=8.1+/-0.2kpc. The distribution of RRab and RRc stars on the horizontal branch shows a clear segregation around the first overtone red edge of the instability strip, which seems to be a common feature in OoI-type cluster with a very red horizontal branch. We carried out a membership analysis of 60447 stars in our field of view (FoV) using the data from Gaia-DR2 and found 1529 likely members; we possess the light curves of 1100 among the member stars. This allowed us to produce a clean colour-magnitude diagram, consistent with an age of 12Gyr, and enabled us to discover close unresolved contaminants for several variable stars. From the proper motion analysis, we found evidence of non-member stars in the FoV of the cluster being tidally affected by the gravitational pull of the bulge of the Galaxy. We found that the RRab variable V6, shows a previously undetected Blazhko effect. Finally, we report 16 new variables of the EW-type (9) and SR-type (7).
