- ID:
- ivo://CDS.VizieR/J/A+A/631/A124
- Title:
- NGC 2345 Stroemgren photometry
- Short Name:
- J/A+A/631/A124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 2345 is a young open cluster hosting seven blue and red supergiants, low metallicity and a high fraction of Be stars which makes it a privileged laboratory to study stellar evolution. We aim to improve the determination of the cluster parameters and study the Be phenomenon. Our objective is also to characterise its seven evolved stars by deriving their atmospheric parameters and chemical abundances. We performed a complete analysis combining for the first time ubvy photometry with spectroscopy as well as Gaia Data Release 2. We obtained spectra with classification purposes for 76 stars and high-resolution spectroscopy for an in-depth analysis of the blue and red evolved stars. We identify a new red supergiant and 145 B-type likely members within a radius of 18.7+/-1.2arcmin, which implies an initial mass, M_cl_~5,200M_{sun}_. We find a distance of 2.5+/-0.2kpc for NGC 2345, placing it at R_GC_=10.2+/-0.2kpc. Isochrone fitting supports an age of 56+/-13Ma, implying masses around 6.5M_{sun}_ for the supergiants. A high fraction of Be stars (~10%) is found. From the spectral analysis we estimate for the cluster an average v_rad}_=+58.6+/-0.5km/1 and a low metallicity, [Fe/H]=-0.28+/-0.07. We also have determined 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. One of the K supergiants, S50, is a Li-rich star, presenting an A(Li)~2.1. An overabundance of Ba is found, supporting the enhanced s-process. NGC 2345 has a low metallicity for its Galactocentric distance, comparable to typical LMC stars. It is massive enough to serve as a testbed for theoretical evolutionary models for massive intermediate-mass stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/142/127
- Title:
- NGC 5822 UBVI and uvbyCaH{beta} photometry
- Short Name:
- J/AJ/142/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 5822 is a richly populated, moderately nearby, intermediate-age open cluster covering an area larger than the full moon on the sky. A CCD survey of the cluster on the UBVI and uvbyCaH{beta} systems shows that the cluster is superposed upon a heavily reddened field of background stars with E(B-V)>0.35mag, while the cluster has small and uniform reddening at E(b-y)=0.075+/-0.008mag or E(B-V)=0.103+/-0.011mag, based upon 48 and 61 probable A and F dwarf single-star members, respectively. The errors quoted include both internal photometric precision and external photometric uncertainties.
- 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/A+A/363/1081
- Title:
- Non-linear limb-darkening law for LTE models
- Short Name:
- J/A+A/363/1081
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new non-linear limb-darkening law, based on the Least-Squares Method (LSM), is presented. This law is able to describe the intensity distribution much more accurately than any of the old ones given that the differences I(model)-I(fitting) are of some order of magnitude smaller than those derived from other approximations. This new law shows several advantages: it represents well the intensity distribution, the flux is conserved with high accuracy and it permits the use of a single law for the whole HR Diagram since that the bi-parametric laws are only marginally valid in certain range of effective temperatures. The limb-darkening coefficients are computed for the 12 commonly used photometric bands u v b y U B V R I J H K. Bolometric and monochromatic calculations are also available. The computations are presented for 19 metallicities ranging from 10^-5^ up to 10^+1^ solar abundances, with log(g) varying between 0 and 5.0 and effective temperatures between 2000K-50000K. Results for microturbulent velocities of 0, 1, 2, 4, 8 km/s are also available. With this set of data it was possible to investigate, for the first time, the influence of such parameters in the limb-darkening. Limb-brightening, instead of limb-darkening, was detected for some models. It is shown that the limb-darkening coefficients derived using the Flux Conservation Method (FCM) do not describe very well the intensity distribution, mainly near the border of the disk. On the contrary, the present coefficients, based on the LSM, represent very well the function I({mu}) at any part of the disk for any filter or wavelength, log(g), effective temperature, metallicity and microturbulent velocity. The results are presented here as synthetic tables containing the limb-darkening coefficients. The 46 tables announced in the paper are also accessible as the "original.tar" file.
- ID:
- ivo://CDS.VizieR/J/A+A/472/565
- Title:
- NW Ser and V1446 Aql uvby light curves
- Short Name:
- J/A+A/472/565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present accurate photometric time series of two Be stars: NW Ser and V1446 Aql. Both stars were observed at the Observatorio de Sierra Nevada (Granada) in July 2003 with an automatic four-channel Stroemgren photometer. We also present a preliminary theoretical study showing that the periodic variations exhibited by these stars can be due to pulsation.
- ID:
- ivo://CDS.VizieR/II/146
- Title:
- Observations of the Ap Star HR 1217 from 1980-86
- Short Name:
- II/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This file contains magnitudes from nearly 50,000 40 second observations of the rapidly oscillating Ap star HR 1217 obtained during nearly 600 hours of observation at various observatories from 1980 to 1986. Most of the observations were made through Johnson B filters, but some were made through other filters. All data in this file were included in a paper entitled The high-overtone p-mode spectrum of the rapidly oscillating Ap star HR 1217 (HD 24712) by Kurtz et al. (1989MNRAS.240..881K) and described in the CDS Inf. Bull. (Kurtz 1989). Much of the information published in Kurtz et al. (1989) had been gathered from previously published literature, and some had been obtained by a team established for that paper. Each record holds one observation with the Heliocentric Julian Date given to 5 decimal accuracy and the magnitude given to 4 decimal accuracy. The observations are grouped so that all observations from a single night from each observatory are listed together. The data published in Kurtz et al. (1989) included observations previously published as follows: Julian Dates Source of data ------------ -------------- JD2444540-2444643 Kurtz (1982MNRAS.200..807K) JD2444849-2444953 Kurtz & Seeman (1983MNRAS.205...11K) JD2445661-2445664 H. J. Wood (unpublished) JD2445690-2445693 Kurtz, Schneider & Weiss (1985MNRAS.215...77K) JD2446712-2446784 original (Kurtz et al. 1989MNRAS.240..881K)
- ID:
- ivo://CDS.VizieR/J/A+A/352/600
- Title:
- O & B stars uvby-Hbeta photometry. I.
- Short Name:
- J/A+A/352/600
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stroemgren and H{beta} photometry of OB-stars generally brighter than 9.5mag in the Canis Major - Puppis - Vela region of Milky Way is reported. The observations are based on the Milky Way luminous-star (LS) identifications and are designed to create a complete, magnitude-limited sample of LS for this field. We present new uvby photometry for 127 LS and H{beta} photometry for 25 of them. These observations are part of an ongoing effort to improve the completeness of the existing uvby{beta} data-base for the bright OB-type stars in the Milky Way, with the aim to investigate the structure of selected star-forming regions.
- ID:
- ivo://CDS.VizieR/J/A+A/352/605
- Title:
- O & B stars uvby-Hbeta photometry. II.
- Short Name:
- J/A+A/352/605
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stroemgren and H{beta} photometry of O and B type stars, generally brighter than 10mag is presented for the fields of the galactic OB associations Monoceros OB2, Canis Major OB1 and Collinder 121. The observations are based on the PPM catalogue identifications and are designed to improve the completeness of the existing uvby{beta} data for the bright early-type stars in these fields. We present new uvby photometry for 343 stars and H{beta} photometry for 213 of them. These observations are part of our effort to study the structure of selected star-forming regions in the Milky Way, utilizing uvby{beta} photometry.
