On the metallicity of open clusters

Paunzen, E.; Heiter, U.; Netopil, M.; Soubiran, C.

doi:10.1051/0004-6361/201014131

Cited by 48 publications

(52 citation statements)

References 93 publications

(98 reference statements)

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“…As emphasized by Paunzen & Netopil (2006), Paunzen et al (2010), and Moitinho (2010), these large discrepancies of the distance moduli, distances, and ages stem from the differences between the heavy-element abundances and the reddenings of the literature as compared to this work, as seen in Table 7. Moreover, the variety of theoretical and observational ZAMSs used in the literature has also been responsible in part for incurring these differences.…”

Section: Correlations Of the Interstellar Reddeningsmentioning

confidence: 64%

CCD UBV(RI)C photometry of twenty open clusters

Oralhan¹,

Karataş²,

Schuster³

et al. 2015

New Astronomy

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Fundamental astrophysical parameters have been derived for 20 open clusters (OCs) using CCD UBV(RI) C photometric data observed with the 84 cm telescope at the San Pedro Mártir National Astronomical Observatory, México.The interstellar reddenings, metallicities, distances, and ages have been compared to the literature values. Significant differences are usually due to the usage of diverse empirical calibrations and differing assumptions, such as concerning cluster metallicity, as well as distinct isochrones which correspond to differing element-abundance ratios, internal stellar physics, and photometric systems. Different interstellar reddenings, as well as varying reduction and cluster-membership techniques, are also responsible for these kinds of systematic differences and errors.The morphological ages, which are derived from the morphological indices (δV and δ1) in the CM diagrams, are in good agreement with the isochrone ages of 12 OCs, those with good red clump (RC) and red giant (RG) star candidates. No metal abundance gradient is detected for the range 6.82 ≤ R GC ≤ 15.37 kpc, nor any correlation between the cluster ages and metal abundances for these 20 OCs.Young, metal-poor OCs, observed here in the third Galactic quadrant, may be associated with stellar over-densities, such as that in Canis Major (Martin et al.) and the Monoceros Ring (Newberg et al.), or signatures of past accretion events, as discussed by Yong et al. and Carraro et al.

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Section: Correlations Of the Interstellar Reddeningsmentioning

confidence: 64%

CCD UBV(RI)C photometry of twenty open clusters

Oralhan¹,

Karataş²,

Schuster³

et al. 2015

New Astronomy

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“…In total, we measured 34 stars in the cluster area, but found no significant deviating Δa values for this young (30 Myr) A42, page 6 of 8 and rather metal-poor (−0.47(10) dex; Paunzen et al 2010) aggregate.…”

Section: Ngc 4103mentioning

confidence: 79%

“…The derived masses range from 2.4 M to 2.9 M which corresponds to early A-types. The overall metallicity of NGC 2437 is solar (Paunzen et al 2010). …”

Section: Ngc 2437mentioning

confidence: 99%

Photoelectric search for peculiar stars in open clusters

Paunzen

Netopil

Maitzen³

et al. 2014

A&A

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Context. The chemically peculiar (CP) stars of the upper main sequence are mainly characterized by strong overabundances of heavy elements. Two subgroups (CP2 and CP4) have strong local magnetic fields which make them interesting targets for astrophysical studies. This star group, in general, is often used for the analysis of stellar formation and evolution in the context of diffusion as well as meridional circulation. Aims. In continuation of a long term study of CP stars (initiated in the 1980s), we present new results based on photoelectric measurements for ten open clusters that are, with one exception, younger than 235 Myr. Observations in star clusters are favourable because they represent samples of stars of constant age and homogeneous chemical composition. Methods. The very efficient tool of Δa photometry was applied. It samples the flux depression at 5200 Å typically for CP stars. In addition, it is able to trace emission line Be/Ae and λ Bootis stars. Virtually all CP2 and CP4 stars can be detected via this tool, and it has been successfully applied even in the Large Magellanic Cloud. For all targets in the cluster areas, we performed a kinematic membership analysis. Results. We obtained new photoelectric Δa photometry of 304 stars from which 207 objects have a membership probability higher than 50%. Our search for chemically peculiar objects results in fifteen detections. The stars have masses between 1.7 M and 7.7 M and are between the zero-and terminal-age-main-sequence. We discuss the published spectral classifications in the light of our Δa photometry and identify several misclassified CP stars. We are also able to establish and support the nature of known bona fide CP candidates. Conclusions. It is vital to use kinematic data for the membership determination and also to compare published spectral types with other data, such as Δa photometry. There are no doubts about the accuracy of photoelectric measurements, especially for stars brighter than 10th magnitude. The new and confirmed CP stars are interesting targets for spectroscopic follow-up observations to put constraints on the formation and evolution of CP stars.

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“…Authors studying this cluster usually assume solar metallicity (e.g., Moitinho et al 1997;McSwain et al 2008). The only metallicity determination available in the literature to date, to our knowledge, is [Fe/H] = −0.47 proposed by Tadross (2003) and repeated by Paunzen et al (2010), based on the mean ultraviolet excess δ(U − B) of bright dwarfs from the photometry of Moitinho et al (1997). The reliability of the estimation cannot be easily established, though (membership of the dwarfs, uncertainty of the metallicity estimate), and we therefore do not report this value in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Stellar variability in open clusters

Mowlavï¹,

Barblan²,

Saesen³

et al. 2013

A&A

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Aims. We analyze the population of periodic variable stars in the open cluster NGC 3766 based on a 7-year multiband monitoring campaign conducted on the 1.2 m Swiss Euler telescope at La Silla, Chili. Methods. The data reduction, light curve cleaning, and period search procedures, combined with the long observation time line, allowed us to detect variability amplitudes down to the millimagnitude (mmag) level. The variability properties were complemented with the positions in the color-magnitude and color-color diagrams to classify periodic variable stars into distinct variability types. Results. We find a large population (36 stars) of new variable stars between the red edge of slowly pulsating B (SPB) stars and the blue edge of δ Sct stars, a region in the Hertzsprung-Russell (HR) diagram where no pulsation is predicted to occur based on standard stellar models. The bulk of their periods ranges from 0.1 to 0.7 d, with amplitudes between 1 and 4 mmag for the majority of them. About 20% of stars in that region of the HR diagram are found to be variable, but the number of members of this new group is expected to be higher, with amplitudes below our mmag detection limit. The properties of this new group of variable stars are summarized and arguments set forth in favor of a pulsation origin of the variability, with g-modes sustained by stellar rotation. Potential members of this new class of low-amplitude periodic (most probably pulsating) A and late-B variables in the literature are discussed. We additionally identify 16 eclipsing binary, 13 SPB, 14 δ Sct, and 12 γ Dor candidates, as well as 72 fainter periodic variables. All are new discoveries. Conclusions. We encourage searching for this new class of variables in other young open clusters, especially in those hosting a rich population of Be stars.

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On the metallicity of open clusters

Cited by 48 publications

References 93 publications

CCD UBV(RI)C photometry of twenty open clusters

CCD UBV(RI)C photometry of twenty open clusters

Photoelectric search for peculiar stars in open clusters

Stellar variability in open clusters

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