Photometric study of the open cluster NGC 2323

Clariá, J. J.; Piatti, Andrés E.; Lapasset, E.

doi:10.1051/aas:1998130

Cited by 28 publications

(26 citation statements)

References 20 publications

(30 reference statements)

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“…Clariá et al (1998) list E(B − V) = 0.23 mag for W171 which corresponds to the mean value of the cluster (Table 1). Its location within the HRD (Fig.…”

Section: Ngc 2323mentioning

confidence: 87%

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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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“…Clariá et al (1998) list E(B − V) = 0.23 mag for W171 which corresponds to the mean value of the cluster (Table 1). Its location within the HRD (Fig.…”

Section: Ngc 2323mentioning

confidence: 87%

“…There are some recent investigations of NGC 2323 that include photometric but no spectroscopic data (Clariá et al 1998;Sharma et al 2006;Frolov et al 2012). Clariá et al (1998) list E(B − V) = 0.23 mag for W171 which corresponds to the mean value of the cluster (Table 1).…”

Section: Ngc 2323mentioning

confidence: 99%

Photoelectric search for peculiar stars in open clusters

Paunzen

Netopil

Maitzen³

et al. 2014

A&A

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“…The position of the stars in the CMD (Fig. 1) seems to indicate that they are clump giants (Clariá et al 2005).…”

Section: Ngc 2447mentioning

confidence: 93%

CNONa and ${^{12}}$C/${^{13}}$C in giant stars of 10 open clusters

Smiljanić

Gauderon²,

North³

et al. 2009

A&A

113

176

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Context. Evolved low-mass stars (0.8 ≤ M/M ≤ 2.5) of a wide range of metallicity bear signatures of a non-standard mixing event in their surface abundances of Li, C, and N, and in their 12 C/ 13 C ratio. A Na overabundance has also been reported in some giants of open clusters but remains controversial. The cause of the extra-mixing has been attributed to thermohaline convection that should take place after the RGB bump for low-mass stars and on the early-AGB for more massive objects. Aims. To track the occurrence of this process over a wide mass range, we derive in a homogeneous way the abundances of C, N, O, and Na, as well as the 12 C/ 13 C ratio in a sample of 31 giants of 10 open clusters with turn-off masses from 1.7 to 3.1 M . The sample includes red giants, clump giants, and early-AGB stars. We study the observational behavior of the abundances as well as the possible correlations between different elements and between the chemical abundances and stellar mass. Methods. A model atmosphere analysis is conducted using high signal-to-noise ratio, high-resolution FEROS and EMMI spectra. We derive atmospheric parameters using Fe i and Fe ii lines. We calculate abundances for Na, C, N, and O, as well as the 12 C/ 13 C ratio using spectral synthesis. For the elements Mg, Ca, Si, Sc, Ti, V, Cr, Co, and Ni, abundances are derived using equivalent widths. Results. A group of first ascent red giants with M/M ≤ 2.5 exhibits lower [N/C] ratios than those measured in clump giants of the same mass range, suggesting an additional increase in the [N/C] ratio after the first dredge-up. The sodium abundances corrected from NLTE are found to be about solar.[Na/Fe] shows a slight increase of 0.10 dex as a function of stellar mass in the 1.8 to 3.2 M range covered by our sample, in agreement with standard first dredge-up predictions. Our results do not support previous claims of sodium overabundances as high as +0.60 dex. An anti-correlation between 12 C/ 13 C and turn-off mass is identified and interpreted as being caused by a post-bump thermohaline mixing. Moreover, we find low 12 C/ 13 C ratios in a few intermediate-mass early-AGB stars, confirming that an extra-mixing process also operates in stars that do not experienced the RGB bump. In this case, the extra-mixing possibly acts on the early-AGB, in agreement with theoretical expectations for thermohaline mixing.

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“…Paunzen et al 2003), UBV (e.g. Clariá et al 1998), IR (e.g. Carraro et al 1999;Vallenari et al 2000), and Vilnius (e.g.…”

Section: Introductionmentioning

confidence: 99%

Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters

Carrera

2012

A&A

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Context. Open clusters are ideal test particles for studying the formation and evolution of the Galactic disk. However, the number of clusters with information about their radial velocities and chemical compositions remains largely insufficient. Aims. We attempt to increase the number of open clusters with determinations of radial velocities and metallicities from spectroscopy. Methods. We acquired medium-resolution spectra (R ∼ 8000) in the region of the infrared Ca II triplet lines (∼8500 Å) for several stars in four open clusters with the long-slit spectrograph IDS at the 2.5 m Isaac Newton Telescope, Roque de los Muchachos Observatory, Spain. Radial velocities were obtained by cross-correlating the observed spectra with those of two template stars. We used the relationships available in the literature between the strength of infrared Ca II lines and metallicities to derive the metal content of each cluster. Results. We provide the first spectroscopic determinations of radial velocities and metallicities for the open clusters Berkeley 26, Berkeley 70, NGC 1798, and NGC 2266. We obtain V r = 68 ± 12, −15 ± 7, 2 ± 10, and −16 ± 15 km s

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Photometric study of the open cluster NGC 2323

Cited by 28 publications

References 20 publications

Photoelectric search for peculiar stars in open clusters

Photoelectric search for peculiar stars in open clusters

CNONa and ${^{12}}$C/${^{13}}$C in giant stars of 10 open clusters

Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters

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