Hochschule für Wirtschaft Zürich

Nissen, Volker; Klauk, Bruno; Deelmann, Thomas; Mohe, Michael

doi:10.1007/978-3-8349-4466-5_14

Cited by 3 publications

(3 citation statements)

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“…This author performed robust derivations of the cluster age, reddening, distance, and metallicity on the basis of Johnson U BV photometry. In the first paper, he used average metallicity values derived from the calibra- Twarog & Twarog (2000) [2] Anthony- Twarog & Twarog (2004) [3] Anthony- [4] Anthony- Twarog et al (2005) [5] Anthony- Twarog et al (2006) [6] Bruntt et al (1999) [7] Cameron (1985b) [8] Clariá (1982) [9] Clariá (1985) [10] Clariá & Lapasset (1983) [11] Clariá & Lapasset (1985) [12] Clariá & Lapasset (1986a) [13] Clariá & Lapasset (1986b) [14] [15] Claria & Mermilliod (1992) [16] Clariá & Minniti (1988) [17] [18] Clariá et al (1991) [19] Clariá et al (1994) [20] Clariá et al (1996) [21] Clariá et al (1999) [22] Clariá et al (2003) [23] Clariá et al (2005) [24] Clariá et al (2007) [25] Clariá et al (2008) [26] Dawson (1981) [27] Eggen (1983) [28] Geisler & Smith (1984) [29] Geisler et al (1992) [30] Janes (1984) [31] Janes & Smith (1984) [32] Kaluzny & Mazur (1991a) [33] Kaluzny & Mazur (1991b) [34] Kaluzny & Mazur (1991c) [35] Kaluzny & Rucinski (1995) [36] Kyeong et al (2008) [37] Lynga & Wramdemark (1984) [38] McClure et al (1981) [39] Mermilliod et al (2001) [40] Nissen (1980) [41] Nissen (1988) [42]…”

Section: A Test Case From the Literaturementioning

confidence: 99%

On the metallicity of open clusters

Paunzen¹,

Heiter

Netopil

et al. 2010

A&A

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Context. Metallicity is one of four free parameters typically considered when fitting isochrones to the cluster sequence. Unfortunately, this parameter is often ignored or assumed to be solar in most papers. Hence an unknown bias is introduced in the estimation of the other three cluster parameters (age, reddening and distance). Furthermore, studying the metallicity of open clusters allows us not only to derive the Galactic abundance gradient on a global scale, but also to trace the local solar environment in more detail. Tracing the solar environment within 4000 × 4000 pc 2 we identify a patchy metallicity distribution as an extension to the Local Bubble that significantly influences the estimation of the Galactic metallicity gradient, even on a global scale. In addition, further investigations of more distant open clusters are clearly needed to obtain a more profound picture at Galactocentric distances beyond 10 000 pc. Conclusions. Only a combination of all available photometric and spectroscopic data will shed more light on how the local and global Galactic properties are correlated with metallicity.

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Section: A Test Case From the Literaturementioning

confidence: 99%

On the metallicity of open clusters

Paunzen¹,

Heiter

Netopil

et al. 2010

A&A

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“…i) The ability to provide robust estimates of intrinsic stellar parameters such as the metal abundance (the m 1 = (v − b) − (b-y ) index, Anthony-Twarog & Twarog 2000;Hilker 2000;Calamida et al 2007, hereafter CA07), the surface gravity (the c 1 = (u −v) −(v−b) index), and the effective temperature (the H β index, Nissen 1988;Olsen 1988;Anthony-Twarog & Twarog 2000). The H β index is marginally affected by reddening, and therefore can also be compared to a simple color such as b-y to provide individual estimates of reddening corrections (Nissen & Schuster 1991).…”

Section: Introductionmentioning

confidence: 99%

A new visual – near-infrared diagnostic to estimate the metallicity of cluster and field dwarf stars

Calamida

Monelli

Milone

et al. 2012

A&A

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We present a theoretical calibration of a new metallicity diagnostic based on the Strömgren index m 1 and on visual -near-infrared (NIR) colors to estimate the global metal abundance of cluster and field dwarf stars. To perform the metallicity calibration we adopt α-enhanced evolutionary models transformed into the observational plane by using atmosphere models computed adopting the same chemical mixture. We apply the new visual-NIR metallicity-index-color (MIC) relations to two different samples of field dwarfs and we find that the difference between photometric estimates and spectroscopic measurements is on average smaller than 0.1 dex, with a dispersion smaller than σ = 0.3 dex. We apply the same MIC relations to a metal-poor (M 92) and a metal-rich (47 Tuc) globular cluster. We find a peak of −2.01 ± 0.08 (σ = 0.30 dex) and −0.47 ± 0.01 (σ = 0.42 dex), respectively.

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“…For details on the approach, the reader is referred to a subset of the several past investigations where it has been applied (Anthony- Twarog et al 2014;Twarog et al 2015;Sales Silva et al 2016). The simultaneous solution for [Fe/H] and E(b − y) based upon m 1 and Hβ for 257 stars is −0.296 ± 0.011 (sem) and 0.042 ± 0.001 (sem) (E(B − V ) = 0.058 ± 0.001, respectively, independent of the standard relation adopted for the Strömgren indices (Olsen 1988;Nissen 1988 For an uncertainty of ±0.009 in the zero-points of the m 1 and hk indices, the changes in [Fe/H] are ±0.122 and ±0.032, respectively. The weighted mean of the two abundances is clearly dominated by hk, leading to [Fe/H] = −0.316 ± 0.033, where the error estimate includes both internal and potential systematic errors.…”

Section: Reddening and Metallicitymentioning

confidence: 93%

WIYN OPEN CLUSTER STUDY. LXXII. A uvbyCaHβ CCD ANALYSIS OF THE METAL-DEFICIENT OPEN CLUSTER NGC 2506

Anthony-Twarog

Deliyannis

Twarog

2016

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Precision uvbyCaHβ photometry of the metal-deficient, old open cluster, NGC 2506, is presented. The survey covers an area 20 × 20 and extends to V ∼ 18 for b − y and Hβ and to V ∼ 17.0 for c 1 and hk. For V brighter than 16.0, photometric scatter among the indices leads to the recovery of 6 known variables within the cluster core and 5 new variables in the outer 5 of the survey field. Proper motions, radial velocities, and precise multicolor indices are used to isolate a highly probable sample of cluster members from the very rich color-magnitude diagram (CMD). From 257 highly probable members at the cluster turnoff, we derive a reddening estimate of E(b − y) = 0.042 ± 0.001 (E(B − V ) = 0.058 ± 0.001), where the errors refer to the internal standard errors of the mean. [Fe/H] is derived from the A/F dwarf members using both m 1 and hk, leading to [Fe/H]= −0.296 ± 0.011 (sem) and −0.317 ± 0.004 (sem), respectively. The weighted average, heavily dominated by hk, is [Fe/H] = −0.316 ± 0.033. Based upon red giant members, we place an upper limit of ±0.010 on the variation in the reddening across the face of the cluster. We also identify two dozen potential red giant cluster members outside the cluster core. Victoria-Regina isochrones on the Strömgren system produce an excellent match to the cluster for an apparent modulus of (m − M ) = 12.75 ± 0.1 and an age of 1.85 ± 0.05 Gyr.

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Hochschule für Wirtschaft Zürich

Cited by 3 publications

References 0 publications

On the metallicity of open clusters

On the metallicity of open clusters

A new visual – near-infrared diagnostic to estimate the metallicity of cluster and field dwarf stars

WIYN OPEN CLUSTER STUDY. LXXII. A uvbyCaHβ CCD ANALYSIS OF THE METAL-DEFICIENT OPEN CLUSTER NGC 2506

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