I Am the Black Crow

King, Elizabeth

doi:10.2307/20623563

Cited by 41 publications

(68 citation statements)

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“…Structural parameters were derived by fitting the twoparameter King (1966a) surface-density profile to the colour−magnitude filtered RDPs. The two-parameter King model essentially describes the intermediate and central regions of globular clusters (King 1966b;Trager et al 1995).…”

Section: Structural Parametersmentioning

confidence: 99%

Astrophysical parameters of 14 open clusters projected close to the Galactic plane

Camargo¹,

Bonatto²,

Bica³

2009

A&A

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Aims. Astrophysical parameters (age, reddening, distance, core and cluster radii) of 14 open clusters (OCs) projected close to the Galactic plane are derived with 2MASS photometry. The OCs are Be 63, Be 84, Cz 6, Cz 7, Cz 12, Ru 141, Ru 144, Ru 172, FSR 101, FSR 1430, FSR 1471, FSR 162, FSR 178, and FSR 198. The OCs Be 63, Be 84, Ru 141, Ru 144, and Ru 172 are studied in more detail than in previous works, while the others have astrophysical parameters derived for the first time. Methods. We analyse the colour−magnitude diagrams (CMDs) and stellar radial density profiles (RDPs) built after field-star decontamination and colour-magnitude filtered photometry. Field-star decontamination is applied to uncover the cluster's intrinsic CMD morphology, and colour−magnitude filters are used to isolate stars with a high probability of being cluster members in view of structural analyses.Results. The open clusters of the sample are located at d = 1.6−7.1 kpc from the Sun and at Galactocentric distances 5.5−11.8 kpc, with age in the range 10 Myr to 1.5 Gyr and reddening E(B−V) in the range 0.19−2.56 mag. The core and cluster radii are in the range 0.27−1.88 pc and 2.2−11.27 pc, respectively. Cz 6 and FSR 198 are the youngest OCs of this sample, with a population of pre-main sequence (PMS) stars, while FSR 178 is the oldest cluster.

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Section: Structural Parametersmentioning

confidence: 99%

Astrophysical parameters of 14 open clusters projected close to the Galactic plane

Camargo¹,

Bonatto²,

Bica³

2009

A&A

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“…Structural parameters of NGC 2477 were derived by fitting the two-parameter King (1966a) surface density profile to the background-subtracted radial distribution of stars. The two-parameter King model essentially describes the intermediate and central regions of normal clusters (King 1966b;Trager et al 1995).…”

Section: Structural Parametersmentioning

confidence: 99%

“…At J = 13.0 the photometric uncertainties amount to J ≈ 0.03 . The fit with the two-parameter King (1966a) surface density profile to the background-subtracted radial density profile resulted in R core = 0.6 ± 0.1 pc and a projected central density of stars of σ 0 ≈ 67 ± 9 stars pc −2 . We derived a limiting radius of R lim = 6.2 ± 0.2 pc, a value ∼3 times larger than the tidal radius estimated by Bergond et al (2001) and Tadross et al (2002).…”

Section: Structural Parametersmentioning

confidence: 99%

Detailed analysis of open clusters: A mass function break and evidence of a fundamental plane

Bonatto¹,

Bica²

2005

A&A

122

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Abstract. We derive photometric, structural and dynamical evolution-related parameters of 11 nearby open clusters with ages in the range 70 Myr to 7 Gyr and masses in the range ≈400 M to ≈5300 M . The clusters are homogeneously analysed by means of J, H and K S 2MASS photometry, which provides spatial coverage wide enough to properly take into account the contamination of the cluster field by Galaxy stars. Structural parameters such as core and limiting radii are derived from the background-subtracted radial density profiles. Luminosity and mass functions (MFs) are built for stars later than the turnoff and brighter than the 2MASS PSC 99.9% completeness limit. The total mass locked up in stars in the core and the whole cluster, as well as the corresponding mass densities, are calculated by taking into account the observed stars (evolved and main sequence) and extrapolating the MFs down to the H-burning mass limit, 0.08 M . We illustrate the methods by analysing for the first time in the near-infrared the populous open clusters NGC 2477 and NGC 2516. For NGC 2477 we derive an age of 1.1 ± 0.1 Gyr, distance from the Sun d = 1.2 ± 0.1 kpc, core radius R core = 1.4 ± 0.1 pc, limiting radius R lim = 11.6 ± 0.7 pc and total mass m tot ≈ (5.3 ± 1.6) × 10 3 M . Large-scale mass segregation in NGC 2477 is reflected in the significant variation of the MF slopes in different spatial regions of the cluster, and in the large number-density of giant stars in the core with respect to the cluster as a whole. For NGC 2516 we derive an age of 160 ± 10 Myr, d = 0.44 ± 0.02 kpc, R core = 0.6 ± 0.1 pc, R lim = 6.2 ± 0.2 pc and m tot ≈ (1.3 ± 0.2) × 10 3 M . Mass-segregation in NGC 2516 shows up in the MFs. Six of the 11 clusters present a slope break in the MF occurring at essentially the same mass as that found for the field stars in Kroupa's universal IMF. The MF break is not associated to cluster mass, at least in the clusters in this paper. In two clusters the low-mass end of the MF occurs above the MF break. However, in three clusters the MF break does not occur, at least for the mass range m ≥ 0.7 M . One possibility is dynamical evolution affecting the MF slope distribution. We also search for relations of structural and evolutionary parameters with age and Galactocentric distance. The main results for the present sample are: (i) cluster size correlates both with age and Galactocentric distance; (ii) because of size and mass scaling, core and limiting radii, and core and overall mass correlate; (iii) massive (m ≥ 1000 M ) and less-massive clusters follow separate correlation paths on the plane core radius and overall mass; (iv) MF slopes of massive clusters are restricted to a narrow range, while those of the less-massive ones distribute over a wider range. Core and overall MF flattening is related to the ratio (τ) of age to relaxation time. For large values of τ the effects of large-scale mass segregation and low-mass stars evaporation can be observed in the MFs. In this sense, τ appears to characterize the evolutionary stat...

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“…Structural parameters of NGC 6611 were derived by fitting the two-parameter King (1966a) surface density profile to the background-subtracted radial distribution of stars. The two-parameter King model essentially describes the intermediate and central regions of normal clusters (King 1966b;Trager et al 1995).…”

Section: Cluster Structurementioning

confidence: 99%

Mass functions and structure of the young open cluster NGC 6611

Bonatto

Santos

Bica

2005

A&A

112

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We use J, H and K S 2MASS photometry to study colour-magnitude (CMDs) and colour-colour diagrams, structure and mass distribution in the ionizing open cluster NGC 6611. Reddening variation throughout the cluster region is taken into account followed by field-star decontamination of the CMDs. Decontamination is also applied to derive the density profile and luminosity functions in the core, halo and overall (whole cluster) regions. The field-star decontamination showed that the lower limit of the main sequence (MS) occurs at ≈5 M . Based on the fraction of K S excess stars in the colour-colour diagram we estimate an age of 1.3 ± 0.3 Myr which is consistent with the presence of a large number of premain sequence (PMS) stars. The distance from the Sun was estimated from known O V stars in the cluster area and the turn-on stars connecting the PMS and MS, resulting in d = 1.8 ± 0.5 kpc. The radial density distribution including MS and PMS stars is fitted by a King profile with a core radius R core = 0.70 ± 0.08 pc. The cluster density profile merges into the background at a limiting radius R lim = 6.5 ± 0.5 pc. From the field-star subtracted luminosity functions we derive the mass functions (MFs) in the form φ(m) ∝ m −(1+χ) . In the halo and through the whole cluster the MFs have slopes χ = 1.52 ± 0.13 and χ = 1.45 ± 0.12, respectively, thus slightly steeper than Salpeter's IMF. In the core the MF is flat, χ = 0.62 ± 0.16, indicating some degree of mass segregation since the cluster age is a factor ∼2 larger than the relaxation time. Because of the very young age of NGC 6611, part of this effect appears to be related to the molecular cloud-fragmentation process itself. We detect 362 ± 120 PMS stars. The total observed mass including detected MS (in the range 5−85 M ) and PMS stars amounts to ∼1600 M , thus more massive than the Trapezium cluster. Compared to older open clusters of different masses, the overall NGC 6611 fits in the relations involving structural and dynamical parameters. However, the core is atypical in the sense that it looks like an old/dynamically evolved core. Again, part of this effect must be linked to formation processes.

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I Am the Black Crow

Cited by 41 publications

References 0 publications

Astrophysical parameters of 14 open clusters projected close to the Galactic plane

Astrophysical parameters of 14 open clusters projected close to the Galactic plane

Detailed analysis of open clusters: A mass function break and evidence of a fundamental plane

Mass functions and structure of the young open cluster NGC 6611

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