Detection of <i>K</i><sub>s</sub>-excess stars in the 14 Myr open cluster NGC 4755

Bonatto, Charles Jose; Bica, E.; Ortolani, S.; Barbuy, B.

doi:10.1051/0004-6361:20054620

Cited by 45 publications

(71 citation statements)

References 38 publications

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“…However, a small fraction appear to present an abnormal excess in (H − K s ), especially vdB 92, in the (J − H) × (H − K s ) diagram, which may come from PMS stars still bearing circumstellar discs, hence with excess in H (e.g. Furlan et al 2009;Bonatto et al 2006a). …”

Section: Fundamental Parametersmentioning

confidence: 99%

The fate of the pre-main sequence-rich clusters Collinder 197 and vdB 92: dissolution?

Bonatto

Bica

2010

A&A

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Context. Since most of the star clusters do not survive the embedded phase, their early dissolution appears to be a major source of field stars. However, catching a cluster in the act of dissolving is somewhat elusive. Aims. We investigate the nature and possible evolution of the young Galactic star clusters Collinder 197 (Cr 197) and vdB 92. Methods. Photometric and structural properties were derived with near-infrared photometry and field-star decontamination. Kinematical properties were inferred from proper motions of the main sequence (MS) and pre-MS (PMS) member stars.Results. The colour-magnitude diagrams (CMDs) are basically characterised by a poorly-populated MS and a dominant fraction ( > ∼ 75%) of PMS stars, and the combined MS and PMS CMD morphology in both clusters consistently constrains the age to within 5 ± 4 Myr, with a ∼10 Myr spread in the star formation process. The MS+PMS stellar masses are ≈660 +101−51 M (vdB 92). Both Cr 197 and vdB 92 appear to be abnormally large when compared to clusters within the same age range. They have irregular stellar radial density distributions (RDPs) with a marked excess in the innermost region, a feature that, at less than 10 Myr, is more likely related to the star formation and/or molecular cloud fragmentation than to age-dependent dynamical effects. The velocity dispersion of both clusters, derived from proper motions, is in the range ∼15−22 km s −1 . Conclusions. Both clusters appear to be in a super-virial state, with velocity dispersions higher than those expected of nearly-virialised clusters of similar mass and size. A possible interpretation is that Cr 197 and vdB 92 deviate critically from dynamical equilibrium, and may dissolve into the field. We also conclude that early cluster dissolution leaves detectable imprints on RDPs of clusters as massive as several 10 2 M . Cr 197 and vdB 92 may be the link between embedded clusters and young stellar associations.

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Section: Fundamental Parametersmentioning

confidence: 99%

The fate of the pre-main sequence-rich clusters Collinder 197 and vdB 92: dissolution?

Bonatto

Bica

2010

A&A

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“…To uncover the intrinsic cluster CMD morphology, we use the field-star decontamination procedure described in Bonatto & Bica (2007b), previously applied in the analysis of low-contrast , embedded , young (Bonatto et al 2006c), faint ), old (Bonatto & Bica 2007a), or in dense-fields (Bonatto & Bica 2007b) OCs. The algorithm works on a statistical basis that takes the relative number densities of stars in a cluster region and offset field into account.…”

Section: Field-star Decontaminationmentioning

confidence: 99%

“…This tool was previously applied to the structural analysis of the OCs M 67 (Bonatto & Bica 2003), NGC 3680 (Bonatto et al 2004b), NGC 188 , NGC 6611 ), NGC 4755 (Bonatto et al 2006c), M 52 and NGC 3690 (Bonatto & Bica 2006) and the faint OCs BH 63, Lyngå 2, Lyngå 12 and King 20 ). The filters were defined based on the distribution of the decontaminated star sequences in the CMDs of open clusters.…”

Section: Structural Parametersmentioning

confidence: 99%

“…13). We considered (i) a sample of bright nearby OCs , including the two young OCs NGC 6611 ), and NGC 4755 (Bonatto et al 2006c The comparison OCs in the sample (i) have ages in the range 70 Myr−7 Gyr, masses within 400−5300 M , and Galactocentric distances in the range 5.8 < ∼ R GC (kpc) < ∼ 8.1. NGC 6611 has ≈1.3 Myr and R GC = 5.5 kpc, and NGC 4755 has ≈14 Myr and R GC = 6.4 kpc.…”

Section: Relations Among Astrophysical Parametersmentioning

confidence: 99%

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

Camargo¹,

Bonatto²,

Bica³

2009

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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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“…Corti & Orellana (2013) give the distance to the cluster as 1.9±0.5 kpc and the age of ∼15 Myr. Bonatto et al (2006) estimated the cluster's age as 14 ± 2 Myr and concluded that the star formation in NGC 4755 began ≈14 Myr ago and proceeded for about the same length of time. Lyra et al (2006) find a value of 2040 ± 250 pc for the distance to the cluster and 7.1 ± 0.2 for the log age.…”

Section: Wind-blown Energy Deposit Of the Most Massive Stars Within Gmentioning

confidence: 99%

Massive stellar content of the Galactic supershell GSH 305+01−24

Kaltcheva¹,

Golev²,

Moran³

2014

A&A

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Aims. The distribution of OB stars along with Hα, 12 CO, dust infrared emission, and neutral hydrogen is carried out to provide a more complete picture of interactions of the young massive stars and the observed supershell GSH 305+01−24. Methods. The studied field is located between 299The investigation is based on nearly 700 O-B9 stars with currently available uvbyβ photometry. The derived stellar physical parameters were used to establish a homogeneous scale for the distances and extinction of light for major apparent groups and layers of foreground and background stars in Centaurus and to study the interaction with the surrounding interstellar medium. Results. The distance to the entire Centaurus star-forming complex is revised, and a maximum of the OB-star distance distribution is found at 1.8 ± 0.4 (rms) kpc. The massive star component of GSH 305+01−24 is identified at about 85−90% completeness up to 11.5−12 mag. The projected coincidence of the OB stars with the shell and the similarities between the shell's morphology and the OB-star distribution indicate a strong interaction of the stellar winds with the superbubble material. We demonstrate that these stars contribute enough wind injection energy to explain the observed size and expansion velocity of the supershell. The derived stellar ages suggest an age gradient over the Coalsack Loop. Continuous star formation might be taking place within the shell with the youngest stars located toward its periphery, and the open cluster NGC 4755 is the oldest. A layer of very young stars at 1 kpc is detected, and its connection to both GSH 305+01−24 and the foreground GSH 304−00−12 H i shells is investigated.

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Detection of K_s-excess stars in the 14 Myr open cluster NGC 4755

Cited by 45 publications

References 38 publications

The fate of the pre-main sequence-rich clusters Collinder 197 and vdB 92: dissolution?

The fate of the pre-main sequence-rich clusters Collinder 197 and vdB 92: dissolution?

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

Massive stellar content of the Galactic supershell GSH 305+01−24

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Detection of Ks-excess stars in the 14 Myr open cluster NGC 4755

Cited by 45 publications

References 38 publications

The fate of the pre-main sequence-rich clusters Collinder 197 and vdB 92: dissolution?

The fate of the pre-main sequence-rich clusters Collinder 197 and vdB 92: dissolution?

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

Massive stellar content of the Galactic supershell GSH 305+01−24

Contact Info

Product

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Detection of K_s-excess stars in the 14 Myr open cluster NGC 4755