Deep near-infrared imaging of W3 Main: constraints on stellar cluster formation

Bik, Arjan; Stolte, A.; Gennaro, Mario; Brandner, W.; Gouliermis, D. A.; Hussmann, B.; Tognelli, E.; Rochau, Boyke; Henning, Th.; Adamo, Angela; Beuther, H.; Pasquali, A.; Wang, Y.

doi:10.1051/0004-6361/201321957

Cited by 27 publications

(29 citation statements)

References 70 publications

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“…Only a very small fraction of the PMS population have infrared-excess protoplanetary disks, implying that the extended cluster has age 2 Myr, much older than the central OB stars. Bik et al (2014) confirm this result and extend it with suggestive evidence from spatial analysis of K-band excess stars and the K luminosity function that the younger PMS stars, like the OB stars, are centrally concentrated. Altogether, it appears that W 3 Main is similar to NGC 2024 and the ONC with a spatial-age gradient in a rich young star cluster.…”

Section: Serpens North Serpens South and Corona Australis Serpenssupporting

confidence: 84%

Core-Halo Age Gradients and Star Formation in the Orion Nebula and NGC 2024 Young Stellar Clusters

Getman

Feigelson

2014

ApJ

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We analyze age distributions of two nearby rich stellar clusters, the NGC 2024 (Flame Nebula) and Orion Nebula cluster (ONC) in the Orion molecular cloud complex. Our analysis is based on samples from the MYStIX survey and a new estimator of pre-main sequence (PMS) stellar ages, Age JX , derived from X-ray and near-infrared photometric data. To overcome the problem of uncertain individual ages and large spreads of age distributions for entire clusters, we compute median ages and their confidence intervals of stellar samples within annular subregions of the clusters. We find core-halo age gradients in both the NGC 2024 cluster and ONC: PMS stars in cluster cores appear younger and thus were formed later than PMS stars in cluster peripheries. These findings are further supported by the spatial gradients in the disk fraction and K-band excess frequency. Our age analysis is based on Age JX estimates for PMS stars and is independent of any consideration of OB stars. The result has important implications for the formation of young stellar clusters. One basic implication is that clusters form slowly and the apparent age spreads in young stellar clusters, which are often controversial, are (at least in part) real. The result further implies that simple models where clusters form inside-out are incorrect and more complex models are needed. We provide several star formation scenarios that alone or in combination may lead to the observed core-halo age gradients.

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Section: Serpens North Serpens South and Corona Australis Serpenssupporting

confidence: 84%

Core-Halo Age Gradients and Star Formation in the Orion Nebula and NGC 2024 Young Stellar Clusters

Getman

Feigelson

2014

ApJ

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“…Additionally, dispersion of circumstellar material is driven by external factors like photo evaporation (Hollenbach et al 2000) or dynamical interactions with surrounding stars (Olczak et al 2010), resulting in a much lower disk fraction in massive stellar clusters (e.g. Stolte et al 2010Stolte et al , 2015Fang et al 2012;Bik et al 2014). …”

Section: Excess Sourcesmentioning

confidence: 99%

The massive stellar population of W49: A spectroscopic survey

Bik

Bestenlehner

et al. 2016

A&A

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Context. Massive stars form on different scales that range from large, dispersed OB associations to compact, dense starburst clusters. The complex structure of regions of massive star formation and the involved short timescales provide a challenge for our understanding of their birth and early evolution. As one of the most massive and luminous star-forming region in our Galaxy, W49 is the ideal place to study the formation of the most massive stars. Aims. By classifying the massive young stars that are deeply embedded in the molecular cloud of W49, we aim to investigate and trace the star formation history of this region. Methods. We analyse near-infrared K-band spectroscopic observations of W49 from LBT/LUCI combined with JHK images obtained with NTT/SOFI and LBT/LUCI. Based on JHK-band photometry and K-band spectroscopy, the massive stars are placed in a Hertzsprung Russell diagram. By comparison with evolutionary models, their age and hence the star formation history of W49 can be investigated. Results. Fourteen O-type stars, as well as two young stellar objects (YSOs), are identified by our spectroscopic survey. Eleven O stars are main sequence stars with subtypes ranging from O3 to O9.5 and masses ranging from ∼20 M to ∼120 M . Three of the O stars show strong wind features and are considered to be Of-type supergiants with masses beyond 100 M . The two YSOs show CO emission, which is indicative of the presence of circumstellar disks in the central region of the massive cluster. The age of the cluster is estimated as ∼1.5 Myr, with star formation continuing in different parts of the region. The ionising photons from the central massive stars have not yet cleared the molecular cocoon surrounding the cluster. W49 is comparable to extragalactic star-forming regions, and it provides us with a unique chance to study a starburst in detail.

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“…We can compare the IMF derived for the young cluster embedded within RCW 41 with those of other well studied young clusters, such as IC 348 and the Trapezium (Muench et al 2003;Luhman et al 2000), Chamaeleon I (Luhman et al 2007), NGC 2024(Levine et al 2006, NGC 2264 (Sung et al 2010), NGC 6611 (Oliveira et al 2009), NGC 7538 (Mallick et al 2014, W3 Main (Ojha et al 2009;Bik et al 2014), and NGC 3603 (Harayama et al 2008). As for these clusters, RCW 41 has an IMF that rise in number with decreasing mass into the subsolar regime, with Salpeterlike power-law slopes.…”

Section: Comparison Of the Rcw 41 Cluster's Imf With Other Young Clusmentioning

confidence: 99%

“…Using such observational techniques, young cluster members can be listed and studied in detail using color−color (CC) diagrams and evolutionary tracks, which will give their age and mass distribution. The age, mass, and spatial distribution of stars in the cluster give important information about a young cluster's evolutionary stage and put constraints on star formation models (e.g., Haisch et al 2000;Muench et al 2003; Levine et al 2006;Comerón et al 2007;Harayama et al 2008;Oliveira et al 2009;Ojha et al 2009;DeRose et al 2009;Gennaro et al 2011;Preibisch et al 2011;Rochau et al 2011;Santos et al 2012;Bik et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Deep near-infrared adaptive-optics observations of a young embedded cluster at the edge of the RCW 41 H II region

Neichel

Samal

Plana

et al. 2015

A&A

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Aims. We investigate the star formation activity in a young star forming cluster embedded at the edge of the RCW 41 H ii region. As a complementary goal, we aim to demonstrate the gain provided by wide-field adaptive optics (WFAO) instruments to study young clusters. Methods. We used deep, JHK s images from the newly commissioned Gemini-GeMS/GSAOI instrument, complemented with Spitzer IRAC observations, in order to study the photometric properties of the young stellar cluster. GeMS is a WFAO instrument that delivers almost diffraction-limited images over a field of ∼2 across. The exquisite angular resolution allows us to reach a limiting magnitude of J ∼ 22 for 98% completeness. The combination of the IRAC photometry with our JHK s catalog is used to build color−color diagrams, and select young stellar object (YSO) candidates. The JHK s photometry is also used in conjunction with pre-main sequence evolutionary models to infer masses and ages. The K-band luminosity function is derived, and then used to build the initial mass function (IMF) of the cluster. Results. We detect the presence of 80 YSO candidates. Those YSOs are used to infer the cluster age, which is found to be in the range 1 to 5 Myr. More precisely, we find that 1/3 of the YSOs are in a range between 3 to 5 Myr, while 2/3 of the YSO are ≤3 Myr. When looking at the spatial distribution of these two populations, we find evidence of a potential age gradient across the field that suggests sequential star formation. We construct the IMF and show that we can sample the mass distribution well into the brown dwarf regime (down to ∼0.01 M ). The logarithmic mass function rises to peak at ∼0.3 M , before turning over and declining into the brown dwarf regime. The total cluster mass derived is estimated to be 78 ± 18 M , while the ratio derived of brown dwarfs to star is 18 ± 5%. When comparing it with other young clusters, we find that the IMF shape of the young cluster embedded within RCW 41 is consistent with those of Trapezium, IC 348, or Chamaeleon I, except for the IMF peak, which happens to be at higher mass. This characteristic is also seen in clusters like NGC 6611 or even Taurus. These results suggest that the medium-to-low mass end of the IMF possibly depends on environment.

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Deep near-infrared imaging of W3 Main: constraints on stellar cluster formation

Cited by 27 publications

References 70 publications

Core-Halo Age Gradients and Star Formation in the Orion Nebula and NGC 2024 Young Stellar Clusters

Core-Halo Age Gradients and Star Formation in the Orion Nebula and NGC 2024 Young Stellar Clusters

The massive stellar population of W49: A spectroscopic survey

Deep near-infrared adaptive-optics observations of a young embedded cluster at the edge of the RCW 41 H II region

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