Age Spread in W3 Main: Large Binocular Telescope/Luci Near-Infrared Spectroscopy of the Massive Stellar Content

Bik, Arjan; Henning, Th.; Stolte, A.; Brandner, W.; Gouliermis, D. A.; Gennaro, Mario; Pasquali, A.; Rochau, Boyke; Beuther, H.; Ageorges, N.; Seifert, W.; Wang, Y.; Kudryavtseva, N.

doi:10.1088/0004-637x/744/2/87

Cited by 62 publications

(116 citation statements)

References 80 publications

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“…An age dispersion of a few Myr could also contribute to differences between age measurements made from MS and PMS stars in very young clusters. Star formation in at least some clusters has been found to occur over a 2-3 Myr time period (e.g., Hosokawa et al [2011]; Delgado et al [2011]; Bik et al [2012] and references therein), while in giant star-forming complexes (e.g., De Marchi et al 2011a) in-falling gas may fuel star formation for even more extended periods of time (e.g., Garcia-Benito et al 2011).…”

Section: Summary and Discussionmentioning

confidence: 99%

Haffner 16: A Young Moving Group in the Making1

Davidge

Carrasco

Winge

et al. 2013

Publications of the Astronomical Society of the Pacific

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ABSTRACT. The photometric properties of main sequence (MS) and pre-main sequence (PMS) stars in the young cluster Haffner 16 are examined using images recorded with the Gemini South Adaptive Optics Imager (GSAOI) and corrected for atmospheric blurring by the Gemini Multi-Conjugate Adapative Optics System (GeMS). A rich population of PMS stars is identified, and comparisons with isochrones suggest an age ≲10 Myr, assuming a distance modulus of 13.5 (D ¼ 5 kpc). This age is consistent with that estimated from the lower cutoff of the MS on the K-band luminosity function and is ∼2 Myr younger than the age found from bright MS stars at visible wavelengths. When compared with the solar neighborhood, Haffner 16 is roughly a factor of 2 deficient in objects with subsolar masses. PMS objects in the cluster are also more uniformly distributed on the sky than bright MS stars. It is suggested that Haffner 16 is dynamically evolved and that it is shedding protostars with subsolar masses. Young low mass clusters like Haffner 16 are one possible source of PMS stars in the field. The cluster will probably evolve on time scales of ∼100-1000 Myr into a diffuse moving group with a mass function that is very different from that which prevailed early in its life.

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Section: Summary and Discussionmentioning

confidence: 99%

Haffner 16: A Young Moving Group in the Making1

Davidge

Carrasco

Winge

et al. 2013

Publications of the Astronomical Society of the Pacific

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“…By means of K-band spectroscopy, their massive star nature was confirmed and the spectral types of these massive stars have been determined (Bik et al 2012) such that the age of the most massive star (IRS2) could be derived. Based on this age determination (2−3 Myr) and the presence of the very young hypercompact HII regions, Bik et al (2012) concluded that W3 Main has been actively forming stars over the last 2−3 Myr.…”

Section: Introductionmentioning

confidence: 99%

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

Bik

Stolte²,

Gennaro

et al. 2013

A&A

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Context. Embedded clusters like W3 Main are complex and dynamically evolving systems that represent an important phase in the star formation process. Aims. We aim to characterize of the entire stellar content of W3 Main in a statistical sense, which will then identify possible differences in the evolutionary phase of the stellar populations and find clues about the formation mechanism of this massive embedded cluster. Methods. Deep JHK s imaging is used to derive the disk fraction, K s -band luminosity functions, and mass functions for several subregions in W3 Main. A two-dimensional completeness analysis using artificial star experiments is applied as a crucial ingredient for assessing realistic completeness limits for our photometry. Results. We find an overall disk fraction of 7.7 ± 2.3%, radially varying from 9.4 ± 3.0% in the central 1 pc to 5.6 ± 2.2% in the outer parts of W3 Main. The mass functions derived for three subregions are consistent with a Kroupa and Chabrier mass function. The mass function of IRSN3 is complete down to 0.14 M and shows a break at M ∼ 0.5 M . Conclusions. We interpret the higher disk fraction in the center as evidence that the cluster center is younger. We find that the evolutionary sequence observed in the low-mass stellar population is consistent with the observed age spread among the massive stars. An analysis of the mass function variations does not show evidence of mass segregation. W3 Main is currently still actively forming stars, showing that the ionizing feedback of OB stars is confined to small areas (∼0.5 pc). The FUV feedback might be influencing large regions of the cluster as suggested by the low overall disk fraction.

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“…This emission, though, is quite narrow and does not affect the wings of the photospheric absorption Brγ lines. Hence the absorption wings can still be used for spectral classification (see Bik et al 2012, for a similar classification procedure). An example of such comparison of the Brγ absorption line wings is shown in Fig.…”

Section: Spectral Classification: Distance and Extinction To Cn15/16/17mentioning

confidence: 99%

Multiple episodes of star formation in the CN15/16/17 molecular complex

Gennaro¹,

Bik²,

Brandner³

et al. 2012

A&A

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Context. We have started a campaign to identify massive star clusters inside bright molecular bubbles towards the Galactic center. The CN15/16/17 molecular complex is the first example of our study. The region is characterized by the presence of two young clusters, DB10 and DB11, visible in the near-infrared, an ultra-compact H ii region identified in the radio, several young stellar objects visible in the mid infrared, a bright diffuse nebulosity at 8 μm coming from PAHs and sub-mm continuum emission revealing the presence of cold dust. Aims. Given its position on the sky (l = 0.• 58, b = −0.• 85) and its kinematic distance of 7.5 kpc, the region was thought to be a very massive site of star formation in proximity of the central molecular zone. One of the two identified clusters, DB11, was estimated to be as massive as ∼10 4 M . However the region's properties were known only through photometry and its kinematic distance was very uncertain given its location at the tangential point. We aimed at better characterizing the region and assess whether it could be a site of massive star formation located close to the Galactic center. Methods. We have obtained NTT/SofI deep JHK S photometry and long slit K band spectroscopy of the brightest members. We have additionally collected data in the radio, sub-mm and mid infrared, resulting in a quite different picture of the region. Results. We have confirmed the presence of massive early B type stars and have derived a spectro-photometric distance of ∼1.2 kpc, much smaller than the estimated kinematic distance. Adopting this distance we obtain clusters masses of M DB10 ≈ 170 M and M DB11 ≈ 275 M . This is consistent with the absence of any O star, confirmed by the excitation/ionization status of the nebula. No He i diffuse emission is detected in our spectroscopic observations at 2.113 μm, which would be expected if the region was hosting more massive stars. Radio continuum measurements are also consistent with the region hosting at most early B stars.

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Age Spread in W3 Main: Large Binocular Telescope/Luci Near-Infrared Spectroscopy of the Massive Stellar Content

Cited by 62 publications

References 80 publications

Haffner 16: A Young Moving Group in the Making1

Haffner 16: A Young Moving Group in the Making1

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

Multiple episodes of star formation in the CN15/16/17 molecular complex

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