The Formation of Secondary Stellar Generations in Massive Young Star Clusters From Rapidly Cooling Shocked Stellar Winds

Wünsch, Richard; Palouš, J.; Tenorio-Tagle, G.; Ehlerová, S.

doi:10.3847/1538-4357/835/1/60

Cited by 46 publications

(56 citation statements)

References 69 publications

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“…For higher densities, radiative cooling should first set in at the cluster center, while the outer lower density regions continue to drive an outflow (Tenorio-Tagle et al 2005Wünsch et al 2007Wünsch et al , 2008. Finally, for higher density, a substantial fraction of the cluster's gas will cool and self-shield (Palouš et al 2014;Wünsch et al 2017), leading to star formation. We assume spherical symmetry, uniform mass and energy deposition, and no gravity.…”

Section: Critical Condition For Coolingmentioning

confidence: 99%

“…Lightelement-enriched material is the result of hot H-burning mixed up to the convective zone of stars (Denisenkov & Denisenkova 1990). This material can then be expelled as winds from fast rotating stars (Decressin et al 2007a,b), asymptotic giant branch (AGB) stars (Ventura et al 2001;Conroy 2012), supermassive stars (Denissenkov & Hartwick 2014), massive binary stars (de Mink et al 2009) or normal massive stars and supernovae (Maeder & Meynet 2006;Prantzos & Charbonnel 2006;Tenorio-Tagle et al 2007;Wünsch et al 2007Wünsch et al , 2017.…”

Section: Introductionmentioning

confidence: 99%

“…We investigate a scenario for second generation formation explored by Wünsch et al (2008); Palouš et al (2014); Wünsch et al (2017) in which massive star winds from the first stellar generation shock and thermalize to produce a region of hot gas in the cluster interior on Myr timescales after the first generation's formation. If the mass loss rate is high enough or if the winds mix with ambient gas left over from cluster formation, the gas is dense enough to become radiative, loses its thermal energy, and can be retained in the GC to fuel a subsequent generation of star formation.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Second-generation stars in globular clusters from rapid radiative cooling of pre-supernova massive star winds

Lochhaas¹,

Thompson²

2017

Monthly Notices of the Royal Astronomical Society

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Following work by Wünsch and collaborators, we investigate a self-enrichment scenario for second generation star formation in globular clusters wherein wind material from first generation massive stars rapidly radiatively cools. Radiative energy loss allows retention of fast winds within the central regions of clusters, where it fuels star formation. Secondary star formation occurs in ∼ 3 − 5 Myr, before supernovae, producing uniform iron abundances in both populations. We derive the critical criteria for radiative cooling of massive star winds and the second generation mass as a function of cluster mass, radius, and metallicity. We derive a critical condition on M/R, above which second generation star formation can occur. We speculate that above this threshold the strong decrease in the cluster wind energy and momentum allows ambient gas to remain from the cluster formation process. We reproduce large observed second generation fractions of ∼ 30 − 80% if wind material mixes with ambient gas. Importantly, the mass of ambient gas required is only of order the first generation's stellar mass. Second generation helium enrichment ∆Y is inversely proportional to mass fraction in the second generation; a large second generation can form with ∆Y ∼ 0.001 − 0.02, while a small second generation can reach ∆Y ∼ 0.16. Like other self-enrichment models for the second generation, we are not able to simultaneously account for both the full range of the Na-O anticorrelation and the second generation fraction.

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Section: Critical Condition For Coolingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Second-generation stars in globular clusters from rapid radiative cooling of pre-supernova massive star winds

Lochhaas¹,

Thompson²

2017

Monthly Notices of the Royal Astronomical Society

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“…Understanding this apparent age trend in R 136 and also 30 Dor region is possible in the future from the formation point of view. Moreover, the question is how the younger population in the center of the cluster can be explained by star cluster formation scenarios (Wünsch et al 2017)? We note that this age difference in the two regions can also be explained by an observational bias because the central region of R 136 is very compact and bright so that the incompleteness level is very low.…”

Section: Age and Extinctionmentioning

confidence: 99%

Uncrowding R 136 from VLT/SPHERE extreme adaptive optics

Khorrami

Vakili

Lanz

et al. 2017

A&A

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This paper presents the sharpest near-IR images of the massive cluster R 136 to date, based on the extreme adaptive optics of the SPHERE focal instrument implemented on the ESO Very Large Telescope and operated in its IRDIS imaging mode. The crowded stellar population in the core of the R 136 starburst compact cluster remains still to be characterized in terms of individual luminosities, age, mass and multiplicity. SPHERE/VLT and its high contrast imaging possibilities open new windows to make progress on these questions. Stacking-up a few hundreds of short exposures in J and Ks spectral bands over a field of view (FoV) of 10.9 × 12.3 centered on the R 136a1 stellar component, enabled us to carry a refined photometric analysis of the core of R 136. We detected 1110 and 1059 sources in J and Ks images respectively with 818 common sources. Thanks to better angular resolution and dynamic range, we found that more than 62.6% (16.5%) of the stars, detected both in J and Ks data, have neighbours closer than 0.2 (0.1 ). The closest stars are resolved down to the full width at half maximum (FWHM) of the point spread function (PSF) measured by Starfinder. Among resolved and/or detected sources R 136a1 and R 136c have optical companions and R 136a3 is resolved as two stars (PSF fitting) separated by 59 ± 2 mas. This new companion of R 136a3 presents a correlation coefficient of 86% in J and 75% in Ks. The new set of detected sources were used to re-assess the age and extinction of R 136 based on 54 spectroscopically stars that have been recently studied with HST slit-spectroscopy (Crowther et al. 2016, MNRAS, 458, 624) of the core of this cluster. Over 90% of these 54 sources identified visual companions (closer than 0.2 ). We found the most probable age and extinction for these sources are 1.8 +1.2 −0.8 Myr, A J = (0.45 ± 0.5) mag and A K = (0.2 ± 0.5) mag within the photometric and spectroscopic error-bars. Additionally, using PARSEC evolutionary isochrones and tracks, we estimated the stellar mass range for each detected source (common in J and K data) and plotted the generalized histogram of mass (MF with error-bars). Using SPHERE data, we have gone one step further and partially resolved and studied the initial mass function covering mass range of (3-300) M at the age of 1 and 1.5 Myr. The density in the core of R 136 (0.1-1.4 pc) is estimated and extrapolated in 3D and larger radii (up to 6 pc). We show that the stars in the core are still unresolved due to crowding, and the results we obtained are upper limits. Higher angular resolution is mandatory to overcome these difficulties.

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“…Krause et al 2013;Martínez-González et al 2014;Wünsch et al 2017). At ∼ 6 Myr, all stars with masses ≥ 40 M ⊙ should have exploded as supernovae (Meynet & Maeder 2003).…”

Section: Star Cluster Wind Modelmentioning

confidence: 99%

Can Dust Injected by SNe Explain the NIR–MIR Excess in Young Massive Stellar Clusters?

Martínez-González

Wünsch

Palouš

2017

ApJ

Self Cite

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We present a physically-motivated model involving the different processes affecting supernova dust grains as they are incorporated into the thermalized medium within young massive star clusters. The model is used to explain the near-to mid-infrared (NIR-MIR) excess found in such clusters and usually modeled as a blackbody with temperature ∼ (400 − 1000) K. In our approach, dust grains are efficiently produced in the clumpy ejecta of core-collapse supernovae, fragmented into small pieces ( 0.05 µm) as they are incorporated into the hot and dense ISM, heated via frequent collisions with electrons and the absorption of energetic photons. Grains with small sizes can more easily acquire the high temperatures (∼ 1000 K) required to produce a NIR-MIR excess with respect to the emission of foreground PAHs and starlight. However, the extreme conditions inside young massive clusters make difficult for these small grains to have a persistent manifestation at NIR-MIR wavelengths as they are destroyed by efficient thermal sputtering. Nevertheless, the chances for a persistent manifestation are increased by taking into account that small grains become increasingly transparent to their impinging ions as their size decreases. For an individual SN event, we find that the NIR-MIR excess last longer if the time required to incorporate all the grains into the thermalized medium is also longer, and in some cases, comparable to the characteristic interval between supernova explosions. Our models, can successfully explain the near-infrared excesses found in the star clusters observed in M33 (Relaño et al. 2016) assuming a low heating efficiency and mass-loading. In this scenario, the presence of the NIR-MIR excess is an indication of efficient dust production in SNe and its subsequent destruction.

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The Formation of Secondary Stellar Generations in Massive Young Star Clusters From Rapidly Cooling Shocked Stellar Winds

Cited by 46 publications

References 69 publications

Second-generation stars in globular clusters from rapid radiative cooling of pre-supernova massive star winds

Second-generation stars in globular clusters from rapid radiative cooling of pre-supernova massive star winds

Uncrowding R 136 from VLT/SPHERE extreme adaptive optics

Can Dust Injected by SNe Explain the NIR–MIR Excess in Young Massive Stellar Clusters?

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