Accretion of pristine gas and dilution during the formation of multiple-population globular clusters

D’Ercole, A.; D’Antona, Francesca; Vesperini, Enrico

doi:10.1093/mnras/stw1583

Cited by 65 publications

(52 citation statements)

References 60 publications

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“…One of the main findings emerging from the study by D' Ercole et al (2016) is that for a given density distribution the return of the pristine gas takes longer for more massive clusters. This result, in conjunction with the high sensitivity of the degree of the hot bottom burning nucleosynthesis experienced by massive AGBs to the metallicity, provide an explanation of the correlation between the shape of the Mg-Al distribution and the mass and metallicity of the clusters found in recent studies (Carretta et al 2009a,b,c;Pancino et al 2017). D'Ercole et al (2016 clearly demonstrated that the mass of the cluster has a strong effect on the extent of the chemical pollution patterns of the species touched by proton-capture nucleosynthesis.…”

Section: Possible Interpretation Of Observed Propertiessupporting

confidence: 62%

A photometric study of globular clusters observed by the APOGEE survey

Mészáros

García-Hernández

Cassisi

et al. 2017

Monthly Notices of the Royal Astronomical Society

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In this paper we describe the photometric and spectroscopic properties of multiple populations in seven northern globular clusters. In this study we employ precise ground based photometry from the private collection of Stetson, space photometry from the Hubble Space Telescope, literature abundances of Na and O, and APOGEE survey abundances for Mg, Al, C, and N. Multiple populations are identified by their position in the C U,B,I -V pseudo-CMD and confirmed with their chemical composition determined using abundances. We confirm the expectation from previous studies that the RGB in all seven clusters are split and the different branches have different chemical compositions. The Mg-Al anti-correlations were well explored by the APOGEE and Gaia-ESO surveys for most globular clusters, some clusters showing bimodal distributions, while others continuous distributions. Even though the structure (i.e., bimodal vs. continuous) of Mg-Al can greatly vary, the Al-rich and Al-poor populations do not seem to have very different photometric properties, agreeing with theoretical calculations. There is no one-to-one correspondence between the Mg-Al anticorrelation shape (bimodal vs. continuous) and the structure of the RGB seen in the HST pseudo-CMDs, with the HST photometric information usually implying more complex formation/evolution histories than the spectroscopic ones. We report on finding two second generation HB stars in M5, and five second generation AGB stars in M92, which is the most metal-poor cluster to date in which second generation AGB stars have been observed.

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Section: Possible Interpretation Of Observed Propertiessupporting

confidence: 62%

A photometric study of globular clusters observed by the APOGEE survey

Mészáros

García-Hernández

Cassisi

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Strong radiative cooling and the stalling of stellar winds promote rapid star formation, significant gas retention, and inhibit the mixing of polluted and pristine gas, which produces a centrally concentrated population of E composition stars. Following the model presented by D'Ercole et al (2016), core-collapse SNe halt star formation for ∼15−40 Myr until enough pristine gas can be accumulated to start the second, delayed formation phase. After ∼40 Myr, the D' Antona et al (2016) model indicates that < 8 M ⊙ AGB stars can start contributing processed gas and mixing with pristine material.…”

Section: Ngc 6402 Chemical Composition Implications For Cluster Formamentioning

confidence: 94%

Light element discontinuities suggest an early termination of star formation in the globular cluster NGC 6402 (M14)

Johnson

Caldwell

Rich

et al. 2019

Monthly Notices of the Royal Astronomical Society

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NGC 6402 is among the most massive globular clusters in the Galaxy, but little is known about its detailed chemical composition. Therefore, we obtained radial velocities and/or chemical abundances of 11 elements for 41 red giant branch cluster members using high resolution spectra obtained with the Magellan-M2FS instrument. We find NGC 6402 to be only moderately metal-poor with [Fe/H] = −1.13 dex (σ = 0.05 dex) and to have a mean heliocentric radial velocity of −61.1 km s −1 (σ = 8.5 km s −1 ). In general, NGC 6402 exhibits mean composition properties that are similar to other inner Galaxy clusters, such as [α/Fe] ∼ +0.3 dex, [Cr,Ni/Fe] ∼ 0.0 dex, and [La/Eu] = −0.08 dex. Similarly, we find large star-to-star abundance variations for O, Na, Mg, Al, and Si that are indicative of gas that experienced high temperature proton-capture burning. Interestingly, we detect three distinct populations, but also find large gaps in the [O/Fe], [Na/Fe], and [Al/Fe] distributions that may provide the first direct evidence of delayed formation for intermediate composition stars. A qualitative enrichment model is discussed where clusters form stars through an early ( < ∼ 5−10 Myr) phase, which results in first generation and "extreme" composition stars, and a delayed phase ( > ∼ 40 Myr), which results in the dilution of processed and pristine gas and the formation of intermediate composition stars. For NGC 6402, the missing intermediate composition stars suggest the delayed phase terminated prematurely, and as a result the cluster may uniquely preserve details of the chemical enrichment process.

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“…Despite the current GC formation scenarios are still uncertain (e.g., Renzini et al 2015), we report in Table 1 the possible ranges of a few relevant quantities expected during the formation of the first generation stars in GCs of two different masses and within the AGB scenario (D'Ercole et al 2008(D'Ercole et al , 2016. D'Ercole et al (2008) study the formation of one proto-GC of stellar mass 10 6 M and half-mass radius of 16 pc and another more massive one, characterised by a stellar mass 10 7 M and an half mass radius of 35 pc.…”

Section: Can We Observe Active Gcs?mentioning

confidence: 99%

Paving the way for the JWST: witnessing globular cluster formation at z > 3

Vanzella¹,

Calura²,

Meneghetti³

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We report on five compact, extremely young (< 10 Myr) and blue (β U V < −2.5, F λ = λ β ) objects observed with VLT/MUSE at redshift 3.1169, 3.235, in addition to three objects at z = 6.145. These sources are magnified by the Hubble Frontier Field galaxy clusters MACS J0416 and AS1063. Their de-lensed half light radii (R e ) are between 16 to 140 pc, the stellar masses are 1 − 20 × 10 6 M , the magnitudes are m U V = 28.8 − 31.4 (−17 < M U V < −15) and specific star formation rates can be as large as ∼ 800 Gyr −1 . Multiple images of these systems are widely separated in the sky (up to 50 ) and individually magnified by factors 3-40. Remarkably, the inferred physical properties of two objects are similar to those expected in some globular cluster formation scenarios, representing the best candidate proto-globular clusters (proto-GC) discovered so far. Rest-frame optical high dispersion spectroscopy of one of them at z = 3.1169 yields a velocity dispersion σ v 20 km s −1 , implying a dynamical mass dominated by the stellar mass. Another object at z = 6.145, with de-lensed31.4), shows a stellar mass and a star-formation rate surface density consistent with the values expected from popular GC formation scenarios. An additional star-forming region at z = 6.145, with de-lensed m U V 32, a stellar mass of 0.5 ×10 6 M and a star formation rate of 0.06 M yr −1 is also identified. These objects currently represent the faintest spectroscopically confirmed star-forming systems at z > 3, elusive even in the deepest blank fields. We discuss how proto-GCs might contribute to the ionization budget of the universe and augment Lyα visibility during reionization. This work underlines the crucial role of JWST in characterizing the restframe optical and near-infrared properties of such low-luminosity high−z objects.

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Accretion of pristine gas and dilution during the formation of multiple-population globular clusters

Cited by 65 publications

References 60 publications

A photometric study of globular clusters observed by the APOGEE survey

A photometric study of globular clusters observed by the APOGEE survey

Light element discontinuities suggest an early termination of star formation in the globular cluster NGC 6402 (M14)

Paving the way for the JWST: witnessing globular cluster formation at z > 3

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