Multiple Stellar Populations of Globular Clusters from Homogeneous Ca–CN–CH–NH Photometry. VII. Metal-poor Populations in 47 Tucanae (NGC 104)*
               
               †

Lee, Jae-Woo

doi:10.3847/1538-4365/ac9795

Cited by 9 publications

(18 citation statements)

References 77 publications

(167 reference statements)

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“…Throughout this work, we will use our own photometric indices (see also Lee 2019Lee , 2022Lee & Sneden 2021), defined as…”

Section: Photometric Indices and Color-magnitude Diagramsmentioning

confidence: 99%

“…In Figure 1, we show our color-magnitude diagrams (CMDs) of M92 using our color indices. In order to remove the luminosity effect in RGB stars in our interest with −2.5 mag V − V HB 3.0 mag, the RGB sequences in the individual color indices were parallelized using the following relation (also see Lee 2019Lee , 2022Lee & Sneden 2021)…”

Section: Photometric Indices and Color-magnitude Diagramsmentioning

confidence: 99%

“…Except for a small number of some special GCs, such as ω Cen, intracluster inhomogeneity in metal abundances is often neglected. However, the conventional assumption of the homogeneity in iron abundances of normal GCs has been challenged recently (e.g., Lardo et al 2022;Lee 2022;Lee & Sneden 2021;Legnardi et al 2022).…”

Section: Introductionmentioning

confidence: 99%

“…The carbon and nitrogen abundance variations can be photometrically determined through very strong absorption band features of NH, CN, and CH molecules. In this regard, we have developed a series of narrowband photometric systems that can measure metallicity and carbon and nitrogen abundances in GC red giant branch (RGB) stars (e.g., Lee 2015Lee , 2022Lee & Sneden 2021).…”

Section: Introductionmentioning

confidence: 99%

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M92 (NGC 6341) Is a Metal-complex Globular Cluster with an Atypical Primordial Population

Lee

2023

ApJL

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We present a multiple stellar population study of the metal-poor globular cluster (GC) M92 (NGC 6341), which is long known for the substantial metallicity dispersion, using our own photometric system. We find two groups with slightly different mean metallicities, the metal-poor (MP) stars with [Fe/H] hk = −2.412 ± 0.03 and the metal-rich (MR) ones with −2.282 ± 0.002. The MP constitutes about 23% of the total mass with a more central concentration. Our populational tagging based on the [C/Fe] ch and [N/Fe] nh provides the mean n(P):n(I):n(E) = 32.2:31.6:36.2 (±2.4), where P, I, and E denote the primordial, intermediate, and extreme populations, respectively. Our populational number ratio is consistent with those of others. However, the MP has a significantly different populational number ratio than the mean value, and the domination of the primordial population in the MP is consistent with observations of Galactic GCs that less massive GCs contain larger fractions of the primordial population. Structural and constituent differences between the MP and MR may indicate that M92 is a merger remnant in a dwarf galaxy environment, consistent with recent suggestions that M92 is a GC in a dwarf galaxy or a remnant nucleus of the progenitor galaxy. Discrepancy between our method and those widely used for the Hubble Space Telescope photometry exists in the primordial population. Significant magnesium and oxygen depletions of −0.8 and −0.3 dex, respectively, and helium enhancement of ΔY ≳ 0.03 are required to explain the presence of this abnormal primordial group. No clear explanation is available with limited information of detailed elemental abundances.

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“…Throughout this work, we will use our own photometric indices (see also Lee 2019Lee , 2022Lee & Sneden 2021), defined as…”

Section: Photometric Indices and Color-magnitude Diagramsmentioning

confidence: 99%

Section: Photometric Indices and Color-magnitude Diagramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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M92 (NGC 6341) Is a Metal-complex Globular Cluster with an Atypical Primordial Population

Lee

2023

ApJL

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“…The 1P and 2P stars appear as discrete stellar populations in the ChMs derived from the upper MS and the RGB and define distinct sequences in the photometric diagrams that are commonly used to identify multiple populations (e.g. Milone et al 2012a;Dondoglio et al 2021;Jang et al 2022;Lee 2022).…”

Section: Introductionmentioning

confidence: 99%

Multiple Stellar Populations in Globular Clusters with JWST: a NIRCam view of 47 Tucanae

Milone¹,

Marino²,

Dotter³

et al. 2023

Preprint

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We use images collected with the near-infrared camera (NIRCam) on board the James Webb Space Telescope and with the Hubble Space Telescope (HST) to investigate multiple populations at the bottom of the main sequence (MS) of 47 Tucanae. The m F115W vs. m F115W −m F322W2 CMD from NIRCam shows that, below the knee, the MS stars span a wide color range, where the majority of M-dwarfs exhibit blue colors, and a tail of stars are distributed toward the red. A similar pattern is observed from the m F160W vs. m F110W − m F160W color-magnitude diagram (CMD) from HST, and multiple populations of M-dwarfs are also visible in the optical m F606W vs. m F606W − m F814W CMD. The NIRCam CMD shows a poorly-populated sequence of faint MS stars that we tentatively associate with a population of very low-mass stars. We introduce a chromosome map of M-dwarfs that reveals an extended first population and three main groups of second-population stars. By combining isochrones and synthetic spectra with appropriate chemical composition, we simulate colors and magnitudes of different stellar populations in the NIRCam filters (at metallicities [Fe/H]=-1.5 and [Fe/H]=-0.75) and identify the photometric bands that provide the most efficient diagrams to investigate the multiple populations in globular clusters. Models are compared with the observed CMDs of 47 Tucanae to constrain M-dwarfs' chemical composition. Our analysis suggests that the oxygen range needed to reproduce the colors of first-and second-population M-dwarfs is similar to that inferred from spectroscopy of red giants, challenging the proposal that the chemical variations are due to mass transfer phenomena in proto-clusters.

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MgAl burning chain in ω Centauri

Alvarez Garay,

Mucciarelli,

Bellazzini

et al. 2024

A&A

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In this study, we report the results of the analysis of Fe, Mg, Al, and Si abundances analysis for a sample of 439 stars in ω Centauri, using high-resolution spectra obtained with the VLT/FLAMES multi-object spectrograph. Our analysis reveals the presence of four distinct Fe populations, with the main peak occurring at a low metallicity, consistent with previous literature findings. We observe a discrete and pronounced Mg–Al anticorrelation, which exhibits variations in shape and extension as a function of metallicity. Specifically, this anticorrelation is present in stars with metallicities lower than approximately −1.3 dex, while it becomes less evident or absent for higher [Fe/H] values. Additionally, we detect (anti)correlations between Mg and Si, and between Al and Si, whose extensions also vary with metallicity, similar to the Mg–Al anticorrelation. These results suggest that the MgAl cycle plays a crucial role in the formation of multiple populations in ω Centauri, with the presence of all (anti)correlations at metallicities lower than –1.3 dex, providing evidence for the burning of Mg at very high temperatures (> 108 K), at least in the metal-poor regime. Furthermore, we observe a clear trend of stars with [Al/Fe] > +0.5 dex as a function of metallicity, confirming for the first time the existence of the two channels of Al production and destruction. This evidence can help to provide further constraints on the potential nature of the polluters responsible for the observed chemical anomalies in this stellar system. Finally, we find that the two most metal-poor populations identified in our sample are compatible with null or very small metallicity dispersion and we discuss how this result fits into a scenario where ω Centauri is the remnant of a disrupted nucleated dwarf galaxy.

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Multiple Stellar Populations of Globular Clusters from Homogeneous Ca–CN–CH–NH Photometry. VII. Metal-poor Populations in 47 Tucanae (NGC 104)* †

Cited by 9 publications

References 77 publications

M92 (NGC 6341) Is a Metal-complex Globular Cluster with an Atypical Primordial Population

M92 (NGC 6341) Is a Metal-complex Globular Cluster with an Atypical Primordial Population

Multiple Stellar Populations in Globular Clusters with JWST: a NIRCam view of 47 Tucanae

MgAl burning chain in ω Centauri

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