Scientific article
OA Policy
English

Using 26 Al to detect ongoing self-enrichment in young massive star clusters

Published inMonthly notices of the Royal Astronomical Society, vol. 534, no. 3, p. 2499-2515
Publication date2024-10-04
First online date2024-09-25
Abstract

Self-enrichment is one of the leading explanations for chemical anomalies in globular clusters. In this scenario, various candidate polluter stars have been proposed to eject gas with altered chemical composition during the self-enrichment process. Most of the proposed polluters will also eject radioactive 26Al into the surroundings. Hence, any detection of 26Al in young massive star clusters (YMCs) would support the self-enrichment scenario if YMCs were indeed the progenitors of globular clusters. Observations of gamma-ray data from COMPTEL and INTEGRAL, as well as detections of 26AlF molecules by the Atacama Large Millimeter-submillimeter Array (ALMA), indicate the maturing of 26Al detection methods. Detection possibilities will be enhanced in the short- to mid-term by the upcoming launch of the Compton Spectrometer and Imager (COSI). The Square Kilometre Array (SKA) could in principle also detect radio recombination lines of the positronium formed from the decay products of 26Al. Here, we show for a sample of YMCs in the nearby Universe, where self-enrichment could plausibly take place. For some nearby galaxies, this could enhance 26Al by an order of one magnitude. Detecting 26 AlF with ALMA appears feasible for many candidate self-enrichment clusters, although significant challenges remain with other detection methods. The Large Magellanic Cloud, with its YMC R136, stands out as the most promising candidate. Detecting a 1.8 MeV radioactive decay line of 26Al here would require at least 15 months of targeted observation with COSI, assuming ongoing self-enrichment in R136.

Keywords
  • ISM: nuclear reactions
  • Nucleosynthesis
  • Abundances
  • Stars: abundances
  • Globular clusters: general
  • Galaxies: clusters: general
  • Galaxies: abundances
Funding
  • Science and Technology Facilities Council [ST/V506709/1]
Citation (ISO format)
NOWAK, Katarzyna et al. Using 26 Al to detect ongoing self-enrichment in young massive star clusters. In: Monthly notices of the Royal Astronomical Society, 2024, vol. 534, n° 3, p. 2499–2515. doi: 10.1093/mnras/stae2227
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Identifiers
Journal ISSN0035-8711
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