A young cluster with an extended main-sequence turnoff: confirmation of a prediction of the stellar rotation scenario

N. Bastian*, F. Niederhofer, V. Kozhurina-Platais, M. Salaris, S. Larsen, I. Cabrera-Ziri, M. Cordero, S. Ekstrom, D. Geisler, C. Georgy, M. Hilker, N. Kacharov, C. Li, D. Mackey, A. Mucciarelli, I. Platais

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

We present Hubble Space Telescope photometry of NGC 1850, a ~100 Myr, ~105 M⊙ cluster in the Large Magellanic Cloud. The colour-magnitude diagram clearly shows the presence of an extended main-sequence turnoff (eMSTO). The use of non-rotating stellar isochrones leads to an age spread of ~40 Myr. This is in good agreement with the age range expected when the effects of rotation in the main-sequence turnoff (MSTO) stars are wrongly interpreted in terms of age spread. We also do not find evidence for multiple, isolated episodes of star formation bursts within the cluster, in contradiction to scenarios that invoke actual age spreads to explain the eMSTO phenomenon. NGC 1850 therefore continues the trend of eMSTO clusters, where the inferred age spread is proportional to the age of the cluster. While our results confirm a key prediction of the scenario where stellar rotation causes the eMSTO feature, direct measurements of the rotational rate of MSTO stars is required to definitively confirm or refute whether stellar rotation is the origin of the eMSTO phenomenon or if it is due to an as yet undiscovered effect.

Original languageEnglish
Pages (from-to)L20-L24
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume460
Issue number1
DOIs
Publication statusPublished - 21 Jul 2016

Keywords

  • Galaxies
  • Individual
  • NGC 1850
  • Star clusters

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