Evidence of deep mixing in IRS 7, a cool massive supergiant member of the Galactic nuclear star cluster - Archive ouverte HAL Access content directly
Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2022

Evidence of deep mixing in IRS 7, a cool massive supergiant member of the Galactic nuclear star cluster

(1) , , , , , , , , , , ,
1
Verne Smith
  • Function : Author
Katia Cunha
  • Function : Author
Sylvia Ekström
Carlos Abia
  • Function : Author
Bertrand Plez
Georges Meynet
  • Function : Author
Solange Ramirez
  • Function : Author
Nikos Prantzos
  • Function : Author
Kris Sellgren
  • Function : Author
Cristian Hayes
  • Function : Author
Steven Majewski
  • Function : Author

Abstract

ABSTRACT The centre of the Milky Way contains stellar populations spanning a range in age and metallicity, with a recent star formation burst producing young and massive stars. Chemical abundances in the most luminous stellar member of the nuclear star cluster (NSC), IRS 7, are presented for 19F, 12C, 13C, 14N, 16O, 17O, and Fe from a local thermodynamic equilibrium analysis based on spherical modelling and radiative transfer with a 25-M⊙ model atmosphere, whose chemistry was tailored to the derived photospheric abundances. We find IRS 7 to be depleted heavily in both 12C (∼–0.8 dex) and 16O (∼–0.4 dex), while exhibiting an extremely enhanced 14N abundance (∼+1.1 dex), which are isotopic signatures of the deep mixing of CNO-cycled material to the stellar surface. The 19F abundance is also heavily depleted by ∼1 dex relative to the baseline fluorine of the NSC, providing evidence that fluorine along with carbon constrain the nature of the deep mixing in this very luminous supergiant. The abundances of the minor isotopes 13C and 17O are also derived, with ratios of 12C/13C ∼ 5.3 and 16O/17O ∼ 525. The derived abundances for IRS 7, in conjunction with previous abundance results for massive stars in the NSC, are compared with rotating and non-rotating models of massive stars and it is found that the IRS 7 abundances overall follow the behaviour predicted by stellar models. The depleted fluorine abundance in IRS 7 illustrates, for the first time, the potential of using the 19F abundance as a mixing probe in luminous red giants.
Not file

Dates and versions

hal-03876386 , version 1 (28-11-2022)

Identifiers

Cite

Rafael Guerço, Verne Smith, Katia Cunha, Sylvia Ekström, Carlos Abia, et al.. Evidence of deep mixing in IRS 7, a cool massive supergiant member of the Galactic nuclear star cluster. Monthly Notices of the Royal Astronomical Society, 2022, 516 (2), pp.2801-2811. ⟨10.1093/mnras/stac2393⟩. ⟨hal-03876386⟩

Collections

CNRS
0 View
0 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More