Using the multi-object adaptive optics demonstrator RAVEN to observe metal-poor stars in and towards the Galactic Centre

M. Lamb, K. Venn, D. Andersen, S. Oya, M. Shetrone, A. Fattahi, L. Howes, M. Asplund, O. Lardière, M. Akiyama, Y. Ono, H. Terada, Y. Hayano, G. Suzuki, C. Blain, K. Jackson, C. Correia, K. Youakim, C. Bradley

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18 Citations (Scopus)


The chemical abundances for five metal-poor stars in and towards the Galactic bulge have been determined from the H-band infrared spectroscopy taken with the RAVEN multi-object adaptive optics science demonstrator and the Infrared Camera and Spectrograph at the Subaru 8.2-m telescope. Three of these stars are in the Galactic bulge and have metallicities between -2.1<[Fe/H] < -1.5, and high [α/Fe]~+0.3, typical of Galactic disc and bulge stars in this metallicity range; [Al/Fe] and [N/Fe] are also high, whereas [C/Fe] < +0.3. An examination of their orbits suggests that two of these stars may be confined to the Galactic bulge and one is a halo trespasser, though proper motion values used to calculate orbits are quite uncertain. An additional two stars in the globular cluster M22 show [Fe/H] values consistent to within 1σ, although one of these two stars has [Fe/H] = -2.01 ± 0.09, which is on the low end for this cluster. The [α/Fe] and [Ni/Fe] values differ by 2σ, with the most metal-poor star showing significantly higher values for these elements. M22 is known to show element abundance variations, consistent with a multipopulation scenario though our results cannot discriminate this clearly given our abundance uncertainties. This is the first science demonstration of multiobject adaptive optics with high-resolution infrared spectroscopy, and we also discuss the feasibility of this technique for use in the upcoming era of 30-m class telescope facilities.

Original languageEnglish
Pages (from-to)3536-3557
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 2017 Mar 1


  • Galaxy: centre
  • Globular clusters: individual: M22
  • Instrumentation: adaptive optics
  • Stars: abundances
  • Techniques: spectroscopic


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