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

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

来源：Monthly Notices of the Royal Astronomical Society, 2017, 465(3): 3536-3557.

DOI：10.1093/mnras/stw2865

• instrumentation: adaptive optics
• techniques: spectroscopic
• stars: abundances
• Galaxy: centre
• globular clusters: individual: M22

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 [alpha/ Fe]similar to+ 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 1 sigma, although one of these two stars has [ Fe/H] = - 2.01 +/- 0.09, which is on the low end for this cluster. The [a/ Fe] and [Ni/ Fe] values differ by 2 sigma, 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.

• 出版日期2017-3