Stellar metallicities beyond the Local Group: the potential of J-band spectroscopy with extremely large telescopes
Stellar metallicities beyond the Local Group: the potential of J-band spectroscopy with extremely large telescopes
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本星系群之外的恒星金属丰度：J波段光谱学与超大望远镜的潜力
DOI：
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发表时间：
2010
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通讯作者：
G. Rousset
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作者：
C. Evans;B. Davies;B. Davies;B. Davies;R. Kudritzki;M. Puech;Yunming Yang;Yunming Yang;J. Cuby;D. Figer;M. Lehnert;S. Morris;G. Rousset
我们提出了一个42米的欧洲极大望远镜（E-ELT）的红巨星和超巨星的模拟J-波段光谱，使用的工具开发的鹰阶段A仪器研究。模拟光谱被用来证明1.15-1.22微米区域的有效性，以恢复准确的恒星金属丰度从太阳和金属贫乏（十分之一太阳）光谱模板。从测试中的光谱分辨率为4万，我们需要连续的信号-噪声比超过50（每两个像素的分辨率元素）恢复输入金属丰度在0.1德克斯。我们强调了用E-ELT直接估计红巨星的恒星金属岩（在-1<[Fe/H]<0的范围内）的潜力，对于红巨星分支尖端附近的恒星，其距离达到~5 Mpc。同样的模拟也被用来说明红超巨星的定量光谱学的潜力，超过本地体积到几十Mpc。钙三重观测在I-波段也进行了模拟，以提供与当代技术的比较。假设EAGLE仪器参数和自适应光学的模拟性能，J波段方法在恢复给定目标的金属丰度估计方面更敏感。这对于红巨星和超巨星的ELT研究来说似乎非常有希望，它提供了一种直接的金属丰度示踪剂，其波长受消光的影响小于短波长诊断，并且通过自适应光学，具有更好的图像质量。
We present simulated J-band spectroscopy of red giants and supergiants with a 42m European Extremely Large Telescope (E-ELT), using tools developed toward the EAGLE Phase A instrument study. The simulated spectra are used to demonstrate the validity of the 1.15-1.22 micron region to recover accurate stellar metallicities from Solar and metal-poor (one tenth Solar) spectral templates. From tests at spectral resolving powers of four and ten thousand, we require continuum signal-to-noise ratios in excess of 50 (per two-pixel resolution element) to recover the input metallicity to within 0.1 dex. We highlight the potential of direct estimates of stellar metallicites (over the range -1<[Fe/H]<0) of red giants with the E-ELT, reaching out to distances of ~5 Mpc for stars near the tip of the red giant branch. The same simulations are also used to illustrate the potential for quantitative spectroscopy of red supergiants beyond the Local Volume to tens of Mpc. Calcium triplet observations in the I-band are also simulated to provide a comparison with contemporary techniques. Assuming the EAGLE instrument parameters and simulated performances from adaptive optics, the J-band method is more sensitive in terms of recovering metallicity estimates for a given target. This appears very promising for ELT studies of red giants and supergiants, offering a direct metallicity tracer at a wavelength which is less afffected by extinction than shortward diagnostics and, via adaptive optics, with better image quality.