M giants with IGRINS: I. Stellar parameters and α -abundance trends of the solar neighborhood population
M giants with IGRINS: I. Stellar parameters and α -abundance trends of the solar neighborhood population
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具有 IGRINS 的 M 巨星：I. 太阳邻域群的恒星参数和 α 丰度趋势
DOI：
10.1051/0004-6361/202346149
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发表时间：
2023
影响因子：
6.5
通讯作者：
Mace, G.
中科院分区：
文献类型：
--
作者：
Nandakumar, G.;Ryde, N.;Casagrande, L.;Mace, G.
由于Teff < 4000 K的恒星的光谱中普遍存在氧化钛特征，因此只能在近红外（NIR）区域分析M巨星等冷星。 在尘埃遮蔽的区域，内球和银河系中心区域，在近红外光谱中观察到的内在明亮的M巨星是研究恒星丰度和恒星种群化学演化的最佳选择。由于测光方法的不确定性，需要一种由近红外光谱确定M巨星恒星参数的方法，目的研究一种由近红外光谱确定M巨星恒星参数的方法。我们验证的方法推导出恒星参数附近的研究M巨星的光谱从浸没光栅红外光谱仪（IGRINS）的光谱库。我们证明了我们的方法的准确性和精度，通过确定恒星参数和α-元素的趋势与金属丰度为太阳附近的M giants.MethodsWe进行了新的观测44 M巨星IGRINS安装在双子座南望远镜。我们还从IGRINS光谱库中获得了六颗邻近M巨星的全HandK波段IGRINS光谱，光谱分辨率R = 45000。 我们使用的工具称为光谱容易结合一维（1D）模型大气中的辐射和对流计划（MARCS）恒星大气models建模的合成光谱，适合观察到的spectrumbest.ResultsThe有效温度，我们从我们的新方法（测试为3400 Teff <$4000 K在这里）与附近的六个良好的研究M巨星，这表明，准确性确实很高。 对于43个太阳邻域M巨星，我们的Teff，logg，[Fe/H]，[C/Fe]，[N/Fe]和[O/Fe]与APOGEE一致，具有平均差异和分散性（我们的方法- APOGEE）分别为−67±33 K、−0.31±0.15 dex、0.02±0.05 dex、0.22±0.13 km s−1、−0.05±0.06 dex、0.06±0.06 dex和0.02±0.09 dex。此外，与APOGEEeff相比，具有小分散的紧密偏移表明我们导出的温度和从APOGEE管道导出的温度具有高精度。恒星参数的典型不确定度为±100 K inTeff、±0.2 dex（logg）、±0.1 dex（[Fe/H]）和±0.1 km s− 1（μ m）。Mg、Si、Ca和Ti的α元素趋势与金属丰度的关系与APOGEE DR 17的趋势一致，也与GILD的光学趋势一致。我们还发现厚盘恒星的丰度明显增强。
ContextCool stars, such as M giants, can only be analyzed in the near-infrared (NIR) regime due to the ubiquitous titanium oxide features in optical spectra of stars withTeff< 4000 K. In dust-obscured regions, the inner bulge and Galactic center region, the intrinsically bright M giants observed in the NIR are an optimal option for studying stellar abundances and the chemical evolution of stellar populations. Because of the uncertainties in photometric methods, a method for determining the stellar parameters for M giants from the NIR spectra themselves is needed.AimsWe develop a method for determining the stellar parameters for M giants from the NIR spectra. We validate the method by deriving the stellar parameters for nearby well-studied M giants with spectra from the spectral library of the Immersion GRating INfrared Spectrograph (IGRINS). We demonstrate the accuracy and precision of our method by determining the stellar parameters andα-element trends versus metallicity for solar neighborhood M giants.MethodsWe carried out new observations of 44 M giant stars with IGRINS mounted on the Gemini South telescope. We also obtained the fullHandKband IGRINS spectra of six nearby well-studied M giants at a spectral resolving power ofR= 45 000 from the IGRINS spectral library. We used the tool called spectroscopy made easy in combination with one-dimensional (1D) model atmospheres in a radiative and convective scheme (MARCS) stellar atmosphere models to model the synthetic spectrum that fits the observed spectrum best.ResultsThe effective temperatures that we derive from our new method (tested for 3400 ≲Teff≲ 4000 K here) agree excellently with those of the six nearby well-studied M giants, which indicates that the accuracy is indeed high. For the 43 solar neighborhood M giants, ourTeff, logg, [Fe/H],ξmicro, [C/Fe], [N/Fe], and [O/Fe] agree with APOGEE with mean differences and a scatter (our method – APOGEE) of −67±33 K, −0.31±0.15 dex, 0.02±0.05 dex, 0.22±0.13 km s−1, −0.05±0.06 dex, 0.06±0.06 dex, and 0.02±0.09 dex, respectively. Furthermore, the tight offset with a small dispersion compared to the APOGEETeffindicates a high precision in our derived temperatures and those derived from the APOGEE pipeline. The typical uncertainties in the stellar parameters are found to be ±100 K inTeff, ±0.2 dex in logg, ±0.1 dex in [Fe/H], and ±0.1 km s−1inξmicro. Theα-element trends versus metallicity for Mg, Si, Ca, and Ti are consistent with the APOGEE DR17 trends for the same stars and with the GILD optical trends. We also find a clear enhancement in the abundances for thick-disk stars.