论文标题
NGC 2403与Blue Supergiants的金属性和距离
The metallicity and distance of NGC 2403 from blue supergiants
论文作者
论文摘要
我们介绍了附近Galaxy NGC 2403中蓝色超级恒星的首次定量光谱分析。我们得出的NGC 2403的径向金属梯度的斜率为-0.14（+/- 0.05）dex/r_e，并且与HII区域氧丰度的分析相符。我们提供了证据表明，在一般而言，基于对极光线的分析，我们在多个金属性的一个数量级上，基于极光线的分析，我们在一般而言的金属丰度中获得的恒星金属性。采用恒星参数和内在光度之间的已知关系，我们发现距离模量m-m = 27.38 +/- 0.08 mag。虽然这可以与基于头孢菌的确定一致，但它比从红色巨型分支的尖端测得的值低0.14。我们更新了从分辨的星形星系中恒星的化学丰度研究中获得的质量金属关系。
We present the first quantitative spectral analysis of blue supergiant stars in the nearby galaxy NGC 2403. Out of a sample of 47 targets observed with the LRIS spectrograph at the Keck I telescope we have extracted 16 B- and A-type supergiants for which we have data of sufficient quality to carry out a comparison with model spectra of evolved massive stars and infer the stellar parameters. The radial metallicity gradient of NGC 2403 that we derive has a slope of -0.14 (+/- 0.05) dex/r_e, and is in accordance with the analysis of H II region oxygen abundances. We present evidence that the stellar metallicities that we obtain in extragalactic systems in general agree with the nebular abundances based on the analysis of the auroral lines, over more than one order of magnitude in metallicity. Adopting the known relation between stellar parameters and intrinsic luminosity we find a distance modulus m-M = 27.38 +/- 0.08 mag. While this can be brought into agreement with Cepheid-based determinations, it is 0.14 mag short of the value measured from the tip of the red giant branch. We update the mass-metallicity relation secured from chemical abundance studies of stars in resolved star-forming galaxies.
