论文标题
在金属贫困的Galaxy NGC 4068中揭示富含氮的巨大恒星
Unveiling the nitrogen-rich massive star in the metal-poor galaxy NGC 4068
论文作者
论文摘要
我们报告了附近低金属性（z〜0.1zsun）矮星银河NGC 4068中不寻常的发射线恒星状对象的识别。我们的观察值是长时间光谱仪和fabry-perot - 实验对于Haiii 4668686868686866aaa and of Hah line s ha line s ha line s ha line s ha line sception sceply-perfertoment [sii]/[nii]该对象的通量比。从观察数据中，我们得出，该对象代表了高降压光度的单星l〜1.5*10^6 lsun被膨胀的星云包围，其运动年龄为t〜0.5myr。星云表现出明显的氮过多（log（n/o）〜 -0.05，对于低金属性星系的预期高约1.4 dex）。我们建议这是一个巨大的蓝色超级巨人（BSG）或狼射线（WR）恒星，其弹出式与星际介质相互作用。我们使用多云的光电离代码计算了星云的模型，将CMFGEN模型的BSG和WR星应用于电离源。我们发现模型的模型和观察到的光谱之间的最佳一致性，假设质量M*〜80mun的低金属级WR星电离，通过强风将星云电离，并用氮气富集星际介质。
We report the identification of the unusual emission-line stellar-like object in the nearby low-metallicity (Z ~ 0.1Zsun) dwarf galaxy NGC 4068. Our observations performed with long-slit spectrograph and Fabry-Perot interferometer demonstrate high velocity dispersion in Ha line, presence of HeII4686A line and peculiarly low [SII]/[NII] fluxes ratio for this object. From observational data, we derived that the object represents a single star of high bolometric luminosity L~1.5*10^6 Lsun surrounded by an expanding nebula with kinematical age of t ~ 0.5Myr. The nebula exhibits significant nitrogen overabundance (log(N/O) ~ -0.05, that is by ~1.4dex higher than expected for low-metallicity galaxies). We suggested that this is a massive blue supergiant (BSG) or Wolf-Rayet (WR) star surrounded by its ejecta interacting with the interstellar medium. We calculated the models of the nebula using CLOUDY photoionization code, applying CMFGEN-modelled BSG and WR stars as ionisation sources. We found a best agreement between the modelled and observed spectra for the model assuming ionization by low-metallicity WR star of mass M*~80Msun, ionizing the nebula through the strong wind and enriching the interstellar medium with nitrogen.
