Chemical abundances for Hf 2-2

We present high-quality optical spectroscopic observations of the planetary nebula (PN) Hf 2-2. The spectrum exhibits many prominent optical recombination lines (ORLs) from...本研究报道了行星状星云（planetary nebula, PN）Hf 2-2的高质量光学光谱观测数据。该光谱展现出多条显著的来自……的光学复合线（optical recombination lines, ORLs）