基于LAMOST光谱新证认12个HⅡ区  

Identification of 12 HⅡ Regions with LAMOST

作　　者：赵东纬 罗阿理[1] 侯文[1] 

机构地区：[1]中国科学院国家天文台,北京100012 [2]中国科学院大学,北京100049

出　　处：《天文学进展》2017年第2期208-219,共12页Progress In Astronomy

基　　金：国家自然科学基金(11390371);973项目(2014CB845704)

摘　　要：基于LAMOST(大天区面积多目标光纤光谱天文望远镜)DR3的单次曝光光谱,分析了集中在反银心方向HⅡ区及HⅡ候选区中的恒星和天光光谱。通过测量HⅡ区及HⅡ候选区的lg(Hα/[SⅡ]λλ6717+6731)和lg(Hα/[NⅡ]λλ6548+6584)线强比,并使用线强比在理论诊断图中的位置对这些候选区进行HⅡ区的判定。对比HⅡ候选区与参照区的Hα等值宽度,辅以搜索候选区内的早型恒星对HⅡ候选区进行证认,最终从65个HⅡ候选区中证认了12个HⅡ区。HⅡ region is one type of emission nebula which is excited by massive stars through ultraviolet radiation. Study of HⅡ regions provides an insight into understanding the structure of the Galaxy. We newly identify 12 HⅡ regions based on the single-exposure spectra of Galactic Anti-Center from LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope) survey in this paper. Firstly, we pick out the sky and stellar spectra from LAMOST DR3 that locate in 65 HⅡ region candidates from Anderson et al.'s catalog of HⅡ regions based on WISE(Wide-field Infrared Survey Explorer) data. For sky spectra and stellar spectra subtracting the stellar components, we calculate the line intensity ratio of both Hα/[SⅡ] and Hα/[NⅡ]. According to the distribution of line intensity ratio in the theoretical criteria diagram, 42 out of 65 HⅡ region candidates are preliminarily selected. Besides, the average equivalent width of Hα and early-type stars(O or B type) harbouring in the HⅡ region candidates are also taken into account in order to provide further constraints on the identification of HⅡ regions. We calculate the Hα equivalent width of 7202 spectra in 65 HⅡ region candidates, and take the average value as the equivalent width of corresponding HⅡ region candidates. So the Hα equivalent width-1 is considered as one of the limitations to identify HⅡ region. Additionally, O or B-type stars are also counted in HⅡ region candidates since OB stars usually exist in HⅡ region. We find that B-type stars are observed in 23 HⅡ region candidates using LAMOST data. Finally, we confirm 12 out of 65 HⅡ regions candidates are HⅡ regions using the criteria of line intensity ratio in combination with both Hα equivalent width-1 and existence of O, B-type stars in the regions.

关 键 词：HⅡ区 LAMOST 线强比 Hα等值宽度 

分 类 号：P155.14[天文地球—天文学]