The Temporal Evolution of the 4--14 Micron Spectrum of V1974 Cygni (Nova Cygni 1992)
The Temporal Evolution of the 4--14 Micron Spectrum of V1974 Cygni (Nova Cygni 1992)
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V1974 Cygni (Nova Cygni 1992) 4--14微米光谱的时间演化
DOI：
10.1086/175134
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
C. Kaminski
中科院分区：
文献类型：
--
作者：
C. Woodward;M. Greenhouse;R. Gehrz;Y. Pendleton;R. Joyce;D. Buren;J. Fischer;N. Jennerjohn;C. Kaminski
我们给出了1992年5月在NASA Kuiper空中天文台(KAO)和1992年10月/11月在亚利桑那州莱蒙山的NASA 1.52m红外望远镜上用HIFOGS中红外光谱仪获得的ONeMG新星V1974天鹅座(Nova Cygni 1992)的4-14微米光谱。这两个时期的光谱都显示了热致辐射(自由辐射)的连续发射，其发射线来自氢和(Ne II)、(Ar III)和Ne VI)。在爆发后约80天的5月期间，中红外光谱中的主要发射线是7.5微米附近的三条谱线(PF-α、HU-β、H11-7)和12.8微米的(Ne II)的混合线。到10月份(大约160天后)，氢发射几乎消失，(Ne II)12.8微米线显著减弱，明显的(Ne VI)发射线出现在7.6微米处。这一行为证实了V1974 Cyg类似于典型的慢ONeMG‘霓虹新星’Nova Qu Vuleculae(1984年第2号)。光谱的显著演化表明，电离条件在1992年5月到1992年10月之间发生了巨大的变化。我们发现，相对于太阳光球层，V1974天鹅座喷出物中的霓虹灯相对于硅的丰度约为10倍。我们给出了(NaIII)7.319微米(NaIV)9.039微米和(NaIV)21.29微米红外钠禁线发射的新模型计算，这可以与最近在ONeMG新星爆发中钠合成的模型预测相比较。我们的结论是，ONeMG新星中的钠丰度可以通过观测红外空间天文台(ISO)和NASA红外望远镜设施(IRTF)的仪器所能获得的钠的红外冕线来确定。
We present 4-14 micron spectra of the ONeMg nova V1974 Cygni (Nova Cygni 1992) obtained during 1992 May on the NASA Kuiper Airborne Observatory (KAO) and from the NASA 1.52 m infrared telescope at Mount Lemmon, Arizona in 1992 October/November with the HIFOGS mid-infrared spectrometer. The spectra at both epochs showed continuum emission from thermal bremstrahlung (free-free radiation) with emission lines from hydrogen and (Ne II), (Ar III), and Ne VI). During May, approximately = 80 days after outburst, the dominant emission lines in the mid-infrared spectra were a blend of three lines (Pf-alpha, Hu-beta, H11-7) near 7.5 microns and (Ne II) at 12.8 microns. By October (approximately 160 days later), the hydrogen emission had virtually disappeared, the (Ne II) 12.8 micron line had weakened considerably, and a pronounced (Ne VI) emission line had appeared at 7.6 microns. This behavior confirms that V1974 Cyg is similar to the prototypical slow ONeMg 'neon nova', Nova QU Vulpeculae (1984 No. 2). The remarkable evolution of the spectrum suggests that the ionization conditions changed drastically between 1992 May and 1992 October. We find that the ejecta of V1974 Cyg were overabundant in neon with respect to silicon by a factor of approximately 10 relative to the solar photosphere. We present new model calculations of infrared sodium forbidden line emission from (Na III) 7.319 microns (Na IV) 9.039 microns, and (Na IV) 21.29 microns that can be compared with recent model predictions of sodium synthesis in ONeMg nova outbursts. We conclude that sodium abundances in ONeMg novae can be determined by observations of infrared coronal lines of sodium that are accssible to the Infrared Space Observatory (ISO) and instruments at the NASA Infrared Telescope Facility (IRTF).