Revealing the Spectroscopic Variations of FU Orionis Object V960 Mon with High-resolution Spectroscopy
Revealing the Spectroscopic Variations of FU Orionis Object V960 Mon with High-resolution Spectroscopy
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DOI：
10.3847/1538-4357/abbef0
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
Y. Takagi;S. Honda;A. Arai;J. Takahashi;Y. Oasa;Y. Itoh
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作者：
Y. Takagi;S. Honda;A. Arai;J. Takahashi;Y. Oasa;Y. Itoh
本文介绍了猎户座FU型恒星V960 Mon的高分辨率光谱结果。V960 Mon的亮度在2014年11月被探测到爆发后持续下降。在此调光过程中，我们进行了中分辨率光谱监测观测，发现吸收特征的等效宽度出现了变化。为了进一步研究V960 Mon的光谱变化，我们分别于2018年1月8日和2020年2月1日利用斯巴鲁望远镜和高色散光谱仪对V960 Mon进行了高分辨率光谱观测。通过将该光谱与凯克天文台和高分辨率梯队光谱仪在2014年至2017年期间拍摄的档案数据进行比较，我们发现随着V960 Mon的褪色，吸收剖面发生了变化。吸收谱线如Fe i和Ca i的谱线轮廓可以用圆盘大气和中心恒星的光谱之和来解释。为解释谱线的变化而建立的模型光谱表明，中心恒星的有效温度为~ 5500 K，与爆发前与盖亚的距离为1.6 kpc的温度相当。光谱还显示，随着V960 Mon的褪色，圆盘大气的有效温度下降。Hα和Ca ii谱线（8498.0,8542.1 Å）的变化也表明V960的Mon光谱以中心星为主。
We present the results of the high-resolution spectroscopy of the FU Orionis-type star V960 Mon. The brightness of V960 Mon decreased continuously after the outburst was detected in 2014 November. During this dimming event, we carried out medium-resolution spectroscopic monitoring observations and found that the equivalent width of the absorption features showed variations. To further investigate the spectroscopic variations, we conducted a high-resolution spectroscopic observation of V960 Mon with the Subaru Telescope and the High Dispersion Spectrograph on 2018 January 8 and 2020 February 1. By comparing this spectrum with the archival data of the Keck Observatory and the High Resolution Echelle Spectrometer taken between 2014 and 2017, we found that the absorption profiles changed as V960 Mon faded. The line profile of absorption lines such as Fe i and Ca i can be explained by a sum of the spectra of the disk atmosphere and the central star. The model spectrum created to explain the variations of the line profiles suggests that the effective temperature of the central star is ∼5500 K, which is comparable to that of the pre-outburst phase with a distance of 1.6 kpc with Gaia. The spectrum also shows that the effective temperature of the disk atmosphere decreased as V960 Mon faded. The variations of the Hα and Ca ii lines (8498.0, 8542.1 Å) also show that the V960 Mon spectrum became central-star dominant.