标题： 人马座变源星红外光谱的短期和长期变化特性 显示英文标题

标题： Short and long term near-infrared spectroscopic variability of eruptive protostars from VVV

摘要： 众多爆发变星光年轻的恒星天体（YSOs），主要是I类系统，最近被近红外VISTA在银河系中的变量（VVV）巡天所探测到。 我们展示了对14个爆发YSO的探索性近红外光谱变化研究。 这些变化在1天和1至2年的间隔内被采样，并与VVV光变曲线结合分析。 在具有FUor光谱的3个目标上观察到了CO倍频吸收特征：所有这些特征在它们更亮时显示出更深的吸收。 这表明当吸积率更高时，来自周围星盘的更强发射伴随着更陡峭的垂直温度梯度。 这证实了快速的VVV类似FUor事件的性质，符合经典FUor的公认图景。 在一个类似于FUor的目标下降到爆发前亮度时没有Br$\gamma$发射，这表明重建恒星磁场是一个缓慢的过程。 在1天的时间尺度内，60个表现出显著但适度的变化，6个源中有2个在Br$\gamma$中有大的变化。 在长达一年的时间尺度上，尽管$K_s$的变化高达1.8星等，H$_2$的流量变化仍然保持适度。 这表明来自分子外流的发射通常起源于离原恒星更远的地方，并且不受年长时间段内相对较大的吸积率变化的影响。 两个目标显示出由Br$\gamma$发射追踪的磁层吸积的开启/关闭迹象。 此外，在一个YSO中还检测到了60。 显示英文摘要

摘要： Numerous eruptive variable young stellar objects (YSOs), mostly Class I systems, were recently detected by the near-infrared Vista Variables in the Via Lactea (VVV) survey. We present an exploratory near-infrared spectroscopic variability study of 14 eruptive YSOs. The variations were sampled over 1-day and 1 to 2-year intervals and analysed in combination with VVV light curves. CO overtone absorption features are observed on 3 objects with FUor-like spectra: all show deeper absorption when they are brighter. This implies stronger emission from the circumstellar disc with a steeper vertical temperature gradient when the accretion rate is higher. This confirms the nature of fast VVV FUor-like events, in line with the accepted picture for classical FUors. The absence of Br$\gamma$ emission in a FUor-like object declining to pre-outburst brightness suggests that reconstruction of the stellar magnetic field is a slow process. Within the 1-day timescale, 60% of H$_2$-emitting YSOs show significant but modest variation, and 2/6 sources have large variations in Br$\gamma$. Over year-long timescales, H$_2$ flux variations remain modest despite up to 1.8 mag variation in $K_s$. This indicates that emission from the molecular outflow usually arises further from the protostar and is unaffected by relatively large changes in accretion rate on year-long timescales. Two objects show signs of on/off magnetospheric accretion traced by Br$\gamma$ emission. In addition, a 60% inter-night brightening of the H$_2$ outflow is detected in one YSO.