We present a near-infrared (NIR) variability analysis for an 6\arcmin $\times$ 6\arcmin region, which encompasses the massive protocluster G286.21+0.17. The total sample comprises more than 5000 objects, of which 562 show signs of a circumstellar disk based on their infrared colors. The data includes HST observations taken in two epochs separated by 3 years in the F110W and F160W bands. 363 objects (7% of the sample) exhibit NIR variability at a significant level (Stetson index >1.7), and a higher variability fraction (14%) is found for the young stellar objects (YSOs) with disk excesses. We identified 4 high amplitude (>0.6 mag) variables seen in both NIR bands. Follow up and archival observations of the most variable object in this survey (G286.2032+0.1740) reveal a rising light curve over 8 years from 2011 to 2019, with a K band brightening of 3.5 mag. Overall the temporal behavior of G286.2032+0.1740 resembles that of typical FU Ori objects, however its pre-burst luminosity indicates it has a very low mass ($<0.12\:M_\odot$), making it an extreme case of an outburst event that is still ongoing.

中文翻译：

---

正在形成的大质量星团中的恒星变异性

我们提出了一个 6\arcmin $\times$ 6\arcmin 区域的近红外 (NIR) 变异性分析，该区域包含巨大的原始星团 G286.21+0.17。总样本包括 5000 多个物体，其中 562 个根据红外颜色显示出星周盘的迹象。数据包括在 F110W 和 F160W 波段中相隔 3 年的两个时期进行的 HST 观测。363 个天体（样本的 7%）表现出显着水平的 NIR 可变性（Stetson 指数 >1.7），并且发现具有盘过剩的年轻恒星天体（YSO）具有更高的可变性分数（14%）。我们确定了在两个 NIR 波段中看到的 4 个高振幅 (>0.6 mag) 变量。本次调查中变化最大的天体（G286.2032+0.1740）的跟踪和档案观察显示，从2011年到2019年的8年间，光变曲线呈上升趋势，K 波段增亮为 3.5 mag。总体而言，G286.2032+0.1740 的时间行为类似于典型的 FU Ori 天体，但其爆发前的光度表明它的质量非常低（$<0.12\:M_\odot$），使其成为仍在进行中的爆发事件。