RX J0123.4-7321 is a well-established Be star X-ray binary system in the Small Magellanic Cloud. Like many such systems, the variable X-ray emission is driven by the underlying behaviour of the mass donor Be star. Previous work has shown that the optical and X-ray were characterized by regular outbursts at the proposed binary period of 119 d. However, around 2008 February the optical behaviour changed substantially, with the previously regular optical outbursts ending. Reported here are new optical (OGLE) and X-ray (Swift) observations covering the period after 2008 that suggest an almost total circumstellar disc loss followed by a gradual recovery. This indicates the probable transition of a Be star to a B star, and back again. However, at the time of the most recent OGLE data (2020 March) the characteristic periodic outbursts had yet to return to their early state, indicating that the disc still had some re-building yet to complete.

中文翻译：

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RX J0123.4-7321 – 故事还在继续：主要的环星盘丢失和恢复

RX J0123.4-7321 是小麦哲伦星云中成熟的 Be 星 X 射线双星系统。像许多这样的系统一样，可变 X 射线发射是由质量供体 Be 星的潜在行为驱动的。先前的工作表明，光学和 X 射线的特征是在建议的 119 天双星周期内有规律的爆发。然而，在 2008 年 2 月左右，光学行为发生了重大变化，之前的常规光学爆发结束了。这里报道的是 2008 年之后的新光学 (OGLE) 和 X 射线 (Swift) 观测结果，这些观测表明几乎完全的星环盘损失，然后逐渐恢复。这表明 Be 星可能转变为 B 星，然后再返回。然而，