Parkes observations for project P1119 semester 2021OCTS_03

Recently, low-frequency periodic radio pulses have been detected from the prototypical M-dwarf flare star, UV Ceti. This shows that the low-frequency emission from this star is driven by auroral activity, in stark contrast to the solar-like coronal activity exhibited at microwave–X-ray wavelengths. However, the driver of this auroral activity is unclear. Possible drivers of this aurora include breakdown of co-rotation with a magnetospheric plasma disk, or the sub-Alfv\'enic interaction of the star with a companion planet. Expected signatures of the latter mechanism include small deviations of the radio pulse period from the stellar rotation period, or a modulation of the pulsed radio emission at the planetary orbital period. To detect these signatures, we require long-term, wide-band monitoring of the radio pulses. In this proposal, we seek to accurately measure the pulse rotation period of UV Ceti by measuring the pulse arrival times over four epochs separated by timescales of days--weeks. This will form an important part of the groundwork for detecting signatures of the auroral engine in future long-term monitoring. If successful, this project will constitute the first steps toward unveiling the signature of star-planet interaction in this benchmark M-dwarf. This will enable this type of emission to be used as a future probe of exoplanetary systems.

近期，研究人员在典型M矮耀星（M-dwarf flare star）UV Ceti中探测到低频周期性射电脉冲。这表明该恒星的低频射电辐射由极光活动（auroral activity）驱动，与微波至X射线波段表现出的类日冕活动形成鲜明反差。不过，该极光活动的驱动源仍不明确。目前提出的潜在驱动机制包括：与磁层等离子体盘（magnetospheric plasma disk）的共转中断，或是恒星与伴行星之间的亚阿尔文相互作用（sub-Alfvénic interaction）。后一种机制的预期观测特征包括：射电脉冲周期相较于恒星自转周期（stellar rotation period）存在微小偏差，或是脉冲射电辐射的调制周期与行星轨道周期（planetary orbital period）相匹配。为探测这类观测特征，我们需要对射电脉冲开展长期、宽波段监测。在本项目申请中，我们计划通过测量四个间隔数天至数周的观测历元内的脉冲到达时间，精准测定UV Ceti的脉冲自转周期。该项工作将为未来长期监测中探测极光驱动源的观测特征奠定重要基础。若本项目取得成功，将成为揭开这颗基准M矮星中恒星-行星相互作用特征的第一步。这将使得这类射电辐射未来可作为系外行星系统（exoplanetary systems）的探测探针。