Teng Weilin, Su Yingna, Ji Haisheng, Zhang Qingmin
Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, 210023, Nanjing, Jiangsu, PR China.
School of Astronomy and Space Science, University of Science and Technology of China, 230026, Hefei, Anhui, PR China.
Nat Commun. 2024 Oct 24;15(1):9198. doi: 10.1038/s41467-024-53538-1.
Some geomagnetic storms' solar origins are ambiguous, making them hard to predict. On March 23, 2023, a severe geomagnetic storm occurred, however, forecasts based on remote-sensing observations failed to predict it. Here, we show clear evidence that this storm originates from the eruption of a trans-equatorial, longitudinal and low-density magnetic flux rope (FR) with weaker coronal emission and no chromospheric signs. The FR's gentle eruption results in a faint full-halo coronal mass ejection (CME), which is missed by forecasters and not included in CME catalogs. Combining magnetic field modeling and in-situ measurements, we reveal the FR's southward axial magnetic field as the main cause of the geomagnetic storm. This CME is the stealthiest one reported causing a severe geomagnetic storm. Our study highlights that erupting trans-equatorial FRs can generate major geomagnetic storms in a stealthy way. Characteristic observational signatures of similar eruptions are proposed to help in future forecasts.
一些地磁风暴的太阳起源尚不明确，这使得它们难以预测。然而，2023年3月23日发生了一场严重的地磁风暴，基于遥感观测的预报却未能对其作出预测。在此，我们展示了明确的证据，表明这场风暴源自一个跨越赤道、呈纵向且低密度的磁通量绳（FR）的喷发，该磁通量绳的日冕发射较弱且没有色球层特征。FR的平缓喷发导致了一次微弱的全晕日冕物质抛射（CME），预报员未能捕捉到这次抛射，且其未被纳入CME目录中。结合磁场建模和实地测量，我们揭示了FR向南的轴向磁场是地磁风暴的主要成因。这次CME是有报道的引发严重地磁风暴的最隐匿的一次。我们的研究强调，喷发的跨赤道FR能够以隐匿的方式引发重大地磁风暴。我们提出了类似喷发的特征性观测特征，以助力未来的预报。
