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arXiv · 2510.05334

Observation and modeling of a geo-effective event observed on 2011 May 28 from the solar surface to 1au

Nishu Karna·Tatiana Niembro
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Abstract

In this study, we present a comprehensive observational and modeling study of a geo-effective event with D_ST index of -80 nT observed on 2011 May 28 when a coronal hole was bordering an active region. We analyze HMI and EUV images and found that this event involved two filament eruptions ~8 hours apart from two different active region closed to each other. We produce 3D magnetic field configurations for the active regions that are consistent with the observations and employ numerical models to track the CME/ICME propagation up to 1\,au. From our, magnetic models we found that the nearby coronal hole reduced the stability threshold of the flux ropes, with axial flux values approximately three times lower than in comparable cases without coronal holes. A derivative analysis applied to STEREO coronagraph and OMNI database in situ data revealed no evidence of CME-CME interaction during the early stages of their evolution and identified distinct signatures of two CMEs, along with the interacting flow associated with the nearby coronal hole at 1 au. Moreover, we used hydrodynamic simulations constrained by remote sensing and in situ data to track the different structures in the solar wind. We found a good agreement between data and the models. Additionally, we found that the presence of the coronal hole may have suppressed interactions between CMEs, with the transients subsequently propagating along the solar wind streams emerging from the coronal hole.

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Nishu Karna, Tatiana Niembro. 2025-10-06. Observation and modeling of a geo-effective event observed on 2011 May 28 from the solar surface to 1au. https://arxiv.org/abs/2510.05334

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