Solar origins of a strong stealth CME detected by Solar Orbiter

O’Kane, Jennifer; Green, L. M.; Davies, Emma E.; Möstl, Christian; Hinterreiter, Jürgen; Forstner, J. L. F. von; Weiss, Andreas J.; Long, David M.; Amerstorfer, Tanja

doi:10.1051/0004-6361/202140622

Cited by 25 publications

(22 citation statements)

References 53 publications

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“…This structure erupted from high altitudes (its bottom was observed to lie at ∼1.4 R in EUVI imagery), possibly resulting in the lack of on-disc signatures, and was characterised by the classic "rolling" motion often observed in slow flux rope events. Similar events featuring extensive activity visible off the limb from one viewpoint, but without corresponding on-disc signatures, are characteristic of solar minimum conditions and were reported in several recent studies (Liewer et al 2021;O'Kane et al 2021).…”

Section: Overview Of the Eruptionsupporting

confidence: 81%

“…The encouraging results of the magnetic field hindcast prediction presented in this work suggest that these events could be accurately forecast even if their exact source region remains elusive in on-disc imagery. Certainly, in this and other reported cases off-limb observations were crucial in connecting a stealth CME at the Sun with its interplanetary counterpart (e.g., Korreck et al 2020;Lario et al 2020;O'Kane et al 2021). Thus, this study highlights the importance of continuous observations of the solar disc and corona away from the Sun-Earth line, not only to enable more accurate space weather forecasts, but also to shed light on the complex characteristics and dynamics of stealthy CMEs that, albeit slow, have potential for considerable geoeffectiveness.…”

Section: Discussionmentioning

confidence: 50%

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Predicting the Magnetic Fields of a Stealth CME Detected by Parker Solar Probe at 0.5 AU

Palmerio,

Kay,

Al-Haddad

et al. 2021

Preprint

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Stealth coronal mass ejection (CMEs) are eruptions from the Sun that are not associated with appreciable low-coronal signatures. Because they often cannot be linked to a well-defined source region on the Sun, analysis of their initial magnetic configuration and eruption dynamics is particularly problematic. In this manuscript, we address this issue by undertaking the first attempt at predicting the magnetic fields of a stealth CME that erupted in 2020 June from the Earth-facing Sun. We estimate its source region with the aid of off-limb observations from a secondary viewpoint and photospheric magnetic field extrapolations. We then employ the Open Solar Physics Rapid Ensemble Information (OSPREI) modelling suite to evaluate its early evolution and forward-model its magnetic fields up to Parker Solar Probe, which detected the CME in situ at a heliocentric distance of 0.5 AU. We compare our hindcast prediction with in-situ measurements and a set of flux rope reconstructions, obtaining encouraging agreement on arrival time, spacecraft crossing location, and magnetic field profiles. This work represents a first step towards reliable understanding and forecasting of the magnetic configuration of stealth CMEs and slow, streamer-blowout events.

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Section: Overview Of the Eruptionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 50%

Predicting the Magnetic Fields of a Stealth CME Detected by Parker Solar Probe at 0.5 AU

Palmerio,

Kay,

Al-Haddad

et al. 2021

Preprint

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“…The two solar wind streams are ballistically mapped to the source surface before a potential field source surface (PFSS) model (Altschuler & Newkirk 1969;Schatten, Wilcox & Ness 1969) is applied, using the pfsspy library (Stansby, Yeates & Badman 2020a), to determine solar origins of the wind (For other studies that use PFSS mapping see e.g. Badman et al 2020;O'Kane et al 2021). Both streams originate near the boundary of the Southern polar coronal hole, separated by ∼30 • in longitude, according to the model (See Fig.…”

Section: Type Of Solar Wind and Source Regionmentioning

confidence: 99%

Plasma properties, switchback patches, and low α-particle abundance in slow Alfvénic coronal hole wind at 0.13 au

Woolley

Matteini

McManus

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The Parker Solar Probe (PSP) mission presents a unique opportunity to study the near-Sun solar wind closer than any previous spacecraft. During its fourth and fifth solar encounters, PSP had the same orbital trajectory, meaning that solar wind was measured at the same latitudes and radial distances. We identify two streams measured at the same heliocentric distance (∼0.13au) and latitude (∼-3.5○) across these encounters to reduce spatial evolution effects. By comparing the plasma of each stream, we confirm that they are not dominated by variable transient events, despite PSP’s proximity to the heliospheric current sheet. Both streams are consistent with a previous slow Alfvénic solar wind study once radial effects are considered, and appear to originate at the Southern polar coronal hole boundary. We also show that the switchback properties are not distinctly different between these two streams. Low α-particle abundance (∼ 0.6 %) is observed in the encounter 5 stream, suggesting that some physical mechanism must act on coronal hole boundary wind to cause α-particle depletion. Possible explanations for our observations are discussed, but it remains unclear whether the depletion occurs during the release or the acceleration of the wind. Using a flux tube argument, we note that an α-particle abundance of ∼ 0.6 % in this low velocity wind could correspond to an abundance of ∼ 0.9 % at 1 au. Finally, as the two streams roughly correspond to the spatial extent of a switchback patch, we suggest that patches are distinct features of coronal hole wind.

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“…This study once again demonstrates the importance of CME observations from far off the Sun-Earth line made possible by the STEREO mission, not only to detect minor CMEs, but also to confirm that they are earthbound. The usefulness of off-limb EUV observations from STEREO-A to identify an approximate source region on the Earth-facing disc was also demonstrated by O'Kane et al (2021a) and Palmerio et al (2021a) for stealth CMEs that erupted as recently as 2020. This is particularly crucial when multiple CMEs occur within a short period.…”

Section: Discussionmentioning

confidence: 89%

Understanding the Origins of Problem Geomagnetic Storms Associated with “Stealth” Coronal Mass Ejections

et al. 2021

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Geomagnetic storms are an important aspect of space weather and can result in significant impacts on space- and ground-based assets. The majority of strong storms are associated with the passage of interplanetary coronal mass ejections (ICMEs) in the near-Earth environment. In many cases, these ICMEs can be traced back unambiguously to a specific coronal mass ejection (CME) and solar activity on the frontside of the Sun. Hence, predicting the arrival of ICMEs at Earth from routine observations of CMEs and solar activity currently makes a major contribution to the forecasting of geomagnetic storms. However, it is clear that some ICMEs, which may also cause enhanced geomagnetic activity, cannot be traced back to an observed CME, or, if the CME is identified, its origin may be elusive or ambiguous in coronal images. Such CMEs have been termed “stealth CMEs”. In this review, we focus on these “problem” geomagnetic storms in the sense that the solar/CME precursors are enigmatic and stealthy. We start by reviewing evidence for stealth CMEs discussed in past studies. We then identify several moderate to strong geomagnetic storms (minimum Dst $< -50$ < − 50 nT) in solar cycle 24 for which the related solar sources and/or CMEs are unclear and apparently stealthy. We discuss the solar and in situ circumstances of these events and identify several scenarios that may account for their elusive solar signatures. These range from observational limitations (e.g., a coronagraph near Earth may not detect an incoming CME if it is diffuse and not wide enough) to the possibility that there is a class of mass ejections from the Sun that have only weak or hard-to-observe coronal signatures. In particular, some of these sources are only clearly revealed by considering the evolution of coronal structures over longer time intervals than is usually considered. We also review a variety of numerical modelling approaches that attempt to advance our understanding of the origins and consequences of stealthy solar eruptions with geoeffective potential. Specifically, we discuss magnetofrictional modelling of the energisation of stealth CME source regions and magnetohydrodynamic modelling of the physical processes that generate stealth CME or CME-like eruptions, typically from higher altitudes in the solar corona than CMEs from active regions or extended filament channels.

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Solar origins of a strong stealth CME detected by Solar Orbiter

Cited by 25 publications

References 53 publications

Predicting the Magnetic Fields of a Stealth CME Detected by Parker Solar Probe at 0.5 AU

Predicting the Magnetic Fields of a Stealth CME Detected by Parker Solar Probe at 0.5 AU

Plasma properties, switchback patches, and low α-particle abundance in slow Alfvénic coronal hole wind at 0.13 au

Understanding the Origins of Problem Geomagnetic Storms Associated with “Stealth” Coronal Mass Ejections

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