NO TRACE LEFT BEHIND: STEREO OBSERVATION OF A CORONAL MASS EJECTION WITHOUT LOW CORONAL SIGNATURES

By E. Robbrecht, S. Patsourakos, A. Vourlidas. 2009

191 citations recorded by the source corpus.

The availability of high-quality synoptic observations of the extreme-ultraviolet (EUV) and visible corona during the SOHO mission has advanced our understanding of the low corona manifestations of coronal mass ejections (CMEs). The EUV imager/white light coronagraph connection has been proven so powerful, it is routinely assumed that if no EUV signatures are present when a CME is observed by a coronagraph, then the event must originate behind the visible limb. This assumption carries strong implications for space weather forecasting but has not been put to the test. This paper presents the first detailed analysis of a frontside, large-scale CME that has no obvious counterparts in the low corona as observed in EUV and Hα wavelengths. The event was observed by the SECCHI instruments onboard the STEREO mission. The COR2A coronagraph observed a slow flux-rope-type CME, while an extremely faint partial halo was observed in COR2B. The event evolved very slowly and is typical of the streamer-blowout CME class. EUVI A 171 Å images show a concave feature above the east limb, relatively stable for about two days before the eruption, when it rises into the coronagraphic fields and develops into the core of the CME. None of the typical low corona signatures of a CME (flaring, EUV dimming, filament eruption, waves) were observed in the EUVI B images, which we attribute to the unusually large height from which the flux rope lifted off. This interpretation is supported by the CME mass measurements and estimates of the expected EUV dimming intensity. Only thanks to the availability of the two viewpoints we were able to identify the likely source region. The event originated along a neutral line over the quiet-Sun. No active regions were present anywhere on the visible (from STEREO B) face of the disk. Leaving no trace behind on the solar disk, this observation shows unambiguously that a CME eruption does not need to have clear on-disk signatures. Also it sheds light on the question of “mystery” geomagnetic storms, storms without clear solar origin (formerly called problem storms). We discuss the implications for space weather monitoring. Preliminary inspection of STEREO data indicates that events like this are not uncommon, particularly during the ongoing period of deep solar minimum.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/ed6f5c3ee08f5ab9d6efcc5a15ace260c885be95

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In Astronomy and Astrophysics

1. M. Temmer
2. N. Lugaz
3. A. Vourlidas
4. Nat Gopalswamy
5. D. Webb
6. T. Howard
7. J. Davies
8. R. Howard

Citations in the corpus

• Space weather: the solar perspective (2021, background): “Later studies showed, that they start at very large heights in the corona without noticeable signatures, such as flare emission, filament eruptions, coronal waves, or coronal dimmings (Robbrecht et al. 2009).”
• How Many CMEs Have Flux Ropes? Deciphering the Signatures of Shocks, Flux Ropes, and Prominences in Coronagraph Observations of CMEs (2012, background): “…has an almost identical appearance in the EUVI-A 195 Å images (not shown here) which suggests that most of the core material was at coronal temperatures (∼1.4 MK) erasing thus any obvious connections to the prominence (see Robbrecht, Patsourakos, and Vourlidas (2009) for a very similar example).”
• ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS (2013, background): “As will be seen later, slow CMEs can also occur as “stealth” events without low coronal signatures (Robbrecht et al. 2009), whose structure and evolution are even more difficult to predict.”
• COMPREHENSIVE ANALYSIS OF CORONAL MASS EJECTION MASS AND ENERGY PROPERTIES OVER A FULL SOLAR CYCLE (2010, background): “Coronagraph studies have shown that a large part of the ejected mass comes from the high corona (e.g., Andrews et al. 1999; Robbrecht et al. 2009).”
• DIRECT EVIDENCE FOR A FAST CORONAL MASS EJECTION DRIVEN BY THE PRIOR FORMATION AND SUBSEQUENT DESTABILIZATION OF A MAGNETIC FLUX ROPE (2012, unknown): “…in QS cavities comes from polarization signals of the coronal magnetic field (Dove et al. 2011), from swirling motions observed in these structures (Wang & Stenborg 2010) and from concave-upward structures in CME cavities (Plunkett et al. 2000; Robbrecht et al. 2009; Vourlidas et al. 2012a).”
• Coronal Mass Ejections: Observations (2012, methodology): “Many CMEs have also been observed to be unassociated with any obvious solar surface activity (Howard and Tappin, 2008; Robbrecht et al., 2009a).”