Observation of a Moreton Wave and Wave-Filament Interactions Associated With the Renowned X9 Flare on 1990 May 24

Abstract

Using Big Bear Solar Observatory film data recently digitized at NJIT, we investigate a Moreton wave associated with an X9 flare on 1990 May 24, as well as its interactions with four filaments F1-F4 located close to the flaring region. The interaction yields interesting insight into physical properties of both the wave and the filaments. The first clear Moreton wavefront appears at the flaring-region periphery at approximately the same time as the peak of a microwave burst and the first of two γ -ray peaks. The wavefront propagates at different speeds ranging from 1500-2600 km s −1 in different directions, reaching as far as 600 Mm away from the flaring site. Sequential chromospheric brightenings are observed ahead of the Moreton wavefront. A slower diffuse front at 300-600 km s −1 is observed to trail the fast Moreton wavefront about one minute after the onset. The Moreton wave decelerates to ∼550 km s −1 as it sweeps through F1. The wave passage results in F1's oscillation which is featured by ∼1 mHz signals with coherent Fourier phases over the filament, the activation of F3 and F4 followed by gradual recovery, but no disturbance in F2. Different height and magnetic environment together may account for the distinct responses of the filaments to the wave passage. The wavefront bulges at F4, whose spine is oriented perpendicular to the upcoming wavefront. The deformation of the wavefront is suggested to be due to both the forward inclination of the wavefront and the enhancement of the local Alfvén speed within the filament channel.

Spatial Organization of Seven Extreme Solar Energetic Particle Events

“…A comprehensive analysis of the secondaries is available for the historic GLE 48 of 1990 May 24 (see in particular Kocharov et al 1994Kocharov et al , 1996aKocharov et al , 1996b. There were no direct observations of associated CME, but a global wave on the solar surface was observed, with a Moreton wave of speed 1500-2600kms −1 (Liu et al 2013). Referring to other events, CME speed may be 1.3-2 times the speed of a Moreton wave on the Sun (e.g., Pohjolainen et al 2001).…”

Advances in Observing Various Coronal EUV Waves in the SDO Era and Their Seismological Applications (Invited Review)

“…Inferring the elusive coronal magnetic field is one of the primary goals of coronal seismology, which complements other approaches including polarimetric measurements using Zeeman and Hanle effects (Lin, Penn, and Tomczyk, 2000), extrapolations of surface magnetograms (Zhao and Hoeksema, 1994;De Rosa et al, 2009), and radio observations of gyro-resonance emission (Gary and Hurford, 1994;White and Kundu, 1997). The fast-magnetosonic speed weakly depends on the direction of the wave vector with respect to the magnetic field, which has a strong vertical component in the quiet Sun and is thus practically assumed to be perpendicular to the predominantly horizontal EIT wave vectors.…”

Large-scale Globally Propagating Coronal Waves

“…It has been known for a long time that Moreton waves can cause filament oscillations (Moreton, 1960(Moreton, , 1964Ramsey and Smith, 1966;Liu et al, 2013), which are usually observed as "winking filaments". If the line-of sight component of the oscillation exceeds 20 km s -1 , the filament vanishes from and subsequently reappears in Hα line center filtergrams (for a review of filament oscillations, see Arregui et al, 2012).…”