Understanding the white-light flare on 2012 March 9: evidence of a two-step magnetic reconnection

Hao, Qing; Guo, Yang; Dai, Y.; Ding, M. D.; Li, Z.; Zhang, X. Y.; Fang, Cheng

doi:10.1051/0004-6361/201219941

Cited by 24 publications

(22 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At 94, 131, and 335Å the emissions keep increasing, peaking after the GOES SXR peak and with different delays: 03:59:15 (94Å), 03:53:11 (131Å), 04:02:05 (335Å), evidencing the cooling of the coronal plasma. Moreover, the peak time of the impulsive phase (determined from HXR and microwave data) closely matches the peak of the white-light flare signature reported by Hao et al (2012), though their data only have one-minute time cadence.…”

Section: Uv/euv Ribbons and Coronal Loopssupporting

confidence: 76%

See 1 more Smart Citation

Implosion of Coronal Loops During the Impulsive Phase of a Solar Flare

Simões

Fletcher

Hudson

et al. 2013

ApJ

View full text Add to dashboard Cite

We study the relationship between implosive motions in a solar flare, and the energy redistribution in the form of oscillatory structures and particle acceleration. The flare SOL2012-03-09T03:53 (M6.4) shows clear evidence for an irreversible (stepwise) coronal implosion. Extreme-ultraviolet (EUV) images show at least four groups of coronal loops at different heights overlying the flaring core undergoing fast contraction during the impulsive phase of the flare. These contractions start around a minute after the flare onset, and the rate of contraction is closely associated with the intensity of the hard X-ray (HXR) and microwave emissions. They also seem to have a close relationship with the dimming associated with the formation of the Coronal Mass Ejection (CME) and a global EUV wave. Several studies now have detected contracting motions in the corona during solar flares that can be interpreted as the implosion necessary to release energy. Our results confirm this, and tighten the association with the flare impulsive phase. We add to the phenomenology by noting the presence of oscillatory variations revealed by GOES soft X-rays (SXR) and spatially-integrated EUV emission at 94 and 335Å. We identify pulsations of ≈ 60 seconds in SXR and EUV data, which we interpret as persistent, semi-regular compressions of the flaring core region which modulate the plasma temperature and emission measure. The loop oscillations, observed over a large region, also allow us to provide rough estimates of the energy temporarily stored in the eigenmodes of the active-region structure as it approaches its new equilibrium.

show abstract

Section: Uv/euv Ribbons and Coronal Loopssupporting

confidence: 76%

“…As described below, these observations produced beautiful examples of large-scale loop contraction, wave excitation, dimming, and complex oscillations of loop structures. Hao et al (2012) described this event as a white-light flare, underscoring the intensity of its energy release.…”

Section: Observational Data and Analysismentioning

confidence: 98%

Implosion of Coronal Loops During the Impulsive Phase of a Solar Flare

Simões

Fletcher

Hudson

et al. 2013

ApJ

View full text Add to dashboard Cite

show abstract

“…It will be promising to use the Optical and Near-infrared Solar Eruption Tracer (ONSET) telescope (Fang et al, 2013). A very interesting observations mentioned by Cheng et al (2015) and Hao et al (2012) show that the 3600Å flare kernel is much smaller than the Hα one. If our analysis is applied, it will lead to a strong Balmercontinuum intensity enhancement as derived from the flux, consistent with our discussion in Section 4.…”

Section: Discussionmentioning

confidence: 94%

New Observations of Balmer Continuum Flux in Solar Flares

2016

View full text Add to dashboard Cite

Increase in the Balmer continuum radiation during solar flares was predicted by various authors but never firmly confirmed observationally using ground-based slit spectrographs. Here we describe a new post-focal instrument -Image Selector -enabling to measure the Balmer continuum flux from the whole flare area, in analogy of successful detections of flaring dMe stars. The system was developed and put into operation at the horizontal solar telescope HSFA-2 of the Ondřejov Observatory. We measure the total flux by a fast spectrometer from a limited but well defined region on the solar disk. Using a system of diaphragms, the disturbing contribution of a bright solar disk can be eliminated as much as possible. Light curves of the measured flux in the spectral range 350 -440 nm are processed, together with the Hα images of the flaring area delimited by the appropriate diaphragm. The spectral flux data are flat-fielded, calibrated and processed to be compared with model predictions. Our analysis of the data proves that the described device is sufficiently sensitive to detect variations in the Balmer continuum during solar flares. Assuming that the Balmer-continuum kernels have at least a similar size as those visible in Hα, we find the flux increase in the Balmer continuum to reach 230% -550 % of the quiet continuum during the observed X-class flare. We also found temporal changes in the Balmer continuum flux starting well before the onset of the flare in Hα.

show abstract

“…Favorable conditions for eruptions include strongly twisted or sheared magnetic structures embedded in a less-sheared magnetic system (Hao et al 2012), the rapid emergence/evolution of strong magnetic flux concentrations (Wang et al 2004a;Sun et al 2012b), and/or a complex magnetic field topology (Sun et al 2012a). …”

Section: Favorable Conditions For Eruptionsmentioning

confidence: 99%

The magnetic field in the solar atmosphere

Wiegelmann

Thalmann

Solanki

2014

Astron Astrophys Rev

182

125

View full text Add to dashboard Cite

This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal mass ejections and flares are magnetically driven. In addition, the field also plays a crucial role in heating the solar chromosphere and corona as well as in accelerating the solar wind. Our main emphasis is the magnetic field in the upper solar atmosphere so that photospheric and chromospheric magnetic structures are mainly discussed where relevant for higher solar layers. Also, the discussion of the solar atmosphere and activity is limited to those topics of direct relevance to the magnetic field. After giving a brief overview about the solar magnetic field in general and its global structure, we discuss in more detail the magnetic field in active regions, the quiet Sun and coronal holes.

show abstract

Understanding the white-light flare on 2012 March 9: evidence of a two-step magnetic reconnection

Cited by 24 publications

References 33 publications

Implosion of Coronal Loops During the Impulsive Phase of a Solar Flare

Implosion of Coronal Loops During the Impulsive Phase of a Solar Flare

New Observations of Balmer Continuum Flux in Solar Flares

The magnetic field in the solar atmosphere

Contact Info

Product

Resources

About