Line-of-Sight and Proper Motions in the Flaring June 1991 ( NOAA 6659 ) Active Region

Bumba, V.; Klvana, M.; Kalman, B.; Györi, L.

doi:10.1017/s0252921100029420

Cited by 3 publications

(5 citation statements)

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“…As we have demonstrated earlier (Bumba 1988;Bumba et al 1993 and the new magnetic flux develops in the place, where at least opposite polarity magnetic fields malie contact and certain magnetic gradient exists. The magnetic situation can be more complicated, gradients large, the developing activity is then also very large.…”

Section: New Activity Is Related To Both the Magnetic And Motion Fielsupporting

confidence: 57%

See 1 more Smart Citation

Doppler and proper motions accompanying formation of an additional magnetic flux in the mature solar active region (NOAA 7216)

Bumba

Klvana

Kalman

1996

Astron. Astrophys. Suppl. Ser.

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Abstract. -We document the evolution of an additional magnetic flux in the photosphere of a fully developed sunspot group, we measure longitudinal magnetic field, line-of-sight motions, and proper motions of sunspots in the group during this process. We demonstrate the close correlation of magnetic field, Doppler and proper motion singularities with the area in which additional magnetic flux appears and the new penumbrae and umbrae develop. We discuss the probable reasons for this fact and for the region's weak flare activity. There exist in the group about eight sunspots with the Evershed effect, differing in form, in dependence on the history of development of the spot in which it is observed.

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Section: New Activity Is Related To Both the Magnetic And Motion Fielsupporting

confidence: 57%

“…(Fig. 1), for details see Bumba et al (1993). In the period June 29-July 10, 1992, the following number of plates were measured (in format monthdaylnumber of plates): 6-2913, 6-3013, 7-0119, 7-0213, 7-03/11, 7-0413, 7-0514, 7-0613, 7-0713, 7-0813, 7-0912 and 7-1013.…”

Section: Introductionmentioning

confidence: 99%

Doppler and proper motions accompanying formation of an additional magnetic flux in the mature solar active region (NOAA 7216)

Bumba

Klvana

Kalman

1996

Astron. Astrophys. Suppl. Ser.

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“…A very pronounced post-flare loop arcade was seen over the limb on 15 June 1991 (Akimov et al 1996). It is also interesting that active region AR-6659 was a very stable group and could be observed already two solar rotations earlier as reported by Bumba et al (1993). We speculate that the large scale loop systems remained intact during the two week observation period so that in the context of a continuous loop acceleration model the same loops could be populated more than one time.…”

Section: Discussionmentioning

confidence: 54%

“…The observations are summarized in Table 1. The active region was also monitored at optical wavelengths including magnetograms (e.g., Sakurai et al 1992;Bumba et al 1993).…”

Section: Introductionmentioning

confidence: 99%

Extended gamma-ray emission of the solar flares in june 1991

Rank

Ryan

Debrunner

et al. 2001

A&A

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Abstract. During the solar flares on 9, 11, and 15 June 1991 the COMPTEL instrument measured extended γ-radiation in the 2.223 MeV neutron-capture line, in prompt nuclear deexcitation lines and in pion-decay radiation for several hours after the flares. The long-term time profiles can be described by a double exponential decay with decay constants on the order of 10 min for the fast and several 100 min for the slow components. We studied the 11 June 1991 flare in more detail and found that during the extended phase the accelerated proton and ion spectrum is harder, the e/p ratio is lower, and the emission profile is smoother, compared to those of the impulsive phase. Pion-decay radiation was not detected before the onset of the extended emission phase. When comparing the three flares to one another, we found a striking similarity in the time profiles of the nuclear line and the neutron capture line emission. However, the pion-decay radiation varied in intensity significantly from flare to flare. The impulsive-phase emissions of the flares show no such similarity. Our measurements indicate that the processes taking place during the extended phase differ from those during the impulsive phase, or in other γ-ray line flares. Based on these results long-term trapping of energetic particles from the impulsive phase seems unlikely, as opposed to continuous particle acceleration.

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“…Whole-disk observations of 10 cm solar image diameter were made on highcontrast photographic films; these were measured with 0.01 mm accuracy on an ASCORECORD measuring machine. The method of observations and their reduction was described in more detail in Bumba et al (1993Bumba et al ( , 1995. For the present work the coordinate measurements of the umbral and penumbral boundaries (1500-2000 points on the best photograph of the day) were used, the measurements were corrected for instrumental and atmospheric effects, then transformed into Carrington coordinates.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Submergence of magnetic flux in interaction of sunspot groups

Kalman

2001

A&A

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Abstract.Submergence of magnetic flux is demonstrated in the process of evolution of sunspot groups NOAA 6850 (26 Sep.-07 Oct. 1991) and 7220/22 (06-17 July 1992). In both cases new magnetic flux emerges immediately behind an existing spotgroup. The new flux does not interact with the old one, as can be seen in YOHKOH X-ray images, so no significant flare activity occurs, although umbrae of different magnetic polarity collide. In both cases the quickly forward moving p-spots of the new flux force the submergence of the f-spots of the older region, these being squeezed from two sides between the old and new p-spots. This leads to the disappearance of about 16 10 21 Mx of f-polarity in AR 6850. In the case of this region the submerged flux interacts with newly emerging magnetic fields and in the next rotation continues its life as the complex and eruptive AR 6891. In AR 7220/22, spots of both polarities submerge in the intermediate part of the complex between the old leader of AR 7220 and the quickly growing AR 7222, leaving in the next rotation a bipolar-looking group (AR 7248), consisting of two p-polarity spots. So, submergence of magnetic flux due to interaction of old and new activity may play an important role in the decay of sunspot groups.

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Line-of-Sight and Proper Motions in the Flaring June 1991 ( NOAA 6659 ) Active Region

Abstract: We present the results of comparison of photoelectrically and photographically made measurements of Doppler and proper motions with the distribution of the longitudinal magnetic field and spot topology in this large complex region.

Cited by 3 publications

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Doppler and proper motions accompanying formation of an additional magnetic flux in the mature solar active region (NOAA 7216)

Doppler and proper motions accompanying formation of an additional magnetic flux in the mature solar active region (NOAA 7216)

Extended gamma-ray emission of the solar flares in june 1991

Submergence of magnetic flux in interaction of sunspot groups

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