Blowout Jets and Impulsive Eruptive Flare in a Bald-Patch Topology |
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Ramesh Chandra Submitted: 2016-10-06 19:20
Context. A subclass of broad EUV and X-ray jets, called blowout jets, have become a topic of research since they could be the link between standard collimated jets and CMEs.
Aims. Our aim is to understand the origin of a series of broad jets, some accompanied by flares and associated with narrow and jet-like CMEs.
Methods. We analyze observations of a series of recurrent broad jets observed in AR 10484 on 21-24 October 2003. In particular, one of them occurred simultaneously with an M2.4 flare on 23 October at 02:41 UT (SOLA2003-10-23). Both events were observed by ARIES Hα Solar Tower-Telescope, TRACE, SOHO, and RHESSI instruments. The flare was very impulsive and followed by a narrow CME. A local force-free model of AR 10484 is the basis to compute its topology. We find bald patches (BPs) at the flare site. This BP topology is present for at least two days before. Large-scale field lines, associated with the BPs, represent open loops. This is confirmed by a global PFSS model. Following the brightest leading edge of the Hα and EUV jet emission, we can temporarily associate it with a narrow CME.
Results. Considering their characteristics, the observed broad jets appear to be of the blowout class. As the most plausible scenario, we propose that magnetic reconnection could occur at the BP separatrices forced by the destabilization of a continuously reformed flux rope underlying them. The reconnection process could bring the cool flux-rope material into the reconnected open field lines driving the series of recurrent blowout jets and accompanying CMEs.
Conclusions. Based on a model of the coronal field, we compute the AR 10484 topology at the location where flaring and blowout jets occurred from 21 to 24 October 2003. This topology can consistently explain the origin of these events.
Authors: R. Chandra, C.H. Mandrini, B. Schmieder, B. Joshi, G.D. Cristiani, H. Cremades, E. Pariat, F.A. Nuevo, A.K. Srivastava, and W. Uddin
Projects: None
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Publication Status: Accepted for the publication in A & A
Last Modified: 2016-10-12 12:19
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Homologous Flares and Magnetic Field Topology in Active Region NOAA 10501 on 20 November 2003 |
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Ramesh Chandra Submitted: 2010-11-08 20:43
We present and interpret observations of two morphologically homologous flares that occurred in active region (AR) NOAA 10501 on 20 November 2003. Both flares displayed four homologous Hα ribbons and were both accompanied by coronal mass ejections (CMEs). The central flare ribbons were located at the site of an emerging bipole in the center of the active region. The negative polarity of this bipole fragmented in two main pieces, one rotating around the positive polarity by ~ 110 deg within 32 hours. We model the coronal magnetic field and compute its topology, using as boundary condition the magnetogram closest in time to each flare. In particular, we calculate the location of quasiseparatrix layers (QSLs) in order to understand the connectivity between the flare ribbons. Though several polarities were present in AR 10501, the global magnetic field topology corresponds to a quadrupolar magnetic field distribution without magnetic null points. For both flares, the photospheric traces of QSLs are similar and match well the locations of the four Hα ribbons. This globally unchanged topology and the continuous shearing by the rotating bipole are two key factors responsible for the flare homology. However, our analyses also indicate that different magnetic connectivity domains of the quadrupolar configuration become unstable during each flare, so that magnetic reconnection proceeds differently in both events.
Authors: R. Chandra, B. Schmieder, C.H. Mandrini, P. Demoulin, E. Pariat, T. Torok, W. Uddin
Projects: SoHO-MDI,SoHO-LASCO,Yohkoh-HXT
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Publication Status: Solar Physics (in press)
Last Modified: 2010-11-10 09:20
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