Twisting flux tubes as a cause of micro-flaring activity

Jess, D. B.; McAteer, R. T. J.; Mathioudakis, M.; Keenan, F. P.; Andic, Aleksandra; Bloomfield, D. Shaun

doi:10.1051/0004-6361:20077916

Cited by 18 publications

(13 citation statements)

References 23 publications

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“…Even with a relatively small number of pixels and onboard storage, RDI was able to show the need for a dedicated high-cadence multi-camera system (see e.g. Jess et al, 2007b) and acted as a pre-cursor to the capabilities possessed by ROSA.…”

Section: Instrumentationmentioning

confidence: 99%

ROSA: A High-cadence, Synchronized Multi-camera Solar Imaging System

et al. 2010

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Rapid Oscillations in the Solar Atmosphere (ROSA) is a synchronized, six camera high cadence solar imaging instrument developed by Queen's University Belfast. The system is available on the Dunn Solar Telescope at the National Solar Observatory in Sunspot, New Mexico, USA as a commonuser instrument. Consisting of six 1k × 1k Peltier-cooled frame-transfer CCD cameras with very low noise (0.02 -15 e s −1 pixel −1 ), each ROSA camera is capable of full-chip readout speeds in excess of 30 Hz, or 200 Hz when the CCD is windowed. Combining multiple cameras and fast readout rates, ROSA will accumulate approximately 12 TB of data per 8 hours observing. Following successful commissioning during August 2008, ROSA will allow multi-wavelength studies of the solar atmosphere at high temporal resolution.

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Section: Instrumentationmentioning

confidence: 99%

ROSA: A High-cadence, Synchronized Multi-camera Solar Imaging System

et al. 2010

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“…These images were multiplied by the umbral binary map, producing a data set which could be analyzed with Fourier techniques. Following the methodology of Jess et al (2007aJess et al ( , 2007b, the wavelet analysis routines of Torrence & Compo (1998) were applied to the 4170 Å continuum umbral time series to search for the presence of oscillatory behavior. Considerable oscillatory power was present throughout the sunspot umbra, with dominant peaks in the Fourier spectrum at 3 and 5 minutes.…”

Section: Photospherementioning

confidence: 99%

The Source of 3 Minute Magnetoacoustic Oscillations in Coronal Fans

Jess

Moortel

Mathioudakis

et al. 2012

ApJ

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We use images of high spatial, spectral, and temporal resolution, obtained using both ground-and space-based instrumentation, to investigate the coupling between wave phenomena observed at numerous heights in the solar atmosphere. Analysis of 4170 Å continuum images reveals small-scale umbral intensity enhancements, with diameters ∼0. 6, lasting in excess of 30 minutes. Intensity oscillations of ≈3 minutes are observed to encompass these photospheric structures, with power at least three orders of magnitude higher than the surrounding umbra. Simultaneous chromospheric velocity and intensity time series reveal an 87• ± 8• out-of-phase behavior, implying the presence of standing modes created as a result of partial wave reflection at the transition region boundary. We find a maximum waveguide inclination angle of ≈40• between photospheric and chromospheric heights, combined with a radial expansion factor of <76%. An average blueshifted Doppler velocity of ≈1.5 km s −1 , in addition to a time lag between photospheric and chromospheric oscillatory phenomena, confirms the presence of upwardly propagating slow-mode waves in the lower solar atmosphere. Propagating oscillations in EUV intensity are detected in simultaneous coronal fan structures, with a periodicity of 172 ± 17 s and a propagation velocity of 45 ± 7 km s −1 . Numerical simulations reveal that the damping of the magnetoacoustic wave trains is dominated by thermal conduction. The coronal fans are seen to anchor into the photosphere in locations where large-amplitude umbral dot (UD) oscillations manifest. Derived kinetic temperature and emission measure time series display prominent outof-phase characteristics, and when combined with the previously established sub-sonic wave speeds, we conclude that the observed EUV waves are the coronal counterparts of the upwardly propagating magnetoacoustic slow modes detected in the lower solar atmosphere. Thus, for the first time, we reveal how the propagation of 3 minute magnetoacoustic waves in solar coronal structures is a direct result of amplitude enhancements occurring in photospheric UDs.

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“…The previous work established the existence of propagating waves in the flux tubes (DePontieu, Erdélýi, and James, 2004;Jess et al, 2007;Andić et al, 2010). Thus, one could expect to observe the wave propagation between photospheric and chromospheric layers especially when we observe along the axis of a flux tube.…”

Section: Discussionmentioning

confidence: 95%

“…De Moortel and Galsgaard (2006) investigated the magnetic reconnection driven by rotational footpoint motions. An observational case was reported by Jess et al (2007) who found rotational movement of oscillation sites (which were identified with the footpoints of flux tubes) during microflaring events.…”

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confidence: 94%

Connection Between Chromospheric Events and Photospheric Dynamics

et al. 2012

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We analyzed chromospheric events and their connection to oscillation phenomena and photospheric dynamics. The observations were done with the New Solar Telescope of Big Bear Solar Observatory using a broad-band imager at the wavelength of a TiO band and FISS spectrograph scanning Ca II and Hα spectral lines. The event in Ca II showed strong plasma flows and propagating waves in the chromosphere. The movement of the footpoints of flux tubes in the photosphere indicated flux tube entanglement and magnetic reconnection as a possible cause of the observed brightening and waves propagating in the chromosphere. An upward propagating train of waves was observed at the site of the downflow event in Hα. There was no clear relationship between photospheric waves and the Ca II and Hα events. Our observations indicate that chromospheric waves that were previously thought to originate from the photosphere may be generated by some events in the chromosphere as well.

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Twisting flux tubes as a cause of micro-flaring activity

Cited by 18 publications

References 23 publications

ROSA: A High-cadence, Synchronized Multi-camera Solar Imaging System

ROSA: A High-cadence, Synchronized Multi-camera Solar Imaging System

The Source of 3 Minute Magnetoacoustic Oscillations in Coronal Fans

Connection Between Chromospheric Events and Photospheric Dynamics

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