Solar bright points in 3840 � and H?

Vorpahl, J. A.; Pope, T.

doi:10.1007/bf00192334

Cited by 20 publications

(16 citation statements)

References 4 publications

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“…Our results are in agreement with previous studies reporting that the spatial distribution of EBs is not random or homogeneous (Vorpahl & Pope 1972;Bruzek 1972;Zachariadis et al 1987). A detailed study of the photospheric patterns for each of the three areas shown in Figure 2, follows in x 4.2.…”

Section: Occurrence Rates and Spatial Distribution Of Ebssupporting

confidence: 92%

“…Indeed, from Figure 9a one notices durations well above 100 minutes, which clearly suggest that the duration distribution function is severely affected by the recurrence effect. Similar EB durations have been obtained in early, low-cadence studies (Bruzek 1972;Vorpahl & Pope 1972).…”

Section: Definitions and Statistical Properties Of Typical Eb Parameterssupporting

confidence: 82%

“…The typical EB lifetimes were estimated from early works to be $20 minutes (Severny 1965). Bruzek (1972) and Vorpahl & Pope (1972), however, reported that certain EBs could be visible for times exceeding 1 hr. The estimation of EB durations depends critically on the temporal resolution (cadence) of the observing instrument, since EBs often tend to recur at approximately the same locations (Vorpahl & Pope 1972;Bruzek 1972;Zachariadis et al 1987).…”

Section: Introductionmentioning

confidence: 96%

“…Bruzek (1972) and Vorpahl & Pope (1972), however, reported that certain EBs could be visible for times exceeding 1 hr. The estimation of EB durations depends critically on the temporal resolution (cadence) of the observing instrument, since EBs often tend to recur at approximately the same locations (Vorpahl & Pope 1972;Bruzek 1972;Zachariadis et al 1987). The generally accepted mean lifetime of EBs is 10-14 minutes (Roy & Leparskas 1973;Kurokawa et al 1982;Payne 1993;Nindos & Zirin 1998).…”

Section: Introductionmentioning

confidence: 96%

“…Other EB properties include association with facular granules (Bruzek 1972;Dara et al 1987), H filigree, calcium bright points and white-light faculae (Wilson 1981), facular points (Kitai & Muller 1984), and photospheric filigree (Denker 1997). Vorpahl & Pope (1972), found that EBs correlate with photospheric bright points (BPs) at 3840 Å , which reach maxima at $3:5 AE 1:0 minutes prior to EB occurrence. Qiu et al (2000) showed that EBs can also be seen as BPs in the ultraviolet (UV) continuum emission at 1600 Å .…”

Section: Introductionmentioning

confidence: 99%

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Statistics, Morphology, and Energetics of Ellerman Bombs

Georgoulis¹,

Rust²,

Bernasconi³

et al. 2002

ApJ

200

287

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We investigate the statistical properties of Ellerman bombs in the dynamic emerging flux region NOAA Active Region 8844, underneath an expanding arch filament system. High-resolution chromospheric H filtergrams (spatial resolution 0>8), as well as photospheric vector magnetograms (spatial resolution 0>5) and Dopplergrams, have been acquired by the balloon-borne Flare Genesis Experiment. H observations reveal the first '' seeing-free '' data set on Ellerman bombs and one of the largest samples of these events. We find that Ellerman bombs occur and recur in preferential locations in the low chromosphere, either above or in the absence of photospheric neutral magnetic lines. Ellerman bombs are associated with photospheric downflows, and their loci follow the transverse mass flows on the photosphere. They are small-scale events, with typical size 1>8 Â 1>1 , but this size depends on the instrumental resolution. A large number of Ellerman bombs are probably undetected, owing to limited spatial resolution. Ellerman bombs occur in clusters that exhibit fractal properties. The fractal dimension, with an average value $1.4, does not change significantly in the course of time. Typical parameters of Ellerman bombs are interrelated and obey power-law distribution functions, as in the case of flaring and subflaring activity. We find that Ellerman bombs may occur on separatrix, or quasi-separatrix, layers, in the low chromosphere. A plausible triggering mechanism of Ellerman bombs is stochastic magnetic reconnection caused by the turbulent evolution of the low-lying magnetic fields and the continuous reshaping of separatrix layers. The total energies of Ellerman bombs are estimated in the range (10 27 , 10 28 ) ergs, the temperature enhancement in the radiating volume is $2 Â 10 3 K, and the timescale of radiative cooling is short, of the order of a few seconds. The distribution function of the energies of Ellerman bombs exhibits a power-law shape with an index $À2.1. This suggests that Ellerman bombs may contribute significantly to the heating of the low chromosphere in emerging flux regions.

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Section: Occurrence Rates and Spatial Distribution Of Ebssupporting

confidence: 92%

Section: Definitions and Statistical Properties Of Typical Eb Parameterssupporting

confidence: 82%