Results 11 to 20 of about 423,592 (152)
, 2023 Taking as its starting point the distinctive megalithic remains of the Neolithic and Bronze Age, Sunspots is a carefully edited long-term photographic study of these fragile rural landscapes where the meaning and belonging of everything feels contested.
Arnold, William
core +6 more sources
Characterizing the Umbral Magnetic Knots of δ-Sunspots
The Astrophysical Journal, 2022 Abstract Delta (δ) spots are active regions (ARs) in which positive and negative umbrae share a penumbra. They are known to be the source of strong flares. We introduce a new quantity, the degree of δ (Doδ), to measure the fraction of umbral flux participating in the δ-configuration and to isolate the dynamics of the magnetic knot, i.e.,
Aimee A. Norton +4 more
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DELTA-SUNSPOTS AND X CLASS FLARES IN SOLAR CYCLE 22 [PDF]
Chinese Journal of Space Science, 1993 AbstractA sample of 221 active regions with δ magnetic configurations from 1986 to 1991 in Solar Cycle 22 is used to investigate the characteristics of δ-sunspots and the relationship between the δ-sunspots and X class X-ray flares.
Zhongxian Shi, Jingxiu Wang
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Unusual StokesVprofiles during flaring activity of a delta sunspot [PDF]
Astronomy & Astrophysics, 2012 13 pages, 10 figures, 1 ...
Fischer, C. E. +4 more
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Prominent Photospheric Downflows on Magnetic Neutral Line in a Delta-Type Sunspot [PDF]
Solar Physics, 2012 It is known that δ-type sunspot groups have a high flare productivity and produce strong flares. In particular, βγδ type sunspots are the most active type of all. A βγδ active region NOAA 9957 with frequent flux cancellations but without any marked flare activity during its decay phase was studied in this work.
Takizawa, K., Kitai, R., Zhang, Y.
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The chromosphere above aδ-sunspot in the presence of fan-shaped jets [PDF]
Astronomy & Astrophysics, 2017 Context.Delta-sunspots are known to be favourable locations for fast and energetic events like flares and coronal mass ejections. The photosphere of this sunspot type has been thoroughly investigated in the past three decades. The atmospheric conditions in the chromosphere are not as well known, however.Aims.This study is focused on the chromosphere of
Robustini, Carolina +2 more
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δ-SUNSPOT FORMATION IN SIMULATION OF ACTIVE-REGION-SCALE FLUX EMERGENCE [PDF]
The Astrophysical Journal, 2015 $δ$-sunspots, with highly complex magnetic structures, are very productive in energetic eruptive events, such as X-class flares and homologous eruptions. We here study the formation of such complex magnetic structures by numerical simulations of magnetic flux emergence from the convection zone into the corona in an active-region-scale domain.
Fang, Fang, Fan, Yuhong
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Strong Transverse Photosphere Magnetic Fields and Twist in Light Bridge Dividing Delta Sunspot of Active Region 12673 [PDF]
Research Notes of the AAS, 2018 Solar Active Region (AR) 12673 is the most flare productive AR in the solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that this region had an unusual high rate of flux emergence, while Huang et al.
Haimin Wang +5 more
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Numerical Simulations of Flare-productive Active Regions: δ-sunspots, Sheared Polarity Inversion Lines, Energy Storage, and Predictions [PDF]
The Astrophysical Journal, 2017 Abstract Solar active regions (ARs) that produce strong flares and coronal mass ejections (CMEs) are known to have a relatively high non-potentiality and are characterized by δ-sunspots and sheared magnetic structures. In this study, we conduct a series of flux emergence simulations from the convection zone to the corona and model four ...
Shin Toriumi, Shinsuke Takasao
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STUDY OF RAPID FORMATION OF A δ SUNSPOT ASSOCIATED WITH THE 2012 JULY 2 C7.4 FLARE USING HIGH-RESOLUTION OBSERVATIONS OF THE NEW SOLAR TELESCOPE [PDF]
The Astrophysical Journal, 2013 Rapid, irreversible changes of magnetic topology and sunspot structure associated with flares have been systematically observed in recent years. The most striking features include the increase of horizontal field at the polarity inversion line (PIL) and the co-spatial penumbral darkening.
Wang, Haimin +6 more
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