The current generation of space and ground-based experiments in solar physics produces many megab... more The current generation of space and ground-based experiments in solar physics produces many megabyte-sized image data arrays. Optical disk technology is the leading candidate for convenient analysis, distribution, and archiving of these data. The authors have been developing data analysis procedures which use both analog and digital optical disks for the study of solar phenomena.
... 80 000, 3508 TA Utrecht, The Netherlands GORAN SCHARMER Stockholm Observatory, 5-13336 Saltsj... more ... 80 000, 3508 TA Utrecht, The Netherlands GORAN SCHARMER Stockholm Observatory, 5-13336 Saltsjdbaden, Sweden Received 1991 February 15; accepted 1992 January21 At the Swedish Solar Observatory on Roque de los Muchachos in La Palma, Canary Islands we ...
<p>This poster was presented at the 224th AAS/SPD conference during 2014 in Boston, MA.<... more <p>This poster was presented at the 224th AAS/SPD conference during 2014 in Boston, MA.</p> <p>Abstract: Over the past few decades there have been a number of papers investigating the connection between flares occurring in succession. Statistically, any connection that affects the timing of successive flares that exists is found to be weak. However, the majority of previous investigations has been limited by only considering the causal connection between soft X-ray flares. More recent case studies have shown convincing evidence that large eruptions cause a global reorganization of overlying magnetic fields that can result in the eruption of both flares and filaments at large distances from the original event. In this work, the connection between GOES X-ray flares (C-, M-, and X-class) and filament eruptions occurring in succession in two different active regions is considered statistically. The filament eruptions are recorded in the Heliophysics Events Knowledgebase by observers using SDO/AIA data. A significant causal connection is found between the two event types, such that large flares are followed by filament eruptions within 24 hours much more often than they are preceded by filament eruptions. This stipulates that the flares either cause the filaments to erupt or affect the eruption timing such that the filament eruptions follow the flares more closely in time.</p> <p></p
Proceedings of the International Astronomical Union, 2010
Observations with the Solar Optical Telescope on Hinode indicate that the Quiet Sun magnetic fiel... more Observations with the Solar Optical Telescope on Hinode indicate that the Quiet Sun magnetic field occurs on every scale of convection including granulation. Data reported here show that, regardless of the position on the disk, the polarity in the inner network regions are balanced to 1 part in 72. This is consistent with both local dynamo processes or the creation of surface features by the granulation downflows.
Solar magnetism displays a host of variational timescales of which the enigmatic 11-year sunspot ... more Solar magnetism displays a host of variational timescales of which the enigmatic 11-year sunspot cycle is most prominent. Recent work has demonstrated that the sunspot cycle can be explained in terms of the intra- and extra-hemispheric interaction between the overlapping activity bands of the 22-year magnetic polarity cycle. Those activity bands appear to be driven by the rotation of the Sun's deep interior. Here we deduce that activity band interaction can qualitatively explain the 'Gnevyshev Gap'-a well-established feature of flare and sunspot occurrence. Strong quasi-annual variability in the number of flares, coronal mass ejections, the radiative and particulate environment of the heliosphere is also observed. We infer that this secondary variability is driven by surges of magnetism from the activity bands. Understanding the formation, interaction and instability of these activity bands will considerably improve forecast capability in space weather and solar activity...
Space Telescopes and Instrumentation 2008: Ultraviolet to Gamma Ray, 2008
The High-resolution Lightweight Telescope for the EUV (HiLiTE) is a Cassegrain telescope that wil... more The High-resolution Lightweight Telescope for the EUV (HiLiTE) is a Cassegrain telescope that will be made entirely of Silicon Carbide (SiC), optical substrates and metering structure alike. Using multilayer coatings, this instrument will be tuned to operate at the 465 Å Ne VII emission line, formed in solar transition region plasma at ~500,000 K. HiLiTE will have an aperture of 30 cm, angular resolution of ~0.2 arc seconds and operate at a cadence of ~5 seconds or less, having a mass that is about 1/4 that of one of the 20 cm aperture telescopes on the Atmospheric Imaging Assembly (AIA) instrument aboard NASA's Solar Dynamics Observatory (SDO). This new instrument technology thus serves as a path finder to a post-AIA, Explorer-class missions.
The current generation of space and ground-based experiments in solar physics produces many megab... more The current generation of space and ground-based experiments in solar physics produces many megabyte-sized image data arrays. Optical disk technology is the leading candidate for convenient analysis, distribution, and archiving of these data. The authors have been developing data analysis procedures which use both analog and digital optical disks for the study of solar phenomena.
... 80 000, 3508 TA Utrecht, The Netherlands GORAN SCHARMER Stockholm Observatory, 5-13336 Saltsj... more ... 80 000, 3508 TA Utrecht, The Netherlands GORAN SCHARMER Stockholm Observatory, 5-13336 Saltsjdbaden, Sweden Received 1991 February 15; accepted 1992 January21 At the Swedish Solar Observatory on Roque de los Muchachos in La Palma, Canary Islands we ...
<p>This poster was presented at the 224th AAS/SPD conference during 2014 in Boston, MA.<... more <p>This poster was presented at the 224th AAS/SPD conference during 2014 in Boston, MA.</p> <p>Abstract: Over the past few decades there have been a number of papers investigating the connection between flares occurring in succession. Statistically, any connection that affects the timing of successive flares that exists is found to be weak. However, the majority of previous investigations has been limited by only considering the causal connection between soft X-ray flares. More recent case studies have shown convincing evidence that large eruptions cause a global reorganization of overlying magnetic fields that can result in the eruption of both flares and filaments at large distances from the original event. In this work, the connection between GOES X-ray flares (C-, M-, and X-class) and filament eruptions occurring in succession in two different active regions is considered statistically. The filament eruptions are recorded in the Heliophysics Events Knowledgebase by observers using SDO/AIA data. A significant causal connection is found between the two event types, such that large flares are followed by filament eruptions within 24 hours much more often than they are preceded by filament eruptions. This stipulates that the flares either cause the filaments to erupt or affect the eruption timing such that the filament eruptions follow the flares more closely in time.</p> <p></p
Proceedings of the International Astronomical Union, 2010
Observations with the Solar Optical Telescope on Hinode indicate that the Quiet Sun magnetic fiel... more Observations with the Solar Optical Telescope on Hinode indicate that the Quiet Sun magnetic field occurs on every scale of convection including granulation. Data reported here show that, regardless of the position on the disk, the polarity in the inner network regions are balanced to 1 part in 72. This is consistent with both local dynamo processes or the creation of surface features by the granulation downflows.
Solar magnetism displays a host of variational timescales of which the enigmatic 11-year sunspot ... more Solar magnetism displays a host of variational timescales of which the enigmatic 11-year sunspot cycle is most prominent. Recent work has demonstrated that the sunspot cycle can be explained in terms of the intra- and extra-hemispheric interaction between the overlapping activity bands of the 22-year magnetic polarity cycle. Those activity bands appear to be driven by the rotation of the Sun's deep interior. Here we deduce that activity band interaction can qualitatively explain the 'Gnevyshev Gap'-a well-established feature of flare and sunspot occurrence. Strong quasi-annual variability in the number of flares, coronal mass ejections, the radiative and particulate environment of the heliosphere is also observed. We infer that this secondary variability is driven by surges of magnetism from the activity bands. Understanding the formation, interaction and instability of these activity bands will considerably improve forecast capability in space weather and solar activity...
Space Telescopes and Instrumentation 2008: Ultraviolet to Gamma Ray, 2008
The High-resolution Lightweight Telescope for the EUV (HiLiTE) is a Cassegrain telescope that wil... more The High-resolution Lightweight Telescope for the EUV (HiLiTE) is a Cassegrain telescope that will be made entirely of Silicon Carbide (SiC), optical substrates and metering structure alike. Using multilayer coatings, this instrument will be tuned to operate at the 465 Å Ne VII emission line, formed in solar transition region plasma at ~500,000 K. HiLiTE will have an aperture of 30 cm, angular resolution of ~0.2 arc seconds and operate at a cadence of ~5 seconds or less, having a mass that is about 1/4 that of one of the 20 cm aperture telescopes on the Atmospheric Imaging Assembly (AIA) instrument aboard NASA's Solar Dynamics Observatory (SDO). This new instrument technology thus serves as a path finder to a post-AIA, Explorer-class missions.
Uploads
Papers by Alan Title