Author name code: martin ADS astronomy entries on 2022-09-14 =author:"Martin, Sara F." OR =author:"Martin, S.F." ------------------------------------------------------------------------ Title: Evolving Classifications of Solar Prominences Authors: Martin, Sara F. Bibcode: 2018cosp...42E2187M Altcode: Classification schemes with main classes and subclasses began with Sechi in 1875 who categorized prominences mostly from their shapes. With the aid of spectroheliograms and photography, the number of different categories of prominences maximized with Petit from 1925-1950 who added classes according their dynamics, and relationships to active regions and solar flares. With the recognition that not all prominences seen at the limb corresponded to features seen against the disk, many observers began referring to disk prominences as "filaments." With the greater abundance of data enabled by the use of birefringent, interference filters and time-lapse photography, many attempts were made through the 1960s to created physically significant prominence (filament) classifications as cited in the two books on solar prominences by Tandberg-Hanssen. Reversal of the trend for increasingly complex classifications began in the 1950s after invention of the magnetograph. Filaments in Hα_ were all found to lie between areas of opposite polarity, line-of-sight magnetic fields. Features, such as flare loops, spicules, and surges acquired separate identities and no longer needed to be classified as prominences. Observations with increased spatial resolution allowed the identity of fine thread-like structure within the basic spine and barb structure of filaments. The recognition of chirality in the threads of filaments and of fibrils in their filament channels enabled the unifying of all filaments under the name channel filaments (channel prominences). 304Å observations aided detection of greater numbers of coronal cloud prominences, funnel prominences, and coronal rain. Funnel prominences and coronal cloud prominence are deduced to be the same basic structures seen from different perspectives but not all coronal rain comes from coronal cloud prominences. Therefore, prominence classifications are reduced to three physically-different phenomena: channel prominences, coronal cloud prominences and coronal rain. An open question is whether all features called coronal rain are fundamentally the same. Title: Observational Evidence of Shallow Origins for the Magnetic Fields of Solar Cycles - a review Authors: Martin, Sara F. Bibcode: 2018FrASS...5...17M Altcode: Observational evidence for the origin of active region magnetic fields has been sought from published information on extended solar cycles, statistical distributions of active regions and ephemeral regions, helioseismology results, positional relationships to supergranules, and fine-scale magnetic structure of active regions and their sunspots during their growth. Statistical distributions of areas of ephemeral and active regions blend together to reveal a single power law. The shape of the size distribution in latitude of all active regions is independent of time during the solar cycle, yielding further evidence that active regions of all sizes belong to the same population. Elementary bipoles, identified also by other names, appear to be the building blocks of active regions; sunspots form from elementary bipoles and are therefore deduced to develop from the photosphere downward, consistent with helioseismic detection of downflows to 3-4 Mm below sunspots as well as long-observed downflows from chromospheric/coronal arch filaments into sunspots from their earliest appearance. Time-distance helioseismology has been effective in revealing flows related to sunspots to depths of 20 Mm. Ring diagram analysis shows a statistically significant preference for upflows to precede major active region emergence and downflows after flux emergence but both are often observed together or sometimes not detected. From deep-focus helioseismic techniques for seeking magnetic flux below the photosphere prior major active regions, there is evidence of acoustic travel-time perturbation signatures rising in the limited range of depths of 42-75 Mm but these have not been verified or found at more shallow depths by helioseismic holographic techniques. The development of active regions from clusters of elementary bipoles appears to be the same irrespective of how much flux an active region eventually develops. This property would be consistent with the magnetic fields of large active regions being generated in the same way and close the same depth as small active regions in a shallow zone below the photosphere. All evidence considered together, understanding the origins of the magnetic fields of solar cycles boils down to learning how and where elementary bipoles are generated beneath the photosphere. Title: A Survery of the Correlation between Filament Chirality and Sigmoid Handedness Authors: V, A.; Hazra, S.; Martin, S. F.; Martens, P. C. Bibcode: 2017AGUFMSH51C2498V Altcode: Sigmoid regions on the Sun are often the regions that cause Coronal Mass Ejections (CMEs). Large CMEs most often have filaments that erupt with them. This study focuses on the statistical relevance of the shape of the sigmoid and the chirality of the filament residing in these sigmoids. The study further extends to the relation between the directionality of filaments and the Earth-directed CMEs. Sigmoid data from Savcheva et al. (2014) between 2007 and 2012 and a compilation of data using the HEK Sigmoid Sniffer (Martens et al. 2012) along with Hinode XRT Soft X-ray images were used for analyzing data between 2013 and 2017. Hence this dataset consists of almost one solar cycle of data. A similar study done previously by Martens et al. (2013) analysed data for a solar cycle using an Advanced Automated Filament Detection & Characterization Code (Bernasconi, Rust & Hakim 2005). Considering that automated chirality detection is not foolproof, we present this study which uses manual determination of chirality for accuracy using high resolution chromospheric images. Mainly full disk images of soft X-ray obtained from Hinode XRT (X-Ray Telescope) have been used to find and ensure the S or Z shape of sigmoids. H-alpha images obtained from BBSO and Kanzelhohe Solar Observatory (KSO) are used in determining the chirality of filaments. The resolutions of BBSO and KSO data are 1k and 4k respectively. A comparison of the analysis of the chirality of filaments using both data will be presented. Although KSO gives a 4k resolution, it is still difficult to determine the chirality of small filaments. For this reason, high resolution images of H-alpha chromospheric filaments obtained from Helio Research and Solar Observing Optical Network (SOON) have been used for further analysis of chirality of those filaments that were undeterminable using the BBSO or KSO full disk images. The results of the comparison using the different resolutions are shown. The results of the correlation between sigmoid shape and filament chirality are also shown. Further, these results are used in determining the correlation with Earth directed CMEs and those that cause geo-magnetic storms. Savacheva, A. S., McKillop, S. C., McCauley, P. I., et al., 2014, 289Bernasconi, P. N., Rust, D. M., & Hakim, D., 2005, Sol. Phys., 228, 97 Martens, P., Yeates, A., & Pillai, K., 2013, IAU, 3000 Title: Transequatorial Coronal Cloud Prominences Versus Transequatorial Channel Prominence Authors: Martin, S. F.; Daga, K. Bibcode: 2016AGUFMSH43C2584M Altcode: Seven transequatorial channel prominences were identified in the McCauley et al. catalog of erupting prominences from June 2010 - Sep 2014 (2015 Solar Phys. 290, 1703). A comparable number of transequatorial coronal cloud prominences were identified in the Martin et al. study of coronal cloud prominences from May 2010 - April 2012 (IAU Symposium 320, 2016, p. 276). The similar locations of these two subsets of two primary prominence classifications make them nearly ideal candidates for comparison of their properties. Coronal rain is an integral dynamic in coronal cloud prominences whereas counterstreaming motion is characteristic of channel prominences. The two subsets are representative of the the differing magnetic structure, mass origin, evolution, and environmental properties of coronal cloud prominences and channel prominences in general. These samples illustrate how coronal cloud prominences require different models than channel prominences. However, both types of prominences appear to be dependent upon pre-existing environments that largely control their structure and dynamics. Title: The Chirality and Lifetime of Filaments and Filament Channels Authors: Daga, Komal; Martin, Sara F. Bibcode: 2016shin.confE.139D Altcode: Two of the most useful properties of individual filaments are not adequately understood. These are chirality and lifetime. The goal in this study is to analyze chirality and lifetime of filament and filament channels over a period of 2 years during the rise of current solar cycle 24 from May 2010 to May 2012. Here we report on the results of cataloging for the initial months.

Systematic documentation of filament chirality will greatly help in forecasting the related helicity of CMEs and their interaction with the magnetic field of Earth. Better knowledge of filament lifetime is needed to anticipate their eruption along with the occurrence of CMEs. We are documenting lifetimes of filaments because their durations are much shorter than previously reported. By studying their lifetimes we gain a better understanding of the close relationship between filament evolution and CME buildup because they evolve and erupt hand-in-hand.

We have determined the chirality of filaments using direct and indirect methods. The direct method is based on the slant of filament barbs observed in Hα. The main indirect method employs the chirality of filament channels as seen in coronal cells in 193 Å images. Another indirect method is based on the skew of flare loops and coronal loops. By comparing these different techniques we are able to learn which method or combination of methods is most effective.

We find very few exceptions to the hemispheric pattern of dextral filaments in the northern hemisphere and sinistral filaments in the southern hemisphere. The exceptions to the hemispheric pattern is primarily due to differential rotation acting on active regions whose relative locations are more north-south than east-west of each other. Most exceptions are recognizable at the time filaments develop. We confirm the overall orientation of CME flux ropes in space can be anticipated from their associated filaments. Title: Distinguishing between coronal cloud prominences and channel prominences and their associations with solar and stellar flares Authors: Martin, Sara F.; Engvold, Oddbjorn; Lin, Yong; da Silva, Jacqueline Alves Bibcode: 2016IAUS..320..278M Altcode: To better understand the differences between coronal cloud prominences and channel prominences, we systematically identified and analyzed coronal cloud prominences recorded in SDO/AIA images at 304 Å from 2010 May 20 through 2012 April 28. For the 225 cases identified, their numbers vary directly with the sunspot number. Their durations are typically less than 3 days. Their most frequent maximum height is 90,000 + and - 10,000 km. We offer our hypothesis that many coronal cloud prominences originate from some of the mass of previously erupted filaments ejected high out of their filament channels; subsequently part of this mass falls and collects in leaky magnetic troughs among coronal magnetic fields which constrain the leaked mass to slowly drain downward along curved trajectories where it appears as coronal rain. Currently there is inadequate evidence for a convincing correspondence between either coronal cloud prominences or channel prominences with stellar prominences detected to date. Title: Distinguishing Between Different Types of Prominences Associated with Solar Flares Authors: Martin, Sara F.; Engvold, Oddbjorn; Lin, Yong Bibcode: 2015IAUGA..2255962M Altcode: In the early days of solar astronomy, any feature that extended above the solar limb was called a prominence. However, many such coronal features have been sufficiently studied to justify more specific names such as flare loops, surges, and flaring arches. Each of these named phenomena has different properties and involves different physical processes from other solar prominences. If we exclude these well-identified phenomena, we find that the majority of the remaining prominences can be grouped into only two categories that are distinctly different from each other. The main two types are (1) channel prominences or channel filaments when seen against the solar disk and (2) coronal cloud prominences, including narrow, down-flows named coronal rain. We illustrate the many significant differences between channel prominences and coronal cloud prominences. One of the fundamental differences is that channel prominences often have patterns of mass motions useful in anticipating many flares while coronal cloud prominences tend to occur hours after major solar flares. We also raise the question of whether the much taller coronal cloud prominences could have a counterpart in prominences on solar-like stars with magnetic fields of greater magnitude than the Sun. Title: Re-interpreting Prominences Classified as Tornadoes Authors: Martin, Sara F.; Venkataramanasastry, Aparna Bibcode: 2015TESS....131206M Altcode: Some papers in the recent literature identify tornado prominences with barbs of quiescent prominences while papers in the much older historic literature include a second category of tornado prominence that does not correspond to a barb of a quiescent prominence. The latter are described as prominence mass rotating around a nearly vertical axis prior to its eruption and the rotation was verified by spectral measurements. From H alpha Doppler-shifted mass motions recorded at Helio Research or the Dutch Open Telescope, we illustrate how the apparent tornado-like motions, identified with barbs, are illusions in our mind’s eye resulting from poorly resolved counterstreaming threads of mass in the barbs of quiescent prominences. In contrast, we confirm the second category of rotational motion in prominences shortly before and during eruption. In addition, we identify this second category as part of the late phase of a phenomenon called the roll effect in erupting prominences. In these cases, the eruption begins with the sideways rolling of the top of a prominence. As the eruption proceeds the rolling motion propagates down one leg or both legs of the prominence depending on whether the eruption is asymmetric or symmetric respectively. As an asymmetric eruption continues, the longer lasting leg becomes nearly vertical and its rotational motion also continues. If only this phase of the eruption was observed, as in some historic cases, it was called a tornado prominence. However, when we now observe entire eruptions in time-lapse sequences, the similarity to terrestrial tornadoes is lost. We conclude that neither prominence barbs, that give the illusion of rotation, nor the cases of true rotational motion, in the legs of erupting prominences, are usefully described as tornado prominences when the complete prominence structure or complete erupting event is observed. Title: Questioning Many Mysteries Authors: Martin, Sara F. Bibcode: 2015SoPh..290.1011M Altcode: 2015SoPh..tmp...35M The first section of this memoir queries my formative years. Indirectly I address the question, did my childhood and early years make a difference in my choice of career? Why and how did I begin my journey to becoming a scientist? Did I choose the field of solar astronomy or did circumstances dictate it for me? In the second section, I travel through my work environments and experiences, talking about interactions and aspects of being a scientist that do not appear in our research papers. What parts of my research were happenstances and what parts did I plan? What does it feel like to be on scientific quests? Using examples in my journey, I also turn to questions that have intrigued me throughout my sojourn as a solar astronomer. How do scientific discoveries come about? What factors lead to little discoveries? And what factors lead to major exciting discoveries? Are there timely questions we do not think to ask? How can small, seemingly scattered pieces of knowledge suddenly coalesce into a deeper understanding - what is called the "Aha!" experience - the times when our mental light switches on, and with child-like wonder we behold a "big picture"? Title: The Magnetic Field Structure of Prominences from Direct and Indirect Observations Authors: Martin, Sara F. Bibcode: 2015ASSL..415..205M Altcode: Solar prominences are fascinating and unique magnetic structures in our solar system. From all observational evidence to date, their intricate structure, dynamics and plasma parameters are apparently all derived from observable source magnetic fields on the Sun. While the processes that convert these source fields to prominence magnetic fields are not fully understood, there is a trail of observational information that gives many clues about how prominence magnetic fields are derived from or related to these source fields and maintained for various lengths of time through multiple processes, over a wide range of spatial scales. This chapter highlights that trail of observational information for two primary magnetic types with very different origins: channel prominences and coronal cloud prominences. Title: Two Categories of Apparent Tornado-like Prominences Authors: Martin, Sara F.; Venkataramanasastry, Aparna Bibcode: 2014AAS...22441403M Altcode: Two categories of solar prominences have been described in the literature as having a pattern of mass motions and/or a shape similar to terrestrial tornados. We first identify the two categories associated with prominences in the historic literature and then show that counterparts do exist for both in recent literature but one has not been called a tornado prominence. One category described as being similar to tornados is associated with the barbs of quiescent filaments but barbs appear to have rotational motion only under special conditions. H alpha Doppler observations from Helio Research confirm that this category is an illusion in our mind’s eye resulting from counterstreaming in the large barbs of quiescent filaments. The second category is a special case of rotational motion occurring during the early stages of some erupting prominences, in recent years called the roll effect in erupting prominences. In these cases, the eruption begins with the sideways rolling of the top of a prominence. As the eruption proceeds the rolling motion propagates down one leg or both legs of an erupting prominence depending on whether the eruption is asymmetric or symmetric respectively. As an asymmetric eruption proceeds, the longer lasting leg becomes nearly vertical and has true rotational motion. If only this phase of the eruption was observed, as in the historic cases, it was called a tornado prominence and spectra recorded in these cases provide proof of the rotational motion. When one observes an entire eruption which exhibits the rolling motion, as accomplished at Helio Research, the similarity to a tornado is lost because the event as a whole has quite a different nature and the analogy to a terrestrial tornado not longer appears suitable or helpful in understanding the observed and deduced physical processes. Our conclusion is that there are no solar prominences with motions that are usefully described as tornado or tornado-like events aside from the fun of observing some prominence barbs whose mass motions yield a fascinating illusion of rotational motion under special conditions. Title: Apparent Solar Tornado-Like Prominences Authors: Panasenco, Olga; Martin, Sara F.; Velli, Marco Bibcode: 2014SoPh..289..603P Altcode: 2013arXiv1307.2303P Recent high-resolution observations from the Solar Dynamics Observatory (SDO) have reawakened interest in the old and fascinating phenomenon of solar tornado-like prominences. This class of prominences was first introduced by Pettit (Astrophys. J.76, 9, 1932), who studied them over many years. Observations of tornado prominences similar to the ones seen by SDO had already been documented by Secchi (Le Soleil, 1877). High-resolution and high-cadence multiwavelength data obtained by SDO reveal that the tornado-like appearance of these prominences is mainly an illusion due to projection effects. We discuss two different cases where prominences on the limb might appear to have a tornado-like behavior. One case of apparent vortical motions in prominence spines and barbs arises from the (mostly) 2D counterstreaming plasma motion along the prominence spine and barbs together with oscillations along individual threads. The other case of apparent rotational motion is observed in a prominence cavity and results from the 3D plasma motion along the writhed magnetic fields inside and along the prominence cavity as seen projected on the limb. Thus, the "tornado" impression results either from counterstreaming and oscillations or from the projection on the plane of the sky of plasma motion along magnetic-field lines, rather than from a true vortical motion around an (apparent) vertical or horizontal axis. We discuss the link between tornado-like prominences, filament barbs, and photospheric vortices at their base. Title: Rapid Formation and Disappearance of a Filament Barb Authors: Joshi, Anand D.; Srivastava, Nandita; Mathew, Shibu K.; Martin, Sara F. Bibcode: 2013SoPh..288..191J Altcode: We present observations of an activated quiescent filament obtained in Hα from the high-resolution Dutch Open Telescope (DOT) on 20 August 2010. The filament developed a barb in 10 min, which disappeared within the next 35 min. A data set from the DOT spanning 2 h was used to analyse this event. Line-of-sight velocity maps were constructed from the Doppler images, which reveal flows in filament spine during this period. Photospheric magnetograms were used from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) to determine the changes in magnetic flux in the region surrounding the barb location. The analysis shows flows in the filament spine towards the barb location preceding its formation, and flows in the barb towards the spine during its disappearance. Magnetograms reveal patches of minority polarity flux close to the end of the barb at its greatest elongation. The flows in the spine and barbs are along numerous threads that compose these typical filament structures. The flows are consistent with field-aligned threads and demonstrate that the replacement time of the mass in barbs, and by inference, in the spine is very rapid. Title: Origins of Rolling, Twisting, and Non-radial Propagation of Eruptive Solar Events Authors: Panasenco, Olga; Martin, Sara F.; Velli, Marco; Vourlidas, Angelos Bibcode: 2013SoPh..287..391P Altcode: 2012arXiv1211.1376P; 2012SoPh..tmp..321P We demonstrate that major asymmetries in erupting filaments and CMEs, namely major twists and non-radial motions are typically related to the larger-scale ambient environment around eruptive events. Our analysis of prominence eruptions observed by the STEREO, SDO, and SOHO spacecraft shows that prominence spines retain, during the initial phases, the thin ribbon-like topology they had prior to the eruption. This topology allows bending, rolling, and twisting during the early phase of the eruption, but not before. The combined ascent and initial bending of the filament ribbon is non-radial in the same general direction as for the enveloping CME. However, the non-radial motion of the filament is greater than that of the CME. In considering the global magnetic environment around CMEs, as approximated by the Potential Field Source Surface (PFSS) model, we find that the non-radial propagation of both erupting filaments and associated CMEs is correlated with the presence of nearby coronal holes, which deflect the erupting plasma and embedded fields. In addition, CME and filament motions, respectively, are guided towards weaker field regions, namely null points existing at different heights in the overlying configuration. Due to the presence of the coronal hole, the large-scale forces acting on the CME may be asymmetric. We find that the CME propagates usually non-radially in the direction of least resistance, which is always away from the coronal hole. We demonstrate these results using both low- and high-latitude examples. Title: Using Coronal Cells to Infer the Magnetic Field Structure and Chirality of Filament Channels Authors: Sheeley, N. R., Jr.; Martin, S. F.; Panasenco, O.; Warren, H. P. Bibcode: 2013ApJ...772...88S Altcode: 2013arXiv1306.2273S Coronal cells are visible at temperatures of ~1.2 MK in Fe XII coronal images obtained from the Solar Dynamics Observatory and Solar Terrestrial Relations Observatory spacecraft. We show that near a filament channel, the plumelike tails of these cells bend horizontally in opposite directions on the two sides of the channel like fibrils in the chromosphere. Because the cells are rooted in magnetic flux concentrations of majority polarity, these observations can be used with photospheric magnetograms to infer the direction of the horizontal field in filament channels and the chirality of the associated magnetic field. This method is similar to the procedure for inferring the direction of the magnetic field and the chirality of the fibril pattern in filament channels from Hα observations. However, the coronal cell observations are easier to use and provide clear inferences of the horizontal field direction for heights up to ~50 Mm into the corona. Title: Elementary Bipoles, the Building Blocks of Active Regions Authors: Martin, Sara F.; Mkhitaryan, M. Bibcode: 2013SPD....44..109M Altcode: New magnetic flux even in very small active regions appears as a succession of tiny bipolar magnetic fields that successively and concurrently appear in tight clusters. These smallest observable bipoles were initially called “elementary bipoles” when first seen in videomagnetograms from the Big Bear Solar Observatory (Martin, S. F. 1990, “Elementary Bipoles of Active Regions and Ephemeral Active Regions” Societa Astronomica Italiana, Memorie 61, 293). The magnetic flux of each pole of elementary bipole is approximately the same and measures 1018 Mx or less depending on both the spatial resolution and sensitivity of the magnetograph with which the measurements are made. The two poles initially occur very close together and rapidly move in opposite directions with a typical speed of 3 km/sec. The elementary bipoles within a cluster tend to emerge with similar orientations. The most common orientation of the elementary bipoles at any given time determines the “orientation” of a whole simple bipolar region. In this paper we illustrate and compare 6 clusters of elementary bipoles during the development of a large active region less than 2 days old when observed in Hα at the Dutch Open Telescope along with HMI/SDO. Each cluster of elementary bipoles behaves like a single simple bipolar active region. However the clusters are so close together that the magnetic flux of each bipolar cluster merges or cancels with adjacent clusters. The study of elementary bipoles provides a means of simplifying our understanding of the development of complex active regions depending on both the spatial resolution and sensitivity of the magnetograph with which the measurements are made. Title: Footpoint detection and mass-motion in chromospheric filaments Authors: V, Aparna; Hardersen, P. S.; Martin, S. F. Bibcode: 2013SPD....44...06V Altcode: A quiescent region on the Sun containing three filaments is used to study the properties of mass motion. This study determines if the footpoints or end-points of the filaments are the locations from where mass gets injected into the filaments. Several hypotheses have been put forth in the past to determine how a filament acquires mass. Trapping of coronal mass in the filament channel due to condensation (Martin, 1996) and injection of mass into the filaments during magnetic reconnection (Priest, et al., 1995) are some of the speculations. This study looks for indications for injection of mass via chromospheric footpoints. The data consists of blue (Hα-0.5 Å) and red (Hα+0.5 Å) wing high resolution Hα images of the W29N37 region of the Sun taken on Oct 30, 2010, from 1200 - 1600 UT. The Dutch Open Telescope was used to obtain the data. The images are aligned and animated to see Doppler motion in the fibrils. Smaller fibrils merge to form longer ones; barbs appear and disappear in one of the long filaments and is seen moving along the length of the filament. A region with no typical filament-like absorption feature is observed to be continuously receiving mass. Fibrils appear to be converging from opposite sides along what appears to be a neutral line; mass motion is seen in these fibrils as well. An eruption occurs in a region of fibrils lumped together at the end of the first hour (1300 UT) followed by plage brightening at 1430 UT near one of the filament regions. Helioviewer (Panasenco, et al., 2011) is used for aligning the images; GIMP is used for precision alignment and animation. Each frame in the sequence is studied carefully to note changes in the filament regions. The footpoints of the filaments are determined by the changes observed in the position of the filament ‘legs’ in each frame. Variations in the magnetic polarity corresponding to changes observed in the chromosphere are analyzed using HMI magnetograms. Bright and dark points on the magnetogram surrounding the filaments are examined for possible locations of footpoints. The HMI images are overlaid with Stonyhurst grids and full disk Hα images to improve the accuracy in determining the location of the footpoints.Abstract (2,250 Maximum Characters): A quiescent region on the Sun containing three filaments is used to study the properties of mass motion. This study determines if the footpoints or end-points of the filaments are the locations from where mass gets injected into the filaments. Several hypotheses have been put forth in the past to determine how a filament acquires mass. Trapping of coronal mass in the filament channel due to condensation (Martin, 1996) and injection of mass into the filaments during magnetic reconnection (Priest, et al., 1995) are some of the speculations. This study looks for indications for injection of mass via chromospheric footpoints. The data consists of blue (Hα-0.5 Å) and red (Hα+0.5 Å) wing high resolution Hα images of the W29N37 region of the Sun taken on Oct 30, 2010, from 1200 - 1600 UT. The Dutch Open Telescope was used to obtain the data. The images are aligned and animated to see Doppler motion in the fibrils. Smaller fibrils merge to form longer ones; barbs appear and disappear in one of the long filaments and is seen moving along the length of the filament. A region with no typical filament-like absorption feature is observed to be continuously receiving mass. Fibrils appear to be converging from opposite sides along what appears to be a neutral line; mass motion is seen in these fibrils as well. An eruption occurs in a region of fibrils lumped together at the end of the first hour (1300 UT) followed by plage brightening at 1430 UT near one of the filament regions. Helioviewer (Panasenco, et al., 2011) is used for aligning the images; GIMP is used for precision alignment and animation. Each frame in the sequence is studied carefully to note changes in the filament regions. The footpoints of the filaments are determined by the changes observed in the position of the filament ‘legs’ in each frame. Variations in the magnetic polarity corresponding to changes observed in the chromosphere are analyzed using HMI magnetograms. Bright and dark points on the magnetogram surrounding the filaments are examined for possible locations of footpoints. The HMI images are overlaid with Stonyhurst grids and full disk Hα images to improve the accuracy in determining the location of the footpoints. Title: Formation of the Coronal Cloud Prominences Inside Magnetic Funnels Authors: Panasenco, Olga; Velli, Marco; Martin, Sara F. Bibcode: 2013enss.confE..94P Altcode: We describe observations of coronal cloud prominences with the Solar Dynamics Observatory and STEREO. Observations of this phenomenon during the month of September 2012, in similar locations but over widely separated periods, are used to investigate the reasons for the appearance of coronal cloud prominces at different times in the same location. In particular, we focus on the large scale structure of the background magnetic field. Using a potential field source-surface extrapolation to compute the coronal field from photospheric maps, we find that coronal cloud prominences always form after filament eruptions and CMEs have occurred nearby. The location of the cloud prominence coincides with a magnetic field region which appears to be open but rapidly expanding, an open field with a funnel structure. Part of the plasma from the neighboring eruption falling back towards the sun is captured and accumulates in these field regions of strong expansion of the field. The plasma suspension at heights of 0.3 Rs, coinciding with the largest gradients in the field naturally lead to a diamagnetic hypothesis for the force counteracting gravity. We study the evolution of the funnel-like open fields during several solar rotations and find a direct relation between funnels and the presence of coronal clouds at great heights in the solar corona. Title: Solar Tornado Prominences: Plasma Motions Along Filament Barbs Authors: Panasenco, Olga; Velli, Marco; Martin, Sara F.; Rappazzo, Franco Bibcode: 2013enss.confE..93P Altcode: Recent high-resolution observations from the Solar Dynamic Observatory (SDO) have reawakened interest in the old and fascinating phenomenon of solar tornado prominences. This class of prominences was first introduced by E. Pettit in 1932, who studied them over many years up to 1950. High resolution and high cadence multi-wavelength data obtained by SDO reveal that the tornado-like properties of these prominences are mainly an illusion due to projection effects. We show that counterstreaming plasma motions with projected velocities up to +/- 45 km/sec along the prominence spine and barbs create a tornado-like impression when viewed at the limb. We demonstrate that barbs are often rooted at the intersection between 4-5 supergranular cells. We discuss the observed oscillations along the vertical parts of barbs and whether they may be related to vortex flows coming from the convection downdrafts at the intersection of supergranules (and possibly smaller convective cells) in the photosphere and their entrained magnetic field. The unwinding of magnetic threads near the photosphere via reconnection might be a source of the waves which are observed as oscillations in prominence barbs. Title: The Build-Up to Eruptive Solar Events Viewed as the Development of Chiral Systems Authors: Martin, S. F.; Panasenco, O.; Berger, M. A.; Engvold, O.; Lin, Y.; Pevtsov, A. A.; Srivastava, N. Bibcode: 2012ASPC..463..157M Altcode: 2012arXiv1212.3646M When we examine the chirality or observed handedness of the chromospheric and coronal structures involved in the long-term build-up to eruptive events, we find that they evolve in very specific ways to form two and only two sets of large-scale chiral systems. Each system contains spatially separated components with both signs of chirality, the upper portion having negative (positive) chirality and the lower part possessing positive (negative) chirality. The components within a system are a filament channel (represented partially by sets of chromospheric fibrils), a filament (if present), a filament cavity, sometimes a sigmoid, and always an overlying arcade of coronal loops. When we view these components as parts of large-scale chiral systems, we more clearly see that it is not the individual components of chiral systems that erupt but rather it is the approximate upper parts of an entire evolving chiral system that erupts. We illustrate the typical pattern of build-up to eruptive solar events first without and then including the chirality in each stage of the build-up. We argue that a complete chiral system has one sign of handedness above the filament spine and the opposite handedness in the barbs and filament channel below the filament spine. If the spine has handedness, the observations favor its having the handedness of the filament cavity and coronal loops above. As the separate components of a chiral system form, we show that the system appears to maintain a balance of right-handed and left-handed features, thus preserving an initial near-zero net helicity. We further argue that the chiral systems allow us to identify key sites of energy transformation and stored energy later dissipated in the form of concurrent CMEs, erupting filaments and solar flares. Each individual chiral system may produce many successive eruptive events above a single filament channel. Because major eruptive events apparently do not occur independent of, or outside of, these unique chiral systems, we hypothesize that the development of chiral systems: (1) are fundamental to the occurrence of eruptive solar events and (2) preserve an approximate balance between positive and negative helicity (right and left-handed chirality) while preparing to release energy in the form of CMEs, erupting filaments, and flares. Title: Large-field high-resolution mosaic movies Authors: Hammerschlag, Robert H.; Sliepen, Guus; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Sütterlin, Peter; Martin, Sara F. Bibcode: 2012SPIE.8444E..06H Altcode: Movies with fields-of-view larger than normal for high-resolution telescopes will give a better understanding of processes on the Sun, such as filament and active region developments and their possible interactions. New active regions can influence, by their emergence, their environment to the extent of possibly serving as an igniter of the eruption of a nearby filament. A method to create a large field-of-view is to join several fields-of-view into a mosaic. Fields are imaged quickly one after another using fast telescope-pointing. Such a pointing cycle has been automated at the Dutch Open Telescope (DOT), a high-resolution solar telescope located on the Canary Island La Palma. The observer can draw with the computer mouse the desired total field in the guider-telescope image of the whole Sun. The guider telescope is equipped with an H-alpha filter and electronic enhancement of contrast in the image for good visibility of filaments and prominences. The number and positions of the subfields are calculated automatically and represented by an array of bright points indicating the subfield centers inside the drawn rectangle of the total field on the computer screen with the whole-sun image. When the exposures start the telescope repeats automatically the sequence of subfields. Automatic production of flats is also programmed including defocusing and fast motion over the solar disk of the image field. For the first time mosaic movies were programmed from stored information on automated telescope motions from one field to the next. The mosaic movies fill the gap between whole-sun images with limited resolution of synoptic telescopes including space instruments and small-field high-cadence movies of high-resolution solar telescopes. Title: High-Resolution Observations of a Filament showing Activated Barb Authors: Joshi, Anand; Martin, Sara F.; Mathew, Shibu; Srivastava, Nandita Bibcode: 2012cosp...39..841J Altcode: 2012cosp.meet..841J Analysis of a filament showing an activated barb using observations from the Dutch Open Telescope (DOT) on 2010 August 20 are presented. The DOT takes Doppler images in Hα, among other wavelengths, in a region about 110 × 110 arcsec^{2} in area, at a cadence of 30~seconds. The offline image restoration technique of speckle reconstruction is applied to obtain diffraction limited images. The filament developed a new barb in 10~minutes, which disappeared within the next 35~minutes. Such a rapid formation and disappearance of a filament barb is unusual, and has not been reported earlier. Line-of-sight velocity maps were constructed from the Doppler images of the target filament. We observe flows in the filament spine towards the barb location prior to its formation, and flows in the barb towards the spine during its disappearance. Photospheric magnetograms from Heliospheric Magnetic Imager on board the Solar Dynamics Observatory, at a cadence of 45~seconds, were used to determine the changes in magnetic flux in the region surrounding the barb location. The variation of magnetic flux in this duration supports the view that barbs are rooted in minor magnetic polarity. Our analysis shows that barbs can be short-lived and formation and disappearance of the barb was associated with cancellation of magnetic flux. Title: Coronal Holes, Filament Channels And Filaments: Observations Of The Self-organization Of The Coronal Magnetic Field Over Solar Cycles 23 And 24 Authors: Panasenco, Olga; Martin, S. F.; Velli, M.; Berger, M. A. Bibcode: 2012AAS...22020202P Altcode: The aim of this work is to understand the relationship between coronal holes, coronal hole boundaries and one of the other main features of the coronal magnetic field, namely filament channels, regions of highly sheared magnetic fields overlying photospheric polarity reversal boundaries. The well-developed filament channel is a necessary ingredient for filament formation. Polar coronal holes and polar crown filament channels always seem to exist together, and even during periods of weakest activity, when nothing indicates the presence of polar crown channels on the solar disk, polar crown prominences appear at the limb proving their existence. Does a similar symbiotic relationship exist also for other coronal holes? There is some indication that for middle and low latitude coronal holes different configurations occur depending on the polarity of the hole relative to the pole. If the polarity is the same, then a coronal pseudostreamer configuration can form with twin filament channels at its base, while if the polarity is opposite, the right conditions for the development of the filament channels and filaments following the hemispheric helicity rule arise. Using SOHO/EIT and MDI, STEREO/EUVI, SDO/AIA and HMI instruments we trace the formation and mutual evolution of coronal holes and their symbiotic filament channels up to and including filament formations, eruptions and subsequent reformations during period 1998-2012 (solar cycles 23 and 24). Title: Coronal Mass Ejections from Magnetic Systems Encompassing Filament Channels Without Filaments Authors: Pevtsov, Alexei A.; Panasenco, Olga; Martin, Sara F. Bibcode: 2012SoPh..277..185P Altcode: Well-developed filament channels may be present in the solar atmosphere even when there is no trace of filament material inside them. Such magnetic systems with filament channels without filaments can result in coronal mass ejections that might appear to have no corresponding solar surface source regions. In this case study, we analyze CMEs on 9 August 2001 and 3 March 2011 and trace their origins to magnetic systems with filament channels containing no obvious filament material on the days around the eruptions. Title: Coronal Holes and Filaments: Life in Symbiosis Authors: Panasenco, O.; Velli, M.; Martin, S. F.; Berger, M. A. Bibcode: 2011AGUFMSH12A..05P Altcode: The aim of this work is to understand the relationship between coronal holes, coronal hole boundaries and one of the other main features of the coronal magnetic field, namely filament channels, regions of highly sheared magnetic fields overlying photospheric polarity reversal boundaries. The well developed filament channel is a necessary ingredient for the filament formation. Polar coronal holes and polar crown filament channels always seem to exist together, and even during periods of weakest activity, when nothing indicates the presence of polar crown channels on the solar disk, polar crown prominences appear at the limb proving their existence. Does a similar symbiotic relationship exist also for other coronal holes? There is some indication that for middle and low latitude coronal holes different configurations occur depending on the polarity of the hole relative to the pole. If the polarity is the same, then a coronal pseudostreamer configuration can form with twin filament channels at its base, while if the polarity is opposite, the right conditions for the development of the filament channels and filaments following the hemispheric helicity rule arise. Using STEREO/EUVI, SDO/AIA and HMI instruments we trace the formation and mutual evolution of coronal holes and their symbiotic filament channels up to and including filament formations, eruptions and subsequent reformations during many solar rotations in 2010-2011. Title: The Disappearing Solar Filament of 2003 June 11: A Three-body Problem Authors: Balasubramaniam, K. S.; Pevtsov, A. A.; Cliver, E. W.; Martin, S. F.; Panasenco, O. Bibcode: 2011ApJ...743..202B Altcode: The eruption of a large quiescent filament on 2003 June 11 was preceded by the birth of a nearby active region—a common scenario. In this case, however, the filament lay near a pre-existing active region and the new active region did not destabilize the filament by direct magnetic connection. Instead it appears to have done so indirectly via magnetic coupling with the established region. Restructuring between the perturbed fields of the old region and the filament then weakened the arcade overlying the midpoint of filament, where the eruption originated. The inferred rate (~11° day-1) at which the magnetic disturbance propagates from the mature region to destabilize the filament is larger than the mean speed (~5º-6° day-1) but still within the scatter obtained for Bruzek's empirical relationship between the distance from a newly formed active region to a quiescent filament and the time from active region appearance to filament disappearance. The higher propagation speed in the 2003 June 11 case may be due to the "broadside" (versus ''end-on") angle of attack of the (effective) new flux to the coronal magnetic fields overlying a central section of the axis of the filament. Title: Origins of Rolling, Twisting and Non-radial Propagation of Eruptive Solar Events Authors: Martin, Sara F.; Panasenco, Olga Bibcode: 2011sdmi.confE.105M Altcode: We demonstrate that major asymmetries in erupting filaments and CMEs are not only related to each other but that major twists and non-radial motions typically are related to the larger, more global environment around eruptive events. This overarching result grew out of a number of earlier studies that we now encapsulate within the bigger picture. If a filament erupts non-radially, as frequently happens, the top of its spine first bends to one side and evolves into a sideways rolling motion. As shown by 304 Angstrom observations from SOHO and STEREO and earlier H alpha Doppler observations, the rolling motion propagates down the legs of erupting filaments resulting in the large scale twists commonly observed in them. The initial rolling initiates twist of opposite chirality in the two legs. In addition to the observed absence of twist in the pre-eruptive state, further evidence that the energy creating the twist comes from above was found in Doppler shifts; the rotational motions in the legs of erupting filaments are not only opposite in sign to each other but the twists in both legs are opposite in sign to that required if the observed sense of twist were generated at the feet or in the legs of the erupting filament. We next demonstrate that the combined ascent and initial bending is non-radial in the same general direction as for the surrounding CME. However, the non-radial motion of the filament is greater than that of the CME. In considering the global environment around CMEs, as can be approximated by the Potential Field Source Surface (PFSS) Model, we found that both erupting filaments and their surrounding CMEs are non-radial only in the direction away from a nearby coronal hole and toward local and global null points. Due to the presence of the coronal hole, the global forces on the CME are asymmetric. The CME propagates non-radially in the direction of least resistance and that is always away from the coronal hole as we demonstrate by comparing low latitude and high latitude examples. Through modeling and comparison with observed events, we anticipate that major twists and non-radial motions in erupting prominences and CMEs will become predictable to the extent that their environments are well-defined and measurable. Title: Stereoscopic Analysis of 31 August 2007 Erupting Prominence Authors: Liewer, P. C.; Hall, J. R.; de Jong, E. M.; Martin, S. F.; Panasenco, O. Bibcode: 2010AGUFMSH51A1658L Altcode: The dramatic prominence eruption of 31 August 2007 and the associated CME were well observed by both STEREO spacecraft, separated by 28° at that time. The eruption occurred as the filament reach the West limb as seen by STEREO B; the filament, the coronal cavity and the CME were all clearly observed. We use tie-pointing and triangulation to determine the 3D trajectories of the erupting filament (seen in EUVI and COR1) and the associated CME and cavity (seen in COR1 and COR2) and we compare these trajectories. From the EUVI 304 data, it can be seen that the prominence footpoints change loctions during the early stages of the eruption and, using stereoscopy, we find that the new footpoints correspond to locations of EUVI 171 “endpoint brightenings” discussed by Wang, Muglach and Kleim (ApJ, 2009) as marking the outer edge of the transient coronal holes. Our observations are consistent with their interpretation of the brightenings resulting from magnetic reconnection between the erupting prominence magnetic field and the overlying coronal arcade. Title: On dynamical properties of filament channels Authors: Martin, S. F.; Panasenco, O. Bibcode: 2010MmSAI..81..662M Altcode: We discuss some of the least understood properties of filament channels. This includes the three-dimensional rotational configuration at their centers and the importance of cancelling magnetic fields to their configuration. Intranetwork magnetic fields play a role by interacting with network magnetic fields and these interactions probably provide the ubiquitous fibrils of the chromosphere which continuously adjust to the configurations of the dominant network magnetic fields. Supergranules play a role by severely restricting the intermingling of opposite polarity magnetic fields and controlling the diffusion rates whereby opposite polarities network magnetic fields slowly converge and form long and long-lived, polarity reversal boundaries where filaments can form. Title: Filaments, filament channels and their visibility during the present solar minimum Authors: Panasenco, O.; Martin, S. F.; Panasenco, A. Bibcode: 2009AGUFMSH11A1494P Altcode: An unexpected aspect of the current long solar minimum between solar cycles 23 and 24 is that polar crown prominences have been observed nearly continuously above the solar limb. However, many of the same polar crown prominences have had only small sections visible against the chromosphere in H-alpha and these sections change from day to day. The presence of much more extensive mass than seen in H-alpha is certain because filaments are seen against the disk much more completely in 304A than in H-alpha. These differences in filament visibility offer a good opportunity to test our concepts of the relationship between filament mass seen in H-alpha and the rate of cancelling magnetic fields in the photosphere. We know from previous observations and theory over more than 20 years that the existence of filaments is closely related to canceling magnetic fields observed at the photosphere. We have made the hypothesis that there is a threshold in the rate of canceling fields below which filaments are not visible against the solar disk in H-alpha but this concept has not been tested. We are testing this hypothesis by calculating the rates of canceling magnetic flux for the different filaments during their passing across the disk for the current minimum and previous maximum of 23rd solar cycle. In our analyses we use data sets from SOHO/MDI, SOHO/EIT, STEREO and ground based observatories. Title: Relating a Prominence Observed from the Solar Optical Telescope on the Hinode Satellite to Known 3-D Structures of Filaments Authors: Martin, S. F.; Panasenco, O.; Agah, Y.; Engvold, O.; Lin, Y. Bibcode: 2009ASPC..415..183M Altcode: We address only a first step in relating limb and disk observations by illustrating and comparing the spines and barbs of three different quiescent prominences and filaments observed in Hα by three different telescopes. Although the appearance of the three quiescent prominences is quite different, we show that each consists of a spine, barbs extending from the spine, and arcs at the base of some of the curtains of barb threads. Title: Interwoven Patterns of Chirality Among Solar Structures: a Review Authors: Martin, Sara F. Bibcode: 2009SPD....40.2501M Altcode: Chirality is the handedness of solar magnetic structures as recognized in two dimensional solar images or in other solar data revealing distinct magnetic patterns. This review covers the historical succession of discoveries of the chirality of solar magnetic structures, beginning with left and right-handed helical magnetic clouds detected in many interplanetary coronal mass ejections. This led to the recognition of corresponding chiralities in coronal loop systems. Separately, chiral patterns in filaments, filament channels, sunspots, sigmoidal structures, and flare loop systems were established, interrelated, and linked to the chirality of coronal loop systems. The result was the finding that all solar chiral patterns fall into two and only two larger chiral systems with one system more prevalent in the northern hemisphere and the other in the southern hemisphere. From chiral characteristics, along with knowledge or assumptions about the magnetic field topology, we have the ability to better deduce the helicities characteristic of many solar structures. Traditionally, helicity is a property of magnetic fields with strict mathematical definitions in two well-known forms: twist and writhe. Application of the principle of the conservation of helicity to chiral systems now leads to more mature interpretations of the helicity of whole solar magnetic field systems as well as their components, which together must contain equivalent amounts of both left and right-handed helicity. From this broadened perspective, comes a better understanding of why right-handed coronal loops necessarily exist above filaments with left-handed barbs that always overly left-handed filament channels and vice versa. Along with this greater understanding, we are collectively at the point of learning to better recognize and predict the senses of roll, twist, and writhe in the axial fields of erupting prominences. These, in turn, confirm the signs of helicity in associated CMEs and magnetic clouds - where we began this brief historical journey. Title: A Dual Beam H-alpha Doppler System to Acquire, Analyse and Anticipate Solar Eruptive Events Directed towards Earth Authors: Joshi, Anand D.; Mathew, Shibu K.; Srivastava, Nandita; Martin, Sara F.; Gupta, Sudhir K. Bibcode: 2009arXiv0905.3037J Altcode: A new instrument with a dual-beam H-alpha Doppler system is being developed at the Udaipur Solar Observatory (USO) in order to improve the quality and quantity of data on quiet, activated and erupting filaments and prominences on the Sun, especially those associated with geo-effective coronal mass ejections. These data can be potentially used to construct three-dimensional topology of erupting filaments as they leave the surface of the Sun and can be compared with multi-wavelength data obtained from space missions such as STEREO, SOHO, and Hinode. The characterization of various optical components for the instrument is being carried out, and some preliminary results are described in the paper. Title: On small active region filaments, fibrils and surges Authors: Lin, Y.; Martin, S. F.; Engvold, O.; Rouppe van der Voort, L. H. M.; van Noort, M. Bibcode: 2008AdSpR..42..803L Altcode: High resolution Hα images and magnetograms (0.2 arc s) of an active region were obtained in alternating time series at 42 s cadences using the Swedish 1-m Solar Telescope on 2004 August 21. The Hα filtergrams reveal an active region filament and surges consisting of thread-like structures which have widths similar to the widths of chromospheric fibrils, both recorded down to the resolution limit in the best images. All observed structures in the active region appear highly dynamic. Fibrils show counterstreaming strongly resembling the counterstreaming threads in filaments. Streaming, along the threads of surges extending more than 10 arc s, is higher in speed (∼20 km s-1) than in the filament and fibrils and appears to flow independently over and above the chromospheric fibrils. Blue shifts seen in the Hα Dopplergrams confirm the outward mass motion of the surges. However, in at least one case, we also see simultaneous downflows from the same site but in the opposite direction and downward toward the chromosphere. We suggest that the site between these two outward and downward flows identifies the place where magnetic reconnection could occur and thereby cause of the surge. This appears to imply that the reconnection site is in the high chromosphere or low corona. Title: A Method of Resolving the 180-Degree Ambiguity by Employing the Chirality of Solar Features Authors: Martin, S. F.; Lin, Y.; Engvold, O. Bibcode: 2008SoPh..250...31M Altcode: 2008SoPh..tmp..105M The 180-degree ambiguity in magnetic field direction along polarity reversal boundaries can be resolved often and reliably by the chiral method. The chiral method requires (1) identification of the chirality of at least one solar feature related to a polarity reversal boundary along which the field direction is sought and (2) knowledge of the polarity of the network magnetic field on at least one side of the polarity reversal boundary. In the context of the Sun, chirality is an observable signature of the handedness of the magnetic field of a solar feature. We concentrate on how to determine magnetic field direction from chirality definitions and illustrate the technique in eight examples. The examples cover the spectrum of polarity boundaries associated with filament channels and filaments ranging from those connected with active regions to those on the quiet Sun. The applicability of the chiral method to all categories of filaments supports the view that active region filaments and quiescent filaments are the extreme ends in a continuous spectrum of filaments. Title: Topological Analyses of Symmetric Eruptive Prominences Authors: Panasenco, O.; Martin, S. F. Bibcode: 2008ASPC..383..243P Altcode: Erupting prominences (filaments) that we have analyzed from Hα Doppler data at Helio Research and from SOHO/EIT 304 Å, show strong coherency between their chirality, the direction of the vertical and lateral motions of the top of the prominences, and the directions of twisting of their legs. These coherent properties in erupting prominences occur in two patterns of opposite helicity; they constitute a form of dynamic chirality called the ``roll effect." Viewed from the positive network side as they erupt, many symmetrically-erupting dextral prominences develop rolling motion toward the observer along with right-hand helicity in the left leg and left-hand helicity in the right leg. Many symmetricaly-erupting sinistral prominences, also viewed from the positive network field side, have the opposite pattern: rolling motion at the top away from the observer, left-hand helical twist in the left leg, and right-hand twist in the right leg. We have analysed the motions seen in the famous movie of the ``Grand Daddy" erupting prominence and found that it has all the motions that define the roll effect. From our analyses of this and other symmetric erupting prominences, we show that the roll effect is an alternative to the popular hypothetical configuration of an eruptive prominence as a twisted flux rope or flux tube. Instead we find that a simple flat ribbon can be bent such that it reproduces nearly all of the observed forms. The flat ribbon is the most logical beginning topology because observed prominence spines already have this topology prior to eruption and an initial long magnetic ribbon with parallel, non-twisted threads, as a basic form, can be bent into many more and different geometrical forms than a flux rope. Title: Filament Substructures and their Interrelation Authors: Lin, Y.; Martin, S. F.; Engvold, O. Bibcode: 2008ASPC..383..235L Altcode: The main structural components of solar filaments, their spines, barbs, and legs at the extreme ends of the spine, are illustrated from recent high-resolution observations. The thread-like structures appear to be present in filaments everywhere and at all times. They are the fundamental elements of solar filaments. The interrelation of the spines, barbs and legs are discussed. From observations, we present a conceptual model of the magnetic field of a filament. We suggest that only a single physical model is needed to explain filaments in a continuous spectrum represented by active region filaments at one end and quiescent filaments at the other end. Title: Chromospheric and coronal manifestations of photospheric cancelling magnetic fields Authors: Panasenco, Olga; Martin, Sara F.; Engvold, Oddbjorn Bibcode: 2008cosp...37.2336P Altcode: 2008cosp.meet.2336P We discuss observable changes in solar features interpreted as evidences of the transfer of magnetic fields from the photosphere to the chromosphere and corona. In the photospheric level, new or decayed active region magnetic fields of opposite polarity encounter each other and cancel along a pre-existing polarity reversal boundary. Concurrently, in the chromospheric level of the solar atmosphere, the cancelling fields appear to lead to the creation and maintenance of a filament channel. The channel is identified by systematic changes in the orientation of fibrils in the chromosphere. We deduce that invisible extensions of the magnetic fields of the chromospheric fibrils into the corona could represent the beginning of the formation of a filament cavity in the low corona, before and/or during the initial appearance of a filament threads. When the filament channel is fully developed, such that there is a local magnetic field aligned with the polarity reversal boundary, the cancelling fields are then associated with the transfer of plasma, as well as magnetic field, into the low corona. We suggest this plasma is observed as new filament threads. Title: STEREO 3D Data of the Fast Formation of the Ribbon-Like Prominences and Their Dynamics During Eruption Authors: Panasenco, O.; Martin, S. F. Bibcode: 2007AGUFMSH41B..07P Altcode: We have analyzed STEREO/SECCHI/EUVI Helium 304Å data and created 3-dimensional geometrical models for the two erupting prominences observed by STEREO. 3D STEREO movies, made by combining views from the two spacecraft, allow us to understand the true 3D structure of the prominences before and during eruption. In a movie from 12 May 2007 we can see the fast filling of the existing filament channel by plasma. This fast formation of the prominence allows us to trace in time and space the appearance of the main structural parts of the prominence: the barbs and the flat ribbon shape of the whole body of the prominence. We have analyzed the formation and development these structures before eruption and the motion of the erupting part of the prominence during eruption. We found that the motion of the erupting prominence shows the roll effect of the top of prominence. The STEREO movie from 16 May 2007 shows us another clear example of the roll effect during prominence eruption. The observed fast filling of the existing filament channel by plasma and the quick formation of the prominence with the ribbon-like geometrical structure, followed by the partial eruption with the obvious roll effect are the clear evidence of non flux rope magnetic nature of prominences. Our qualitative model of prominence formation by cancelling of magnetic flux at the photosphere and magnetic reconnection in the chromosphere and corona is in agreement with the STEREO observational facts of formation and eruption of prominences. Title: Comparisons of the Spines of Prominences (Filaments) in Hα and He II (304Å) Images Authors: Martin, Sara F.; Engvold, O.; Lin, Y. Bibcode: 2007AAS...21012006M Altcode: 2007BAAS...39..245M Prominence (filament) spines are being analyzed in Hα images from ground-based observatories and in He II 304 Αngstrom (Å) images from the EIT experiment on board the SoHO satellite. Our comparisons show the spines of quiescent prominences are often longer and slightly taller in He II 304Å images than seen in Hα images. Spines are also sharper and more clearly defined in He II 304Å than in Hα images. The prominences (filaments) in some cases appear earlier and can also last longer in 304Å than in Hα. Examples are shown on the disk and above the limb where the spines of separate filaments (prominences) merge in 304Å images before they appear to merge in Hα. In one case, the spine of a quiescent filament disappears in Hα but remains visible in He II images. These observations are consistent with our measurements of a typical quiescent prominence that shows the Hα brightness decreases with height in the prominence, whereas the brightness at He II 304Å slightly increases with height. Thus we find that the spines of quiescent prominences are always more readily visible in 304Å than in Hα. The relative variation of prominence brightness with height reflects a difference in conditions for excitation of these two lines. This is consistent with a presumed increase of temperature with height, in combination with a slight decrease of electron density with height and with the theory that the He II 304Å line is controlled by EUV radiation from the surrounding corona, whereas Hα is influenced by radiation from the chromosphere below. SFM acknowledges support from NSF grant ATM-0519249 and Y.L. from Norwegian Research Council grant FRINAT171012. Title: Observations of the Merging of Two Quiescent Filaments Authors: Mikurda, Katarzyna; Martin, S. F. Bibcode: 2007AAS...210.5302M Altcode: 2007BAAS...39..164M The two filaments were observed close to disk center in the same field of view of approximately 9x9 arc. min. The observations were made using a tunable lithium niobate, narrow band etalon on the 25 cm Martin Solar Telescope at Helio Research in southern California. One filament was close to the equator and was oriented nearly east-west and the other, to the west, was oriented north-south with the north end approximately 120 Mm from the west end of the equatorial filament. Continued observations were made of these filaments for 2 to 5.5 hours per day between October 10 and 15, 2004. The observations were made at multiple wavelengths within + and - 1 Å around Hα.

We compared Hα centerline images with data taken by SOHO/EIT at 304A and observed significant differences in the evolution of the filaments at these wavelengths. For example, in EIT 304 Å images the two filaments seem to join on October 12, i.e. about two days earlier than in Hα. Moreover, the observed merging took longer (over three days) in Hα than in EIT 304 Å images, where it took place on a single day. The dynamics of the merger event is demonstrated with Hα and EIT 304 Å movies.

The Doppler velocities calculated from the line wings images before, during and after the merging event were in the normal range for quiescent filaments. In our investigation of subsequent SOHO/EIT images at 304 Å we found no sign of an eruption due to the merging of the filaments.

The contribution of KM was supported under NASA grant NAG5-10852 and SFM acknowledges NSF grant ATM-0519249. Title: Merging of Filaments in a Dual-Filament System Authors: Mikurda, K.; Martin, S. F. Bibcode: 2006IAUJD...3E..92M Altcode: Introduction: The dual filament system merges to form one extended filament. Methods: The filaments were observed at Helio Research at multiple wavelengths around Hα using a tunable filter and a narrow band Fabry-Perot etalon as part of the Joint Observing Campaign (JOP 178). These observations are used to create two-dimensional Dopplergrams. The Hα images are compared with data taken onboard the SOHO (Solar and Heliospheric Observatory) spacecraft (EIT at 304 A and LASCO C2). The GONG magnetograms provide the information on photospheric magnetic fields. Results and Discussion: The filaments were observed on the solar disk between October 10 and 16, 2004. We compare the morphology of the filament system in Hα and He II line at 304 A and discuss its evolution. We investigate the photospheric magnetic flux cancellation rate during the merging process. There is no clear evidence of an eruption associated with the merging of the filaments from either EIT or LASCO in contrary to some previous findings. Title: A Simple Method of Resolving the 180 Degree Ambiguity Employing the Chirality of Solar Features Authors: Martin, Sara F.; Lin, Y.; Engvold, O. Bibcode: 2006SPD....37.0129M Altcode: 2006BAAS...38..220M The 180 degree ambiguity in magnetic field direction along polarity reversal boundaries can be resolved simply and reliably by a technique that we name "chiral method". For a given polarity boundary, the chiral method requires identifying the chirality of at least one solar feature related to the polarity boundary, familiarity with the one-to-one associations between the chirality of solar features, and the polarity of the network magnetic field on at least one side of the polarity boundary. We demonstrate the technique in 6 examples. The examples cover the spectrum of polarity boundaries associated with filament channels and filaments ranging from those associated with active regions to those on the quiet Sun.The applicability of the chiral method to all categories of filaments supports the view that active region filaments and quiescent filaments are the extreme ends in a continuous spectrum of filaments. An example is shown of a filament where the chirality could not be determined in low resolution images because of lack of consistency in barb orientation; however, at high resolution, all threads of this barb were found to be consistent with just one sense of chirality. The chiral method is almost universally applicable because many types of data, that reveal chirality in solar features, are now readily available over the world-wide web. Solar features that most commonly reveal chirality are filaments, filament channels, sigmoids, and both quiescent and dynamic coronal loop systems. Assuming that the chirality of the solar features is identified correctly, the method is fail-safe and physically meaningful because chirality is an observational representation of the helicity and there are clear differences between left-handed and right-handed solar structures.Support from US NSF grant ATM-0209395 and NASA grant NAG5-10852 are acknowledged for S.F.M. and Y.L. Title: "Coronal Cloud" Prominences And Their Association With Coronal Mass Ejections Authors: Lin, Yong; Martin, S. F.; Engvold, O. Bibcode: 2006SPD....37.0121L Altcode: 2006BAAS...38Q.219L "Coronal cloud" prominences appear to form as bright knots of mass condensing out of the corona while some of their mass also continuously drains down along curved streamers to the chromosphere. Movies of such "suspended cloud" prominences were recorded in Hα by Dunn as early as the 1950s (1976, Solar Physics 49, 283). They have been also observed in HeI 10830 Å and EIT 304 Å .Four Hα "coronal clouds" were recorded at Helio Research (2004/09/16-17, 2004/11/16-17 and 2005/12/12). Their apparent heights are estimated in the range between 66,000-240,000 km, much higher than the more common prominences and filaments with spines and barbs. Near the surface, the downflows accelerate at a typical speed of 40 km s-1. By comparing the positions of the coronal clouds with magnetograms several days prior to or after the coronal clouds were observed at the limb, we are able to show that the condensations of mass are located above or adjacent to complex active regions. The condensations of the fainter coronal clouds have a V-shaped appearance which suggests to us that these concentrations of mass might be trapped at junctions of separatrix magnetic surfaces.For each of our 4 cases, LASCO movies show a CME 1-2 days prior to the "coronal clouds" and encompassing or overlapping the range of latitudes. In one case, the LASCO movie also shows a downflow after the CME which is radially above the coronal cloud. We suggest that downflows associated with CMEs provide the mass for "coronal clouds" formation even though the downflows are not clearly observed in three of the 4 cases; the downflows could be blocked from our sight by the LASCO occulting disk and/or obscured by the more prevalent outflows of mass.Support from US NSF grant ATM-0209395 and NASA grant NAG5-10852 are acknowledged. Title: Dynamics of an active region filament, fibrils and surges in high resolution Authors: Lin, Y.; Martin, S. F.; Engvold, O.; Rouppe van der Voort, L. H. M.; van Noort, M. Bibcode: 2006cosp...36.3193L Altcode: 2006cosp.meet.3193L High resolution H alpha and magnetograms 0 2 arc sec of an active region were obtained in alternating time series at 42 sec cadences using the Swedish 1-m Solar Telescope on 2004 August 21 The 79 times 52 arcsec field of view was centered at N11 W5 The H alpha filtergrams reveal an active region filament and surges consisting of thread-like structures which have widths similar to the widths of chromospheric fibrils both recorded down to the resolution limit in the best images All observed structures in the active region are highly dynamic The flow speeds in some active filament threads 25 km s -1 are higher than typical speeds in quiescent filament threads Fibrils show counterstreaming strongly resembling the counterstreaming threads in filaments The transverse speeds of mass within fibrils are comparable to the typical speeds of mass flows in quiescent filament threads sim 10 km s -1 Streaming along the threads of surges extending more than 10 arc sec is higher in speed sim 20 km s -1 than in the filament and fibrils and appears to flow over the chromospheric fibrils Small surges near one end of the filament appear to flow into the filament thereby mass seems to be added to the filament Blue shifts seen in the H alpha Dopplergrams confirm the outward mass motion of the surges However in at least one case we also see simultaneous red shifts from the same site in the opposite direction toward the chromosphere We suggest that the site between these two opposite motions identifies the place where magnetic Title: A theory of the roll effect in prominence eruption Authors: Choe, G. S.; Cheng, C. Z.; Martin, S. F. Bibcode: 2006cosp...36.3469C Altcode: 2006cosp.meet.3469C It is often observed in prominence eruptions that the top part of the prominence ribbon bends in one direction to make the ribbon horizontally flat Also the legs of the erupting prominence undergo twisting motions of opposite senses This effect is discovered and named as roll effect by S F Martin The sense of rolling is found to depend on the chirality of the prominence The roll effect acts for breaking of the geometrical symmetry of the system Unless the prominence environment is systematically asymmetric the symmetry-breaking evolution of a prominence can hardly be understood in the framework of the conventional magnetohydrodynamics MHD with isotropic electrical conductivity When the electrical conductivity is anisotropic the symmetry of the system is not conserved We investigate the solar magnetic field evolution with anisotropic electrical conductivity Now the motion of the magnetic field is not tied to the plasma center of mass motion but has a component against the current direction Thus the rising motion of the magnetic field is skewed to a certain direction conditioned by the current When magnetic reconnection takes place in a magnetic loop or arcade the direction of the current in the current sheet region and in the legs of the current sheet is almost opposite to the current direction in the underlying reconnected loops This explains why the Doppler shift at the top and outer parts of the erupting prominence is of the opposite sense to that in the bottom part between the prominence legs Furthermore this reasoning can account for how the Title: Evidence for the Formation of Faint, High Prominences in the Aftermath of two Faint CMEs Authors: Martin, S. F.; Engvold, O. Bibcode: 2005AAS...20720401M Altcode: 2005BAAS...37.1502M On 16 and 17 September 2004, changes in two unusually high prominences were recorded for intervals of several hours in the Hα line at Helio Research using a 10-inch aperture telescope equipped with a narrow band (1/10 fwhm) filter. The high prominences, each reaching an altitude 200,000 km, appeared above a long low-lying prominence that was well-observed crossing the limb and had a maximum altitude of 60,000 km. The lower prominence had a horizontal axis and barbs while the high prominence in Hα consisted of many strands of nearly vertical structure but with only a few threads with mass streaming downward close to the chromosphere. Because there were no apparent geometric properties or mass flows in common between the high prominences and the low one, it is deduced that the high prominences were associated with photospheric polarity reversal boundaries and filament channels that were at least 20-33 degrees beyond the west limb and associated with a large decaying active region. Additionally, LASCO movies revealed two faint CMEs on 14 Sep (19:12 UT) and 15 Sep (21:24 UT) evidently from the backside of the Sun and near the same position angles as the high prominences. These events were also most likely related to the polarity reversal boundaries within or on the border of the large active region beyond the west limb. We suggest that each of the high prominences developed in the 1-2 day aftermath of each of the successive CMEs. We further suggest that the prominences are related to the formation of current sheets anticipated by (Lin and Forbes 2000) or magnetic interfaces (Lin and van Ballegooijen 2001) that, in either case, are continuing to evolve one to two days after the eruptive events. Support from NSF grant ATM-0209395 is acknowledged. Title: Formation of an Extraordinarily Long Filament Channel Authors: Anderson, M.; Martin, S. F. Bibcode: 2005ASPC..346..201A Altcode: We analyze an example of how the Sun's surface processes appear to cause filament channels to evolve from medium-scale into global-scale phenomena. The channel was nearly linear when it reached a maximum length of 160 heliographic degrees. Because filament channels need to be of the same chirality (helicity) to merge and because most quiescent filaments in the northern and southern hemispheres have opposite chirality, this example is among the largest that the Sun could be expected to produce.

We focus on filament channels because they are more fundamental than the filaments that form and erupt from them. The physical factors and processes that contributed to the formation and development of the channels from medium-scale into this global-scale filament were: (1) the presence and diffusion of the magnetic flux of active regions, (2) canceling magnetic fields, (3) differential rotation, (4) the pattern of orientation of the magnetic field bipoles of active regions per hemisphere known as Joy's law, and (5) the hemispheric chirality pattern for filament channels and their filaments. We suggest two additional factors, not included in this study, that might play significant roles in contributing to the overall form of the giant channels. These are: (7) meridional circulation and the (8) reconfiguring of solar magnetic fields during all scales of eruptive events. Title: On the origin and configuration of the 20 March 2003 interplanetary shock and magnetic cloud at 1 AU Authors: Berdichevsky, D. B.; Richardson, I. G.; Lepping, R. P.; Martin, S. F. Bibcode: 2005JGRA..110.9105B Altcode: 2005JGRA..11009105B On 20 March 2003, a forward shock was observed in the near-Earth solar wind, followed 8 hours later by an interplanetary magnetic cloud (IMC), in a configuration having several uncommon features: Both were parts of a 38-hour interval containing transient solar outflows that occurred in an extended high-speed stream from a Y-shaped extension of the south polar coronal hole. (In contrast, IMCs, and ejecta in general, were rarely observed within high-speed streams at low heliolatitudes during cycle 23.) The most likely solar source for the IMC is AR 10314, located at S15°, just above the "fork" of the Y-shaped coronal hole. Several solar flares occurred in this active region on 17-18 March, as well as a succession of four coronal mass ejections (CMEs). Velocity considerations narrow the most likely source of the 38-hour interval of activity to two CMEs on 17 March 2003 associated with solar flares at W33° and W39°. The IMC axis had a north-south orientation, which is unusual for IMCs during this solar cycle. Its left-handedness implies an association with a left-skewed coronal arcade, which is less common in the Southern Hemisphere. Considering the shock observed ahead of the IMC, we conclude based on orientation and ram pressure arguments that this shock was not driven by the IMC, as might be presumed, but was the flank of an unrelated shock that overtook the IMC approximately halfway between Sun and Earth, heating the plasma and accelerating particles within the IMC. The CME associated with the X-class flare, at 1208 UT on 18 March in AR 10314 appears to be the solar source for this shock. Title: Sequential Chromospheric Brightenings beneath a Transequatorial Halo Coronal Mass Ejection Authors: Balasubramaniam, K. S.; Pevtsov, A. A.; Neidig, D. F.; Cliver, E. W.; Thompson, B. J.; Young, C. A.; Martin, S. F.; Kiplinger, A. Bibcode: 2005ApJ...630.1160B Altcode: Analyses of multiwavelength data sets for a solar eruption at ~21:30 UT on 2002 December 19 show evidence for the disappearance of a large-scale, transequatorial coronal loop (TL). In addition, coronal manifestations of the eruption (based on SOHO EIT and LASCO images) include large-scale coronal dimming, flares in each associated active region in the northern and southern hemispheres, and a halo CME. We present detailed observations of the chromospheric aspects of this event based on Hα images obtained with the ISOON telescope. The ISOON images reveal distant flare precursor brightenings, sympathetic flares, and, of most interest herein, four nearly cospatial propagating chromospheric brightenings. The speeds of the propagating disturbances causing these brightenings are 600-800 km s-1. The inferred propagating disturbances have some of the characteristics of Hα and EIT flare waves (e.g., speed, apparent emanation from the flare site, subsequent filament activation). However, they differ from typical Hα chromospheric flare waves (also known as Moreton waves) because of their absence in off-band Hα images, small angular arc of propagation (<30°), and their multiplicity. Three of the four propagating disturbances consist of a series of sequential chromospheric brightenings of network points that suddenly brighten in the area beneath the TL that disappeared earlier. SOHO MDI magnetograms show that the successively brightened points that define the inferred propagating disturbances were exclusively of one polarity, corresponding to the dominant polarity of the affected region. We speculate that the sequential chromospheric brightenings represent footpoints of field lines that extend into the corona, where they are energized in sequence by magnetic reconnection as coronal fields tear away from the chromosphere during the eruption of the transequatorial CME. We report briefly on three other events with similar narrow propagating disturbances that were confined to a single hemisphere. Title: Roll Effect in Prominence Eruption Explained by Anisotropic Electrical Conductivity Authors: Choe, G. S.; Cheng, C. Z.; Martin, S. F. Bibcode: 2005AGUSMSP44A..01C Altcode: When a prominence erupts, it generally rises non-radially and the top part of the prominence ribbon bends in one direction to make the ribbon horizontally flat. Also the legs of the prominence undergo twisting motions of opposite senses. This phenomenon was discovered and named as "role effect" by S. F. Martin. This effect can hardly be understood in the framework of ideal MHD or MHD with isotropic conductivity. Such breaking of a geometrical symmetry in the evolution of an initially symmetric system can take place when the electrical conductivity is anisotropic. We perform simulations of a solar plasma evolution with anisotropic electrical conductivity. Now the magnetic field does not only move together with plasma bulk flows, but also against electric currents. Thus the rising motion of the field is skewed to one direction. When magnetic reconnection takes place in a magnetic loop or arcade, the direction of the current in the current sheet region and in the region connected to this current sheet by field lines is opposite to that in the underlying reconnected loops. This explains why the Doppler shift at the top and outer parts of the erupting prominence is opposite to that in the bottom part between the prominence legs. Furthermore, this reasoning can account for how the sign of the roll effect depends on the chirality of the prominence as observed. Title: Minor Planet Observations [671 Stony Ridge] Authors: Rogers, J. E.; Brewster, S. C.; Hadlen, D. A.; Hoff, J. M.; Martin, S. F.; Sable, P. K.; Hadlen, D. Bibcode: 2004MPC..52503...5R Altcode: No abstract at ADS Title: Minor Planet Observations [671 Stony Ridge] Authors: Rogers, J. E.; Brewster, S. C.; Hadlen, D. A.; Sable, P.; Hoff, J. M.; Martin, S. L.; Martin, S. F.; Hoff, J. Bibcode: 2004MPC..51593...6R Altcode: No abstract at ADS Title: H alpha Doppler Observations and Movies of the X-class Flares on 2003 Nov 2 and 2003 Nov 4 Authors: Martin, S. F. Bibcode: 2004AAS...204.4711M Altcode: 2004BAAS...36..738M The most energetic X-class flares on 2003 Nov. 2 and Nov. 4 were observed at Helio Research at multiple wavelengths around the Hydrogen alpha line. The flares were recorded in 0.5 Angstrom steps in the range of -2 to +2 Angstroms using a tunable filter of 1 Angstrom half-width. The tunable filter was employed in the Helio Research 25 cm aperture telescope with a field of view limited to 10 X 10 arc min.

The flare of Nov 2 was observed entirely against the solar disk. The images reveal the brightest parts of the extended flare. The time-lapse movies of these images show how the bright core of the chromospheric part of the flare spreads across each of 3 large sunspot umbrae of the associated active region.

The Nov 4 flare was observed primarily as complex system loops above limb with an occulting disk blocking most of the solar disk. These sets of images show the development and evolution of the flare loop system. Doppler motions in the range of - 90 to + 90 km/sec within the loops are well revealed in these time-lapse series at 9 wavelengths shown as time-lapse movies.

The observations and analyses are supported under NASA grant NAG5-10852 and are available for correlative studies with data sets from other observatories. Title: Solar Coronal Magnetic Filaments: The Roll Effect in Erupting Prominences Authors: Bangert, P. D.; Martin, S. F.; Berger, M. A. Bibcode: 2003SPD....34.0508B Altcode: 2003BAAS...35..815B Based on observations, we suggest that the magnetic field of a filament (or prominence) should be treated as a ribbon. We then use the ribbon hypothesis to explain an observable effect which we term the roll effect. Briefly, the nature of the roll effect is manifested by a filament ribbon in its slow pre-eruptive rise through the tendency to be non-radial, with a small preferential roll in one direction. When it erupts and further rises, the most elevated portion bends over in the roll direction and is forced to become nearly horizontal. Propagation of the roll down the legs of the filament twists them in opposite directions as we verify in observed examples. The direction of this rolling has a one-to-one correspondence with the combination of filament chirality that is known to be in one-to-one correspondence with the polarity of the photospheric magnetic field on either side of the filament. Because the rolling can occur in only two possible forms of handedness, they constitute an observable form of chirality specific to erupting filaments. Establishing this bijection is the major concern of this talk.

The contribution of PDB was partially supported by a Valerie Mysercough Prize, SFM was supported by NASA grant NAG5-5917 and MAB gratefully acknowledges funding by PPARC grant PPA/G/S/1999/00059. Title: Prominence and Filament Activity Recorded with a New, Tunable, One-Angstrom Filter Authors: Martin, S. F.; Martin, D. C. Bibcode: 2003SPD....34.2011M Altcode: 2003BAAS...35..846M New observations using a one-Angstrom Hα tunable multi-layer interference filter demonstrate the efficacy of this filter in detecting key Doppler shifts in filaments and prominences both before and during their eruption. The new filter is superior as a prefilter. However, here we emphasize its merits as a stand-alone filter. The new filter was constructed from 2 single-period interference filters. Used in tandem, the two filters allow us to achieve an effective one Angstrom passband that is tunable by mechanical tilting over a useful range of at least 6 Angstroms. Employed in a solar telescope and starting at Hα line center, an observer can detect all filaments on the solar disk, a goal not achievable with most other one-Angstrom filters. The observer can then initiate manual or automated tuning of the filter to determine whether a filament has normal, low Doppler shifts or increased Doppler shifts signaling that it is either activated or in the early stage of eruption. Our few initial observations reveal activations as readily as through much more expensive, ultra-narrow passband filters of the Fabry-Perot or birefringent type. Less visibility of chromospheric fine structure might be considered either an asset or disadvantage depending upon the observational goals. Minor changes in the filter passband with wavelength are a possible downside to be weighed against its relative low cost, minimal mass, and ruggedness which make it practical for monitoring major solar activity in space experiments as well as from the ground. The development and use of this filter was possible through NASA grant NAG5-9517. Title: Signatures of Large Scale Coronal Eruptive Activity, Associated Flares, and Propagating Chromospheric Disturbances Authors: Balasubramaniam, K. S.; Pevtsov, A. A.; Neidig, D. F.; Cliver, E. W.; Young, C. A.; Martin, S. F.; Kiplinger, A. L. Bibcode: 2003SPD....34.0505B Altcode: 2003BAAS...35..814B Analyses of multi-wavelength data sets on 2002 December 19 at approximately 2150 UT show evidence of a large-scale, transequatorial coronal eruption associated with simultaneous flares in active regions in both hemispheres. The coronal manifestations (based on EIT, LASCO, and TRACE images) include a large coronal dimming, an opening/restructuring of magnetic fields, the formation of a transient coronal hole, and a halo CME. In the chromosphere, ISOON H-alpha images show distant flare precursor brightenings and several sympathetic flares. Originating near the main flare is a rapidly propagating (800 km/s), narrowly channeled disturbance detectable as a sequential brightening of numerous pre-existing points in the H-alpha chromospheric network. This disturbance is not a chromospheric Moreton wave, but it does produce a temporary activation of a transequatorial filament. This filament does not erupt nor do any other filaments in the vicinity. MDI magnetograms show that the brightened network points are all of the same polarity (the dominant polarity among the points in the disturbance's path), suggesting that the affected field lines extend into the corona where they are energized in sequence as the eruption tears away.

Three other similar eruptive events (non-transequatorial) that we studied, while they are less impressive, show most of the same phenomena including distant sympathetic flares and a propagating disturbance showing close adherence to the monopolarity rule. Two of these events do include filament eruptions near the main flare. We conclude that the observations of these four events are consistent with large scale coronal eruptive activity that triggers nearly simultaneous surface activity of various forms separated by distances on the same scale as the coronal structures themselves. A filament eruption at the main flare site appears not to be a necessity in this type of eruptive activity. Title: Signs of helicity in solar prominences and related features Authors: Martin, Sara F. Bibcode: 2003AdSpR..32.1883M Altcode: The chirality of filaments and features in their environment are reviewed in preparation to discuss how some of the observational signatures of chirality have been differently interpreted as corresponding to either positive or negative helicity. Complete agreement exists among authors that the positive and negative signs of chirality of sigmoids and coronal arcades correspond respectively to positive and negative signs of helicity. However, to date there has not been a consensus on whether the observational definitions of right and left handed signatures of the chirality of filaments and filament channels correspond respectively to positive and negative signs of twist helicity or to the inverse. Three proposed observational tests are discussed on how to establish the correct associations but only Doppler velocity measurements during erupting prominences have been generally regarded as a definitive test. Doppler shifts in spectra and multi-wave length sets of filtergrams of filament eruptions recorded with at least three different instruments at different observatories have provided data showing the largely unexpected result that both signs of twist helicity exist in different parts of erupting prominences. Supporting evidence of both signs of helicity in some erupting prominences are additionally shown in 195A images from TRACE, 304A images from EIT/SOHO and vortical motions in the chromosphere observed at NSO/Sacramento Peak Observatory. This accumulation of evidence also reveals a general pattern of dual helicity associated with a rolling motion in the top and twist of opposite helicity in the legs of these erupting prominences. A force generating a rolling motion implies no introduction of twist unless applied non-uniformly to a non-rigid structure. If the non-rigid structure is part of a closed magnetic field system, like a prominence, and a force is applied at its top as inferred from the observations, both signs of twist helicity are necessarily produced. It is suggested that such an unknown force produces the observed "roll effect" in erupting prominences and that the source of this initiating force needs to be identified. Title: The Skew of High-Latitude X-ray Arcades in the Declining Phase of Cycle 22 Authors: Mc Allister, A. H.; Mackay, D. H.; Martin, S. F. Bibcode: 2002SoPh..211..155M Altcode: The chirality of high-latitude coronal arcades in the declining phase of cycle 22 has been studied. It is found that the observed skew of the high-latitude arcades is opposite to the dominant arcade skew at lower latitudes. This new result which applies only to the declining phase of the solar cycle is consistent with differential rotation and the simulations of Mackay and van Ballegooijen (2001). Limitations of the present study are discussed along with its consequences for the global pattern of filaments in each hemisphere. The results suggest that, for the declining phase, the previously observed global pattern may be more complex with latitudinal variations. Future observing programs required to clarify the issue are discussed. Title: Solar Prominence Dynamics Authors: Martin, S. F. Bibcode: 2002AAS...200.3102M Altcode: 2002BAAS...34..684M In their most stable state, prominences are characterized by continuous mass flows at speeds of 5-20 km/sec along every part of their structure. In images having high spatial resolution, prominences always consist of very fine threads. Recent Hα Doppler observations show finely interleaved motions in opposite directions and over long distances along these threads, a phenomenon known as counterstreaming. This fine-scale bi-directional streaming is evidence that the local magnetic field within prominences is everywhere parallel with the prominence threads. At the sides of intermediate and quiescent prominences, are groups of threads along which mass flows to and from the chromosphere. These are known as barbs; prominence threads and barbs reveal whether a prominence is right-handed (dextral) or left-handed (sinistral). Counterstreaming along the barbs leads to the conclusion that the mass of prominence is continuously supplied from the low chromosphere or at the temperature minimum very near the photosphere. To understand the dynamics of these continuous mass flows, we must look to the sea of continuously interacting, small-scale bipolar magnetic fields beneath prominences. In He II 304A images from the EIT experiment on the SOHO satellite, the speeds along the high axis of prominences are reported to be faster than in Hα with common speeds in the range of 10-30 km/sec. Prominences are also a few thousand kilometers taller and often tens of thousands of kilometers longer in He II 304A. Prominences seen against the solar disk are often called filaments. Many filaments exhibit activated intervals when their flows are accelerated; at these times, they reveal additional varieties of motion. Activations can be caused by small flares near one end of a filament, by impact from flare waves, or by emerging magnetic regions near the filament but they also occur for no obvious reason. Only some activated intervals lead to eruption. NASA grants NAG5-9517 and NAG5-10852 are gratefully acknowledged. Title: A test of real-time prediction of magnetic cloud topology and geomagnetic storm occurrence from solar signatures Authors: McAllister, A. H.; Martin, S. F.; Crooker, N. U.; Lepping, R. P.; Fitzenreiter, R. J. Bibcode: 2001JGR...10629185M Altcode: On the basis of the location, orientation, and surrounding magnetic field configuration of an erupting filament observed on September 27, 1997, an Earth-encounter with a magnetic cloud having specific topological properties and an ensuing geomagnetic storm were predicted for September 30, assuming an average Sun-Earth transit time. A subsequent comparison with solar wind and geomagnetic data surrounding September 30 yielded a mixed level of success. Although a geomagnetic storm occurred on October 1, ironically, the strong southward magnetic field responsible for it was not encountered at the leading edge of the cloud, as predicted, but rather in the preceding sheath. In retrospect, the most likely sources of the southward field in the sheath were either a preceding CME or magnetic flux from high in the corona, not draped or turbulent flux from the ambient solar wind as is often supposed. With the aid of a flux rope model, we show that the elevation and polarity of the cloud axis and the chirality of the cloud were predicted correctly but that the trajectory of the spacecraft (and Earth) through what was deduced to be the leg of a flux rope loop precluded encounter with its leading southward field. The storm began with a sudden commencement near 0100 UT on October 1, corresponding to passage of a shock-like discontinuity, and the Dst storm index reached a minimum of -108 nT 14 hours later at 1500 UT. The leading edge of the cloud, however, coincident with the onset of counterstreaming electrons confirming its identification, was not encountered until 1700 UT. The disagreement between the predicted and actual arrival time reflects not only the lack of speed prediction capabilities but also the inability to predict whether encounter will be head-on with the apex of a flux rope loop or, as deduced in this case, passage through one of its legs. Title: East and West Limb Erupting Events Associated with the Same Filament Channel Authors: Martin, S. F. Bibcode: 2001AGUSM..SH42A05M Altcode: Separated by an interval of 10 days, two major filaments erupted from the same filament channel. The first began on the disk near the east limb; the second also began on the disk but near the west limb. Both erupting filaments were exceptionally bright with complex helical structure. The second filament formed at the location of the first eruptive and within one day after the first eruptive. The orientation of the filament channel was SW to NE extending out of NOAA active region 9262 with an average angle of 35 degrees relative to the solar equator. These circumstances offer the unusual opportunity to study similar filament eruptions and their corresponding CMEs from different viewing directions and to try to determine if the apparent structure of the events is strongly dependent on viewing direction. The leading front of the CME with the east limb eruptive was a faint arc in the EIT FeXII 195A images. In the LASCO C2 field, a CME was found with the first eruptive although it was not reported on the LASCO preliminary CME listing; it consisted of a succession of ejecta along nearly radial trajectories and hence did not look like most published examples of CMEs. The CME with the west limb eruptive had the form of a classical arch but lacked a clear cavity. Both events were also nearly concurrent with but slightly lagging an adjacent CME. In these examples, the large difference in the appearance of the CMEs could be due at least in part to the difference in viewing direction. However, some of the differences could also be due to interaction with the adjacent CMEs at different locations. In the LASCO C3 fields of view, each of the subject events appeared to merge with an adjacent CME into a single larger or longer-enduring CME. The subject events are consistent with the idea of triggering by interaction with the adjacent CMEs. Title: Small Magnetic Bipoles Emerging in a Filament Channel Authors: Chae, Jongchul; Martin, Sara F.; Yun, H. S.; Kim, Junghoon; Lee, Sangwoo; Goode, Philip R.; Spirock, Tom; Wang, Haimin Bibcode: 2001ApJ...548..497C Altcode: Observations have shown that quiescent prominences or filaments have a hemispheric magnetic pattern of chirality. Motivated by the question of whether the filament chirality is of subsurface origin or not, we have studied small magnetic bipoles that emerged in a quiescent filament channel at latitude N45°. During our 5 day observing run, performed in 1999 October, a huge filament erupted and reformed shortly in the same filament channel. Using high-cadence, long-integration line-of-sight magnetograms taken at Big Bear Solar Observatory, we identified a total of 102 bipoles that showed an average total flux of 2.8×1019 Mx, an average separation of 7400 km at the time of full development, and an emergence rate of 430 hr-1 per the entire solar surface area. These properties indicate that most of the bipoles are ephemeral regions. The most important finding in the present study is that the magnetic axes of the bipoles emerging in the filament channel are systematically oriented; a negative (trailing) pole is observed to be located preferentially to the south-east of its companion positive (leading) pole. This preferred orientation does not match either the Hale law of active region orientation or a theory that attributes the axial field of a filament to emerging bipoles. We propose two possible subsurface field configurations of bipoles consistent with the observed preferential orientation and discuss physical implications of our results for understanding filament magnetic fields. Title: The origin and development of the May 1997 magnetic cloud Authors: Webb, D. F.; Lepping, R. P.; Burlaga, L. F.; DeForest, C. E.; Larson, D. E.; Martin, S. F.; Plunkett, S. P.; Rust, D. M. Bibcode: 2000JGR...10527251W Altcode: A complete halo coronal mass ejection (CME) was observed by the SOHO Large-Angle and Spectrometric Coronagraph (LASCO) coronagraphs on May 12, 1997. It was associated with activity near Sun center, implying that it was aimed earthward. Three days later on May 15 an interplanetary shock and magnetic cloud/flux rope transient was detected at the Wind spacecraft 190 RE upstream of Earth. The long enduring southward magnetic fields associated with these structures triggered a geomagnetic storm. The CME was associated with a small coronal arcade that formed over a filament eruption with expanding double ribbons in Hα emission. The flare was accompanied by a circular EUV wave, and the arcade was flanked by adjacent dimming regions. We surmise that these latter regions marked the feet of a flux rope that expanded earthward into the solar wind and was observed as the magnetic cloud at Wind. To test this hypothesis we determined key parameters of the solar structures on May 12 and compared them with the modeled flux rope parameters at Wind on May 15. The measurements are consistent with the flux rope originating in a large coronal structure linked to the erupting filament, with the opposite-polarity feet of the rope terminating in the depleted regions. However, bidirectional electron streaming was not observed within the cloud itself, suggesting that there is not always a good correspondence between such flows and ejecta. Title: Model Prediction for an Observed Filament Authors: Aulanier, G.; Srivastava, N.; Martin, S. F. Bibcode: 2000ApJ...543..447A Altcode: This paper presents the results of a ``blind test'' for modeling the structure of an observed filament using the three-dimensional magnetohydrostatic model recently developed by Aulanier et al. in 1999. The model uses a constant shear α, and it takes into account the effects of pressure and gravity. The test consisted of predicting the structure of a filament (observed in the southern hemisphere) with a minimum observational input: only a line-of-sight magnetogram, with a straight line drawn on it to show the location of the filament, was provided. The filament was chosen by the observers (N. S. and S. F. M.) because it had a definite overall left-handed structural pattern known as sinistral, but the direction of component of the magnetic field along the filament axis was uncertain from the combination of Hα data and magnetograms. The modeler (G. A.) evaluated and fixed the values of some of the free parameters of the model while some others were varied in reasonable ranges. The Hα image of the filament was revealed only after the modeling. For α>0, the three-dimensional distribution of magnetic dips computed by the model fairly well reproduces the structure of the filament and its barbs. Moreover, the models for which α<0 do not match well the observations. This study then shows the first successful theoretical prediction for the magnetic field of an observed filament. It shows that the method based on the Aulanier et al. model is a powerful tool, not only for purposes of modeling, but also for prediction of the chirality, helicity, and morphology of observed filaments. Title: Orientation of Emerging Bipoles in a Filament Channel Authors: Chae, J.; Goode, P. R.; Spirock, T. J.; Wang, H.; Martin, S. F.; Yun, H. S.; Kim, Jung-Hoon; Lee, Sangwoo Bibcode: 2000SPD....31.0405C Altcode: 2000BAAS...32R.835C Observations have shown that quiescent prominences or filaments have a hemispheric magnetic pattern of chirality or handedness. Motivated by the question of whether the filament chirality is of sub-surface origin or not, we have studied magnetic bipoles emerging in a quiescent filament channel at latitude N45° . During our 5 day observing run performed in 1999 October, a huge filament erupted and another began to form in the same filament channel. Using high cadence deep line-of-sight magnetograms, we identified a total of 102 small emerging bipoles, which display the following statistical properties: 1) an average flux of 1.2x 1019 Mx and an average separation of 7200 km; 2) an inferred global emergence frequency of 600 hr-1 all over the solar surface; and 3) a preferred orientation that a negative (trailing) pole is located at the south-east of the companion positive (leading) pole. The majority of the bipoles appear to be ephemeral regions which are systematically smaller than those previously studied with Kitt Peak full disk daily magnetograms. The preferred orientation of these bipoles differs greatly from both the filament axial field direction and the active region polarity law. We conclude that factors other than the Hale polarity law are the cause of asymmetry in the orientation of small bipoles having total magnetic fluxes below 2 x 1019 Mx. Title: Factors Related to the Origin of a Gradual Coronal Mass Ejection Associated with an Eruptive Prominence on 1998 June 21-22 Authors: Srivastava, Nandita; Schwenn, Rainer; Inhester, Bernd; Martin, Sara F.; Hanaoka, Yoichiro Bibcode: 2000ApJ...534..468S Altcode: We present observations of a coronal mass ejection (CME) associated with an eruptive prominence during 1998 June 21-22 by LASCO (Large Angle Spectroscopic Coronagraph) aboard SOHO (Solar and Heliospheric Observatory). Various features in the three-part structured, white-light CME as observed by LASCO-C2 and C3 coronagraphs were compared with features in the other wavelengths, for example, in Fe XIV and Fe X emission lines obtained from LASCO C1, in Hα from Helio-Research and at 17 GHz obtained from Nobeyama Radioheliograph. We have investigated conditions in several data sets to understand the eruptive and the pre-eruptive scenario of the CME. The CME and the eruptive prominence accelerate up to ~20 Rsolar and then decelerate to the velocity of the ambient slow solar wind. The analysis clearly shows that this particular CME is a typical case of a very slow or gradual CME for which it is difficult to define an exact onset time. The CME could be tracked for about 30 hours until it crossed a distance of 30 Rsolar and disappeared from the field of view of the LASCO-C3 coronagraph. The height-time profiles of various features of this CME suggest that the leading edge of the CME and the top of the prominence or the core follow similar pattern, implying a common driver for both the CME and the eruptive prominence. The observations provide strong evidence that the CME and the prominence eruption resulted from a common cause which is the global restructuring of the magnetic field in the corona in an extensive volume of space near and including the CME. The restructuring in turn was a consequence of newly emerging flux regions near and within the neighboring active regions close to the base of the CME. Title: Observations of the 24 September 1997 Coronal Flare Waves Authors: Thompson, B. J.; Reynolds, B.; Aurass, H.; Gopalswamy, N.; Gurman, J. B.; Hudson, H. S.; Martin, S. F.; St. Cyr, O. C. Bibcode: 2000SoPh..193..161T Altcode: We report coincident observations of coronal and chromospheric `flare wave' transients in association with a flare, large-scale coronal dimming, metric radio activity and a coronal mass ejection. The two separate eruptions occurring on 24 September 1997 originate in the same active region and display similar morphological features. The first wave transient was observed in EUV and Hα data, corresponding to a wave disturbance in both the chromosphere and the solar corona, ranging from 250 to approaching 1000 km s−1 at different times and locations along the wavefront. The sharp wavefront had a similar extent and location in both the EUV and Hα data. The data did not show clear evidence of a driver, however. Both events display a coronal EUV dimming which is typically used as an indicator of a coronal mass ejection in the inner corona. White-light coronagraph observations indicate that the first event was accompanied by an observable coronal mass ejection while the second event did not have clear evidence of a CME. Both eruptions were accompanied by metric type II radio bursts propagating at speeds in the range of 500-750 km s−1, and neither had accompanying interplanetary type II activity. The timing and location of the flare waves appear to indicate an origin with the flaring region, but several signatures associated with coronal mass ejections indicate that the development of the CME may occur in concert with the development of the flare wave. Title: Minifilament Eruption on the Quiet Sun. I. Observations at Hα Central Line Authors: Wang, Jingxiu; Li, Wei; Denker, Carsten; Lee, Chikyin; Wang, Haimin; Goode, Philip R.; McAllister, Alan; Martin, Sara F. Bibcode: 2000ApJ...530.1071W Altcode: The eruption of miniature filaments on the quiet Sun has been analyzed from time sequences of digital Hα filtergrams obtained at Big Bear Solar Observatory during 1997 September 18-24. The 2 days with the best image quality were selected for this initial study. During 13 hr of time-lapse observations on these 2 days, in an effective 640''x480'' area of quiet Sun close to the disk center, 88 erupting miniature filaments were identified. On average, these small-scale erupting filaments have a projected length of 19,000 km, an observed ejection speed of 13 km s-1, and a mean lifetime of 50 minutes from first appearance through eruption. The total mass and kinetic energy involved in a miniature filament eruption is estimated to be 1013 g and 1025 ergs, respectively. They are distinguished from macrospicules by the same criteria that large-scale filaments, before and during eruption, are distinguished from surges. Prior to eruption, one end, both ends, or the midsection of a miniature filament is superposed over a polarity reversal boundary on line-of-sight magnetograms. We conclude that miniature filaments are the small-scale analog to large-scale filaments. Title: The Essential Role of Magnetic Reconnection in Erupting Prominences and CMEs Authors: McAllister, H.; Martin, S. F. Bibcode: 2000AdSpR..26..469M Altcode: Reconnection has been invoked by various researchers in the different steps of filament formation, evolution, and eruption, but it has been hard to obtain conclusive observational evidence. The association of magnetic clouds with the CMEs over erupting filaments has been suggested as being the result of reconnection behind the CMEs as they leave the Sun. In previous work we have shown that magnetic cloud topology can be predicted from the pre-eruption filament and post-eruption coronal arcade structure if reconnection is assumed to be involved in the eruption process. In this paper we outline the stages in the eruption process, indicating how reconnection can play a role. The case of the eruption on September 27, 1997, in which the topological properties of a magnetic cloud were successfully predicted from the solar observations, illustrates the fact that reconnection plays an important part in the life of prominences and CMEs, as well as in flares Title: Simultaneous Hα and X-ray Observations of Prominence Eruption and Disappearance Authors: Tonooka, H.; Matsumoto, R.; Miyaji, S.; Martin, S. F.; Canfield, R. C.; Reardon, K.; McAllister, A.; Shibata, K. Bibcode: 2000AdSpR..26..473T Altcode: Prominence eruptions or disappearances observed with an Hα limb filtergraph can be classified into 3 categories, the eruptive prominence, the quasi-eruptive prominence, and the disappearing prominence. We investigated their mechanism by comparing the results of simultaneous observations by Yohkoh SXT and Hα. We found that soft X-ray features change in both eruptive prominences and quasieruptive prominences, whereas no significant change takes place in disappearing prominences.In one prominence eruption event soft X-ray cusp structure suggests that the reconnection point is just below the Hα prominence Title: Magnetic reconnection as the cause of a photospheric canceling feature and mass flows in a filament Authors: Litvinenko, Yuri E.; Martin, Sara F. Bibcode: 1999SoPh..190...45L Altcode: Magnetic reconnection in the temperature minimum region of the solar photosphere can account for the canceling magnetic features on the Sun. Litvinenko (1999a) showed that a reconnection model explains the quiet-Sun features with the magnetic flux cancelation rate of order 1017 Mx hr−1. In this paper the model is applied to cancelation in solar active regions, which is characterized by a much larger rate of cancelation ∖ ge1019 Mx hr−1. In particular, the evolution of a photospheric canceling feature observed in an active region on July 2, 1994 is studied. The theoretical predictions are demonstrated to be in reasonable agreement with the measured speed of approaching magnetic fragments, the magnetic field in the fragments, and the flux cancelation rate, deduced from the combined Big Bear Hα time-lapse images and videomagnetograms calibrated against the daily NSO/Kitt Peak magnetogram. Of particular interest is the prediction that photospheric reconnection should lead to a significant upward mass flux and the formation of a solar filament. Hα observations indeed showed a filament that had one of its ends spatially superposed with the canceling feature. Title: Counter-streaming gas flows in solar prominences as evidence for vertical magnetic fields Authors: Zirker, J. B.; Engvold, O.; Martin, S. F. Bibcode: 1998Natur.396..440Z Altcode: Solar prominences are sheets of relatively cool and dense gas embedded in the surrounding hotter corona. An erupting prominence can inject a mass of up to 1015g into the solar wind as part of a coronal mass ejection. These eruptions must depend critically on the topology of the prominence's magnetic field. In all present models,, the prominence hangs on horizontal or helical field lines, while an overlying magnetic arcade temporarily restrains the prominence from erupting. Such models are inconsistent, however, with the slow upward vertical gas flows that are seen in prominences. Here we report counter-streaming flows along closely spaced vertical regions of a prominence, between its top and the lower solar atmosphere. As the flows must be aligned with the magnetic field, this observation implies that a field connects the prominence directly to the photosphere, contrary to all existing models. These magnetic `tethers' might help prevent a prominence from erupting. Title: Conditions for the Formation and Maintenance of Filaments (Invited Review) Authors: Martin, Sara F. Bibcode: 1998SoPh..182..107M Altcode: Observational conditions for the formation and maintenance of filaments are reviewed since 1989 in the light of recent findings on their structure, chirality, inferred magnetic topology, and mass flows. Recent observations confirm the necessary conditions previously cited: (1) their location at a boundary between opposite-polarity magnetic fields (2) a system of overlying coronal loops, (3) a magnetically-defined channel beneath, (4) the convergence of the opposite-polarity network magnetic fields towards their common boundary within the channel and (5) cancellation of magnetic flux at the common polarity boundary. Evidence is put forth for three additional conditions associated with fully developed filaments: (A) field-aligned mass flows parallel with their fine structure (B) a multi-polar background source of small-scale magnetic fields necessary for the formation of the filament barbs and (C) a handedness property known as chirality which requires them to be either of two types, dextral or sinistral. One-to-one relationships have been established between the chirality of filaments and the chirality of their filament channels and overlying coronal arcades. These findings reinforce earlier evidence that every filament magnetic field is separate from the magnetic field of the overlying arcade but both are parts of a larger magnetic field system. The larger system has at least quadrupolar footprints in the photosphere and includes the filament channel and subphotospheric magnetic fields, This `systems' view of filaments and their environment enables new perspectives on why arcades and channels are invariable conditions for their existence. Title: Soft X-Ray Features of Prominence Eruption and Disappearance Authors: Tonooka, H.; Matsumoto, R.; Miyaji, S.; Martin, S. F.; Canfield, R. C.; Reardon, K.; McAllister, A.; Shibata, K. Bibcode: 1998ASSL..229..371T Altcode: 1998opaf.conf..371T No abstract at ADS Title: Filament Chirality: A Link Between Fine-Scale and Global Patterns (Review) Authors: Martin, S. F. Bibcode: 1998ASPC..150..419M Altcode: 1998IAUCo.167..419M; 1998npsp.conf..419M No abstract at ADS Title: Plasma Streaming as Indicator of Field Topology in a Quiescent Filament Authors: Zirker, J. B.; Engvold, O.; Martin, S. F. Bibcode: 1997AAS...19112004Z Altcode: 1997BAAS...29.1402Z Although it is generally accepted that quiescent filaments have strong horizontal axial magnetic field (Leroy,1984) the field configuration in the legs (``barbs'' or ``feet'') is controversial. Previous observations indicate both rising and falling Doppler motions in such appendages, at speeds less than ``free-fall'' (Dunn,1960; Yi et al,1991; Zirker et al, 1994). Such observations could be consistent with the presence of horizontal magnetic fields that are slowly drifting up and down carrying plasma with them. However the H alpha fine-structure strongly suggests the presence of vertical or highly inclined magnetic field lines. Without vector field observations it is difficult to choose between these alternatives. In an attempt to clarify the issue, H alpha observations of a quiescent filament were made during its passage across the disk, from 12 to 20 April, 1993 at the Big Bear Observatory. Remarkable high-speed flows (of order 20 km/s ) were seen along the axial "spine" of the filament. Substantially slower motions were detected in the barbs. The paradox of non-free-fall motions in the predominantly vertically directed threads of barbs, will be discussed briefly. Bommier,V., Landi Degli'Innocenti,E., Leroy, J-L., and Sahal-Brechot, S.: 1994, Solar Phys. 154,231 Dunn, R.B.,1960, Ph D Thesis, Harvard University Engvold,O.: 1976,Solar Phys.49,283. Leroy,J-L. Bommier,V. nd Sahal Brechot,S.:1984, Astronomy and Astrophysics, 131,33. Yi,Z.,Engvold,O. and Keil,S.L.: 1991, Solar Phys. 132,63. Zirker,J.B.,Engvold,O.and Yi,Z. 1994, Solar Phys. 150,81. Title: Global Magnetic Patterns of Chirality Authors: Zirker, J. B.; Martin, S. F.; Harvey, K.; Gaizauskas, V. Bibcode: 1997SoPh..175...27Z Altcode: During the past five years at least six manifestations of a global organization of solar magnetic fields have been recognized. The magnetic chirality (handedness) of the following features shows a hemispheric preference: filament channels, quiescent filaments, sunspot whorls, superpenumbral fibrils, coronal arcades, and interplanetary clouds associated with CMEs. Although the patterns are clear in the data, their interpretation and their possible connection to the dynamo is open to question. This paper reviews the observations of the patterns, corrects some misinterpretations, and offers a scenario for the origin of the most marked pattern, the chirality of filaments. We suggest the pattern arises from the reconnection of coronal loops, under the influence of supergranulation and differential rotation. Unlike alternative scenarios, ours relies only on observable surface motions and fields. Title: A Conceptual Model of the Formation of Filament Barbs Authors: Martin, S. F. Bibcode: 1997SPD....28.1706M Altcode: 1997BAAS...29..921M Barbs are the structures along the sides of a filament that connect its horizontal axis to chromosphere. The barbs, previously called 'legs' can be considered as magnetic field conduits along which mass is continuously guided and transported to and from the chromosphere. In the model presented, the barbs represent a secondary stage in filament formation which follows an intial stage in which a nearly horizontal axial magnetic field is first formed along a filament channel. Barb formation is most effectively and readily illustrated where the filament channel is broad and well-developed such as exists among the decaying network remnants of active regions. In these circumstances, the filament channel is a region of relatively low magnetic flux density compared to adjacent areas further from the polarity inversion. H-alpha filtergrams show that the axial parts of the filament are low and nearly contiguous with the chromosphere. The low height of the axial field, and the relative absence of concentrations of network magnetic field, are favorable conditions for magnetic reconnection between the axial field of the filament and new ephemeral regions and intranetwork magnetic fields beneath the filament. These reconnections lead to the formation of the barbs joining parts of the newly emerged fields to the axial field of the filament. Barb formation and motions seen in H-alpha filtergrams provide the evidence for this initial part of the conceptual model. The remaining part of the model is a demonstration of why only right-bearing barbs are seen on dextral filaments and left-bearing barbs on sinistral filaments; this is due to the sinistral or dextral magnetic configuration of the filament channel which does not permit the survival of barbs of the non-observed chirality as will be illustrated. Title: Filament disturbance and associated magnetic changes in the filament environment. Authors: Wang, J.; Shi, Z.; Martin, S. F. Bibcode: 1996A&A...316..201W Altcode: The morphology and velocity patterns of a disturbing filament in an active region, and the evolution of its surrounding magnetic fields are described in this paper. The disturbance is characterized by vigorous loosening rotation and upward motion. It starts at sites of new emerging flux and cancelling magnetic features beneath the filament, and where microflares take place. In the filament environment, two small emerging flux regions and seven cancelling magnetic features are identified. Major disturbance is associated with flux cancellation at several sites, underlying the central part of the filament. We suggest that the surrounding magnetic fields of the filament and the magnetic fields in the filament have been partly reconnected at the photospheric level. This results in a complicated magnetic topology, and appears to be the cause of the filament activation. Title: YOHKOH SXT Observations of Prominence Eruption and Disappearance Authors: Tonooka, H.; Matsumoto, R.; Miyaji, S.; Martin, S. F.; Canfield, R. C.; Reardon, K.; McAllister, A.; Shibata, K. Bibcode: 1996mpsa.conf..493T Altcode: 1996IAUCo.153..493T No abstract at ADS Title: The Skew of X-ray Coronal Loops Overlying H alpha Filaments Authors: Martin, S. F.; McAllister, A. H. Bibcode: 1996mpsa.conf..497M Altcode: 1996IAUCo.153..497M No abstract at ADS Title: The initiation of coronal mass ejections by newly emerging magnetic flux Authors: Feynman, J.; Martin, S. F. Bibcode: 1995JGR...100.3355F Altcode: We present observational evidence that eruptions of quiescent filaments and associated coronal mass ejections (CMEs) occur as a consequence of the destabilization of large-scale coronal arcades due to interactions between these structures and new and growing active regions. Both statistical and case studies have been carried out. In a case study of a ``bugle'' observed by the High-Altitude Observatory Solar Maximum Mission coronagraph, the high-resolution magnetograms from the Big Bear Solar Observatory show newly emerging and rapidly changing flux in the magnetic fields that apparently underlie the bulge. For other case studies and in the statistical work the eruption of major quiescent filaments was taken as a proxy for CME eruption. We have found that two thirds of the quiescent-filament-associated CMEs occurred after substantial amounts of new magnetic flux emerged in the vicinity of the filament. In addition, in a study of all major quiescent filaments and active regions appearing in a 2-month period we found that 17 of the 22 filaments that were associated with new active regions erupted and 26 of the 31 filaments that were not associated with new flux did not erupt. In all cases in which the new flux was oriented favorably for reconnection with the preexisting large-scale coronal arcades; the filament was observed to erupt. The appearance of the new flux in the form of new active regions begins a few days before the eruption and typically is still occurring at the time of the eruption. A CME initiation scenario taking account of these observational results is proposed. Title: The Skew of X-Ray Coronal Loops Overlying Hα Filaments Authors: Martin, S. F.; McAllister, A. H. Bibcode: 1995SPD....26..603M Altcode: 1995BAAS...27R.961M No abstract at ADS Title: Footpoints of Solar Filaments Authors: Martin, Sara F. Bibcode: 1994AAS...18512303M Altcode: 1994BAAS...26.1522M Quiescent filaments are characterized in part by appendages or `barbs' along each side of the long axis or `spine' of the filament. Observations of the barbs at the limb and against the disk show that the barbs are paths along which mass flows from the spine to the chromosphere or vice-versa. The barbs and their chromospheric and photospheric footpoints were studied using Hα filtergrams of a filament and corresponding photospheric line-of-sight magnetograms revealing enhanced network magnetic fields adjacent to the filament. These data were acquired from 13 thru 17 May 1992 at the Big Bear Solar Observatory. The footpoints of the major barbs were found to coincide with patches of minority polarity among the photospheric magnetic fields on each side of the filament. The minority polarity consists of small patches of magnetic field opposite in polarity to the areas of dominant unipolar network magnetic field on the same side of the filament. This finding is consistent with the magnetic field in the barbs being `inverse', that is, the reverse of the direction of the component of the magnetic field of the coronal arcade high above and perpendicular to the spine of the filament. Title: Preflare State Authors: Rust, David M.; Sakurai, Takashi; Gaizauskas, Victor; Hofmann, Axel; Martin, Sara F.; Priest, Eric R.; Wang, Jing-Xiu Bibcode: 1994SoPh..153....1R Altcode: Discussion on the preflare state held at the Ottawa Flares 22 Workshop focused on the interpretation of solar magnetograms and of Hα filament activity. Magnetograms from several observatories provided evidence of significant build up of electric currents in flaring regions. Images of X-ray emitting structures provided a clear example of magnetic relaxation in the course of a flare. Emerging and cancelling magnetic fields appear to be important for triggering flares and for the formation of filaments, which are associated with eruptive flares. Filaments may become unstable by the build up of electric current helicity. Examples of heliform eruptive filaments were presented at the Workshop. Theoretical models linking filaments and flares are briefly reviewed. Title: Material Ejection Authors: Webb, David F.; Forbes, Terry G.; Aurass, Henry; Chen, James; Martens, Piet; Rompolt, Bogdan; Rusin, Vojtech; Martin, Sara F. Bibcode: 1994SoPh..153...73W Altcode: This paper reviews the major discussions and conclusions of the Flares 22 Workshop concerning the physical processes involved in mass ejecta events, with an emphasis on large-scale phenomena, especially Coronal Mass Ejections (CMEs). New insights have been gained from recent data obtained from the SMM andYohkoh spacecraft and from several new ground-based radio and optical instruments, as well as from theoretical advances concerning the origins, driving mechanisms and long-term evolution of CMEs. Title: Solar Fine-Scale Structures in the Corona, Transition Region, and Lower Atmosphere Authors: Moses, Dan; Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Webb, D. F.; Davis, J. M.; Harvey, J. W.; Recely, F.; Martin, S. F.; Zirin, H. Bibcode: 1994ApJ...430..913M Altcode: The American Science and Engineering Soft X-ray Imaging Payload and the Naval Research Laboratory High Resolution Telescope and Spectrograph (HRTS) were launched from White Sands on 1987 December 11 in coordinated sounding rocket flights. The goal was to investigate the correspondence of fine-scale structures from different temperature regimes in the solar atmosphere, and particularly the relationship between X-ray bright points (XBPs) and transition region explosive events. We present results of the analysis of co-aligned X-ray images, maps of sites of transition region explosive events observed in C IV 105, HRTS 1600 A spectroheliograms of the Tmin region, and ground-based magnetogram and He I 10830 A images. We examined the relationship of He I 10830 A dark features and evolving magnetic features which correspond to XBPs. We note a frequent double ribbon pattern of the He I dark feature counterparts to XBPs. We discuss an analysis of the relationship of XBPs to evolving magnetic features by Webb et al., which shows that converging magnetic features of opposite polarity are the most significant magnetic field counterparts to XBPs. The magnetic bipolar features associated with XBPs appear as prominent network elements in chromospheric and transition region images. The features in C IV observations corresponding to XBP sites are in general bright, larger scale (approximately 10 arcsec) regions of complex velocity fields of order 40 km/s, which is typical of brighter C IV network elements. These C IV features do not reach the approximately 100 km/s velocities seen in the C IV explosive events. Also, there are many similar C IV bright network features without a corresponding XBP in the X-ray image. The transition region explosive events do not correspond directly to XBPs. The explosive events appear to be concentrated in the quiet Sun at the edges of strong network, or within weaker field strength network regions. We find a greater number of C IV events than expected from the results of a previous Spacelab 2 HRTS disk survey. We attribute this at least partly to better spatial resolution with the newer HRTS data. The full-disk X-ray image shows a pattern of dark lanes in quiet Sun areas. The number density of C IV events is twice as large inside as outside a dark lane (4.6 x 10-3 vs. 2.3 x 10-3 explosive events per arcsec 2). The dark lane corresponds to an old decaying magnetic neutral line. We suggest that this provides an increased opportunity for small-scale convergence and reconnection of opposite polarity magnetic field features, in analogy with the results of Webb et al. for XBPs but at a reduced scale of reconnection. Title: HRTS Observations of Explosive Events in a Flaring Active Region Authors: Dere, K. P.; Martin, S. F. Bibcode: 1994kofu.symp..289D Altcode: Explosive events are a highly dynamic, small-scale phenomena that are commonly observed on the Sun with the NRL High Resolution Telescope and Spectrograph (HRTS). There is now considerable evidence which suggests that they are signatures of magnetic reconnection during flux emergence and cancellation. Data from the Big Bear Solar Observatory and the HRTS instrument are used to demonstrate the direct correspondence between explosive events and evolving magnetic structures. Title: A Converging Flux Model of an X-Ray Bright Point and an Associated Canceling Magnetic Feature Authors: Priest, E. R.; Parnell, C. E.; Martin, S. F. Bibcode: 1994ApJ...427..459P Altcode: X-ray bright points are an important part of the solar corona and therefore of the coronal heating problem. When it was first realized that bright points are always situated above opposite polarity magnetic fragments in the photosphere, it was natural to suggest that such fragments represent emerging flux and that an X-ray bright point is caused by reconnection of the emerging flux with an overlying coronal magnetic field. However, a recent important discovery at the Big Bear Solar Observatory is that the magnetic fragments of opposite polarity are usually not emerging but are instead coming together and disappearing and so are referred to as canceling magnetic features. Sometimes a tiny filament is observed to form and erupt at the same time. A unified model is here proposed which explains these observational features and has several phases: (1) a preinteraction phase, in which two photospheric fragments are unconnected magnetically and begin to approach one another, until eventually oppositely directed fields from the fragments come into contact at a second-order null point; (2) an interaction phase, in which the null point becomes an X-point and rises into the corona; an X-ray bright point is created for typically 8 hr by coronal reconnection, driven by the continued approach of the photospheric sources; long hot loops and Yohkoh X-ray jets may be created by the reconnection, and rapid variability in bright point emission may be produced by an impulsive burst regime of reconnection; the explosive events seen with High Resolution Telescope and Spectrograph (HRTS) may be produced as the X-point passes through the upper chromosphere; (3) a cancellation phase, in which a canceling magnetic feature is produced by photospheric reconnection as the fragments come into contact and decrease in strength; above the canceling fragments a small filament may form and erupt over typically an hour. An important role is played by the interaction distance (d), which is proportional to the magnetic flux of the fragments and inversely proportional to the overlying magnetic field strength. It determines the fragment separation at which the interaction phase begins and the resulting maximum height of the reconnection point. It is suggested that coronal reconnection driven by footpoint motion represents an elementary heating event that may be heating normal coronal loops and may be at the root of the nanoflare/microflare process. Bright points may well be at the large-scale end of a broad spectrum of events of the type modeled in this paper, which are heating the solar corona. At very small scales, such events in 'furnaces' in the coronal hole network may even produce high-frequency waves that propagate out and drive the solar wind (Axford 1993). Title: Large-scale velocity fields and small-scale magnetic fields during the maximum of solar cycle 22 Authors: Martin, Sara F.; Harvey, K. L. Bibcode: 1994cait.reptQ....M Altcode: Studies of the solar cycle have revealed that the size distribution of active regions does not vary with the solar cycle. Size, rate of rise, and lifetime of active regions are roughly proportional although a wide range of variation exists among these parameters. The polar field typically reverses about 2 years after solar maximum. The new solar cycle does not seem to start until after the reversal of the sign of the magnetic poles. However, the new solar cycle does overlap appreciably with the previous cycle and begins 3 or more years prior to the minimum in sunspot producing active regions. The solar cycle begins with ephemeral regions at high latitudes. From the analysis of active region and ephemeral region data over more than a whole solar cycle it is concluded that ephemeral regions are in all respects the small-scale end of the distribution of active regions. No rationale was found for excluding ephemeral regions as one of the effects of the solar dynamo. The search for the early ephemeral regions associated with solar cycle 23 at high latitudes yielded the tentative conclusion that it was detected during our observing runs during the spring of 1993 although confirming data is needed. Title: An observational and conceptual model of the magnetic field of a filament Authors: Martin, S. F.; Echols, Ch. R. Bibcode: 1994ASIC..433..339M Altcode: No abstract at ADS Title: A Correlation Between Sunspot Whirls and Filament Type Authors: Rust, D. M.; Martin, S. F. Bibcode: 1994ASPC...68..337R Altcode: 1994sare.conf..337R No abstract at ADS Title: Magnetic field configurations basic to filament channels and filaments Authors: Martin, S. F.; Bilimoria, R.; Tracadas, P. W. Bibcode: 1994ASIC..433..303M Altcode: No abstract at ADS Title: Observational Criteria for Filament Models Authors: Martin, Sara F. Bibcode: 1994ASPC...68..264M Altcode: 1994sare.conf..264M No abstract at ADS Title: Transition Region Explosive Events in an X-Ray Dark Lane Region of the Quiet Sun Authors: Cook, J. W.; Moses, D.; Brueckner, G. E.; Dere, K. P.; Bartoe, J. -D. F.; Webb, D.; Davis, J. M.; Harvey, J. W.; Recely, F.; Martin, S. F.; Zirin, H. Bibcode: 1993BAAS...25.1181C Altcode: No abstract at ADS Title: Magnetic Field Configurations Basic to Filament Channels and Filaments Authors: Martin, S. F.; Bilimoria, R.; Tracadas, P. W. Bibcode: 1993BAAS...25.1217M Altcode: No abstract at ADS Title: The Initiation of Coronal Mass Ejections Authors: Feynman, J.; Martin, S. F. Bibcode: 1993BAAS...25.1203F Altcode: No abstract at ADS Title: The Correspondence Between X-Ray Bright Points and Evolving Magnetic Features in the Quiet Sun Authors: Webb, D. F.; Martin, S. F.; Moses, D.; Harvey, J. W. Bibcode: 1993SoPh..144...15W Altcode: Coronal bright points, first identified as X-ray Bright Points (XBPs), are compact, short-lived and associated with small-scale, opposite polarity magnetic flux features. Previous studies have yielded contradictory results suggesting that XBPs are either primarily a signature of emerging flux in the quiet Sun, or of the disappearance of pre-existing flux. With the goal of improving our understanding of the evolution of the quiet Sun magnetic field, we present results of a study of more recent data on XBPs and small-scale evolving magnetic structures. The coordinated data set consists of X-ray images obtained during rocket flights on 15 August and 11 December, 1987, full-disk magnetograms obtained at the National Solar Observatory - Kitt Peak, and time-lapse magnetograms of multiple fields obtained at Big Bear Solar Observatory. We find that XBPs were more frequently associated with pre-existing magnetic features of opposite polarity which appeared to be cancelling than with emerging or new flux regions. Most young, emerging regions were not associated with XBPs. However, some XBPs were associated with older ephemeral regions, some of which were cancelling with existing network or intranetwork poles. Nearly all of the XBPs corresponded to opposite polarity magnetic features which wereconverging towards each other; some of these had not yet begun cancelling. We suggest that most XBPs form when converging flow brings oppositely directed field lines together, leading to reconnection and heating of the newly-formed loops in the low corona. Title: Large-scale velocity fields and small-scale magnetic fields during the maximum of solar cycle 22 Authors: Martin, Sara F.; Harvey, K. L. Bibcode: 1992cait.rept.....M Altcode: One key accomplishment from the research during FY 1991 was the finding by K. Harvey and P. Foukal that the photospheric network is the third significant component that accounts for observed variations in the total solar irradiance (the first previously recognized component is the temporary decreases due to sunspots and the second is variation due to plage brightness). Other key accomplishments were the K. Harvey results from studying magnetic flux over the solar cycle: (1) increases in the total magnetic flux by a factor of 4 to 5 from solar minimum to solar maximum with the variation from active regions flux (greater than 25 Gauss) by more than a factor of 20 from cycle minimum to maximum while the variation from quiet sun fields (less than 25 Gauss) was no more than a factor of 2; (2) interpretation of (1) as meaning that more than 70 percent of the magnetic flux in active regions disappears without dispersing; (3) slower decreases of weak fields in phase with the decrease in strong fields; and (4) irregular pulses of new flux which appear to be primarily associated with active region complexes. Title: Ultraviolet Explosive Events and Evolving Magnetic Fields Authors: Dere, K. P.; Martin, S. F. Bibcode: 1992AAS...180.5604D Altcode: 1992BAAS...24..821D No abstract at ADS Title: An Observational Conceptual Model of the Formation of Filaments Authors: Martin, S. F. Bibcode: 1992LNP...399..331M Altcode: 1992esf..coll..331M; 1992IAUCo.133..331M No abstract at ADS Title: The Solar Cycle Pattern in the Direction of the Magnetic Field along the Long Axes of Polar Filaments Authors: Martin, Sara F.; Marquette, William H.; Bilimoria, Rajash Bibcode: 1992ASPC...27...53M Altcode: 1992socy.work...53M No abstract at ADS Title: The Role of Cancelling Magnetic Fields in the Buildup to Erupting Filaments and Flares Authors: Martin, S. F.; Livi, S. H. B. Bibcode: 1992LNP...399...33M Altcode: 1992IAUCo.133...33M; 1992esf..coll...33M We present a scenario for understanding the role of cancelling magnetic fields in the build-up to eruptive solar flares. The key intermediate step in this scenario involves the formation of a filament magnetic field in the corona above a photospheric polarity inversion where cancelling magnetic fields are observed. The formation of a filament magnetic field is accomplished in several recent models by first interpreting the cancelling fields as a visible effect of a slow, steady magnetic reconnection. This reconnection results in a reconfiguring of the magnetic field; line-of-sight pairs of closely-spaced opposite-polarity fields disappear from the photosphere thereby accounting for the cancellation; simultaneously the horizontal component is increased in the corona above the polarity inversion. The new and increasing horizontal component is synonymous with the building of a magnetic field where mass can accumulate to forma filament. If the magnetic reconnection continues for a sufficient length of time, the changing equilibrium between the growing filament magnetic field and the overlying, coronal magnetic field will result in a very slow, simultaneous ascent of both the filament magnetic field and the overlying coronal magnetic field with greater motion in the outer, weaker coronal field. This upward stretching of the magnetic fields eventually results in a closer spacing of oppositely-directed corona) magnetic fields (resembling a tangential discontinuity) beneath the filament. As depicted in some flare models, magnetic reconnection then suddenly occurs in the corona beneath the filament; flare loops form in the lower part of the reconnected field and a corona) mass ejection and erupting filament comprise the upper part of the reconnected field. To illustrate the observable phases of this scenario, we describe the build-up to two simple eruptive flares in a small active region. Title: The chromospheric and transition region manifestations of an Ellerman bomb. Authors: Cook, J. W.; Brueckner, G. E.; Dere, K. P.; Martin, S. F.; Gayley, K. G. Bibcode: 1992BAAS...24.1074C Altcode: No abstract at ADS Title: Elementary Bipoles of Active Regions and Ephemeral Active Regions Authors: Martin, S. F. Bibcode: 1991BAAS...23.1053M Altcode: No abstract at ADS Title: Studies of solar magnetic fields during the rise of solar cycle 22 Authors: Martin, Sara F. Bibcode: 1991cait.reptQ....M Altcode: New information about the solar cycle and the changing magnetic fields includes: (1) Every solar cycle has a duration of 18 to 22 years even though the peak between successive cycles is approximately 11 years. This means that there are two solar cycles on the sun nearly all of the time; the exception is the few years preceeding solar maximum. (2) A large-scale velocity field was discovered around the perimeter of one of the major active regions that developed during the rise of the current solar cycle. If averaged over a several month interval, the velocity would be of the same order of magnitude as the velocity pattern of the torsional oscillation signal that varies systematically over the solar cycle. The newly discovered velocity pattern can be interpreted as either a severe contamination to the torsional oscillation signal or another way of observing the torsional oscillation velocity field. (3) The analyses of small-scale magnetic fields on the quiet sun has shown that network magnetic fields are continuously being replaced by intranetwork magnetic fields. The replacement occurs when intranetwork magnetic fields collide with network magnetic fields; both polarities are observed to cancel each other at a mean rates of 1018 Maxwells/hour. The non-cancelling components of the intranetwork magnetic field replace the cancelled components of the network. No net long-term increases or decreases in magnetic flux occur as a consequence of these processes. Title: Properties of the Largescale and Smallscale Flow Patterns in and around AR:19824 Authors: Schrijver, C. J.; Martin, S. F. Bibcode: 1990SoPh..129...95S Altcode: We trace the photospheric motions of 170 concentrations of magnetic flux tubes in and around the decaying active region No. 19824 (CMP 23 October 1986), using a series of magnetograms obtained at the Big Bear Solar Observatory. The magnetograms span an interval of just over five days and cover an area of about 4 × 5 arc min centered on the active region. We find a persistent large-scale flow pattern that is superposed on the small-scale random motions of both polarities. Correction for differential rotation unveils the systematic, large-scale flow surrounding the core region of the magnetic plage. The flow (with a mean velocity of 30 m s−1) is faster and more pronounced around the southern side of the core region than around the northern side, and it accelerates towards the western side of the active region. The northern and southern branches of the large-scale flow converge westward of the core region, dragging along the westernmost sunspot and some of the magnetic flux near it. The overall pattern of the large-scale flow resembles the flow of a river around a sand bar. The long-term evolution of the active region suggests that the flow persists for several months. We discuss the possible association of the large-scale flow with the torsional oscillation. Title: Elementary bipoles of active regions and ephemeral active regions Authors: Martin, Sara F. Bibcode: 1990MmSAI..61..293M Altcode: The general properties of elementary bipoles (EBs), the class of moving magnetic features identified by Frazier (1972) as building blocks of new solar active regions, are described, and variations in their characteristics are illustrated with extensive videomagnetograms obtained at Big Bear Solar Observatory during 1984-1989. Consideration is given to ephemeral active regions consisting of EBs with only one positive and one negative pole, multiple-pole ephemeral regions, reversed-polarity EBs, interactions among EBs and adjacent magnetic features, and the EBs of small and medium active regions. The detection of EBs prior to the appearance of arch filaments confirms the relationship found by Frazier. Title: Small-Scale Magnetic Features Observed in the Photosphere Authors: Martin, S. F. Bibcode: 1990IAUS..138..129M Altcode: No abstract at ADS Title: Conditions for the Formation of Prominences as Inferred from Optical Observations Authors: Martin, Sara F. Bibcode: 1990LNP...363....1M Altcode: 1990IAUCo.117....1M; 1990doqp.coll....1M In the optical region of the electromagnetic spectrum, the conditions most frequently associated with the formation of prominences are: (1) the existence of opposite polarity photospheric magnetic fields on opposing sides of a prominence, (2) a coronal arcade that connects the magnetic fields on opposing sides of a prominence, (3) a transverse magnetic field configuration in the chromospheric and photospheric polarity inversion zones that is approximately perpendicular to the direction of maximum magnetic field gradient between adjacent patches of opposite polarity line-of-sight magnetic flux, (4) in active regions or decaying active regions, the alignment of chromospheric fibrils in a polarity inversion zone approximately parallel to the transverse magnetic field component and parallel to the long axis of the future prominence, (5) the long-term (hours to days) converging flow of small patches of opposite polarity magnetic flux towards a common polarity inversion zone, and (6) the cancellation of encountering patches of magnetic flux of opposite polarity at a photospheric polarity inversion boundary (interpreted as the transport of magnetic flux upwards or downwards through the photosphere). Because these are observed conditions found from magnetograms and filtergrams at various wavelengths, they do not necessarily represent independent physical conditions. Although none of these conditions have proven to be individually sufficient for prominence formation, a combination of 3 of these conditions might prove to be both necessary and sufficient. The following hypothesis is offered for study and evaluation: condition (2) and the combination of conditions (5) and (6), if dynamically maintained for a sufficient length of time, will invariably result in the formation of a prominence. Title: Flaring Arches - Part Two Authors: Svestka, Zdenek; Farnik, Frantisek; Fontenla, Juan M.; Martin, Sara F. Bibcode: 1989SoPh..123..317S Altcode: We discuss first the development of the coronal arch-shaped structure of ∼ 57000 km length which was born at or before 08:00 UT on 6 November, 1980 and became the site of 13 quasi-periodic brightenings in hard X-rays from 10:00 to 14:30 UT. The same structure became the site of a series of 17 flaring arches between 15:30 and 24:00 UT on that day. The periodicity of ∼ 19 min, defined well for the quasi-periodic variations, seems to be partly retained during the occurrence of the flaring arches. Title: The Footpoints of Giant Arches Authors: Martin, Sara F.; Svestka, Zdenek F.; Bhatnagar, Arvind Bibcode: 1989SoPh..124..339M Altcode: We have detected chromospheric footpoints of the giant post-flare coronal arches discovered by HXIS a few years ago. Hα photographs obtained at Big Bear and Udaipur Solar Observatories show chromospheric signatures associated with 5 sequential giant arch events observed in the interval from 6 to 10 November, 1980. The set of footpoints at one end of the arches consists of enhancements within a plage at the northeast periphery of the active region and the set of footpoints at the other end of the arch consists of brightenings of the chromosphere south of the active region. Both sets of footpoints show very slow brightness variations correlated in time with the brightness variations of the X-ray arches. Current-free modelling of the coronal magnetic field by Kopp and Poletto (1989), based on a Kitt Peak magnetogram, confirms the identification of the two sets of footpoints by showing magnetic field lines connecting them. Title: Correspondence between solar fine-scale structures in the corona, transition region, and lower atmosphere from collaborative observations Authors: Moses, J. Daniel; Cook, J. W.; Bartoe, J. -D. F.; Brueckner, G. E.; Dere, K. P.; Webb, D. F.; Davis, John M.; Recely, F.; Martin, S. F.; Zirin, H. Bibcode: 1989sxsr.reptR....M Altcode: The Soft X-Ray Imaging Payload and the High Resolution Telescope and Spectrograph (HRTS) instrument were launched from White Sands on 11 December 1987 in coordinated sounding rocket flights to investigate the correspondence of coronal and transition region structures, especially the relationship between X-ray bright points (XBPs) and transition region small spatial scale energetic events. The coaligned data from X-ray images are presented along with maps of sites of transition region energetic events observed in C IV (100,000 K), HRTS 1600 A spectroheliograms of the Tmin region and ground based magnetogram and He I 10830 A images. Title: Mass Motions Associated with Solar Flares Authors: Martin, Sara F. Bibcode: 1989SoPh..121..215M Altcode: 1989IAUCo.104..215M Mass motions are a principal means by which components of solar flares can be distinguished. Typical patterns of mass motions in Hα are described for chromospheric flare ribbons, remote chromospheric flare patches, flare loops, flaring arches, surges, erupting filaments and some expanding coronal features. Interrelationships between these phenomena are discussed and illustrations of each are presented. Title: Flare energetics. Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veck, N. J. Bibcode: 1989epos.conf..377W Altcode: The authors have sought to establish a comprehensive and self-consistent picture of the sources and transport of energy within a flare. To achieve this goal, they chose five flares in 1980 that were well observed with instruments on the Solar Maximum Mission, and with other space-borne and ground-based instruments. The events were chosen to represent various types of flares. Details of the observations available for them and the corresponding physical parameters derived from these data are presented. The flares were studied from two perspectives, the impulsive and gradual phases, and then the results were compared to obtain the overall picture of the energetics of these flares. The authors also discuss the role that modeling can play in estimating the total energy of a flare when the observationally determined parameters are used as the input to a numerical model. Finally, a critique of our current understanding of flare energetics and the methods used to determine various energetics terms is outlined, and possible future directions of research in this area are suggested. Title: The identification and interaction of network, intranetwork, and ephemeral-region magnetic fields Authors: Martin, Sara F. Bibcode: 1988SoPh..117..243M Altcode: Network magnetic fields, ephemeral active regions, and intranetwork magnetic fields are illustrated and discussed in several contexts. First, they are presented in relation to the appearance and disappearance of magnetic flux. Second, their properties in common with all solar magnetic features are discussed. Third, their distinguishing characteristics are emphasized. Lastly, their interactions are illustrated. Title: Development of Noble Liquid Detectors for Gamma Ray Spectroscopy. Authors: Marquette, William H.; Martin, Sara F. Bibcode: 1988SoPh..117..227M Altcode: We describe the decay phase of one of the largest active regions of solar cycle 22 that developed by the end of June 1987. The center of both polarities of the magnetic fields of the region systematically shifted north and poleward throughout the decay phase. In addition, a substantial fraction of the trailing magnetic fields migrated equatorward and south of the leading, negative fields. The result of this migration was the apparent rotation of the magnetic axis of the region such that a majority of the leading polarity advanced poleward at a faster rate than the trailing polarity. As a consequence, this region could not contribute to the anticipated reversal of the polar field. Title: The extended solar activity cycle Authors: Wilson, P. R.; Altrocki, R. C.; Harvey, K. L.; Martin, S. F.; Snodgrass, H. B. Bibcode: 1988Natur.333..748W Altcode: The solar cycle has been defined in terms of a sequential periodic variation in sunspot numbers, the period being the interval between successive minima, currently averaging 11.2 years. But a number of observations have indicated that the activity cycle may begin at higher latitudes before the emergence of the first sunspots of the new cycle. Here we report results from sunspot cycle 21 concerning the ephemeral active regions, the coronal green-line emission and the torsional oscillation signal, which confirm the earlier suggestions. In particular, we report the appearance of a high-latitude population of ephemeral active regions in the declin-ing phase of sunspot cycle 21, with orientations that tend to favour those for cycle 22 rather than 21. Taken together, these data indicate that sunspot activity is simply the main phase of a more extended cycle that begins at high latitudes before the maximum of a given sunspot cycle and progresses towards the equator during the next 18-22 yr, merging with the conventional 'butterfly diagram' (the plot of the latitudes of emerging sunspots against time) as it enters sunspot latitudes. We suggest that this extended cycle may be understood in the perspective of a model of giant convective rolls that generate dynamo waves propagating from pole to equator. Title: An Eruptive Prominence and Associated Cm-Mm Emission Outside the Solar Limb Authors: Zodi, A. M.; Correia, E.; Costa, J. E. R.; Kaufmann, P.; Martin, S. F.; Kundu, M. R. Bibcode: 1988SoPh..116...83Z Altcode: We present radio maps at 22 and 44 GHz which show the emission before and after the eruption of a quiescent prominence located at the west limb. The observed radiation following the eruption is not consistent with thermal bremsstrahlung mechanism. It can be interpreted as due to gyrosynchrotron emission of nonthermal electrons. Our observations appear to be similar to the microwave radiation observed in post-flare loops; this radiation is due to nonthermal electrons trapped in the closed magnetic structures formed after the prominence eruption. Title: The Correspondence Between Small-Scale Coronal Structures and the Evolving Solar Magnetic Field Authors: Webb, D. F.; Moses, J. D.; Davis, J. M.; Harvey, J. W.; Martin, S. F.; Zirin, H. Bibcode: 1988BAAS...20..722W Altcode: No abstract at ADS Title: Flaring Arches - Part One Authors: Martin, Sara F.; Svestka, Zdenek F. Bibcode: 1988SoPh..116...91M Altcode: `Flaring arches" is a name assigned to a particular component of some flares. This component consists of X-ray and Hα emission which traverses a coronal arch from one to the other of its chromospheric footpoints. The primary footpoint is at the site of a flare. The secondary footpoint, tens of thousands of kilometers distant from the source flare, but in the same active region, brightens in Hα concurrent with the beginning of the hard X-ray burst at the primary site. From the inferred travel time of the initial exciting agent we deduce that high speed electron streams travelling through the arch must be the source of the initial excitation at the secondary footpoint. Subsequently, a more slowly moving agent gradually enhances the arch first in X-rays and subsequently in Hα, starting at the primary footpoint and propagating along the arch trajectory. The plasma flow in Hα shows clearly that material is injected into the arch from the site of the primary footpoint and later on, at least in some events, a part of it is also falling back. Title: Studies of flares and disappearing magnetic flux Authors: Martin, Sara F. Bibcode: 1988cait.rept.....M Altcode: Research accomplishments include: (1) research on flaring arches; (2) a collaborative paper on Anomalously Dense Flare Loops was published; (3) the footprints of the giant arches previously discovered by Z. Svestka were found in hydrogen alpha observations from the Big Bear Solar Observatory and the Udaipur Solar Observatory; (4) several sets of new observations showing a relationship between cancelling magnetic fields and flares were acquired and analyzed; and (5) a new hypothesis is advanced that cancelling magnetic fields are necessary conditions for the energy build-up to solar flares. Title: The cancellation of magnetic flux on the quiet sun Authors: Wang, Jingxiu; Shi, Zhongxian; Martin, Sara F.; Livi, Silvia H. B. Bibcode: 1988VA.....31...79W Altcode: The mutual loss of magnetic flux in closely spaced, opposite polarity magnetic fields is herein defined as ;cancellation;. The combination of two cancelling components is referred to as a cancelling magnetic feature. In this paper, a classification scheme for cancelling magnetic features according to the origins of their two halves is proposed; the observed properties of flux cancellation are summarized. The cancellation appears to be the observational evidence of magnetic reconnection taking place in or above the photospheric layer. Title: Multi-thermal observations of newly formed loops in a dynamic flare Authors: Švestka, Zdeněk F.; Fontenla, Juan M.; Machado, Marcos E.; Martin, Sara F.; Neidig, Donald F.; Poletto, Giannina Bibcode: 1987SoPh..108..237S Altcode: The dynamic flare of 6 November, 1980 (max ≈ 15:26 UT) developed a rich system of growing loops which could be followed in Hα for 1.5 hr. Throughout the flare, these loops, near the limb, were seen in emission against the disk. Theoretical computations of deviations from LTE populations for a hydrogen atom reveal that this requires electron densities in the loops close to, or in excess of 1012 cm -3. From measured widths of higher Balmer lines the density at the tops of the loops was found to be 4 x 1012 cm -3 if no non-thermal motions were present, or 5 × 1011 cm -3 for a turbulent velocity of ~ 12 km s -1. Title: The appearance and disappearance of magnetic flux on the quiet sun Authors: Zirin, Harold; Martin, Sara F. Bibcode: 1987cait.reptQ....Z Altcode: Significant new discoveries and findings were made concerning solar magnetic fields. The majority of magnetic flux on the sun is observed to disappear when magnetic fields of one polarity migrate into or develop in juxtaposition with fields of opposite polarity. The cancellation of magnetic fields can be interpreted as: (a) submergence (b) reconnection or (c) dissipation (annihilation). Large-scale filaments are observed to form in the chromosphere immediately above the boundaries between areas of network magnetic field of opposite polarity where network cancellation occurs. Small-scale filaments develop in association with small-scale cancelling magnetic fields at the rate of hundreds per day. Magnetic fields associated with large-scale solar convection cells, known as intranetwork magnetic fields, can be detected everywhere on the visible disk of the sun by using the videomagnetograph to integrate successive, 1/15 sec. magnetic field images for intervals of 1 to 10 minutes. The intranetwork field appears to be a few seconds of arc in diameter, and have field strengths of the order of a few to tens of Gauss. The intranetwork fields appear to originate at the centers of supergranules and flow to the boundaries of the cells in approximately radial patterns. Title: Flaring arches Authors: Martin, Sara F.; Švestka, Zdenek F. Bibcode: 1987SoPh..113..303M Altcode: 1982SoPh..113..303M No abstract at ADS Title: Do moving magnetic features represent sunspot decay? Authors: Wang, J. -X.; Martin, S. F.; Livi, S. H. B. Bibcode: 1987PBeiO..10...58W Altcode: No abstract at ADS Title: Characterization of the Total Flare Energy Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veek, N. J. Bibcode: 1986epos.conf.5.41W Altcode: 1986epos.confE..41W No abstract at ADS Title: Energetics of the Impulsive Phase Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veek, N. J. Bibcode: 1986epos.conf..5.5W Altcode: 1986epos.confE...5W No abstract at ADS Title: Energetics of the Gradual Phase Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veek, N. J. Bibcode: 1986epos.conf.5.20W Altcode: 1986epos.confE..20W No abstract at ADS Title: Review of Impulsive Phase Phenomena Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veek, N. J. Bibcode: 1986epos.conf.5.60W Altcode: 1986epos.confE..60W No abstract at ADS Title: Small-scale eruptive filaments on the quiet sun. Authors: Hermans, Linda M.; Martin, Sara F. Bibcode: 1986NASCP2442..369H Altcode: 1986copp.nasa..369H A study of a little known class of eruptive events on the quiet sun was conducted. All of 61 small-scale eruptive filamentary structures were identified in a systematic survey of 32 days of H alpha time-lapse films of the quiet sun acquired at Big Bear Solar Observatory. When fully developed, these structures have an average length of 15 arc seconds before eruption. They appear to be the small-scale analog of large-scale eruptive filaments observed against the disk. At the observed rate of 1.9 small-scale eruptive features per field of view per average 7.0 hour day, the rate of occurence of these events on the sun were estimated to be greater than 600 per 24 hour day.. The average duration of the eruptive phase was 26 minutes while the average lifetime from formation through eruption was 70 minutes. A majority of the small-scale filamentary sturctures were spatially related to cancelling magnetic features in line-of-sight photospheric magnetograms. Similar to large-scale filaments, the small-scale filamentary structures sometimes divided opposite polarity cancelling fragments but often had one or both ends terminating at a cancellation site. Their high numbers appear to reflect the much greater flux on the quiet sun. From their characteristics, evolution, and relationship to photospheric magnetic flux, it was concluded that the structures described are small-scale eruptive filaments and are a subset of all filaments. Title: Recent observations of the formation of filaments. Authors: Martin, Sara F. Bibcode: 1986NASCP2442...73M Altcode: 1986copp.nasa...73M Two examples of the formation of small filaments in H alpha are described and illustrated. In both cases, the formation is seen to be the spontaneous appearance of strands of absorbing mass that evolve from no previous structure. The initial development of the filaments appears to consist of the accumulation of these absorptive strands along approximately parallel paths in a channel between large-scale, opposite polarity magnetic fields on either side of the filaments. The strands exhibit continuous changes in shape and degree of absorption which can be due to successive condensations resulting in new strands, mass motions within the strands, and outflow of the mass from the strands. For at least several hours before the formation of both filaments, small-scale fragments of opposite polarity, line-of-sight magnetic flux adjacent to or immediately below the filaments, and at the ends of the filaments, were cancelling. This type of magnetic flux disappearance continued during the development of the filaments and is commonly observed in association with established filaments. Cancellation is interpreted as an important evolutionary change in the magnetic field that can lead to configurations suitable for the formation of filaments. Title: Flares Chosen for Energetics Study Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veek, N. J. Bibcode: 1986epos.conf.5.47W Altcode: 1986epos.confE..47W No abstract at ADS Title: Relationships among the Phases Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veek, N. J. Bibcode: 1986epos.conf.5.39W Altcode: 1986epos.confE..39W No abstract at ADS Title: The Formation and Decay of Sunspots in Enhanced Solar Network Authors: Livi, S. H. B.; Martin, S. F. Bibcode: 1986BAAS...18..991L Altcode: No abstract at ADS Title: Small-Scale Eruptive Filaments on the Quiet Sun Authors: Hermans, L. M.; Martin, S. F. Bibcode: 1986BAAS...18..991H Altcode: No abstract at ADS Title: Flaring Arches in Hα and X-Rays Authors: Martin, S. F.; Svestka, Z. Bibcode: 1986BAAS...18Q.898M Altcode: No abstract at ADS Title: Observations of chromospheric flare dynamics at the next solar maximum specific recommendations of the Chromospheric Flare Dynamics Group. Authors: Canfield, R. C.; Gaizauskas, V.; Kurokawa, H.; Martin, S. F.; Svestka, Z. Bibcode: 1986lasf.conf..489C Altcode: No abstract at ADS Title: Survey of an active region in H&alpha; and X-rays. Authors: Schadee, Aert; Martin, Sara F. Bibcode: 1986lasf.conf..360S Altcode: 1986lasf.symp..360S The authors studied Hale Active Region No. 16918 during almost 15 hours of simultaneous observation by Big Bear Solar Observatory (H&alpha;) and HXIS (3.5 - 5.5 keV) aboard SMM on 18 - 22 June 1980. Title: Flare energetics. Authors: Wu, S. T.; de Jager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.; Crannell, C. J.; Doyle, J. G.; Hyder, C. L.; Kopp, R. A.; Lemen, J. R.; Martin, S. F.; Pallavicini, R.; Peres, G.; Serio, S.; Sylwester, J.; Veck, N. J. Bibcode: 1986NASCP2439....5W Altcode: In this investigation of flare energetics, the authors establish a comprehensive and self-consistent picture of the sources and transport of energy within a flare. They chose five flares in 1980 that were well observed with instruments on the SMM, and with other space-borne and ground-based instruments. Details of the observations available for them and the corresponding physical parameters derived from these data are presented. The flares were studied from two perspectives, the impulsive and gradual phases, and then the results were compared to obtain the overall picture of the energetics of these flares. The authors also discuss the role that modeling can play in estimating the total energy of a flare when the observationally determined parameters are used as the input to a numerical model. Title: A dynamic flare with anomalously dense flare loops Authors: Svestka, Z.; Fontenla, J. M.; Machado, M. E.; Martin, S. F.; Neidig, D. F.; Poletto, G. Bibcode: 1986AdSpR...6f.253S Altcode: 1986AdSpR...6..253S The dynamic flare of 6 November 1980 (max. ~ 15:26 UT) developed a rich system of growing loops which could be followed in Hα for 1.5 hours. Throughout the flare, these loops, near the limb, were seen in emission against the disk. Theoretical computations of b-values for a hydrogen atom reveal that this requires electron densities in the loops to be close to 1012 cm-3. From measured widths of higher Balmer lines the density at the loops of the loops was found to be 4 × 1012 cm-3 if no non-thermal motions were present. It is now general knowledge that flare loops are initially observed in X-rays and become visible in Hα only after cooling. For such a high density a loop would cool through radiation from 107 K to 104 K within a few minutes so that the dense Hα loops should have heights very close to the heights of the X-ray loops. This, however, contradicts the observations obtained by the HXIS and FCS instruments on board SMM which show the X-ray loops at much higher altitudes than the loops in Hα. Therefore, the density must have been significantly smaller when the loops were formed and the flare loops were apparently both shrinking and becoming denser while cooling. Title: Ephemeral regions versus pseudo ephemeral regions Authors: Martin, S. F.; Livi, S. H. B.; Wang, J.; Shi, Z. Bibcode: 1985svmf.nasa..403M Altcode: New studies of the quiet Sun reveal that ephemeral active regions constitute minority rather than a majority of all the short lived, small scale bipolar features on the Sun. In contrast to the recognized patterns of growth and decay of ephemeral regions, various examples of the creation of other temporary bipoles nicknamed pseudo ephemeral regions are illustrated. The pseudo ephemeral regions are the consequence of combinations of small scale dynamic processes of the quiet Sun including: (1) fragmentation of network magnetic fields, (2) the separation of opposite polarity halves of ephemeral regions as they grow and evolve, and (3) the coalescence of weak network or intranetwork magnetic fields. New observations offer the possibility of resolving the discrepancies that have arisen in the association of ephemeral regions with X-ray bright points. Many X-ray bright points may be related to those pseudo ephemeral regions which have begun to exhibit magnetic flux loss. Title: Images of a Major Compact Flare in Hard X-rays and H-alpha Authors: Svestka, Z.; Martin, S. F. Bibcode: 1985BAAS...17..628S Altcode: No abstract at ADS Title: The cancellation of magnetic flux. I - On the quiet sun Authors: Livi, S. H. B.; Wang, J.; Martin, S. F. Bibcode: 1985AuJPh..38..855L Altcode: Digital and photographic magnetograms recorded at 2.5 min intervals on July 9, 1984 are used to study the disappearance of magnetic flux in an area of the quiet sun; attention is given to 16 examples of flux disappearance and three ephemeral regions meeting minimum flux and change percentage criteria. Flux disappearance is noted to have occurred only in closely spaced features of opposite polarity, and is accordingly designated 'cancellation'. The cancellation phenomenon occurred in combinations of network features, intranetwork features, and ephemeral regions. It is concluded that cancellation is the dominant mechanism through which magnetic flux is observed to disappear on the quiet sun. Title: Ephemeral regions vs. pseudo ephemeral regions. Authors: Martin, S. F.; Livi, S. H. B.; Wang, J.; Shi, Z. Bibcode: 1985NASCP2374..403M Altcode: The authors retain the definition of an ephemeral region as a feature which appears to originate as a compact bipole and grows as a unit in total flux for at least a short time after its birth. In contrast to the recognized patterns of growth and decay of ephemeral regions, various examples of the creation of other temporary bipoles nicknamed "pseudo ephemeral regions" are illustrated. The pseudo ephemeral regions are the consequence of combinations of small scale dynamic processes of the quiet sun including: (1) fragmentation of network magnetic fields, (2) the separation of opposite polarity halves of ephemeral regions as they grow and evolve, and (3) the coalescence of weak network or intra-network magnetic fields. The authors suggest that many X-ray bright points may be related to the pseudo ephemeral regions. They also suggest that vector magnetograms should also reveal distinct differences between real and pseudo ephemeral regions. Title: The cancellation of magnetic flux. II - In a decaying active region Authors: Martin, S. F.; Livi, S. H. B.; Wang, J. Bibcode: 1985AuJPh..38..929M Altcode: An active region was studied in detail during its period of decay from 3 to 8 August 1984 using Hα filtergrams and videomagnetograms acquired at the Big Bear Solar Observatory. The decay was initiated by a process of fragmentation in which very small knots of magnetic flux separated from larger concentrations of flux. The disappearance of magnetic flux was always observed when the small fragments of flux encountered other small fragments or concentrations of flux of opposite polarity. This type of disappearance of magnetic flux, called 'cancellation', is shared by both polarities of magnetic field. Cancellation was the only observed means of major loss of flux in the photospheric magnetic fields of the active region. Approaching fragments of opposite polarity flux always collided and, after apparent collision, permanent loss of magnetic flux was subsequently and invariably observed. Thus, cancellation is a highly predictable phenomenon. Title: The cancellation of magnetic flux II - in a decaying active region. Authors: Martin, S. F.; Livi, S. H. B.; Wang, J. Bibcode: 1985MPARp.212..179M Altcode: No abstract at ADS Title: The cancellation of magnetic flux I - on the quiet sun. Authors: Livi, S. H. B.; Wang, J.; Martin, S. F. Bibcode: 1985MPARp.212..178L Altcode: No abstract at ADS Title: Relationships of a growing magnetic flux region to flares Authors: Martin, S. F.; Bentley, R. D.; Schadee, A.; Antalova, A.; Kucera, A.; Dezső, L.; Gesztelyi, L.; Harvey, K. L.; Jones, H.; Livi, S. H. B.; Wang, J. Bibcode: 1984AdSpR...4g..61M Altcode: 1984AdSpR...4...61M Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic flux region within a complex of active regions, Hale No. 16918. This analysis was done as a part of a continuing study of the circumstances associated with flares in Hale Region 16918, which was designated as an FBS target during the interval 18 - 23 June 1980. We studied the initiation and development of both major and minor flares in Hα images in relation to the identified potential flare sites at the boundaries of the growing flux region and to the general development of the new flux. This study lead to our recognition of a spectrum of possible relationships of growing flux regions to flares as follows: (1) intimate interaction with adjacent old flux - flare sites centered at new/old flux boundary, (2) forced or ``intimidated'' interaction in which new flux pushes old field having lower flux density towards a neighboring old polarity inversion line where a flare then takes place, (3) ``influential'' interaction - magnetic lines of force over an old polarity inversion line, typically containing a filament, reconnect to the new emerging flux; a flare occurs with erupting filament when the magnetic field overlying the filament becomes too weak to prevent its eruption, (4) inconsequential interaction - new flux region is too small or has wrong orientation for creating flare conditions, (5) incidental - flare occurs without any significant relationship to new flux regions. Title: Dynamic Signatures of Quiet Sun Magnetic Fields Authors: Martin, S. F. Bibcode: 1984ssdp.conf...30M Altcode: Three categories of quiet sun magnetic fields are currently recognized: network magnetic fields, ephemeral active regions, and intra-network magnetic fields. A few basic characteristics of each of these types of magnetic fields are briefly reviewed. The second objective of the paper is to present new observational data showing interactions between these types of magnetic fields. Title: Solar-active-region growth rates. Authors: Hermans, L. M.; Martin, S. F. Bibcode: 1983PASP...95Q.597H Altcode: No abstract at ADS Title: Early Signs of New Active Regions Authors: Martin, S. F. Bibcode: 1983BAAS...15..971M Altcode: No abstract at ADS Title: Rates of Growth of Active Regions Authors: Hermans, L. M.; Martin, S. F. Bibcode: 1983BAAS...15..701H Altcode: No abstract at ADS Title: Dynamic signatures of quiet sun magnetic fields Authors: Martin, S. F. Bibcode: 1983STIN...8420464M Altcode: The collision and disappearance of opposite polarity fields is observed most frequently at the borders of network cells. Due to observational limitations, the frequency, magnitude, and spatial distribution of magnetic flux loss have not yet been quantitatively determined at the borders or within the interiors of the cells. However, in agreement with published hypotheses of other authors, the disapperance of magnetic flux is speculated to be a consequence of either gradual or rapid magnetic reconnection which could be the means of converting magnetic energy into the kinetic, thermal, and nonthermal sources of energy for microflares, spicules, the solar wind, and the heating of the solar corona. Title: Analysis of flares observed during the solar maximum year Authors: Zirin, H.; Martin, S. F.; Walton, S. R. Bibcode: 1982cait.rept.....Z Altcode: This report encompasses three major projects: (1) Qualitative characterization of the H-alpha profiles of the flare of 5 November 1980 at 2233 UT; (2) Construction of a film projector/digitizer for the purpose of projecting half-frame 35mm images onto a television camera detector; (3) Images of solar plages near the limb in broadband continuum, and analysis thereof. These projects are described in the respective three sections of this report. Title: Study of the Post-Flare Loops on 1973JUL29 - Part Four - Revision of T and NE Values and Comparison with the Flare of 1980MAY21 Authors: Švestka, Z.; Dodson-Prince, H. W.; Martin, S. F.; Mohler, O. C.; Moore, R. L.; Nolte, J. T.; Petrasso, R. D. Bibcode: 1982SoPh...78..271S Altcode: We present revised values of temperature and density for the flare loops of 29 July 1973 and compare the revised parameters with those obtained aboard the SMM for the two-ribbon flare of 21 May 1980. The 21 May flare occurred in a developed sunspot group; the 29 July event was a spotless two-ribbon flare. We find that the loops in the spotless flare extended higher (by a factor of 1.4-2.2), were less dense (by a factor of 5 or more in the first hour of development), were generally hotter, and the whole loop system decayed much slower than in the spotted flare (i.e. staying at higher temperature for a longer time). We also align the hot X-ray loops of the 29 July flare with the bright Hα ribbons and show that the Hα emission is brightest at the places where the spatial density of the hot elementary loops is enhanced. Title: Emerging magnetic flux, flares and filaments - FBS interval 16-23 June 1980 Authors: Martin, S. F.; Dezso, L.; Antalova, A.; Kucera, A.; Harvey, K. L. Bibcode: 1982AdSpR...2k..39M Altcode: 1982AdSpR...2...39M 17 emerging magnetic flux regions with arch filaments related to new sunspots were identified in Hale Active Region No. 16918 during the 7 day interval from 16-22 June. Most of the new flux regions were clustered around the filament channel between the old opposite polarity fields as were most of the flares. The two largest regions of new magnetic flux and a few of the smaller flux regions developed very near the end points of filaments. This suggests that the emergence of flux in existing active regions might be non-random in position along a filament channel as well as in distance from a filament channel.

We have analyzed the positions of 88 flares to date during about half of each day. We find that slightly more than half (50%) of the flares, irrespective of their size, are centered within the new flux regions. About 1/5 (20%) were centered on the border between the new flux and the adjacent older magnetic field. Less than 1/3 occurred outside of the newly emerging flux regions but in many cases were very close to the newly emerging flux. We conclude that at least 2/3 of the flares are intimately related to the emerging flux regions while the remaining 1/3 might be either indirectly related or unrelated to the emerging flux. Title: A Formula for Forecasting the Probability of Eruption of Quiescent Filaments Authors: Martin, S. F.; Lawrence, V. W. Bibcode: 1981BAAS...13..847M Altcode: No abstract at ADS Title: A formula for forecasting the probability of eruption of quiescent filaments. Authors: Martin, S. F.; Lawrence, V. W. Bibcode: 1981BAAS...13Q.847M Altcode: No abstract at ADS Title: X-Ray Observations of Two Different Systems of "Post Flare" Loops Authors: Svestka, Z.; Dodson-Prince, H. W.; Mohler, O. C.; Martin, S. F.; Moore, R. L.; Nolte, J. T.; Petrasso, R. D. Bibcode: 1981BAAS...13R.542S Altcode: No abstract at ADS Title: New Information on the Spatial Distribution of Active Regions Authors: Martin, S. F.; Hermans, L. M.; Marquette, W. H. Bibcode: 1981BAAS...13..551M Altcode: No abstract at ADS Title: Preflare conditions, changes and events Authors: Martin, S. F. Bibcode: 1980SoPh...68..217M Altcode: Prefiare conditions, changes and events are loosely categorized as distinct, evolutionary or statistical. Distinct preflare phenomena are those for which direct physical associations with flares are implied. Also, they are not known to occur in a like manner during the absence of flares. These include the early stage of filament eruptions within active centers, preflare vortical structures, some transient X-ray emitting features, 5303 Å accelerating coronal arches, and increases in circular polarization at cm wavelengths. Evolutionary preflare changes are considered to be any long-term effect that may be related to the flare build-up even though the same changes may occur in the absence of flares. This category covers the development of current sheets or strongly sheared magnetic fields, evolving magnetic features, emerging flux regions, the development of satellite fields around sunspots, the evolution of reverse polarity field configurations, the merging of adjacent active centers, sunspot motions and the development of velocity patterns. Statistical preflare changes logically include both distinct and evolutionary preflare changes. However, in addition, there are preflare conditions and events that are not necessarily linked to the flare in either a direct physical or indirect evolutionary way. Such parameters or events that may only be statistically significant are certain magnetic field properties, the brightness of active centers at various wavelengths, the previous occurrence of flares and subflares, increased turbulence in filaments and certain radio events. Title: Factors Related to the Eruption of Quiescent Filaments Authors: Hermans, L. M.; Martin, S. F.; Marquette, W. H. Bibcode: 1980BAAS...12..914H Altcode: No abstract at ADS Title: An Attempt to Identify Flare Precursor Mass Motions in Real Time Authors: Dunn, J. M.; Martin, S. F. Bibcode: 1980BAAS...12..904D Altcode: No abstract at ADS Title: On the Relationship Between the Eruption of Quiescent Filaments and the Development of New Active Centers Authors: Hermans, L. M.; Martin, S. F. Bibcode: 1980BAAS...12..477H Altcode: No abstract at ADS Title: Application of Digital Image Processing Techniques to Faint Solar Flare Phenomena Authors: Glackin, D. L.; Martin, S. F. Bibcode: 1980BAAS...12..525G Altcode: No abstract at ADS Title: A Comparison of Solar Cycle 21 with Previous Solar Cycles Authors: Marquette, W. H.; Martin, S. F. Bibcode: 1980BAAS...12..508M Altcode: No abstract at ADS Title: Dynamics of Flare Sprays Authors: Tandberg-Hanssen, E.; Martin, S. F.; Hansen, R. T. Bibcode: 1980SoPh...65..357T Altcode: During solar cycle No. 20 new insight into the flare-spray phenomenon has been attained due to several innovations in solar optical-observing techniques (higher spatial resolution cinema-photography, tunable pass-band filters, multi-slit spectroscopy and extended angular field coronagraphs). From combined analysis of 13 well-observed sprays which occurred between 1969-1974 we conclude that (i) the spray material originates from a preexisting active region filament which undergoes increased absorption some tens of minutes prior to the abrupt chromospheric brightening at the `flare-start', and (ii) the spray material is confined within a steadily expanding, loop-shaped (presumably magnetically controlled) envelope with part of the material draining back down along one or both legs of the loop. Title: The preflare state Authors: van Hoven, G.; Barbosa, D. D.; Birn, J.; Cheng, C. -C.; Hansen, R. T.; Jackson, B. V.; Martin, S. F.; McIntosh, P. S.; Nakagawa, Y.; Anzer, U. Bibcode: 1980sfsl.work...17V Altcode: 1980sofl.symp...17V The accumulation, storage and irreversible release of the free energy necessary for a solar flare are discussed on the basis of data obtained from the Apollo Telescope Mount on Skylab and other pertinent sources. Skylab and OSO 7 observations of possible flare precursors and flare evolution are presented, and the evolution of the flare of Sept. 5, 1973, the most completely observed flare of the Skylab program, is described in detail, with account given to magnetic structures and H alpha radiation. Theories of the preflare state are then reviewed, with attention given to the force-free fields and coronal arcades, thermal and magnetic structures and the MHD stability of coronal loops. Title: Mechanical energy output of the 5 September 1973 flare Authors: Webb, D. F.; Cheng, C. -C.; Dulk, G. A.; Martin, S. F.; McKenna-Lawlor, S.; McLean, D. J.; Edberg, S. J. Bibcode: 1980sfsl.work..471W Altcode: 1980sofl.symp..471W The mechanical energy flux of observed macroscopic mass plasma motions in the solar flare of Sept. 5, 1973, is estimated. Consideration is given to the cool eruptive material in the eruptive filament and large surge as revealed by H alpha observations, the moving emission front seen in Ca II as well as H alpha, the piston-driven shock and mass ejection coronal transient observed in radio spectra and flare core motions, and mechanical energy estimates of 5.6 x 10 to the 29th to 8.9 x 10 to the 30th, 9.0 x 10 to the 29th, 2 x 10 to the 30th (thermal) and 10 to the 31st (magnetic), and 9 x 10 to the 24th erg are obtained, respectively, in agreement with previous estimates. It is concluded that the mechanical energy of large-scale mass motions dominates the radiative output of the flare by more than two orders of magnitude, and that a significant portion of the mechanical energy is in the form of magnetic flux delivered to interplanetary space. Title: Forecasting of Solar Flares based on Magnetic Field Configurations Authors: Harvey, K. L.; Martin, S. F. Bibcode: 1980STP.....3...30H Altcode: No abstract at ADS Title: Particle acceleration in the process of eruptive opening and reconnection of magnetic fields Authors: Svestka, Z.; Martin, S. F.; Kopp, R. A. Bibcode: 1980IAUS...91..217S Altcode: No abstract at ADS Title: Application of digital image processing techniques to faint solar flare phenomena Authors: Glackin, D. L.; Martin, S. F. Bibcode: 1980SPIE..264..236G Altcode: 1981SPIE..264..236G Digital image processing of eight solar flare events was performed using the Video Information Communication and Retrieval language in order to study moving emission fronts, flare halos, and Moreton waves. The techniques used include contrast enhancement, isointensity contouring, the differencing of images, spatial filtering, and geometrical registration. The spatial extent and temporal behavior of the faint phenomena is examined along with the relation of the three types of phenomena to one another. The image processing techniques make possible the detailed study of the history of the phenomena and provide clues to their physical nature. Title: An Experiment in Predicting The Eruption Of Filaments Authors: Martin, S. F.; Edberg, S. J.; Hermans, L. M.; Dunn, J. M. Bibcode: 1979BAAS...11..659M Altcode: No abstract at ADS Title: Ephemeral Active Regions during Solar Minimum Authors: Martin, S. F.; Harvey, K. H. Bibcode: 1979SoPh...64...93M Altcode: Ephemeral active regions (ER) identified on Kitt Peak daily full-disk magnetograms from April through November 1975 were analyzed and compared with larger active regions during the same interval. The 1975 ER were also compared with ER data from 1970, 1973, 1976, and 1977. ER were found to vary approximately with the sunspot cycle. However, a minimum in the number of ER occurred at least one year prior to sunspot minimum. All evidence to date indicates that the early ER minimum was due to the rise of solar cycle 21 primarily in the form of ER. ER were statistically identified as belonging to both outgoing solar cycle 20 and incoming cycle 21 by maxima in their distribution in latitude and by their statistically dominant orientation as a function of latitude. From the identification of ER with specific solar cycles and the persistent presence of high latitude ER maxima since 1970, it is suggested that the outgoing and incoming solar cycles may co-exist on the sun longer than the 0-3 year period of overlap between successive cycles already known from the properties of large sunspot-producing active regions. Title: Study of the Post-Flare Loops on 1973JULY29 - Part Three - Dynamics of the Hα Loops Authors: Martin, S. F. Bibcode: 1979SoPh...64..165M Altcode: Bright and dark curvilinear structures observed between the two major chromospheric ribbons during the flare of 29 July 1973 on films from the Big Bear Solar Observatory are interpreted as a typical system of coronal loops joining the inner boundaries of the separating flare ribbons. These observations, made through a 0.25 Å Hα filter, only show small segments of the loops having Doppler shifts within approximately ± 22 km s−1 relative to the filter passband centered at Hα, Hα -0.5 Å or Hα +0.5 Å. However, from our knowledge of the typical behavior of such loop systems observed at the limb in Hα and at 5303 Å, it has been possible to reconstruct an appoximate model of the probable development of the loops of the 29 July flare as they would have been viewed at the limb relative to the position of a prominence which began to erupt a few minutes before the start of the flare. It is seen that the loops ascended through the space previously occupied by the filament. On the assumption that Hα fine structures parallel the magnetic field, we can conclude that a dramatic reorientation of the direction of the magnetic field in the corona occurred early in the flare, subsequent to the start of the eruption of the filament and prior to the time that the Hα loops ascended through the space previously occupied by the filament. Title: A query into the source of proton emission from solar flares, report 2 Authors: Martin, S. F. Bibcode: 1979sosylrept.....M Altcode: Seven solar flares that were followed by major proton events were examined to determine the diverse and common properties of major flares. The most probable site of primary proton acceleration is cospatial with the site and instant of formation of coronal loops. Because loop formation occurs through the entire duration of major solar flares over significantly large areas of active centers, it is proposed that proton injection occurs from a relatively large volume of space in the corona of active centers and is continuous throughout, and possibly even after, the visible duration of the related chromospheric flare. The flare veil is hypothesized to occur as a result of proton charge exchange taking place in the white-light transient. The Kopp and Pneuman model of loop formation by magnetic reconnection is suggested as an adequate and satisfactory model for all major flares with the provision that the beginning of rapid magnetic field reconnection is coincident with flare start. Title: Discussion Authors: Hirayama, T.; Maltby, P.; Malville, J.; Martin, S. F.; Rust, D. M.; Spicer, D. S. Bibcode: 1979phsp.coll..267H Altcode: 1979IAUCo..44..267H No abstract at ADS Title: Discussion Authors: Acton, L. W.; Anzer, U.; Engvold, O.; Martin, S. F.; Pneuman, G. W.; Rust, D. M.; Tandberg-Hanssen, E.; Zirin, H. Bibcode: 1979phsp.coll..164A Altcode: 1979IAUCo..44..164A No abstract at ADS Title: Application of Digital Image Processing to Solar Data Authors: Glackin, D. L.; Martin, S. F. Bibcode: 1978BAAS...10..641G Altcode: No abstract at ADS Title: Ephemeral Active Regions during Solar Minimum. Authors: Harvey, K. L.; Martin, S. F. Bibcode: 1978BAAS...10..417H Altcode: No abstract at ADS Title: Interpretations of the Moving Emission Front Observed with the Flare of 5 September 1973. Authors: Martin, S. F. Bibcode: 1978BAAS...10Q.462M Altcode: No abstract at ADS Title: Inferences about the Rotation and Eruption of Prominences. Authors: Martin, S. F.; Hansen, R. T. Bibcode: 1977BAAS....9..314M Altcode: No abstract at ADS Title: Ephemeral active regions during the solar minimum. 1: General properties and trends over the solar cycle. 2: Characteristics of individual ephemeral regions Authors: Martin, S. F.; Harvey, K. L. Bibcode: 1976sosylrept.....M Altcode: General properties of ephemeral active regions were studied using Kitt Peak daily magnetograms from Apr. - Nov. 1975. Although this interval was prior to sunspot minimum, ephemeral regions related to incoming cycle 21 were already more numerous than ephemeral regions related to outgoing cycle 20. The transition between the old and new solar cycle was identified by a reversal of the statistically dominant orientation of regions and sometimes by a minimum in the latitude distribution where adjacent cycles overlapped. During this interval the transition between cycle 20 and 21 was at N18 deg and S24 deg. Comparing this 1975 data with previously studied data from 1970 and 1973, we find evidence that incoming cycle 21 was already present on the sun at middle and high latitudes in 1973 and 1970. Extrapolating backward and forward in time from these three periods, we find that it is conceivable that two solar cycles may be present on the sun at all times. It appears that further statistical studies of ephemeral active regions may yield long-term prognostic information on the future course of solar activity. The birth of 90 ephemeral regions was recorded. Prior to the birth of regions, existing network was found to disappear or show lateral displacement. The growth and decay rates of regions were comparable. In the decaying phase, some flux elements simply disappeared; some merged with network or other elements of regions of similar polarity; some collided and simultaneously disappeared with network or elements of other regions of opposite polarity. All clearly identifiable ephemeral regions dissipated by these processes while continuing to expand. Title: Early recognition of major solar flares in Halpha . Authors: Martin, S. F.; Ramsey, H. E. Bibcode: 1976npsa.conf..301M Altcode: No abstract at ADS Title: A Comparison of Flares in Hα and D3 (He I). Authors: Ramsey, H. E.; Martin, S. F.; Harvey, K. L. Bibcode: 1975BAAS....7..424R Altcode: No abstract at ADS Title: Helical Motion in an Eruptive Prominence. Authors: Martin, S. F.; Hansen, R. T. Bibcode: 1975BAAS....7..472M Altcode: No abstract at ADS Title: A comparison of flares and prominences in D3 and H(alpha) Authors: Ramsey, H. E.; Martin, S. F.; Harvey, K. L. Bibcode: 1975lock.rept.....R Altcode: During 1973, flares were photographed using a 0.4A filter on the D3 line of HeI and, in 1974, with an additional passband at 0.8A into the red wing. During most of this period, time-lapse photographs also were taken on either or both the H(alpha) multi-slit spectrograph and the H(alpha) Doppler filter. On a separate telescope, limb events were photographed in D3 and H(alpha) through similar 8A filters. Very few flares displayed D3 in emission in part of the flare. For large flares, some absorption parts of the D3 flare correspond closely to the H(alpha) flare both spatially and temporally. However, the D3 flare boundaries are more sharply defined. It seemed D3 absorption events were correlated more frequently with surges and active filaments than with flare elements. The relative brightness of D3 and H(alpha) were examined for a number of solar phenomena observed at the limb. High velocity portions of surges, erupting filaments and loops brightened more in H(alpha) were examined for a number of solar phenomena observed at the limb. High velocity portions of surges, erupting filaments and loops brightened more in H(alpha) than in D3. In limb flares, D3 brightened more than H(alpha). Title: Ephemeral Active Regions in 1970 and 1973 Authors: Harvey, K. L.; Harvey, J. W.; Martin, S. F. Bibcode: 1975SoPh...40...87H Altcode: A study of ephemeral active regions (ER) identified on good quality full-disk magnetograms reveals: On the average 373 and 179 ER were present on the Sun in 1970 and 1973 respectively. The number varies with the solar cycle. Title: A multi-slit spectrograph and Hα Doppler system Authors: Martin, S. F.; Ramsey, H. E.; Carroll, G. A.; Martin, D. C. Bibcode: 1974SoPh...37..343M Altcode: A multiple entrance slit spectrograph was built for time-lapse photography of the spectra of flares and other transient solar phenomena. This spectrograph employs narrow-band filters to limit the wavelength range of the spectrograph to several angstroms centered at Hα or other spectral lines. The passband of the filter, and the dispersion of the spectrograph determine the number of parallel slits through which light may be passed to achieve multiple adjacent spectral displays. By using a 7 Å filter, a dispersion of 10.8 Å mm−1, and 35 mm film, adjacent Hα spectra are imaged from 30 parallel slits. A system of mirrors and relay lenses transfers the slitjaw image to the same film plane as the spectral image. A 2 frame camera is used to simultaneously record both images on adjacent frames. Filtering of the reference spatial image to 1.0 Å allows the observer to see the position of the slits relative to the Hα centerline structure and to match the brightness of the spatial image to the spectral display. A polarizing beamsplitter, prior to the slits, provides a prefiltered second solar image to a narrow band Hα Doppler filter for simultaneous photography in the wings of the Hα line. The multislit monochromatic spectrograph and Hα Doppler system constitute a flexible instrument in which components may be substituted to achieve different passbands width, image scales, dispersions and corresponding numbers and spacings of adjacent spectra at a selected wavelength. Title: Ephemeral active regions in 1970 and 1973 Authors: Harvey, K. L.; Martin, S. F.; Harvey, J. W. Bibcode: 1974lock.reptR....H Altcode: The work reported here was undertaken to learn more about the spatial distribution of Ephemeral active regions (ER), lifetime, solar cycle variation, and association with major active centers. Primary consideration was given to the question of whether or not ER represent, in part, a new class of solar activity or are simply small active regions. Title: Correlation of a Flare-Wave and Type II Burst Authors: Harvey, Karen L.; Martin, Sara F.; Riddle, Anthony C. Bibcode: 1974SoPh...36..151H Altcode: We have studied the relation of a flare-induced wave and the type II and III radio bursts associated with the 26 April 1969, 2258 UT flare. Our observations suggest the flare-wave and type II bursts were produced by a common source. Title: Rare Observations of the Flare-Related Wave Effects Authors: Martin, S. F.; Harvey, K. L. Bibcode: 1974fpsw.conf...39M Altcode: No abstract at ADS Title: Ephemeral Active Regions Authors: Harvey, Karen L.; Martin, Sara F. Bibcode: 1973SoPh...32..389H Altcode: Ephemeral active regions attain maximum development within 1 day or less of their initial appearance and are typically observed for 1-2 days. They appear mostly as small bipolar regions having a typical dimension of about 30000 km and a maximum total flux of the order of 1020 Mx. The ephemeral regions generally do not produce sunspots and flares, though they are identified in Hα as small active centers. Title: The Evolution of Prominences and Their Relationship to Active Centers (A Review) Authors: Martin, Sara F. Bibcode: 1973SoPh...31....3M Altcode: A necessary condition for the formation of prominences is established where components of the magnetic field of opposite sign lie juxtaposed. This condition is sometimes recognizable prior to the formation of prominences in active centers and between adjacent active centers in Hα by paths of fibrils aligned nearly end to end. Prominences are usually not found in active regions until they are about 4 days old. After this time, the number of prominences appears to be a function of the large-scale complexities in the magnetic field pattern whether these are a result of emerging flux, the merging of adjacent active centers, or the coalescing of remnant fields of active centers. Prominences may disappear by the slow or rapid flow of mass into the chromosphere or by the more violent eruptives. The formation of new active centers has been associated with the eruption of some filaments related to weak chromospheric fields. Title: A Multi-Slit Spectrograph Authors: Martin, Sara F. Bibcode: 1973BAAS....5S.276M Altcode: No abstract at ADS Title: Early Recognition of Major Solar Flares in Hα Authors: Martin, S. F.; Ramsey, H. E. Bibcode: 1972PrAA...30..371M Altcode: No abstract at ADS