The basic results of the SMA were presented and summarized in two SMA Symposia Proceedings, edited by Simon (1984 (I) we will refer to this publication using abbreviation SIM) and by De Jager and Svestka (1986, DJS (II)). Other papers discussing SMA results can be found in Proceedings of SMM Workshops (Kundu and Woodgate, 1986 - KAW (III); Poland, 1986 - POL (IV); Dennis et al., 1987 (DOK (V)) and three other meetings held at Kunming (De Jager and Chen Biao, 1985, JCB (VI)) Irkutsk (Stepanov and Obridko, 1986 (SAO (VII)) and Sacramento Peak (Neidig, 1986, NEI (VIII)). A summary of Soviet contributions to the SMA (until 1985) was prepared by Stepanov (in SAO, p. 5). Kindly note that this Section does not mention most of the SMA results that belong to the topics of the subsequent sections of this report: thus the SMA results of space observations should be found in Section VI, radio observations in Section VII, etc. The present report will be mostly limited to those results of the SMA which use or interpret optical ground-based data.

Although the solar activity began to decrease rapidly after 1983, the analysis and interpretation of the observations made with instruments aboard the SMM, Hinotori, P78-1, ISEE-3 (ICE), PVO, Venera, and PROGNOZ spacecraft continued to produce important scientific results. The observational results inspired new theoretical studies or extensions of the earlier studies. Several symposia and workshops were organized for presentation and discussion of coordinated studies or studies in progress.

Given here are reports on the scientific and business meetings held in Baltimore involving Commission 9 only. Reports on the following Joint Commission Meetings co-sponsored by Commission 9 (JCM 3 and JCM 6), and on three additional meetings organised jointly with other Commissions, will be found elsewhere in this Volume or in Highlights of Astronomy (Volume 8):

1. - High Angular Resolution Imaging from the Ground (JCM 3)

2. - Stellar Photometry with Array Detectors (JCM 6)

3. - Problems of IR Extinction and Standardization (with Commission 25)

4. - Future Space Programs (with Commission 44)

5. - Gamma-ray, X-ray, Extreme and Far UV, IR and Radio Astronomy from Space (with Commissions 40 and 44)

This section does not mention some results reported in sections V and VI. Other papers can be found in proceedings of CESRA Workshops (Benz 1985 (I), Pick and Trottet 1986 (II)).

By far the most significant event for Solar Flares as a whole over the past 3 years has been the operation of the Solar Maximum Mission Satellite, together with the accompanying data analysis, ground-based support and theoretical modelling. This has culminated in the series of SMM Flare Workshops, whose proceedings have now appeared (Kundu and Woodgate 1986 (I)), with chapters on a wide variety of topics which indicate the enormity and complexity of the flare problem.

Solar Physics has been traditionally divided into Structure and Radiation of the Solar Atmosphere (commission 12) and Solar Activity (commission 10). There has been increasing evidence that solar activity, which is basically of magnetic origin, occurs on a great variety of scales arid thus immediately touches upon the structure of the solar atmosphere as well as the structure and dynamics of the convection zone. As a consequence progress in the field of origin and evolution of solar magnetic fields from a large scale, ‘the dynamo’, to small scale is included in this report. In the past few years particular attention has been paid to the fact that the fluctuations in the magnetic field are much larger than the mean field and that the dynamo modes may be stochastically excited. The question whether there is a magnetic reservoir at the bottom of the convection zone still remains to be resolved. The interaction of the convection and the magnetic field resulting in an enhancement of the magnetic field in the intergranular lanes is studied by numerical modelling.

A brief review was given of the substance of the discussion of the previous business meeting of Nov. 21 1985 on the subject matter of the commission. There was general endorsement of the view of that meeting that the purpose of the Commission was to keep a watching brief on the energy exchange processes of atomic and molecular physics, and of related spectral and structure data of atomic and molecular species. Such information is essential to the use of astronomical observations for astrophysical diagnosis and modelling.

Traditionally the theory of the solar dynamo has been divided into two parts. The first, more difficult part, is the derivation of equations governing the mean magnetic field; the second, easier, is the solution of this equation, and the interpretation of the result in terms of observed solar magnetism. This report follows the traditional division.

In astrophysics, as in all research fields in which molecular spectra play important roles, there has been a continuing need for compendia of information on individual band systems. Firstly there is a requirement by observers and experimenters for aids to definitive identification of observed spectral features. Secondly there are needs by observers, by those who make diagnostic interpretations of spectral profiles, and also by theorists, for definitive critical compilations of appropriate molecular data with reference to the relevant literature. The continued popularity of various editions to Pearse and Gaydon’s Identification of Molecular Spectra (1) and to Huber and Herzberg’s Constants of Diatomic Molecules (2) are clear evidence of this.

Considerable progress has been made during the last four years in the theoretical and empirical investigation of the small scale solar magnetic field and associated phenomena. Although the basic outlines established in the 1970s of the structure of the field, namely small fluxtubes or magnetic elements with kllogauss fields embedded in a relatively field free medium have survived, many of the details have changed and some of the large gaps in our knowlegde of these captivating structures have been filled. In the following we briefly outline some of the highlights.

Tribute is paid to those members of Commission 15 who have passed away since the last General Assembly: Dr. Ludwig BIERMANN, Dr. Nicholas BOBROVNIKOFF, Dr. Richard Heinrich GIESE, Dr. Marie-Therese MARTEL, Dr. Reginald WATERFIELD.

The Commission had one Business Session, two Science Sessions on “News in Cometary Research” (organized by C. Arpigny), one Science Session on “News in Minor Planet Research” (organized by A.W. Harris), a Joint Discussion with Commission 20 on “Major Observing Programs and Data Bases” (organized by Y. Kozai and L. Kresak), and a Joint Discussion with Commission 22 on “Interrelation of Meteor Streams, Comets and Asteroids” (organized by P. Babadzhanov and L. Kresak)

The crucial role of magnetic fields in any mechanism to heat the outer solar atmosphere has been generally accepted by all authors. However, there is still no agreement about the detailed function of the magnetic field. Heating mechanisms can be divided up into 4 classes: (I) The magnetic field plays a passive role as a suitable medium for the propagation of Alfvén waves from the convection zone into the corona (Ionson, 1984). (II) In closed magnetic structures the slow random shuffling of field lines by convective motions below the surface induces electric currents in the corona which heat it by Joule dissipation (Heyvaerts and Priest, 1984). (Ill) Emerging flux which is generated in the convection zone reacts with ionized material while magnetic field lines move through the chromosphere, transition zone and corona. Rapid field line annihilation, reconnection and drift currents result in heating and material ejection (Brueckner, 1987; Brueckner et al., 1987; Cook et al., 1987). (IV) Acoustic waves which could heat the corona can be guided by magnetic fields. Temperature distribution, wave motions and shock formation are highly dependent on the geometry of the flux tubes (Ulmschneider and Muchmore, 1986; Ulmschneider, Muchmore and Kalkofen, 1987).

Studies of the global (spatially unresolved) output from the sun are important for two main reasons: (1) the global solar output directed towards the earth plays a central role in solar-terrestrial relations, and (2) global solar observations form a link between (neccessarily) global observations of stars and the more refined spatially resolved observations which are available for the sun. This report covers both aspects (insofar as they concern the sun), using the time-scales of various phenomena as a basic distinguishing characteristic. Note that certain studies of spatially unresolved solar output have not been discussed, since they are actually directed toward the investigation of phenomena of strictly limited spatial extent [e.g. radiospectrograph observations (e.g. Wiehl et al. 1985) and studies of X-ray bursts (e.g. Thomas et al. 1985)]. Collections of relevant papers may be found in De Jager and Svestka (1985) and Labonte et al. (1984), while a review of germane stellar work is available in Baliunas and Vaughan (1985) and solar-terrestrial work in Donnelly and Heath (1985). A comprehensive summary of the subject by Hudson will appear soon in Review of Geophysics and Planetary Physics.

This report complements the report on solar instrumentation presented by Commission 10 In that subjects treated there are not repeated here. Both reports taken together should give a fair, though necessarily incomplete, idea of solar instrumentation activity during the period June 1984 through June 1987.