Activity in Red-Dwarf Stars

IAU Colloquium No. 71 had its immediate origins in a small gathering of people interested. in the optical and UV study of flare stars which took place during the 1979 Montreal General Assembly. We recognized that a fundamental change was taking place in the study of these objects. Space-borne instruments (especially lUE and Einstein) and a new genera tion of ground-based equipment were having a profound effect on the range of investigations it was possible to make. To extract maximum benefit from these new possibilities it would be necessary as never before to have good communication with colleagues in other disciplines, for instance,. with atomic and solar physicists. Similarly, studies of phenomena associated with the outer atmospheres of the late-type stars could now hope to give significant insights into certain aspects of solar activity. So, in view of the wide range of backgrounds of those participating, the meeting had an unusually high proportion of invited reviews while most of the contributed papers were presented as posters. It is gratifying that in the short time since the meeting a good deal of correspondence has been received from participants remarking on the success of this format. Once the decision had been taken in principle to hold the meeting, a very considerable amount of work fell on the two organizing committees, viz. the Scientific and Local Organizing Committees. The Scientific Organizing Committee was chaired by D.J. Mullan and consisted of A.D.

Proceedings of the 71st Colloquium of the International Astronomical Union held in Catania, Italy, August 10-13, 1982

Inhalt
Introductory Address.- Magnetic Fields and Activity of the Sun and Stars: An Overview.- Global and Photospheric Physical Parameters of Active Dwarf Stars (Invited Paper).- Mean Colors and Effective Temperatures of K and M Dwarfs.- The Quiescent Chromospheres and Transition Regions of Active Dwarf Stars: What Are We Learning from Recent Observations and Models? (Invited Paper).- The Structure and Energy Balance in Main Sequence Stars.- The Distribution of Chromospheric Emission Strengths Among Red Dwarfs.- Chromospheric Emission and Rotation of Main Sequence Stars.- Late-Type Ca II Emission-Line Stars in the Southern Hemisphere.- The Atmosphere of a Probably Very Young BY Dra-Type Flare Star.- Some Properties of Stellar Transition Regions.- Quiescent Coronae of Active Chromosphere Stars (Invited Paper).- Einstein and IUE Observations of Nearby Red Dwarfs (Invited Paper).- X-Ray Emission from Flare Stars.- Stellar X-Ray Activity in the Hyades.- Spots, Spot-Cycles and Magnetic Fields of Late-Type Dwarfs (Invited Paper).- Optical Photometry of Flares and Flare Statistics (Invited Paper).- The ITA Survey on Red Dwarf Variable Stars Final Report.- Synopsis of BY Dra and II Peg Light Curves: Variability and Possible Evidence of Differential Rotation.- Two-Spot Modeling of Synoptic Light Curves of II Peg.- Variable K-Type Stars in the Pleiades.- Stellar Activity and Calcium Emission Variability.- EV Lacertae: Is Flare Activity Related to an Unseen Planet-Like Companion?.- An Unusual Flare on EV Lac.- Optical and Ultraviolet Stellar Flare Spectroscopy (Invited Paper).- Results from Optical and UV Stellar Flare Spectroscopy (Invited Paper).- Observations of Ho and He II ?4686 Lines in the Spectra of Flares of UV Cet-Type Stars.- The Timescales of Variations in Continuum and Hydrogen Lines During Stellar Flares.- Far-Ultraviolet and Visible Observations of Flares on dMe Stars.- IUE Spectra of the BY Dra/Flare Star AU Mie.- Flare-Like Activity of Red Giant Stars.- X-Ray Observations of Stellar Flares (Invited Paper).- Quiescent and Flaring Radio Emission from dMe Stars (Invited Paper).- Flares on the Sun: Selected Results from SMM (Invited Paper).- Flares on the Sun: Selected Results from HINOTORI (Invited Paper).- Solar Flares with SMM and Implications for the Physics of Stellar Flares.- The Interpretation of EUV Spectra of Sunspots.- Possible Origins of the 12? Emission Lines in the Solar Spectrum.- Multiple Wavelength Observations of Flaring Active Regions.- Magnetic Development of Flaring Regions at Centimeter Wavelengths.- Very Long Baseline Interferometry of Solar Flares.- RS CVn Stars: Photospheric Phenomena and Rotation (Invited Paper).- RS CVn Stars: Chromospheric Phenomena (Invited Paper).- Doppler Imaging of Starspots.- Twenty Years of Dedicated Photometry of RS CVn at Catania Observatory.- Periods of Unevolved Late-Type Close Binaries: Evidence of Magnetic Activity.- Migrating Waves in Solar-Type Short-Period Eclipsing Binaries.- Features of the Wave-Like Distortion in Some RS CVn Binaries.- On the Distortion Wave in the Short Period RS CVn Type Eclipsing Binary WY Cancri.- Recent Photometry of AR Lacertae.- HK Lacertae.- The Solar-Type Eclipsing Binary System AI Phoenicis.- Light Curves and Ca II Emissions of V711 Tauri During 198182.- A Flare-Like Event from the Short-Period System XY UMa.- RS CVn Systems: The High Energy Picture (Invited Paper).- Preliminary Results of a Five-Year Survey of Radio Emission from RS CVn and Similar Binaries.- Activity Correlations in Close Binary Systems.- IUE Spectra of RS CVn Stars.- Coronal and Chromospheric Structure in AR Lac II: Physical Characteristics of the Atmosphere.- Contact Binary Stars (Invited Paper).- The Evolutionary Status of Short-Period RS CVn and Related W UMa Eclipsing Binaries.- Angular Momentum Loss and the Formation of W UMa Systems.- Activity of Contact Binaries.- Rotation-Activity Connections in Main Sequence Binaries.- The VW Cephei System.- A Bright Spot and a Serendipitous Stellar Flare on the Contact-Binary VW Cep.- Numerical Analysis of Orbital Period Variations and a Mechanism for Changes in the Light Curve of VW Cep.- On Activities of UV Cet-Type Flare Stars and of T Tau-Type Stars (Invited Paper).- The Variability of the T Tauri Star DI Cephei.- Optical Monitoring of T Tauri Stars.- Periodic Light Variability in Four Late-Type Pre-Main-Sequence Stars.- New Results on the Binary Companion of T Tauri.- Chromospheric Properties of T Tauri Stars Determined from EUV Spectra.- Quasi-Periodic Variations of Balmer Line Profiles in Spectra of the T Tau-Type Star RW Aurigae.- Eruptive Phenomena as a Source of the Observed Variations of Intrinsic Polarization in Long Period and T Tau Variables.- The Interaction of Fast Particles with Frozen Gases in T Tau Nebulae: The Physical Background.- On the Origin of H2 in T Tau Stars.- Models of Spots and Flares (Invited Paper).- Magnetic Instabilities in Stellar Atmospheres (Invited Paper).- Flaring Processes in Stellar Atmospheres: The Importance of Electromagnetic Coupling (Invited Paper).- Empirical Models of Stellar Flares: Constraints on Flare Theories (Invited Paper).- Dynamo Theory in the Sun and Stars (Invited Paper).- Photospheric Sources of Magnetic Field Aligned Currents.- Turbulent Sound Generation in Red Dwarf Stars.- A New Triggering Mechanism for Red Dwarf Flares.- Theory and Observations of Negative Preflares in UV Cet Stars.- Flares on Red Dwarf Stars as a Result of the Dynamical Response of the Chromosphere to the Heating.- MHD Thermal Instabilities in Inhomogeneous Atmospheres.- Magnetic Accretion Model for the Activities of Very Young Stars.- Interacting Magnetospheres in RS CVn Binaries: Coronal Heating and Flares.- Basic Parameters Determining X-Ray Emission Level in Stars of Spectral Type Later than F5.- Future Research Directions: Theoretical Approach and Perspective (Invited Paper).- Observational Approach and Perspective (Invited Paper).- Summary of the Colloquium.