Activity in red-dwarf stars : proceedings of the 71st Colloquium of the International Astronomical Union held in Catania, Italy, August 10-13, 1982

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. Front Matter....Pages i-xxvi Introductory Address....Pages 1-3 Magnetic Fields and Activity of the Sun and Stars: An Overview....Pages 5-14 Front Matter....Pages 15-15 Global and Photospheric Physical Parameters of Active Dwarf Stars....Pages 17-33 Mean Colors and Effective Temperatures of K and M Dwarfs....Pages 35-38 The Quiescent Chromospheres and Transition Regions of Active Dwarf Stars: What are We Learning from Recent Observations and Models?....Pages 39-60 The Structure and Energy Balance in Main Sequence Stars....Pages 61-65 The Distribution of Chromospheric Emission Strengths Among Red Dwarfs....Pages 67-70 Chromospheric Emission and Rotation of Main Sequence Stars....Pages 71-73 Late-Type Ca II Emission-Line Stars in the Southern Hemisphere....Pages 75-76 The Atmosphere of a Probably Very Young by Dra-Type Flare Star....Pages 77-77 Some Properties of Stellar Transition Regions....Pages 79-81 Quiescent Coronae of Active Chromosphere Stars....Pages 83-108 Einstein and IUE Observations of Nearby Red Dwarfs....Pages 109-124 X-Ray Emission from Flare Stars....Pages 125-129 Stellar X-Ray Activity in the Hyades....Pages 131-134 Front Matter....Pages 135-135 Spots, Spot-Cycles and Magnetic Fields of Late-Type Dwarfs....Pages 137-156 Optical Photometry of Flares and Flare Statistics....Pages 157-174 The ITA Survey on Red Dwarf Variable Stars — Final Report....Pages 175-177 Synopsis of by Dra and II Peg Light Curves: Variability and Possible Evidence of Differential Rotation....Pages 179-184 Two-Spot Modeling of Synoptic Light Curves of II Peg....Pages 185-188 Front Matter....Pages 135-135 Variable K-Type Stars in the Pleiades....Pages 189-193 Stellar Activity and Calcium Emission Variability....Pages 195-199 EV Lacertae: Is Flare Activity Related to an Unseen Planet-Like Companion?....Pages 201-202 An Unusual Flare on EV Lac....Pages 203-205 Optical and Ultraviolet Stellar Flare Spectroscopy....Pages 207-221 Results from Optical and UV Stellar Flare Spectroscopy....Pages 223-235 Observations of H β and He II λ 4686 Lines in the Spectra of Flares of UV Cet-Type Stars....Pages 237-238 The Timescales of Variations in Continuum and Hydrogen Lines During Stellar Flares....Pages 239-243 Far-Ultraviolet and Visible Observations of Flares on dMe Stars....Pages 245-248 IUE Spectra of the by Dra/Flare Star AU Mic....Pages 249-250 Flare-Like Activity of Red Giant Stars....Pages 251-254 X-Ray Observations of Stellar Flares....Pages 255-272 Quiescent and Flaring Radio Emission From dMe Stars....Pages 273-286 Flares on the Sun : Selected Results from SMM....Pages 289-305 Flares on the Sun : Selected Results from Hinotori....Pages 307-320 Solar Flares with SMM and Implications for the Physics of Stellar Flares....Pages 321-324 The Interpretation of EUV Spectra of Sunspots....Pages 325-326 Possible Origins for the 12μ Emission Lines in the Solar Spectrum....Pages 327-330 Multiple Wavelength Observations of Flaring Active Regions....Pages 331-334 Magnetic Development of Flaring Regions at Centimeter Wavelengths....Pages 335-337 Very Long Baseline Interferometry of Solar Flares....Pages 339-341 RS CVn Stars: Photospheric Phenomena and Rotation....Pages 343-361 RS CVn Stars: Chromospheric Phenomena....Pages 363-377 Doppler Imaging of Starspots....Pages 379-385 Twenty Years of Dedicated Photometry of Rs CVn at Catania Observatory....Pages 387-390 Periods of Unevolved Late-Type Close Binaries: Evidence of Magnetic Activity....Pages 391-392 Migrating Waves in Solar-Type Short-Period Eclipsing Binaries....Pages 393-394 Features of the Wave-Like Distortion in Some RS CVn Binaries....Pages 395-398 On the Distortion Wave in the Short Period RS CVn Type Eclipsing Binary WY Cancri....Pages 399-400 Recent Photometry of AR Lacertae....Pages 401-402 HK Lacertae....Pages 403-405 The Solar-Type Eclipsing Binary System AI Phoenicis....Pages 407-408 Light Curves and Ca II Emissions of V711 Tauri during 1981–82....Pages 409-410 A Flare-Like Event from the Short-Period System XY UMa....Pages 411-413 RS CVn Systems : The High Energy Picture....Pages 415-427 Preliminary Results of a Five-Year Survey of Radio Emission from RS CVn and Similar Binaries....Pages 429-437 Activity Correlations in Close Binary Systems....Pages 439-442 IUE Spectra of RS CVn Stars....Pages 443-444 Coronal and Chromospheric Structure in AR Lac. II. Physical Characteristics of the Atmosphere....Pages 445-446 Contact Binary Stars....Pages 447-461 The Evolutionary Status of Short-Period Rs CVn and Related W UMa Eclipsing Binaries....Pages 463-464 Angular Momentum Loss and the Formation of W UMa Systems....Pages 465-468 Activity of Contact Binaries....Pages 469-473 Rotation-Activity Connections in Main Sequence Binaries....Pages 475-477 The VW Cephei System....Pages 479-480 A Bright Spot and a Serendipitous Stellar Flare on the Contact-Binary VW Cep....Pages 481-483 Numerical Analysis of Orbital Period Variations and a Mechanism for Changes in the Light Curve of VW Cep....Pages 485-486 On Activities of UV Cet-Type Flare Stars and of T Tau-Type Stars....Pages 487-495 The Variability of The T Tauri Star DI Cephei....Pages 497-500 Optical Monitoring of T Tauri Stars....Pages 501-502 Periodic Light Variability in Four Late-Type Pre-Main-Sequence Stars....Pages 503-504 New Results on the Binary Companion of T Tauri....Pages 505-507 Chromospheric Properties of T Tauri Stars Determined from EUV Spectra....Pages 509-511 Quasi-Periodic Variations of Balmer Line Profiles in Spectra of the T Tau-Type Star RW Aurigae....Pages 513-514 Eruptive Phenomena as a Source of the Observed Variations of Intrinsic Polarization in Long-Period and T Tauri Variables....Pages 515-518 The Interaction of Fast Particles with Frozen Gases in T Tau Nebulae: The Physical Background....Pages 519-521 On The Origin of H 2 in T Tau Stars....Pages 523-524 Front Matter....Pages 525-525 Models of Spots and Flares....Pages 527-543 Magnetic Instabilities in Stellar Atmospheres....Pages 545-558 Flaring Processes in Stellar Atmospheres: The Importance of Electromagnetic Coupling....Pages 559-560 Front Matter....Pages 525-525 Empirical Models of Stellar Flares : Constraints on Flare Theories....Pages 561-578 Dynamo Theory in the Sun and Stars....Pages 579-599 Photospheric Sources of Magnetic Field Aligned Currents....Pages 601-603 Turbulent Sound Generation in Red Dwarf Stars....Pages 605-608 A New Triggering Mechanism for Red Dwarf Flares....Pages 609-611 Theory and Observations of Negative Preflares in UV Cet Stars....Pages 613-615 Flares on Red Dwarf Stars as a Result of the Dynamical Response of the Chromosphere to the Heating....Pages 617-619 MHD Thermal Instabilities in Cool Inhomogeneous Atmospheres....Pages 621-623 Magnetic Accretion Model for the Activities of Very Young Stars....Pages 625-627 Interacting Magnetospheres in RS CVn Binaries — Coronal Heating and Flares....Pages 629-632 Basic Parameters Determining X-Ray Emission Level in Stars of Spectral Type Later Than F5....Pages 633-635 Front Matter....Pages 637-637 Future Research Directions: Theoretical Approach and Perspective....Pages 639-650 Observational Approach and Perspective....Pages 651-652 Summary of the Colloquium....Pages 653-661 Back Matter....Pages 663-669