Highlights of Astronomy: Part II As Presented at the XVIth General Assembly 1976 (International Astronomical Union Highlights, 4-2)

It has become a tradition in the Union to publish the Invited Discourses and the Proceedings of the Joint Discussions held at a Gene­ ral Assembly in a separate volume entitled HIGHLIGHTS OF ASTRONOMY. This is the fourth volume of its kind and it contains some of the scientific highlights of the Grenoble General Assembly. In order to reduce its size it was decided to publish its content in two separate parts. The part (I) contains the full texts of the In­ vited Discourses given by Prof. J.-C. Pecker and by Dr. C. Sagan, and an abstract of Dr. P. Morrison's paper, thus complying with his wish to forego publication of the full text of his Discourse. Furthermore it collects the proceedings of three Joint Discussions and one Joint Meeting all of which are related essentially to observations from space, to external galaxies and to cosmology. Part (TI) contains the proceedings of the four Joint Discussions and one Joint Meeting related essentially to stars and the structure of our Galaxy. Clearly Volume 4 (parts I and TI) of the Highlights reflects only a part of the scientific activities which took place at the Grenoble General Assembly. Many more important papers and discussions were held during Commission meetings and joint meetings. They may be found in the Commissions' reports published in the Transactions Vol. XVI B, 1977. Front Matter....Pages I-7 Front Matter....Pages 1-7 Introductory Remarks....Pages 9-10 Discussion....Pages 37-39 M Dwarfs at Lower z Distances....Pages 11-19 Available Stellar Data in Galactic Polar Areas....Pages 21-22 Bibliography on Galactic Structure in the Direction of Polar Caps....Pages 23-24 M Dwarfs and the Missing Mass....Pages 25-25 Some Research Programmes into Galactic Structure at the Galactic Caps under Way at the Royal Greenwich Observatory....Pages 27-28 The Space Density of M Dwarfs — An Observational Program....Pages 29-30 The Luminosity Function of Late-Type Main-Sequence Stars in the Direction of the North Galactic Cap....Pages 31-31 Galactic Mass Density in the Vicinity of the Sun....Pages 33-33 The Frequency of Faint M Giant Stars at High Galactic Latitudes....Pages 35-36 The Stellar Distribution Above the Galactic Plane: An Introduction....Pages 41-48 Some Results of Classification of Stars in Kapteyn Areas Applied to Galactic Structure in NGP....Pages 49-50 Mean Chemical Abundance of the F Stars as a Function of Distance from the Galactic Plane....Pages 51-52 RGU Three-Colour-Photometry Towards the North Galactic Pole: Halo-To-Disk Mass Ratio....Pages 53-54 Density Law, Vertical Distribution and Vertical Gradient of Metal Abundances for G and K Giants....Pages 55-55 Polarization Measurements and Extinction Near the NGP....Pages 57-58 Parallaxes of Selected Stars Near the North Galactic Pole....Pages 59-60 Progress Report on a Search for Parallax Stars in the Region of the South Galactic Cap....Pages 61-61 Search for Large Radial Velocities in Direction of NGP Using the Fehrenbach Techniques....Pages 63-63 Front Matter....Pages 1-7 Discussion....Pages 87-87 The Gravitational Field of the Galaxy in the Z Direction....Pages 65-66 Berkeley Studies of Faint Stars at High Latitudes....Pages 67-67 Swedish Programmes Concerning the Z Distribution of Stars....Pages 69-69 Studies of A and F Stars in the Region of the North Galactic Pole....Pages 71-71 The Distribution of Field Horizontal-Branch Stars in the Galactic Halo....Pages 73-74 A New Program to Determine K(z) from Main Sequence Stars....Pages 75-76 Objective-Prism Radial Velocities at High Latitudes....Pages 77-77 Discussion of the Calculation of the Density Law (Dz)....Pages 79-82 Motions of Near-Polar K-Giants Along the Z-Coordinate....Pages 83-86 The Role of Proper Motions in Determining the Luminosity and Density Functions....Pages 89-93 Concluding Remarks Part II....Pages 95-96 Current Results and Suggestions for Future Work....Pages 97-98 Front Matter....Pages 99-101 Introductory Talk....Pages 103-104 Observational Evidence for Atmospheric Physical Characteristics Relevant to Stellar Evolution....Pages 105-114 Behaviour of Microturbulence with Evolution....Pages 115-118 Observational Evidence for Atmospheric Chemical Composition Peculiarities Relevant to Stellar Evolution....Pages 119-135 Sensitivity of Internal Structure to the Surface Boundary Condition....Pages 137-142 Boundary Conditions with Mass-Loss: General Considerations....Pages 143-154 Mass Loss in Stars of Moderate Mass by Stellar Winds and Effects on the Evolution....Pages 155-173 Front Matter....Pages 99-101 Boundary Condition with Mass Loss: The Radiatively-Driven Wind Model....Pages 175-175 Stratification of Elements in a Quiet Atmosphere: Diffusion Processes....Pages 177-191 Competition Between Diffusion Processes and Hydrodynamical Instabilities in Stellar Envelopes....Pages 193-203 Mixing Between Burned Core Material and Surface Layers....Pages 205-208 Decay of Light Elements in Stellar Envelopes....Pages 209-216 Conclusion....Pages 217-218 Front Matter....Pages 219-221 Observations of Small-Scale Photospheric Magnetic Fields....Pages 223-239 Small Scale Solar Magnetic Fields: Theory....Pages 241-250 Some Comments on the Measurement of Small Scale Strong Magnetic Fields on the Sun....Pages 251-254 Line Profiles of Faculae and Pores....Pages 255-260 Facular Models, the K-Line, and Magnetic Fields....Pages 261-264 Small Magnetostatic Flux Tubes....Pages 265-266 Flows in Magnetic Flux Tubes....Pages 267-270 Discussion....Pages 271-272 Concluding Remarks....Pages 273-275 Front Matter....Pages 277-279 Introduction....Pages 281-281 Present Status of Spectral Classification in the Conventional Wavelength Range with Emphasis Upon Early-Type Stars....Pages 283-288 Spectral Classification of Early Type Stars from the Low Dispersion Ultraviolet Spectra....Pages 289-301 Spectral Classification of B and A Stars from the Line Features of S2/68 Spectra....Pages 303-303 Behaviors of B Star Continua and Absorption Features Determined from the TD1 S2/68 “Ultraviolet Bright Star Spectrophotometric Catalogue” and from Copernicus Spectra....Pages 305-305 Front Matter....Pages 277-279 Discussion....Pages 307-309 Spectral Classification Using ANS Photometric Data....Pages 311-313 Spectral Classification with Objective-Prism Spectra from Skylab....Pages 315-322 Discussion....Pages 323-324 An Atlas of Ultraviolet Stellar Spectra....Pages 325-337 A New Temperature Scale for B Stars Based on OAO-2 Data....Pages 339-339 Extreme Ultraviolet Observations of White Dwarfs....Pages 341-347 The Near Ultraviolet Spectrum of Fe III as a Classification Criterion....Pages 349-351 A Catalogue of 0.2 Å Resolution Far-Ultraviolet Stellar Spectra Measured with Copernicus....Pages 353-354 Spectral Classification from Copernicus Data....Pages 355-359 The Ultraviolet Spectrum of Beta Lyrae....Pages 361-362 The Mg II Features Near 2800Å and Spectral Classification....Pages 363-364 Discussion....Pages 365-366 Concluding Remarks....Pages 367-369 Front Matter....Pages 371-375 Heterogeneity of the Solar Atmosphere....Pages 377-387 The Heterogeneity of Surfaces of Magnetic Ap Stars....Pages 389-394 Starspots on by DRA-Type Stars....Pages 395-396 Star Spots on Ar Lac Type Stars....Pages 397-403 Direct Observations of the Heterogeneity of Supergiant Disks....Pages 405-405 On the Spottedness and Magnetic Field of T Tau-Type Stars....Pages 407-407