Observations in Central Asia in 1965-1966 by both photographic and radar methods allowed a determination of the radiants and orbits of Leonids (Babadzhanov and Getman 1970). Photographs showed that meteoroids undergo quasi-continuous fragmentation (QCF) in the Earth’s atmosphere. Taking account of QCF, the density of the Leonid meteoroids were found to lie between 1 and Agcm-3 the average being 2gcm-3 (Babadzhanov 1994), in agreement with the density range of between 0.2 and 6gcm-3 given by Maas et al (1990) for dust grains from comet P/1 Halley, with values below 0.6 being rare. Further, the icy grains have a density of about 1gcm-3 while silicate grains have a mean density 2.5 times higher.

A total of eighteen times of minimum lights for YY Eri were determined from relatively new or unpublished photoelectric observations collected from Korea and Turkey. All minima available to us were intensively analyzed to deduce the character of period variation of YY Eri. It is either formed by a sinusoidal variation superimposed on an upward parabola, or a set of abrupt changes. The abrupt changes appeared to have alternatively occured in the pattern of two increases following one decrease, which may be an indication of sinusoidal variations rather than real sudden changes of period. Upward parabolic variation can be due to a secular period increase caused by mass transfer from less massive to more massive component. The sinusoidal character can arise from a third body or from a strong magnetic activity cycle. Long term sinusoidal light level variation in the light curves supports the cyclic magnetic activity effect on the orbital period. However, the third body hypothesis can not be ruled out by the present data.

Although the evolution of binary systems has been qualitatively interpreted with the evolutionary scenario, the quantitative interpretation of any observed system is still unsatisfactory due to the difficulty of the quantitative treatment of mass and angular momentum transfer/loss. To reach a true understanding of the evolution of binary systems, we have to accumulate more observational evidence. So far, we have observed several binaries that are short-period and noncontact, and found the existence of extremely small-mass systems. In the present paper, we study another short-period (P=0.659d), noncontact, eclipsing binary system, V392 Ori. We have made photometric and spectroscopic observations of V392 Ori. The light curves are found to vary, suggesting the existence of circumstellar matter around the system. Combining the photometric and spectroscopic results, we obtain parameters describing the system; we find the mass of the primary component is only 0.6Mʘ- undermassive for its spectral and luminosity class A5V, suggesting that a considerable amount of its original mass has been lost from the system during the course of evolution. The low-mass problem is very important for investigation of the evolution of close binary systems: largemass loss within and/or after the main-sequence will have a significant influence on the future evolution of binary systems.

The possibility of a storm of Leonid meteors in November 1998 and 1999 offers exciting opportunities for using unusual meteor observing techniques, because of high flux and because the Leonids are unique probes for the study of the parent comet 55P/Tempel-Tuttle and the Earth’s upper atmosphere.

The past few years have seen the emergence of new observational approaches to the study of pulsating stars. Massive photometric surveys are discovering new variables by the tens of thousands. For example, the number of Cepheids and RR Lyrae has increased manifold over the past two years – many of these new distant pulsating stars have now better light curves than their well-known nearby counterparts. The new observational breakthrough has opened many theoretical issues. Some of these can be tackled with the set of new opacities (from Lawrence Livermore and from the Opacity Project), others seem to require new theoretical insights.

Analysis of the eclipsing (period=3.39 days) binary V342 Aquilae at visible wavelengths reveals that the system is heavily enshrouded with gas, masking the identity of the underlying stars. In the ultraviolet V342 Aquilae shows six times more attenuation at phases outside of eclipse than most Algols. It is likely, then, that V342 Aquilae is the most enshrouded short period Algol system known. Our ultraviolet spectra show very pronounced Fe II absorption lines arising from ground and metastable levels, indicating an extensive circumstellar gas envelope. The strength of this absorption shows both an orbital and a cycle-to-cycle variability. The eclipse spectra display very strong emission from lines such as C II, Si IV, and C IV, with a striking similarity to the interacting binary TT Hydrae (B9.5V+K0III). We have deduced that the system consists of a late B star with a late GIII-IV companion and a mass ratio on the order of 0.5. A detailed descriptionof the observations, as well as deduced geometrical and physical properties of the system are presented. The apparent conflict of these observations with presently understood theory of binary evolution will be discussed.

In a recent series of papers, it was shown that the metallicity and the absolute V, I and K mean magnitudes of RRab stars can be accurately calculated using only their periods and the low order Fourier parameters of the V light curves. The application of these formulae in conjunction with the synthetic colours of the model atmospheres and with the theoretical pulsation periods enables us to determine all the basic physical parameters (i.e. logL, logT, logM and [Fe/H]) of any variable with an accurate light curve. As a result, we might trace evolutionary tracks on the H—R diagram by plotting the stars with the same mass and metallicity. From a present sample of nearly 300 stars, signs of differences in the evolutionary statescan be suspected but not yet proven.

The accumulation of large numbers of precise light and colour curves, onthe one hand, will further improve the empirical formulae and therefore theaccuracy of the derived parameters and, on the other hand, will increase our chances of constructing better-populated empirical evolutionary tracks.

The last two decades brought a rich harvest of information about the outer planets, their satellites, and their ring systems that dramatically improved our knowledge about these bodies and evolutionary processes in the Solar System. This progress was due both to the successful Pioneer and Voyager missions, and to progressively improved techniques of ground-based observations. These data give insight into numerous new phenomena and mechanisms operating on the outer planets and also give important clues about the intimate relationships between all objects of the Solar System family. Results from the Galileo probe and orbiter have taken us further along that track.

There is a gap in the distribution of the orbital periods of cataclysmic variables (CVs) between 2 and 3 hours. The period gap is explained at present by cessation of the mass transfer making CVs fainter and preventing them from being discovered. After restarting the mass transfer, CVs have been believed to evolve with the orbital periods becoming shorter, as angular momentum is released by gravitational wave radiation. In this view, the mass transfer rate depends almost only on the orbital period.

However, reconsideration of these views is urged by a series of recent discoveries of ER UMa stars (a subclass of SU UMa stars having enormous mass-transfer rates), dwarf novae bridging “classical” SU UMa stars and ER UMa stars, and the first in-the-gap dwarf nova, PG 1510+234. These objects suggest two possibilities; 1) (a part of) SU UMa stars undergo large secular changes of the mass-transfer rate, and 2) there exist parameters overlooked but strongly influential in the evolution of CVs.

Results from the Galileo probe and orbiter are compared with Voyager and ground-based results. The probe made measurements to the 20-bar level, well below the nominal cloud base at 5 bars and well below the level where sunlight is absorbed. The winds increased with depth within the clouds and then remained constant below cloud base. This rules out most “thin weather layer” models of Jovian meteorology. Water, H2S, and NH3 were depleted relative to “solar” abundances at the nominal cloud base but increased with depth below 10 bars. Apparently the probe entered a dry downdraft that penetrated to 20 bars. Consistent with this result, the orbiter found water varying by factors of 100 from place to place, with the lowest values at the sites that resemble the one where the probe went in. The orbiter also revealed that these sites are regions of horizontal convergence of the cloud top winds, which is consistent with the downdraft hypothesis.

The Galileo Near Infrared Mapping Spectrometer (NIMS) obtains spectral images in the wavelength range 0.7 to 5.2 μm with a spectral resolving power of approximately 200. This spectral range allows NIMS to sense cloud-reflected solar radiation, thermal emission produced in the deep atmosphere, and auroral emission from the thermosphere of Jupiter. Using 5 μm thermal emission spectroscopy, the amount of water vapor in the deep atmosphere, at approximately the (i to 8 bar level, is found to vary by a factor > 100. Deep atmosphere ammonia was also found to vary, with a spatial behavior different from that of water vapor. No evidence is found for a massive water cloud. Using reflected solar radiation in conjunction with thermal emission, two cloud layers are found, the upper at 0.5 bars and a lower one at 1-1.3 bars. The inferred absorption properties of these clouds are consistent with ammonia crystals (the upper cloud) and ammonium hydrosulfide particles (the lower cloud).

Theoretical models and observational evidence for various processes in magnetic cataclysmic variables are briefly reviewed. Among them: modulation of the accretion rate by the magnetic field of the white dwarf; excitation of the orientation change of the magnetic axis of the white dwarf with respect to the secondary; structure of the accretion column and its instability; mass and angular momentum transfer; magnetic activity of the secondary; high/low luminosity state transitions; QPO’s, ”shot noise” and ”red noise” in polars, intermediate polars and nova-like objects.

UVS results from Jupiter show the Io torus colder and brighter than the Voyager observations. Aurora near Jupiter’s poles emit 1-4 MR from altitudes of 300 – 400 km. Ganymede and Callisto have extended hydrogen exospheres. The near-UV reflectance of the Galilean satellites shows SO2, magnetospheric alteration, and O3. Remote sensing of Jupiter’s stratospheric haze determines that it thickens and darkens towards higher latitudes.

Results of 2D numerical simulation of the magneto rotational mechanism of a supernova explosion are presented. Simulation has been done for the real equations of state and neutrino energy losses have been taken into account. Simulation has been done on the basis of an Implicit Lagrangian scheme on atriangular grid with grid reconstructuring. It is shown that, due to differential rotation of the star, a toroidal component of the magnetic field appears and grows with time. Rotational momentum transfers outwards as the toroidal component grows with time. With the evolution of the process, part of the envelope of the star is ejected. The amounts of the thrown-off mass and energy are estimated. The results of the simulation could be used as a possible explanation for the supernova explosion picture.

For a number of interesting contributed papers at the JD8 it was not obvious at the meeting or later that their contents and conclusions are germane to the main theme of secular evolution evidences. The editors have decided that these papers should be listed by title only. They appear below in alphabetized order by (first or only) author.

Insights into both the detailed composition of Jupiter’s atmosphere and unexpected local meteorological phenomena were revealed by in-situ measurements from the Galileo Probe Neutral Mass Spectrometer taken on December 7, 1995. Measurements of the neutral atmospheric composition from a pressure of 0.5 bar to approximately 21 bar revealed the mixing ratios of the major species helium and hydrogen as well as numerous minor constituents including methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. This instrument measured the isotope ratios 3He/4He, D/H, and 13C/12C as well as the isotopes of neon, argon, krypton, and xenon. A summary is given of progress that has been made in refining preliminary estimates of the abundances of condensable volatiles and noble gases as a result of an ongoing laboratory study using a nearly identical engineering unit. The depletion of simple condensable species to depths well below their expected condensation levels is explained by a local downdraft in the region of the probe entry. The mass spectrometer data suggests that different species may recover at different depths and this may be due to lateral mixing of Jovian air.

The character of the winds and the amount of mass-loss from stars during the red giant and supergiant stage of evolution are critical to the progression of that evolution. We therefore summarize here the results of a series of programs utilizing the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST) to study the winds and mass-loss from the surface of evolved, low-gravity cool stars. We discuss the structure of the chromospheres in which the base of these stellar winds lie, the velocity of the wind and its acceleration with height, and what these spectra tell us about the mass-loss from these stars. Because of its relevance to this Joint Discussion, we will also discuss in some detail what we have learned about real-time variability of these phenomena and the implied somewhat erratic nature of the mass-loss process in at least some of these stars.

Galileo radio-occultation measurements show that all four of the Galilean satellites possess ionospheres. Peak ionospheric densities for the icy satellites are several thousand electrons per cubic centimeter, and the distributions are not spherically symmetric. Io’s ionosphere is much denser and remarkably similar to that measured by Voyager.

For more than a decade we have been able to acquire and analyse a significant amount of photometric data of the highly variable R Coronae Borealis (RCB) stars. This has made been possible by a photometric service observing programme instigated at the Observatory. These photometric data have been combined with less extensive spectroscopic coverage, particularly of the decline phase of these stars. These have been supplemented by observations obtained at Mount Stromlo and Siding Spring Observatories for a radial velocity study. Significantly more spectroscopic observations are now being acquired with the development of a new medium resolution spectrograph at Mount John University Observatory.

In this poster we will present recent photometric and spectroscopic results for a number of the RCB stars in our sample. This observational and analysis work can be used to provide further insight into the nature of these stars, their likely progeny and progenitors and the processes that are involved in the formation and evolution of the obscuring dust clouds which cause the decline phase.

One important aspect of satellite-magnetosphere interactions concerns surface modification effects resulting from ion sputtering and/or electrostatic transport. For example, the Galileo measurements showed that the net mass loss rate at Europa could be as much as 40 meters of material per 100 million years. Magnetospheric ion-sputtering effects therefore have the interesting potential of providing an independent method to date the age of Europa’s surface. Ion sputtering can also lead to the ejection of large amounts of H atoms and H2 molecules into the Jovian magnetosphere as well as the formation of extended oxygen exospheres in the vicinity of the Galilean icy satellites. The newly discovered ionosphere of Europa could be of sputtering origin as well.