Without doubt, the Leonid stream is the most famous of all the known meteoroid streams. The reason for this is not hard to find, the display of meteors that it produces at times far surpassess anything that any other shower can produce. The showers of 1799, 1833 and 1966 all have numerous engravings or photographs recording the splendidness of the displays. The recorded history of the appearances of spectacular Leonid displays dates back for two millenia. Though the associated parent comet, 55/P Tempel-Tuttle, was only discovered in 1861.

Observations over the past four decades have revealed significant changes in the spectrum of Hen-1357. Here we present HST images and spectra showing the most recent developments. In 1950, Henize saw only Hα in emission; but more recent observations by Parthasarathy et al. in 1992 showed strong forbidden lines consistent with a young planetary nebula. The spherically aberrated 1992 HST images, in which Bobrowsky first optically resolved the nebula, showed a compact nebula surrounding the central star. Nebular gas appeared most strongly concentrated in an ellipse with its major axis subtending 1".6 from NW to SE. If this ellipse is actually a circular ring viewed obliquely, then our line of sight is inclined from the symmetry axis by 5°. Above and below the ring of gas are two bubbles containing lower-density gas. At the tip of each bubble, there is a hole where the gas inside the bubbles has broken through and is now escaping. The windblown appearance is consistent with the blueshifted Si IV (1394-1403Å) and Al III (1855-1863Å) doublets observed by Parthasarathy et al. that indicated the presence of a strong stellar wind. The N V (1239-1243Å) to C IV (1548-1551Å) ratio has increased in recent years, consistent with a young nebula becoming increasingly ionized. Our recent (1996) spectra reveal additional developments that show the realtime development of this young nebula. Finally, the new HST Planetary Camera images of the nebula show detailed structure indicating a much more complex object than previously known, including the presence of a companion star 0".3 from the central star.

The peculiar outburst of the star baptized Sakurai’s Object (SO) is a conceivable example of a late He shell flash in a post-AGB object. The new source of nuclear energy forces such objects toward high luminosities and eventually low effective temperatures; they cross the HR diagram in a comparable fashion as FG Sge did in the past - i.e., they move noticeably on the HR diagram on human timescales. From monitoring campaigns of SO during the last year, first estimates of its cooling rate were derived and in particular cyclic light variability was established. We present first results from attempts to model stellar envelopes appropriate for SO. As we hypothesize the light variability to be attributable to stellar pulsations, we aim at constraining the basic stellar parameters based on stability analyses of our envelope models. Radial, nonadiabatic stability computations provided predictions of the modal content which should be observable as SO evolves. The particular components in such mode spectra of SO as they are to appear in the coming years should indeed help to constrain basic stellar parameters such as mass and luminosity.

The parent comet of the Leonids, 55P/Tempel-Tuttle, was recovered in 1997. An improved orbit for the interval 1366 to 1997 together with predictions before 1366 were calculated by Nakano (1997). These orbital elements are used to determine the longitude of the descending node of the cometary orbit so that this can be compared with the solar longitude of meteors found in historic records. A number of catalogues listing the appearances of meteors showers have already been published. Most notable of these are Imoto and Hasegawa (1958), Zhuang (1977), Mason (1995), Rada and Stephenson (1992), Kidger (1993) and Hasegawa (1996). Nearly fifty records of the Leonids from AD855 to the end of the 19th century are found in these catalogues.

We report on dramatic change in Sakurai’s object (RA: 17h52m32.7s, DEC: −17d41’07”, J2000.0). Discovered by the Japanese amateur astronomer Y. Sakurai in Feb. 1996, this object was first classified as a slow nova (Nakano S., Sakurai Y., Hazen M., McNaught R.H., Benetti S., Duerbeck H.W., Leibundgut B., 1996, IAU Circ. 6322). Further study revealed a spectrum rich in C, N and O-lines, but poor in hydrogen, as well as an old planetary nebula surrounding the star; it was then realized that this might be a star undergoing a late He-flash (Benetti, S. et al. 1996, IAU Circ. 6325). Despite the fact that 10 to 20% of all low mass stars will experience a late He-flash (Iben I. Jr., MacDonald J., 1996), it is an extremely rare observational event, due to its short duration. The most recent example is V605 Aql/A58 in 1919 (Eitter W.C., 1987, ESO Messenger, 14: see also Clayton C.G., De Marco O., 1997, AJ for a review).

In March 1997 we discovered dramatic change in the optical spectrum of Sakurai’s object using the 2.5 m Du Pont telescope at Las Campanas, Chile. The dominating features now are the prominent bands of CN (bandheads at 388.8 and 421.6 nm) and C2 (Swan-Bands at 439.2, 473.7, 516.5, 558.5 and 565.5 nm)(Kerber F., Gratl, H., Roth, M., 1997, IAU Circ. 6601) that were not evident a year ago (Duerbeck, H.W., Benetti, S., 1996, ApJ 468, L111).

The recognition of the astronomical origin of meteors is intimately connected to the Leonid meteors, and their tendency to “storm” with a period of 33 years. It was the Leonid storm of 1799, observed by Alexander von Humboldt among others, that first established the geographical extent of the phenomenon, with observations reported over 90 degrees of longitude and 60 degrees of latitude. During the 1833 storm, Olmsted (1834) at Yale and Twining (1834) at West Point established the radiant point in Leo, and the cosmic origin was clinched when H. A. Newton (1863), also at Yale, determined that the cycle repeated in intervals of sidereal years, not tropical years. Inspired by the 1866 storm, Adams (1866), Schiaparelli (1867), and Le Verrier (1867) determined a 33.25 year period and other orbital elements for the meteor stream; two years after the discovery of Comet Tempel-Tuttle in 1865, that comet was recognized as the parent body of the Leonid stream after von Oppolzer (1867) calculated a period of 33.17 years for the comet. Astronomers confidently predicted another storm in 1899, but none appeared, though there were good showers in 1901-1903. The years 1930-32 also brought fairly good showers, but 1966 brought the strongest storm witnessed in modern times, with an estimated 100,000 meteors per hour. Steady progress was made in meteor studies in the 20th century, especially with new photographic and radar techniques. The current question is what will happen in the 1997-1999 period; the only certainty is that the event will be studied with an even wider array of techniques.

The annual November Leonid meteor showers and the occasional Leonid meteor storms (e.g. 1833, 1966) are far better known than is the Leonid parent body, comet 55P/Tempel-Tuttle. Since A.D. 902, enhanced Leonid meteor showers have been recorded around the time of the parent comet’s returns to perihelion (Yeomans 1981). To date, the parent comet itself, however, has not been seen for more than a few days at any apparition except in late 1865 and early 1866. The impending perihelion return of comet Tempel-Tuttle again raises the possibility of strong meteor displays in 1998-99 as well as a chance to observe the elusive parent comet.

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models.

The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

The recorded history of the appearances of spectacular Leonid displays have been discussed for example in Yeomans (1981) and also in other papers at this meeting. The similarity in the orbits and that of comet 55P/Tempel-Tuttle is a strong indication that they are related. Further proof of this comes from the fact that the most spectacular displays associated with this stream are seen at time intervals that are multiples of the orbital period of the comet. The explanation for the occurrence of storms is thus that a well populated group of meteoroids are located close to the parent comet. Such a grouping of meteoroids would be formed if the comet were still active, not an unreasonable assumption. However, this raises an other question, namely why have the older of these meteoroids ejected perhaps several thousand years ago, not spread about the orbit. Standard models (eg Williams 1992) suggest that in 20 or so orbits meteoroids will have spread all the way from being close to the comet to being at the opposite point of the orbit. Hence, meteors in similar numbers should be seen every November coming from the Leonid stream. This is not the case, the average zenithal hourly rate of meteors in non-storm years being less than 10 as opposed to several thousand during a storm.

We present the results of the analysis of the photometrical behaviour of Nova 1934 DQ Her for a time interval about 40 years based on our data and those published by different authors. Our observation were done in UBVRI in 1982-1997 during apptoximatly 170 nights. They give the possibility of investigating different types of the activity of the old nova with amplitudes of brightness variability from several tenths of magnitudes to 1m. The light oscillations on a time-scale of either several days or several dozens of days would be conditioned by the change of the velocity of the accretion from the disc on the white dwarf caused by the intrinsic disc instability or by the irregular receiving of matter from the secondary component of the system - a red dwarf. The cyclic change of the light of DQ Her on a time-scale of about several years could be the reaction of the accretion disc in response to the activity of the secondary star.

Observations of the Wolf-Rayet eclipsing binary HD 5980 in the Small Magellanic Cloud show how one component of this binary system unexpectedly underwent an eruption transforming its spectral type from a hot WNE to a cooler and luminous WN11 type. Radial velocity analysis of the preoutburst spectra indicates that both components of the binary are massive stars of WN type. The component that erupted is found to be the more massive one. Differential analysis of the H Balmer and Heɪɪ Pickering emission line strengths indicates that the hydrogen content changes with the cooling of the spectrum. The maximum light of the eruption of HD 5980 had a duration of a few months, but the slow change from a WNE spectrum to WNL type took about 10 years. The present spectrum of HD 5980 is described. The environment and orbital parameters of this massive binary suggest that the lower metal content of the Small Magellanic Cloud changes the spectral appearance of WR type stars, as compared with their galactic counterparts.

We know the Leonid shower primarily from its record of visual appearances over the last millenium. The period of the stream and its status as a cosmic phenomenon are all intimately linked to historical visual observations of the stream. The advent of modern observational techniques in meteor astronomy such as radar and photography has not decreased the value of visual recordings of the stream; on the contrary, visual observations form our primary means of long-term monitoring of the shower.

1. Supernovae and Their Remnants

The Crab Nebula is expanding and its pulsar is slowing down, both on time scales that indicate some very interesting real-time stellar evolution must have occurred about 1000 years ago, as indeed we know from Chinese and other ancient records. The Crab was, in fact, the first SNR to be confidently identified as such and to have its expansion rate measured and the first pulsar to have its first and second time derivatives measured. Among the interesting related details are (a) the current expansion is a bit faster than the average since the 1054 explosion, indicating outward pressure from the relativistic electrons and magnetic field responsible for the synchrotron emission, (b) some of the central synchrotron emission features wiggle and oscillate around at much larger speeds than the expansion but in a non-secular way, (c) the braking index of the pulsar is about 2.5 rather than 3.0 (as predicted for a pure magnetic dipole emitter), (d) energy is conserved (it wasn’t obviously so before 1968), in that the pulsar is losing rotational kinetic energy fast enough to keep up the supply of optical and X-ray emitting electrons, and (e) glitches in the slowing of the pulsar (for which data go back to a 1964 balloon flight) indicate complex coupling of crust to interior, presumably a magnetic one.

Radar techniques can be a powerful adjunct for studying meteor storms in general because of their sensitivity, capacity for continuous observations and their use of current techniques facilitating the handling of data. While some radars are limited to only a range-time presentation (and so adequate for a time-profile description of a storm event), some facilities have the additional capacity to determine directional information or orbital elements which are valuable in delineating the dynamics and spatial structure of stream meteoroids. The following outlines the application of radar techniques to meteor storm recording and summarizes current and planned facilities.

The radio emission from supernovae provides a direct probe of a supernova’s circumstellar environment, which presumably was established by mass-loss episodes in the late stages of the progenitor’s presupernova evolution. The observed synchrotron emission is generated by the SN shock interacting with the relatively high-density circumstellar medium which has been fully ionized and heated by the initial UV/X-ray flash. The study of radio supernovae therefore provides many clues to and constraints on stellar evolution. We will present the recent results on several cases, including SN 1980K, whose recent abrupt decline provides us with a stringent constraint on the progenitor’s initial mass; SN 1993J, for which the profile of the wind matter supports the picture of the progenitor’s evolution in an interacting binary system; and SN 1979C, where a clear change in presupernova mass-loss rate occurred about 104 years before explosion. Other examples, such as SNe 19941 and 1996cb, will also be discussed.

Video techniques, which provide high sensitivity, portability, moderate spatial resolution and excellent temporal resolution promise to be one of the most valuable methods for study of the forthcoming Leonid storm(s). While an unintensified video camera will detect very bright meteors (typically about 0 magnitude), some sort of image intensifier is needed to attain high meteor rates. Most current systems use a second or third generation microchannel plate (MCP) image intensifier lens or fibre-optically coupled to a charge coupled device (CCD) video detector.

We are observing meteor showers using the MU radar located at Shigaraki, Japan. This is a Mesosphere, Stratosphere and Troposphere radar, belonging to the Kyoto University, with a frequency and a peak power of 46.5M.ffz and 1MW, respectively. This system is characterized by the versatility of the antenna array. By using four antennas out of 475 Yagi arrays together with four receiver channels, we can observe more than several hundred meteor echoes per hour. The beam applied at the meteor observation is a static “doughnut beam”, which is the rotational symmetrical pattern to the vertical line. This beam is effective enough to detect meteor echoes of which the zenith angle is smaller than about 50°, which characterizes the MU radar as an all sky monitoring radar of meteor echoes. For the low velocity meteors, most of the echoes satisfy a condition of the perpendicular reflection, and we can derive the position of the radiant point statistically, and succeeded its application for the Geminids (Watanabe et al. 1992a). For the high velocity meteors, most of the echoes are in the overdense condition. However, we can discriminate the echoes of a specific meteor shower out of the data by checking the echo duration, the height, the strength or the combination of them. We have been monitoring the Perseids from 1990, and succeeded to reveal the unusual activity in 1991 (Watanabe et al. 1992b). For the Leonids, we are continuing the observation from 1991. The drastic increase of the activity has been detected around 23h UT on November 17, 1994. The number of the observed long duration echoes, which came from possibly bright Leonids meteors, were 80 per hour. This should be the beginning of the Leonids activity toward the 1998-1999. We are planning to continue this observation until the end of the activity in the 2000’s.

It is inevitable that understanding of some indicators of stellar evolution is not so definite as we could wish. This can be equally true of observational material and of the beginning and intermediate stages of theoretical development. Even though these matters may be arguable and untidy, they are not negligible and, in fact, represent obvious recognized opportunities for the near future. It is possible that these matters are really the most valuable consequence of the meeting. Subject matter of this kind was presented at the JD8, in both invited and contributed forms, and their summaries follow here in the same approximation to stellar evolution stages that characterized Part II.

We present a new analysis of R127 (HDE 269858) - the classical Luminous Blue Variable in the LMC - during various phases of its spectral evolution over the past two decades, ranging from 9,000K to 28.000K. High quality CTIO, ESO and AAT spectroscopy are utilised to trace the variation in stellar properties for R127 with spectroscopic phase. R127 is found to possess almost identical stellar properties to AG Carinae during each stage, with a comparable helium enriched surface composition (H/He=2 by number). Results obtained from recent HST/FOS spectroscopy also indicate near identical nebular conditions to AG Carinae, with comparable electron densities and temperatures. In contrast with expectations, nebulae represent lightly processed material, suggestive of H-rich red supergiant envelopes. We discuss the importance of our results for LBVs, and the wider picture of massive stellar evolution within different environments.

Since September 1996 there has been in operation a new forward-scatter system for meteor observation transmitting signal simultaneously along two mutually almost rectangular baselines with the transmitter at Budrio (ϕB = 44.6° λB = 11.5° E) near Bologna, Italy and the receivers at Modra (ϕL = 48.3° N; λL = 17.3° E), Slovakia and Lecce (ϕL = 40.3° N; λL = 18.2° E) in Southern Italy. The equipment utilizes a continuous wave transmitting frequency at 42.7 MHz, with a mean power of 0.25 kW.