Solar activity varying with an 11-year cycle is chaotic at large time scales. The evidence comes from an analysis of observations of the sunspot number and of radioactive carbon. Thereby an estimate of the dimension of the solar attractor can be obtained.

The origin of the sunspots can be associated with the interactions of the regular, large-scale, chaotic, and intermittent magnetic fields.

Spherically symmetric models for classical novae as thermonuclear run-aways (TNR) of hydrogen-rich, accreted, envelopes on top of cold white dwarfs (WD) are in very good agreement with observations (Starrfield, Sparks & Truran 1974, 1985; Prialnik, Shara & Shaviv 1978; Prialnik 1986; MacDonald 1980). Multi-dimensional investigations are needed since the burning rate is very sensitive to the temperature and small fluctuations in temperature can lead to large differences between the flash times of different points on the burning shell; these differences can be much larger than the rise time of the nova light curve. Convection is assumed to be the mechanism that couples the burning process at different points in the shell so that the overall phenomena is spherically symmetric.

The various mechanisms whereby stars might lose matter are considered, together with the observational evidence of the mass loss rates associated with these mechanisms. The results are shown in a diagram giving the fractional mass that a star loses by various mechanisms as a function of initial mass.

This study is based on the catalogue of 69 open clusters by Barkhatova et al. (1987) and cluster distances taken from Hagen (1970). Most of the dimensionless characteristics discussed here are insensitive to the distance scale. Galactocentric cylindrical coordinates of clusters and the corresponding velocities have been calculated with the accepted galactocentric distance of the Sun R⊙ = 8.2 kpc and the galactocentric velocity of the Sun sR = −9 km/s, sθ = 228 km/s, sz = 7 km/s.

Few studies concern the H alpha profile of the Be stars and it is difficult to do a fine analysis of the line structure, and of its variations from the results obtained with different resolutions and accuracies.

Then, it was useful to apply modern technics for the observation of this line to get an homogeneous material, sensitive enough to show fast variations of the order of few minutes because an accurate photometry is available using linear response receivers.

Sanduleak and independently Seggewiss discovered a very red star near the open cluster NGC 6231. Bessell and collaborators concluded it to be a variable of the R Coronae Borealis type.

A pair of spectrograms of this object were obtained in July 1970. The spectrograph dispersion in the range of 3800–4500 Å is around 80 Å mm−1 and in the range of 4500–7000 Å 155 Å mm−1.

An outstanding feature of the spectrograms is their ‘veiled’ aspect, making it rather difficult to observe the lines. We observe the 4226 Å of Ca I, H and K of Ca II, 4030/4034 Å of Mn I, the G band; and several lines belonging to the Fe I multiplets. The Hα and Hβ lines are clearly seen in emission. Hδ is absent or very faint. A spectrogram of RY Sagitarii taken in July 16, 1971, when the visual magnitude of the star was around 4 mag. below its maximum light, shows some similarities with the spectrograms of the Sanduleak-Seggewiss star, e.g. they do not show the ultraviolet CN absorption bands and in the spectra of both stars a line is seen at approximately 3896 Å, which may be H8.

If we accept that the star belongs to NGC 6231, its distance modulus is 11.5. Its intrinsic color may be assumed to be close to (B–F)0 = 1.0(G or K star). The observed color is (B–K) = 3.5. Adopting R = 3, the visual absorption is 7.5. As the visual magnitude of the star is V= 12.5, its absolute magnitude becomes – 6.5.

Details will be published elsewhere.

Six streams of dust were unexpectedly detected by the Ulysses dust detector while this spacecraft was approximately within one AU distance from Jupiter (Grün et al., 1993). Stream durations ranged from hours to days for individual streams. It was clear that the dust in these streams (or bursts), from their directionality of approach to the spacecraft and from the nearness of stream occurrences to Jupiter, emanated from the Jovian system.

Following the original report, Baguhl et al. (1994) later relaxed the criteria for differentiating true dust impacts from “noise pulses” and found almost triple the number of dust impacts in the six streams already found. They also found 5 more streams that, except for one stream, clearly emanated from the Jovian system. The criteria were relaxed in such a way as to not introduce “noise events” into the data.

Rotation is one of the most important observable in stellar astrophysics driving strongly the evolution of stars. This review presents the main observational results on the rotation of Red Giant and Horizontal-Branch stars carried out along the past 50 years. The review brings, in particular, the most recent results based on very accurate measurements of rotational velocity obtained mostly along the last decade.

Extensive spectroscopic studies of stars with and without planets have concluded that stars hosting planets are significantly more metal-rich than those without planets. More subtle trends of different chemical elements begin to appear as the number of detected extrasolar planetary systems continues to grow. I review our current knowledge concerning the observed abundance trends of various chemical elements in stars with exoplanets and their possible implications.

The basic requirements for high precision spectral line profile measurements are reviewed, with the observatory at the University of Western Ontario serving to illustrate several of the points.

We summarize here some of the distribution properties of CO clouds in our galaxy as determined by observation and by computer simulations of these observations. The simulations adequately account for the number of clouds, their spatial separation, and their relative velocities with respect to one another. The principal shortcoming of the axisymmetric simulations is their failure to describe adequately the clustering of clouds seen in the velocity-longitude domain.

Observations of the night-sky brightness were organized at 106 places in Japan by a promotion of the Environmental Agency with the help of many local governments. Two kinds of measurements were carried out: 1) Number of stars were counted in a region of triangle formed by Alpha Lyr, Epsilon Lyr, and Zeta Lyr by at least 10 contributors at each point. 2) Photographs of a star field at the zenith at each point were taken with the same type of camera and film. These results gave us a good idea on distribution of night-sky brightness in Japan.

It is becoming increasingly evident that the older stellar components of the Magellanic Clouds are significantly younger, on the average, than the old star component of the Galaxy. Magellanic Cloud red globular-like clusters of the NGC 419 variety, and the common field stars of similar type, are almost certainly to be classified as intermediate-age populations by galactic standards. The oldest galactic population, seen in the galactic halo, globular clusters, and oldest galactic clusters, is apparently very sparse in the Magellanic Clouds, although in the SMC at least something very similar is seen in and near NGC 121.

A method for testing the possible correlation between axial rotations of pairs of stars is developed. The test is applied to a sample of visual binaries. It is concluded that some kind of coupling between the spins of components of visual binaries does in fact exist.

Radial and nonradial pulsations are excited in low-mass helium stars with effective temperatures between 7000 and 35000 K. In the case of the most luminous stars, these are driven by strange-mode instabilities (Saio & Jeffery 1988). Less luminous helium stars are mostly non-variable, except around 25000 K. V652Her is the prototype radially pulsating helium star, with Teff ~ 25000 K and a pulsation period of 0ḍ08 (Hill et al. 1981). The pulsation was only understood to be driven by the K-mechanism with the introduction of Z-bump opacity (Saio 1993).

The importance of Z-bump instability in low-mass helium stars has been investigated further through a series of pulsation models (Jeffery & Saio 1999a). It is shown that Z-bump pulsations can persist to surprisingly high hydrogen abundances in low-mass stars, and may consequently be excited in several helium-rich hot subdwarfs with Teff ~ 25000 K. Within the Z-bump instability region, both radial and nonradial pulsations are excited, and multi-periodic variability is expected.

Pulsation properties are closely linked to the global dimensions of a pulsating star by the period – mean density relation. When spectroscopic measurements are also available, the twin constraints of period and surface gravity can place very tight limits on the stellar radius (Jeffery & Saio 1999b). These are in excellent agreement with independent measurements for V652 Her and place a lower limit on the mass of the recently discovered Z-bump pulsator BXCir (Kilkenny et al. 1999).

Collecting all the data and references for a given star is generally a very time-consuming task, because the star may have many identifications. It is therefore a very first need to know the various identifications which may be used in the primary literature concerning a given star, in order to retrieve the whole set of information about the star.

The Catalogue of Stellar Identifications (CSI), which tries to solve this problem of cross-identifications, is therefore the fundamental file of the Stellar Data Center. It was created five years ago by J. Jung (1971), who was the first Director of the Center, with the help of Madame Bischoff and Madame Morin. The CSI was first a merging of some fundamental catalogues: SAO, HD, AGK2, CPC (Cape Photographic Catalogue for 1950), YZ (Yale Zone Catalogue), and GC. For each star, the information was the following:

On résume l’ensemble des décalages vers le rouge dont on dispose à partir de la raie 21 cm. La plus grande valeur obtenue pour la raie HI en émission est z =0.0369, et z = 0.692 en absorption. Il y a un excellent accord avec les décalages vers le rouge mesurés optiquement (lorsqu’ils existent). Les deux techniques donnent la même valeur (en moyenne), et montrent que les décalages vers le rouge sont indépendants des longueurs d’onde dans un intervalle de longueur d’onde de ~5x105 et un intervalle en z de -0.0012 à +0.692. C’est une condition nécessaire, mais non suffisante pour interpréter les décalages vers le rouge par l’effet Doppler. Des limites sont fixées pour la variation possible de certaines constantes atomiques fondamentales en fonction de z, et si z est une mesure de la loi d’expansion de Hubble, en fonction du temps, jusqu’à des temps au moins égaux à 35% de l’âge de l’Univers.

Increased sophistication in both, direct impact detectors and zodiacal light measurements encourages to discuss the compatibility of the results obtained by these quite different methods of investigating interplanetary dust. Taking recent measurements of particle fluxes and velocities obtained by the space missions of Pioneer 8/9 (Berg and Grün 1973), Heos 2 (Hoffmann et al. 1975), and comparing them with submicron-sized craters on lunar surface samples (Schneider et al. 1973, Fechtig et al. 1974) there seem to be two types of interplanetary dust populations: larger (>10−12 g) micrometeorites orbiting around the sun as the classical zodiacal dust cloud and a second component of very small (<10−12 g) particles coming radially from the direction of the sun with high velocities (>50 km/s). On the basis of the flux data referred to above and adopting for both components velocities of 10 or 50 km/s relative to the detector, respectively, a differential distribution function n(a) · da was found for the particle radii (a) as shown at a logarithmic scale in fig. 1. A density of 3 g/cm3 was adopted in order to convert particle masses into radii. The regions A, B, C (see Table 1) correspond approximately to the regimes of “submicron particles”, the classical zodiacal cloud particles, and the meteoritic component of the interplanetary dust complex. From this information the brightness I(ε) of the zodiacal light in the ecliptic plane can be computed as a function of elongation by approximating the distribution function n(a) in the different regions by simple power laws a−k ·da and by adopting a resonable scattering function σ(θ) for the average scattering behaviour of one particle of the mixture depending on the scattering angle θ. By use of an inverse (v = 1) decrease of particle number densities n = no · r−v with solar distance r(AU), where no is the number density at r=1 AU, one obtains with a particle size distribution law n(a)da ~ a−k da in the different intervals of sizes (Table 1) the intensity of the zodiacal light (in stars of 10th magnitude per square degree, S10) as shown in fig. 2. The two models (Maximum, Minimum) correspond to an upper and to a lower limit of particle number densities compatible with the in situ measurements, respectively.