Long slit high and low resolution spectroscopy of S266 was conducted in order to investigate its precise nature. The Hα high resolution profile shows two different components; the narrow one extends all over the nebula while a very broad (ΔVFWHM = 700 km s−1) indicates that a strong wind is associated with the central star. From the narrow component we have worked out radial velocity (VLRS = 23 km s−1) which yields to a kinematic distance of a 9 kpc. This value implies a galactocentric distance of 19 kpc which makes this region one of the most distant in the Galaxy.

We have used the IRAM 30-m telescope to make high angular resolution observations of the silicon-bearing molecule, SiO and SiS in region of massive star formation. We have mapped the J=2-l and the J=5-4 lines of SiO with angular resolutions of 26 and 12” respectively. For all the sources mapped, the SiO emission is more extended that the beam. The extreme cases are found toward NGC7538 and W49N where the SiO emission has sizes of 1x0.5 pc and 2.8x1 pc respectively. This result is in contrast with the size of the SiO region in Orion-IRc2 which is of the order 0.03 pc. The maxima of the SiO emission are found at the position of the H2O masers. This indicates, as previously thought, that SiO emission probes the high temperature regions and/or the shocked gas and dust surrounding young stars. In the DR21(OH) region we have found the unique SiO source which is not associated to H20 maser emission. This SiO condensation is 40” south of DR21(OH) and it was first detected as a source of 350µm emission. The SiO emission is elongated in the east-west direction. From an analysis of the FIR continuum emission this object appears to be cool (Tk < 30) and it has been proposed that this source represents a pre-stellar condensation which may be evolving toward the star formation stage. The detection of SiO, howevwer, casts some doubts about the evolutionary stage of this source. Futher high angular resolution observations are necessary to establish the nature of this source.

It has been suggested that in NGC 2024 star forming processes are still going on, and dense cores found by 1.3 mm continuum observations are identified as possible protostellar condensations. To trace the molecular gas of high density, we observed the CS (J=7-6) line using the 30 m IRAM MRT for the first time at submillimetre frequencies (spat, resol. 8.5”). These and complementary observations of lower J CS/C34S transitions as well as the temperature probing NH3(1,1) and (2,2) non-metastable lines enable us to determine temperature and density of 3 selected cores, their kinematics and their masses. These parameters are compared with what is expected for protostellar condensations.

We present maps of the regions RCW57 and W59 in the frequency of 22 GHz with 4.’6 angular resolution. The thermal radio sources RCW57 II are well resolved in the map. RCW57 I presents, at this frequency a diameter twice as large as that reported at 5 GHz, obtained with similar resolution, but coincides with the size of the source at the wavelenght of 1 mm. In the map of the RCW57 region we detected also the supernova remnant G291.0-0.1, of plerionic type. We find a break in the spectrum of this source between 8 and 22 GHz, with the spectral index changing from −0.29 to −0.77. This behaviour is also found in other remnats of the same type.

The remarkable filament system seen in radio observations in the vicinity of the galactic center includes two thin filaments which arch away from the galactic plane (E.G. Yusef-Zadem et al 1984). The brightest part of each of these thermal structures is located at GO.10+0.02 and GO.07+0.04. Morris and Yusef-Zadem (1989) reason that photoionization by OB stars is unlikely on geometrical and morphological grounds. They suggest a magnetohydrodynamic mechanism to account for the radio emission and ionization. Erickson et al. (1968) were able to explain most of their observations of the far infrared (FIR) fine structure line emission from these locations in terms of a photoionization model.

The Chamaeleon dark clouds form a large complex of interstellar obscuring material situated at ≈ 15° below the galactic plane. Although it is accepted as being one of the closest low-mass star formation region to the Sun, its distance has been debated issues. The proposed distance is in general dependent on the value assumed for the ratio of total-to-selective extinction, which in the Chamaeleon clouds has proved controversial, leading to distances estimates ranging from 115 to 215 pc.

‘Classical’ stellar wind-driven bubbles are either energy or momentum driven, and evolve in smooth media containing only radial density gradients. Real bubbles are produced from winds from moving stars and which blow into non-homogeneous media. The resulting mixing of clump material can produce a variety of thermal, dynamical and chemical effects. In this review we discuss some of the modifications to classical bubbles which ensue, using observational examples where appropriate.

The contribution of A supergiant stars to the return of mass and energy to the interstellar medium is not very important. Abbott (1982) analised a sample of early stars and concluded that B and A supergiants provided less than 8 % of the mass input to the ISM by stellar winds. However, A-type supergiants are important in the framework of the stellar winds-mass loss phenomenology since they are located at the boundary between hot and cool stars, where radiative acceleration may not be sufficiently efficient to drive the wind.

In this review I will concentrate on older remnants, by which I mean those in which radiative cooling is important somewhere and the swept up mass is sufficiently large for the details of the initial explosion not to matter. For such remnants it is the optical emission which is crucial since it allows us to deduce a great deal about the physical state of the emitting gas provided we are careful about how we interprete it. Without discussing any particular remnant in detail, I will consider how large and small scale density variations in the ambient medium affect the appearance and energetics of such remnants.

An asymmetry of optical emission lines that appeared in Sept. 1988 is interpreted as evidence of dust condensation within the metal-rich ejecta of SN 1987A. A quantitative analysis of this spectroscopic effect is given and shown to be compatible with the photometric record. Moreover, observational and theoretical estimates of the bolometric light curve come into agreement when the far-IR excess is interpreted as thermal emission by grains in the ejecta. A grain population comprising small silicate grains with an admixture of graphite or amorphous carbon particles is suggested by the data. The relevance of this discovery to suggestions that supernovae are major sources of interstellar dust is briefly discussed.

As part of a general ESO program to monitor the spectrum of SN 1987A, we are collecting intermediate high resolution (R = λ/Δλ ≈ 2x104) spectra of the supernova. By the end of the year 1987 it was possible to see narrow emission features due to [OIII] and hydrogen in spectra taken with the ESO Cassegrain echelle spectrograph (CASPEC) (Wampler and Richichi 1988, 1989). At that time, the velocities of these lines were about 286 km/sec and their widths were about 14 km/sec (FWHM). It is almost certain that these lines arise from a cloud of highly ionized gas that was first detected in ultraviolet spectra obtained by IUE in May 1987 (Fransson et al. 1989). This cloud is presumably a circumstellar shell that surrounded the progenitor of SN 1987A and was ionized by the initial UV flash from the supernova explosion. In the ideal case of an expanding spherical shell that is large enough for light travel times to be important, one would expect the intensity of an emission line to increase and then decrease again as the light from the front of the shell fades. At the same time the velocity of the line would increase as the integrated light became dominated by light from the back (receding) hemisphere. The IUE light curve (Fransson et al. 1989) for the ultraviolet [NV] line was consistent with the photometric behavior expected from a nebula about 400 light days in diameter. At the distance of the LMC, one light year is equal to a span of one arc-second, and the photometric behavior of [NV] is consistent with the extent of the nebula measured by Wampler and Richichi (1989).

We consider the evolution of a multicomponent medium: stars and gas clouds embedded in an ambient gaseous medium. The stars and gas clouds are treated stellar dynamically, using a velocity moment expansion of the Boltzmann equation. The basic equations and interaction terms are discussed. Examples of 2-D numerical calculations are presented (see also Kunze et al., this meeting).

Several arclike structures are seen on the high resolution IRAS images (processes via GEISHA system of Groningen) centred on the Be star 6 Cephei, among others an extended bow shock which indicates the rapd motion of the star and the interstellar matter relative to each other. 6 Cephei is embedded in a giant infrared-emitting shell which is thougth to be a three million year old supernova remnant, therefore in this case the presence of the bow shock around the star shows the interaction of a supernova blast wave with the stellar wind of a Be star. In this paper an attempt is made to reveal the history of the interactions of the star with its surroundings during different periods of its life which are recorded on the infrared maps. Some aspects of the formation and evolution of 6 Cephei can be inferred also from its infrared environment.

We have mapped the CO J=2-l and J=l-0 emission with high angular resolution (about 10” and 20”, respectively) from the young planetary nebulae NGC2346, M2-9 and NGC6720 (the Ring nebula in Lyra). The observations were carried out by using the IRAM 30-m dish at Pico Veleta (near Granada, Spain).

The western part of the nebula N120, in the LMC, was observed in Hα with the equipment CIGALE at ESO. This equipment consists mainly of a scanning Perot-Fabry interferometer and a two-dimensional photon counting system. The spectral step used here is 0.41 Ǡover free spectral range of 8.24 Ǡ. The total field of view of 7’ x 7’ is covered by 256 x 256 pixels (each pixel being there 2.6” x 2.6”).

This paper reviews recent developments in the study of bipolar outflows and their possible collimation by disklike structures. The exciting stars of most bipolar outflows are embedded in dense cores, self-gravitating structures with masses in the range of 1 to 103M⊙. In many cases, these dense cores are flattened, with its major axis aligned perpendicular to the axis of the outflow. These flattened structures, the interstellar toroids, appear to play a role in the large scale (0.1 pc) collimation of the bipolar outflows. However, a considerable number of observations point to the presence of collimation on much smaller scales. In particular, the results of Sargent and collaborators have revealed the existence of circumstellar disks (with radii of ~1000 AU) that are gravitationally bound to their stars. I also review recent models of accretion disks around T Tauri stars have been successful in explaining the general features of the continuum spectra of T Tauri stars from the ultraviolet to the infrared. Some radio results that have not been considered by these models are discussed.

Open slit spectra of planetary nebulae, in which images of the object are recorded in the light of several spectral lines on a single plate, have long proven a useful diagnostic of nebular properties and morphology. Fortunately, the reasonably simple structure of most planetaries greatly aids interpretation of the images. The dust-enshrouded mass-losing asymptotic giant branch stars from which planetaries evolve have now also been imaged at millimeter wavelengths. These high-resolution images have demonstrated the role of photochemistry in molding the composition of circumstellar shells. This powerful techinique is less well-developed as a tool for analyzing the structure of localized density concentrations in molecular clouds, the cores in which stars form. Even pre-astral cores, in which stars have not yet formed, may have an extended and intricate geometry which renders mapping tedious and masks their true structure. Their basic pre-astral structure may be complexly contorted by the character and extent of star formation within them. How, then, does our perception of the structure of a core depend upon the line in whose light it is imaged? Which lines optimally determine physical structure? How should chemical differences, perceived by comparisons of images in different lines, be used to determine the physical characteristics of a core?

There is now a substantial body of evidence that disk-like structures of gas and dust surround many protostars and young stellar objects (e.g. Rodriguez, these proceedings). We are currently studying a number of these disks to establish whether they have properties compatible with those attributed to the proto-solar nebula, in the early stages of evolution of our solar system. The frequency with which such proto-planetary disks are associated with young stars is also being investigated.

We summarize the observed properties and deduced physical characteristics of the Beta Pictoris circumstellar nebula obtained from a detailed analysis of existing IR and optical data. On the basis of these results, we reject the hypothesis that the observed feature is a bipolar nebula surrounding an evolved star. We claim the nebula is a flattened disk of orbiting particles making up a planetary system in its clearing out phase as small grains collide, erode, and are swept out by radiation pressure.

Near-infrared images of the Serpens molecular cloud core have been carried out at UKIRT (Mauna Kea Observatory) using the infrared array camera, IRCAM. A large-scale diffuse nebulosity extending over the central part of the core is observed. Over 100 K-sources are detected in the 30 arc min2 cloud core. Some of them are PMS objects which were previously unknown. For the first time, a near-infrared counterpart of the far-infrared source Seroens FIRS1 has been detected. The 2.2 µm source appears as a point like object at the apex of an extended knotty, jet-like nebulosity oriented towards the northwest. In addition, a group of 11 stellar objects is seen in the position of the IR/radio source SVS4. These objects are embedded in a very faint nebulosity and form one of the densest clustering of young stars found in dark clouds.