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Hubble Space Telescope (HST) and ground-based [O II] and [N II] images obtained in the period 1996-1999 reveal a complex, ionized optical nebula around the symbiotic binary CH Cyg extending out to 18'' or 5000 AU from the central stars. The observed velocity range of the nebula, derived from long-slit echelle spectra, is 130 km s-1. In spite of its complex appearance, the velocity data show that the basic morphology of the inner regions of the optical nebula is that of a bipolar outflow extending nearly along the plane of the sky out to some 2000 AU from the center. Even if the extension of this bipolar outflow and its position angle are consistent with those of the radio jet produced in 1984 (extrapolated to the time of our optical imagery), no obvious optical counterpart is visible to the original, dense radio bullets ejected by the system. We speculate that the optical bipolar outflow might be the remnant of the interaction of the bullets with a relatively dense circumstellar medium.

New Hubble Space Telescope images and Cerro Tololo Inter-American Observatory echelle spectra of the nebula around the symbiotic Mira Henize 2-104 are presented. The nebula consists of two nested hourglass-shaped structures and a collimated polar jet. Spatiokinematical modeling shows that all three outflows were ejected during approximately the same epoch, namely, about 5700 years ago, with the adopted distance of 4.4 kpc, in a mass-loss event unrelated to the present outburst. We present a tentative model in which the outer pair of lobes and jets are produced by a high-velocity outflow from the white dwarf companion to the Mira, while the inner, slowly expanding lobes are produced by the Mira wind itself.

UBV(RI)CCCD photometry of a 2.1 × 3.3 arcmin2field centred on the young open cluster Haffner 18 is presented and discussed. Spectroscopic classification of seven stars is also provided. 44 cluster members are identified, the earliest type being O6. The distance to the cluster is found to be 6.3 kpc, corresponding to a galactocentric distance of 12.7 kpc (for a Sun galactocentric distance of 8.5 kpc). An excellent fit to the observed main sequence is achieved by a solar composition isochrone of 2 × 106yr reddened by E(B − V)= 0.62 mag. Differential reddening of intracluster origin is present. Pre‐main‐sequence members are likely to be present over the 6 mag range explored by our observations (reaching down to earliest A spectral types). The presence of differential reddening and pre‐main‐sequence members agrees with the evidence for a bright parent nebulosity embedding the whole cluster. The radial velocity of the cluster is consistent with the Hron model of Galactic rotation.

This paper presents the first successful interferometric observations of angular diameters with the astrometer Fine Guidance Sensor (FGS) aboard the Hubble Space Telescope, the only optical interferometer operating in space. We report single-epoch angular diameters in visible light for the two Mira-type variables, R Leonis and W Hydrae, along two orthogonal directions. Although the relatively large bandpass of the instrument will limit the use of the new diameters for improving on our knowledge of the atmospheric structure of Mira variables, the milliarcsecond precision of the FGS measurements show with unprecedented clarity that the atmospheres of the two stars do not have circular symmetry, with the "major" axis exceeding the "minor" axis by about 11% and 20% for R Leo and W Hya, respectively. There is also evidence of nonsymmetric brightness distributions over the stellar disks. Besides the intrinsic interest of these results, asymmetries measured in a wide optical band, such as that used in the present work, are of relevance for the interpretation of the HIPPARCOS astrometry of Mira variables.