Recent results obtained from studies of bipolar nebulae with a variety of techniques are described. Nebular polarization maps and spectropolarimetry, near-infrared spectroscopy, far-infrared photometry, radio maser and continuum work all have contributed to our knowledge of this heterogeneous class of objects. Some are certainly pre-main-sequence; others are likely to represent the rapid transition from red giant to planetary nebula. At least one dust-shrouded carbon star (CIT 6) and one visual binary with an O-star primary (MWC 349) have bipolar structure. Equatorial dusty disks must be common occurrences at different phases of stellar evolution.

I have examined all InfraRed Astronomy Satellite (IRAS) data relevant to the 173 galactic Wolf-Rayet (WR) stars in an updated catalogue provided by van der Hucht (priv. comm.), including the 13 stars newly discovered by Shara et al. (1991). Using the exact coordinates given in these lists, I have examined the IRAS Point Source Catalog (PSC), the Faint Source Catalog, Faint Source Reject Catalog, and generated 1-dimensional spatial profiles (“ADDSCAN”s), and 2-dimensional full-resolution images (“FRESCO”s). The goal was to assemble the best set of observed IRAS colour indices for different WR types, in particular for known dusty WCL objects. These colour indices define zones in the IRAS colour-colour plane. By searching the PSC for otherwise unassociated sources that satisfy these colours, I have identified potential new WR candidates, too faint to have been recognized in previous optical searches. I have extracted these candidates' IRAS Low Resolution Spectrometer (LRS) data and compared the spectra with the highly characteristic LRS shape for known dusty WCL stars. Any surviving candidates must now be examined by optical spectroscopy. This work represents a much more rigorous and exhaustive version of the LRS study that identified IRAS 17380-3031 (WR98a) as the first new WR (WC9) star discovered by IRAS (Cohen et al. 1991).

The class of Low-Excitation Herbig-Haro Objects are characterised by [SII] and [OI] lines which are comparable in strength to H-Alpha, by [NI] lines that are comparable to H-Beta, relatively weak [NII] and [OII] lines, little or no [OIII] emission and a very strong blue-UV “excess”. This blue and UV continuum in low-excitation HH Objects was noted as a problem by Brugel, Böhm and Mannery (1981), Ortalani and D'Odorico (1980) and Böhm, Böhm-Vitense and Brugel (1981). The first suggestion that it results from collisionally enhanced Hydrogen two-photon (2q) continuum was by Dopita (1981). The subsequent observations of Dopita, Binette and Schwartz (1982) proved that this was indeed the case. However, although very close correlations between this enhancement and the emission-line spectrum were found, a fair theoretical description could only be obtained for very youthful shock models with ages of order 30 years. However, there seems to be no reason why low excitation HH shocks should be much younger than the high excitation shocks.

The fact that bipolar flows are widespread among stars of very different spectral types is emphasized. First, the stars associated with the phenomenon are divided into broad types: protostars and pre-main-sequence stars; red giants; symbiotic objects; protoplanetaries; planetaries; novae and cataclysmic variables; and peculiar hot stars. Second, the evidence for circumstellar “disks” or toroids is considered among these different categories of star. Finally, the possible role of binarity is discussed.

We report a search for masers from the A-doublet of the ground-state of OH at 18cm, carried out with the Jodrell Bank Lovell Telescope and with the 25m Dwingeloo telescope. All objects north of δ = −20° which appear in the IRAS Point Source Catalog with fluxes > 1000 Jy at 60μm and 100μm were observed in all four lines and both circular polarisations over the required velocity range. Preliminary results of 52 maser sources are reported here.

I update previous estimates of the separate contributions for radiative energy, integrated total stellar wind mass and dust mass from Wolf-Rayet stars and other massive (OBA) stars. In the context of the intriguing dusty WC9 stars, I: (1) discuss the observability (or otherwise) between 0.4 and 23 μm of the condensation route from hot gas to carbon-rich grains; (2) urge caution in the use of 10 μm infrared spectra of these luminous stars to deduce the importance of silicates as a component of the interstellar medium, and (3) speculate on a possible new method for discovering new members of this relatively rare subtype based on IRAS Low Resolution Spectra. I review the observational evidence for dust condensation around SN 1987A.

We have constructed a detailed model for the infrared (IR) point source sky that comprises geometrically and physically realistic representations of the galactic disk, bulge, stellar halo, spiral arms (including the “local arm”), molecular ring, and the extragalactic sky. We represent each of the distinct galactic components by up to 87 types of galactic source, each fully characterized by scale heights, space densities, and absolute magnitudes at BVJHK, 12, and 25 μm, and a spectrum from the IRAS Low Resolution Spectrometer (LRS). Our model has been guided by a parallel Monte Carlo simulation of the Galaxy at 12 μm. The content of our galactic source table constitutes an excellent match to the 12 μm luminosity function in the simulation, as well as to the luminosity functions at V and K. We are able to predict differential and cumulative IR source counts for any bandpass lying fully within the IRAS LRS range (7.7–22.7 μm) as well as for the IRAS 12 and 25 μm bands. These source counts match the IRAS observations extremely well. The model can be used to predict the character of the point source sky expected for observations from future IR space experiments (e.g., ISO, SIRTF, LDR).

We are combining images in the mid-infrared (from MSX, the US Midcourse Space Experiment) with those from the high resolution UKST/AAO Hα survey of the Galactic Plane to investigate the relationship between the mid-infrared (MIR) and optical emission line properties of candidate Planetary Nebulae (PN) discovered by the Hα survey. Preliminary results indicate that only 10–20% of likely bona fide PN have a counterpart detected in the MIR. By sharp contrast one can readily recognize pre-main- sequence objects and HII regions emitting Hα and largely embedded in dust by the simultaneous presence of 8.3 and 21.3-μm emission suggestive of dust spanning a variety of temperatures. The sharpest criteria for recognizing true PN appear to be optical morphology and spectra (particularly the presence of [OIII]), and, where detected, MIR characteristics.

Combined ISO SWS and LWS spectroscopy is presented of the late WC-type planetary nebula nucleus CPD-56†8032 and its carbon-rich nebula. The extremely broad coverage (2.4–197 μm) enables us to recognize the clear and simultaneous presence of emission features from both oxygen- and carbon-rich circumstellar materials. Removing a smooth continuum highlights bright emission bands characteristic of polycyclic aromatic hydrocarbons (hereafter PAHs) in the 3–15 μm region, bands from crystalline silicates longwards of 18 μm, and the 43- and 62-μm bands of crystalline water ice. We discuss the probable evolutionary state and history of this unusual object in terms of (a) a recent transition from an O-rich to a C-rich outflow following a helium shell flash; or (b) a carbon-rich nebular outflow encountering an O-rich comet cloud orbiting in a Kuiper-belt-like distribution.

We use ISO-PHOT maps around five WN stars to derive their far-infrared fluxes. In some cases we also detect a nebula around the star.

We present new medium-deep wide field galaxy counts at J- and K-bands, performed in the ELAIS fields. The source detection limits are at J = 19.5 and K = 18.0 magnitudes. The sky coverage is 1 degree2, making our survey the largest to date at these wavelengths and magnitudes. Counts in this brightness range are critical for normalization of models when explaining the deepest galaxy counts. In our survey fields we find evidence for a higher than expected local galaxy density. If normalized to our counts, galaxy models do not need strong brightness evolution or exotic populations to be explained even at the faintest levels. We measure clearly sub-Euclidean slopes of d log N(m)/dm ~ 0.45 to 0.50 at 13 < K < 17.5 and 14.5 < J < 19. Normal, passively evolving stellar populations along with a high normalization of the local luminosity function and an open cosmological model best fit both the slope and amplitude of our number counts. We report a preliminary value, ~ 30 n Wm−2sr−1, for the K-band extragalactic background light using zodi-subtracted DIRBE-data and our observed star counts. The value is consistent with, e.g., Matsumoto (these Proceedings 2001) and Gorjian, V., Wright, E. L., & Chary, R. R. 2000, ApJ, 536, 550, but is considerably higher than extrapolations from faint galaxy counts.

Recognition of an isotropic cosmic near-infrared (NIR) and mid-infrared (MIR) background involves the removal of the zodiacal foreground (both scattered and reradiated), of the truly diffuse Galactic foreground (dominated by fluorescent bands of polcyclic aromatic hydrocarbons), and of resolved and unresolved Galactic point sources. I discuss model simulations of the near- and mid-infrared point source sky from which one can assess its particular contribution to the diffuse Galactic infrared foreground. I will also indicate the transitional stage which characterizes our knowledge of fundamental stellar parameters that are essential inputs to any such models. Using the latest version of the SKY model (Wainscoat et al. 1992; Cohen 1993; Cohen 1994; Cohen et al. 1994; Cohen 1995; Ruphy et al. 1997), I will demonstrate matches to deep point source counts for a variety of passbands and galactic latitudes, and will try to quantify the uncertainties achievable in model predictions of the integrated surface brightness due to the smearing of all these foreground point sources.

In 1988, a Joint Commission (9 and 25) meeting on the causes of the well-known limitations on the precision of infrared astronomy led to several suggestions to improve matters (see Milone 1989). These included better reporting of the photometric systems in use by practitioners, redesign of the infrared passbands to be more optimally placed inside the atmospheric windows, and development of a method to ascertain the water vapor content of the atmosphere when the astronomical infrared measurements were being made. An Infrared Astronomy Working Group was formed to look into the matter. Advice and suggestions were solicited from the community at large. All who volunteered information became, de facto, members of the Working Group. A small subgroup composed of Andrew Young, Chris Stagg, and Milone set to work on the central of the recommendations: improvement of the passbands. Young, Milone, k Stagg (1994) (hereafter YMS) summarized the work: existing JHKLMN and Q infrared passbands were found to be both far from standardized, and all too frequently defined, to various degrees, by the water vapor and other components of the terrestrial atmosphere. Following extensive numerical simulations with a MODTRAN 3 terrestrial-atmospheres model package, and Kurucz stellar atmospheres, we suggested a set of improved infrared passbands designed explicitly to fit within, and not be defined by, the terrestrial atmospheric windows; however, we sought to optimize them so as to get the maximum throughput consistent with plausible limitations on precision of manufacture of the filters. In 1995 and again in 1997, a number of improvements were made in the code with which the improved passbands were designed. While they do not much affect the optimization trials and thus the passband recommendations, they have been used to extend the modeling.

We present first efforts to establish a network of absolutely calibrated continuous infrared spectra of standard stars across the 1-35μm range in order to calibrate arbitrary broad and narrow passbands and low-resolution spectrometers from ground-based, airborne, balloon, and satellite-borne sensors. The value to photometry of such calibrated continuous spectra is that one can integrate arbitrary filters over the spectra and derive the stellar in-band flux, monochromatic flux density, and hence the magnitude, for any site. This work is based on new models of Sirius and Vega by Kurucz which were calculated by him, for the first time, with realistic stellar metallicities and a customized finely-gridded infrared wavelength scale. We have absolutely calibrated these two spectra and have calculated monochromatic flux densities for both stars, and isophotal wavelengths, for a number of infrared filters. Preliminarily, the current IRAS point source flux calibration is too high by 2, 6, 3, and 12% at 12, 25, 60, and 100μm, respectively.

We studied mammal and bird track formation at the northern edge of Lake Manyara, Tanzania, to develop models for interpreting fossil tracks and trackways. Lake Manyara is a closed-basin, alkaline lake in the East African Rift System. The area has a high vertebrate diversity, allowing us to investigate tracks in an environment similar to that of many ancient track-bearing sequences. Three study sites, two on mud flats adjacent to the lake margin and a third on a delta floodplain, provided contrasting environments in which to assess the types of biological data that can potentially be extracted from fossil trackways.

Our censuses of mammals and their tracks revealed that most species that occur within the study area leave a track record, and that common species leave abundant tracks, although numbers of trackways are not proportional to numbers of individuals. Logarithmic increases in track sampling area yield a linear increase in the proportion of both the medium and large-sized local mammals represented in a track record. Transect vs. area mapping methods produced different censusing results, probably because of differences in monitoring periods and areal coverage.

We developed a model of expected track production rates that incorporates activity budget and stride length data in addition to abundance data. By using these additional variables in a study of diurnal birds, we obtained a much better estimator relating track abundance to trackmaker abundance than that provided by census data alone. Proportions of different types of tracks predicted by the model differ significantly from the observed proportions, almost certainly because of microenvironmental differences between the censusing and track counting localities. Censuses of fossil tracks will be biased toward greater numbers of depositional-environment generalists and away from habitat-specific species.

Trackways of migratory animals were dominantly shoreline-parallel, whereas trackways of sedentary species were more variable. A strong shoreline-parallel environmental zonation at the Alkaline Flats site exerted an influence on trackmaker distribution patterns, initial track formation, and track preservation. Variations in habitat usage by different species, as well as species abundance and directionality of movement, were all important in determining the number of preservable tracks a species produced within a given environmental zone.

Fossil trackways are time-averaged, although over entirely different temporal scales than are bones. Unlike bones, tracks are not space-averaged. Therefore, wherever possible, fossil track and bone studies should be used to complement each other, as they provide fundamentally different pictures of paleocommunities. Tracks provide “snapshot” views of localized assemblages of organisms useful in reconstructing autecological relationships, whereas bones yield a broader image of a local fauna in which seasonal and microenvironmental variation are more commonly smoothed out.

A sensor which detects mechanical stresses and stores the position and the strength of these loads by color change of embedded quantum dots (QDs) is presented. The top and bottom electrodes of the sensor are inkjet-printed which leads to a fast and accurate deposition of thin (approx. 50 - 300 nm) and conductive layers. The used silver and poly(3,4-ethylenedioxythio-phene) polystyrene sulfonate (PEDOT:PSS) inks are optimized in terms of printability and opportunities of functionality forming without influencing the active layer of the sensor. The active layer of the sensor is spin-coated and consists of the QDs embedded in semi-conducting poly(9-vinylcarba-zole) (PVK). The hole transport characteristic of PVK and the band level alignment of the used materials ensures the preferred injection of only one type of charge carrier into the QDs. As a result the mechanical stress is visualized by a decreasing in photoluminescence (PL) of the QDs.