Conference Highlights: Stromlo Workshop on High‐Velocity Clouds

While it may be somewhat unusual to claim that an area of research only 35 years old is already undergoing a renaissance, this statement is not that far from the truth when one considers the field of high-velocity clouds (HVCs). A reflection of this assertion can be found by surveying the literature of the past 12 months; what started with a review in the 1997 Annual Review of Astronomy and Astrophysics by Bart Wakker and Hugo van Woerden culminated with the first international workshop devoted solely to HVCs, held 1998 August 14 and 15 at Mount Stromlo Observatory. In the interim, the field has been rife with new developments, a few of which even received coverage by the mainstream media, shedding much-needed positive light on this small, but hearty, band of researchers. The Stromlo Workshop on HVCs afforded the opportunity for each of these researchers to bring us up to speed on this rapidly evolving field. The summary that follows cannot do justice to all the workshop participants, and at some level is almost certainly biased by the present authors’ prejudices, for which we apologize in advance. Key contributions since the Wakker & van Woerden review include (1) the first determinations of a true metallicity for an HVC (i.e., ∼0.25 Z, for HVC 287.5 22.5 240, from Lu et al., and ∼0.1 Z, for Complex C, from Wakker et al.); (2) the recognition of a leading arm counterfeature to the Magellanic Stream by Putman et al., indicative of a tidal origin; (3) the first determination of a distance bracket for an HVC (i.e., kpc for Complex A, from van Woerden et al.); (4) d 4–11 the burgeoning cottage industry of emission-line (primarily Ha) observations of HVCs, led most noticeably by Tufte et al. and Bland-Hawthorn et al.; and (5) the proposal by Blitz et al. that HVCs are intergalactic remnants of the formation of the Local Group. While all-sky H i surveys for HVCs have existed since the late-1980s, a major step forward in ensuring uniformity in spatial and velocity resolution can be expected in the coming year with the release of Villa Elisa Southern Sky Survey (VESSS; Morras et al.), a direct analog to the Leiden-Dwingeloo Survey (LDS) in the north. Higher angular resolution surveys, on a sub-Nyquist sampled spatial grid, will ultimately be available once the Parkes Multibeam HVC Survey (Putman et al.) completes its scans of the sky from . A crucial d 90 – 25 first step will be the compilation of a new catalog of anomalousvelocity H i gas, from the LDS and VESSS, with far more