THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT
1998

2. Scientific Highlights from 1998

UKIRT continued to be used for a remarkably wide range of science programmes; highlights are identified below from the two semesters in 1998 (with a slight extension into 1999 due to the plethora of results from UFTI early in the year).

2.1. Sub-Stellar, Stellar and Interstellar

The search for brown dwarfs continued apace, with a number of novel approaches including the use of the Orion molecular cloud to mask sources in the background field (Roche & Lucas, Oxford). This programme has turned up a number of extremely promising candidate brown dwarfs.

In an ambitious programme which has required very sophisticated data reduction to approach a result, velocity variations due to Earth-mass companions in the habitable zone near brown dwarfs were sought by Walker (UBC), Ramsay Howat (UKATC) and Puxley (Gemini). This programme uses telluric near-infrared water vapour lines to provide velocity fiducials, in a search for velocity variations due to planetary companions to brown dwarfs. Velocity accuracy of around 1 km/s has been obtained, and further improvements are expected with modified cross-correlation methods.

High spatial-resolution imaging polarimetry of 20 protoplanetary nebulae was carried out by Young (Hertfordshire) in semester 1998A. The polarized flux revealed a resolved, detached shell around IRAS 19114+0002, and many other targets were found to be highly polarized including some with no evidence of asphericity. This programme used IRCAM3 with 2 x magnifier and IRPOL.

Spectroscopy of a sample of O-rich stars was obtained by Sylvester (UCL) with CGS3. The targets were selected on the basis of unusual IRAS low-resolution spectra, suggesting the presence of silicon carbide. The Unidentified (but probably carbonaceous) Infrared Bands were detected in two sources, interestingly in the light of the standard expectation that all carbon in O-rich stars is bound up in CO.