Ian R. Tuohy

Evidence for X-ray emission from Kepler's supernova remnant

THE remnant of Keplers supernova of 1604 AD has long eluded detection at X-ray wavelengths, principally because of its proximity to a source confused region in the direction of the galactic centre. We present here the first evidence for weak soft X-ray emission from Keplers remnant, which was beyond the capability of earlier X-ray surveys1 but is now possible because of the increased sensitivity provided by the low energy detectors (LEDs) of the A 2 experiment on the HEAO 1 spacecraft. (The A 2 experiment on HEAO 1 is a collaborative effort led by E. Boldt of GSFC and G. Garmire of CIT, with collaborators at GSFC, CIT, JPL, and UCB). The LEDs are described in detail by Rothschild et al.2 Briefly, the data reported here were acquired using the LED1 narrow field of view (1.5° FWHM in the scan direction) which has an effective area of 175 cm2 and is sensitive to X-rays between 0.2 and 3 keV.

STARLAB: An Ultraviolet/Optical Space Telescope

Mount Stromlo and Siding Spring Observatories are actively developing large format photon counting detectors suitable for operation in space over a broad wavelength range. It is intended that these detectors be used in the Scientific Instrument Package of the STARLAB telescope. A description is given of the STARLAB facility, with emphasis on the contribution being made by Australia.

Zeeman Features from Accretion Columns in AM Herculis-Type Systems

Absorption features seen in the bright phase spectra of E1405-451 are identified with Zeeman features of Hα originating from cool (T∼104–105°K) material surrounding the accretion shock. The presence of apparently unshocked material surrounding the cyclotron emission region is surpring and may indicate that accretion occurs onto a larger fraction of the stellar surface than had previously been thought possible.

A Dynamical Study of the Young Oxygen-Rich Supernova Remnant in the Small Magellanic Cloud

We present a velocity map of the young oxygen-rich supernova remnant (1E0102.2–7219) in the Small Magellanic Cloud, obtained with the Anglo-Australian Telescope. The velocity structure is complex, and implies a high degree of asymmetry during the Type II supernova explosion. Our data can be modelled geometrically in terms of a severely distorted ring of oxygen-rich ejecta. This result, together with the evidence for expanding rings in similar remnants, suggests non-spherical ejection to be an intrinsic characteristic of Type II supernovae. We have also obtained two-dimensional spectroscopy of the diffuse halo of emission which partially surrounds 1E0102.2–7219. The halo exhibits the high excitation line of HeII λ4686, and is either a fossil HII region created by a UV flash accompanying the supernova, or alternately, is being excited by intense UV radiation from the remnant itself. It is the first clear association of a high excitation region with a supernova remnant.