Infrared observations of SS433

Abstract

The special features of SS433 have been chronicled over the past 12 months^1–4. Most unusual of its features is the triple set of hydrogen and helium emission lines. Whilst one of these sets remains at rest, the other two exhibit velocity peregrinations of amplitude 0.27 c. These moving satellites have been interpreted^5,6 as outflowing gas in directly opposing jets which precess with a period of 164 days. I describe here observations of SS433 in the 1–4-µm spectral region made in March and April 1979 with the 3.9-m Anglo–Australian Telescope. These observations show that the Paschen and Brackett lines of hydrogen also exhibit moving satellites, substantiate the high reddening deduced from optical data, and indicate surprisingly strong free–free emission in the near IR.