Abstract

Observations of the interstellar and circumstellar absorption components obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) along the line of sight toward the Wolf-Rayet-luminous blue variable (LBV) system HD 5980 in the Small Magellanic Cloud are analyzed. Velocity components from C I, CI *, C II, CII *, C IV, NI, N V, O I, Mg II, Al II, Si II, Si II*, Si III, Si IV, S II, S III, Fe II, Ni II, Be I, Cl I, and CO are identified, and column densities estimated. The principal velocity systems in our data are (1) interstellar medium (ISM) components in the Galactic disk and halo (V-hel = 1.1 +/- 3, 9 +/- 2 km s(-1)); (2) ISM components in the SMC (V-hel = +87 +/- 6, +110 +/- 6, +132 +/- 6, +158 +/- 8, +203 +/- 15 km s(-1)); (#) SMC supernova remnant SNR 0057 - 7226 components (V-hel = +312 +/- 3, +343 +/- 3, +33, +64 km s(-1)); (4) circumstellar (CS) velocity systems (V-hel = -1020, -840, -630, -530, -300 km s(-1)); and (%) a possible system at -53 +/- 5 km s-1 (seen only in some of the Si II lines and marginally in Fe II) of uncertain origin. The supernova remnant SNR 0057 - 7226 has a systemic velocity of +188 km s(-1), suggesting that its progenitor was a member of the NGC 346 cluster. Our data allow estimates to be made of T-e similar to 40,000 K, n(e) similar to 100 cm(-3), N(H) similar to (4-12) x 10(18) cm(-2) and a total mass between 400 and 1000 M-. for the supernova remnant (SNR) shell. We detect C I absorption lines primary in the +132 and +158 km s(-1) SMC velocity systems. As a result of the LBV-type eruptions in HD 5980, a fast-wind/slow-wind circumstellar interaction region has appeared, constituting the earliest formation stages of a windblown H II bubble surrounding this system. Variations over a timescale of 1 year in this circumstellar structure are detected.