Spatially resolved spectroscopy of Z Canis Majoris components

P. J. V. Garcia, E. Thiébaut, R. Bacon

Abstract
We present adaptive optics integral field spectrograph observations of the Z CMa binary in the 6203 Å-6528 Å, band with a spectral resolution of 3200 and spatial resolution of 0.24 arcsec, made with the OASIS instrument coupled to the PUE'O bonnette. Using the binary parameters derived from speckle interferometry, we are able to recover the spectrum of each component, in spite of a spatial sampling (0.11 arcsec) similar to the system separation (0.1 arcsec). The component that dominates the optical continuum presents a spectrum similar to the one from the system in its pre-outburst phase. The other component (so-called "IR companion") shows an emission line spectrum. Extended emission is detected in [OI]λ6300. This emission presents an unresolved peak plus an elongated structure, similar to that found in Classical T Tauri Stars' microjets. The low velocity component is unresolved and slightly shifted from the stellar continuum location. The high velocity component is extended but also contributes to the unresolved peak. This microjet is spatially associated with the infrared companion and with the system's powerful parsec-scale jet. The upper limit of the microjet width is 0.24 arcsec, and its length is ~ 1arcsec . This size combined with the material velocity results in a dynamical time scale of ~ 10 yrs, compatible with its origin in the 1987 outburst. Based on observations collected at the Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique, and University of Hawaii.

Astronomy and Astrophysics
Volume 346, Page 892
June 1999

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