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C. Grady (Eureka Scientific, NOAO, and GSFC), K. Stapelfeldt (JPL), M. Clampin (STScI), D. Padgett (SIRTF Science Center), B. Woodgate (NASA's GSFC), T. Henning (AIU and University Observatory, Jena, Germany), V. Grinin (Crimean Astrophysical Observatory, Ukraine), A. Quirrenbach (UCSC), B. Stecklum (Thuringer Landessternwarte Tautenburg, Germany), M. Sitko (U. Cincinnati), J. Biggs (Perth Observatory, Australia)
We present HST/STIS white light coronagraphic imaging data for the optically bright, classical T Tauri star, SU Aur. Previous optical imagery has detected "cometary" nebulosity beginning north of the star and wrapping around to the west and ultimately south (Nakajima & Golimowski 1995). The STIS data demonstrate that this nebulosity consists of a fan of nebulosity similar to that seen around R CrA, with wisp and clump structure down to the resolution limit of the telescope. This nebulosity has an opening angle of ~70 degrees and a vertical extent of at least 12.2" (1842 AU at d=151 pc). The fan is visible in WFPC2 V, R, and I images, in addition to the STIS broad-band (0.2-1.0 micron) data, indicating detection of reflection nebulosity. A distinctive feature of the HST imagery of SU Aur is the presence of radial streamers seen at V and in the STIS data. The central streamer, which roughly bisects the fan of nebulosity, extends at least 8" (1200 AU) from the star at PA=295+/-1 degrees. The STIS data demonstrate that this feature is accompanied, on the opposite side of the star, by a string of bow-shaped nebulosities, extending 7.3" (1100 AU) from the star at PA=114+/-1 degrees. We interpret the fan of nebulosity as arising from the walls of a partially exposed outflow cavity. The scale and morphology of the central streamer and the PA=114 string of knots are consistent with the appearance of bipolar outflows as seen by STIS.
SU Aur is a 4 Myr old (de Warf et al. 1998), 1.9+/-0.1 solar mass star. The bipolar outflow reported here is the second collimated outflow detected in association with an isolated, several million year old intermediate-mass star. Given the small number of coronagraphically imaged intermediate-mass stars, this result indicates that collimated outflows, similar to those routinely detected in association with lower mass T Tauri stars, appear to be common among their higher mass analogs and to persist for much of the star's pre-main sequence lifetime.
Based on observations made with the NASA/ESA Hubble Space Telescope, as part of proposal 9136, the Perth Observatory, and the Thuringer Landessternwarte 'Karl Schwarzchild' Tautenberg. Support for this proposal was provided by NASA through a grant from the STScI, which is operated by the AURA Inc., under NASA contract NAS 5-26555.
The author(s) of this abstract have provided an email address for comments about the abstract: cgrady@echelle.gsfc.nasa.gov