Unveiling SU Aurigae in the Near-Infrared: New High Spatial Resolution Results Using Adaptive Optics

Abstract

We present new results on the circumstellar nebulosity around SU Aurigae, a T Tauri star of about 2 M_solar and 5 Myr old at 152 pc in the J, H, and K bands using high-resolution adaptive optics imaging (0.30") with the Penn State Near-IR Imager and Spectrograph at the 100 inch (2.5 m) Mount Wilson telescope. A comparison with Hubble Space Telescope STIS optical (0.2-1.1 μm) images shows that the orientation of the circumstellar nebulosity in the near-IR extends from position angle 210° to 270° in the H and K bands and up to 300° in the J band. We call the circumstellar nebulosity seen between 210° and 270° an ``IR nebulosity.'' We find that the IR nebulosity (which extends up to 3.5" in the J band and 2.5" in the K band) is due to scattered light from the central star. The IR nebulosity is either a cavity formed by the stellar outflows or part of the circumstellar disk. We present a schematic three-dimensional geometric model of the disk and jet of SU Aur based on STIS and our near-IR observations. According to this model, the IR nebulosity is part of the circumstellar disk seen at high inclination angles. The extension of the IR nebulosity is consistent with estimates of the disk diameter of 50-400 AU in radius, from earlier millimeter K-band interferometric observations and SED fittings.