We report the codiscovery of the spatially-resolved dust disk of the Vega-like star HR 4796A. Images of the thermal dust emission at λ = 18 µm show an elongated structure approximately 200 AU in diameter surrounding the central A0V star. The position angle of the disk, 30 • ± 10 • , is consistent to the position angle of the M companion star, 225 • , suggesting that the disk-binary system is being seen nearly along its orbital plane. The surface brightness distribution of the disk is consistent with the presence of an inner disk hole of approximately 50 AU radius, as was originally suggested by Jura et al. on the basis of the infrared spectrum. HR 4796 is a unique system among the Vega-like or β Pictoris stars in that the M star companion (a weak-emission T Tauri star) shows that the system is relatively young, ∼ 8 ± 3 Myr. The inner disk hole may provide evidence for coagulation of dust into larger bodies on a timescale similar to that suggested for planet formation in the solar system.
We present diffraction-limited, 10 mm imaging polarimetry data for the central regions of the archetypal Seyfert active galactic nucleus NGC 1068. The position angle of polarization is consistent with three dominant polarizing mechanisms. We identify three distinct regions of polarization: (1) north of the nucleus, arising from aligned dust in the narrow emission line region, (2) south, east, and west of the nucleus, consistent with dust being channeled toward the central engine, and (3) a central minimum of polarization consistent with a compact (≤22 pc) torus. These observations provide continuity between the geometrically and optically thick torus and the host galaxy's nuclear environments. These images represent the first published mid-IR polarimetry from an 8 m-class telescope and illustrate the potential of such observations.
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