Abstract:
We have imaged the circumstellar debris disk around the A0 Ve/B9.5 Ve star HD 141569 (D = 99 pc), at λ = 12.5, 17.9, and 20.8 μm using the Keck II telescope, and confirm the general morphology from other recently published mid-infrared observations. Model fits to an assumed flat radially symmetric dust disk yield an inclination i = 53° ± 5° and a position angle of -6° ± 4° for the tilt axis and indicate the presence of a depression in optical depth by a factor of about 4 within a radial distance of 30 AU (0ˮ.3) from the star. Such a depression is suggestive of a density depletion and is consistent with published spectral energy distributions that indicate the absence of a near-infrared excess even though a mid-infrared excess is present. Our mid-infrared results, in conjunction with previously published near-infrared scattering images, suggest that the two wavelength regimes are viewing, respectively, the inner and outer parts of a common disk structure, which is dominated by small (probably submicron) grains throughout.
