A ring of warm dust in the HD 32297 debris disk

作者：Fitzgerald Michael P^*; Kalas Paul G; Graham James R

来源：Astrophysical Journal, 2007, 670(1): 557-564.

DOI：10.1086/521699

• circumstellar matter
• infrared : stars
• planetary systems : protoplanetary disks stars : formation
• stars : individual (HD 32297)

We report the detection of a ring of warm dust in the near-edge-on disk surrounding HD 32297 with the Gemini North Michelle mid-infrared imager. Our N'-band image shows elongated structure consistent with the orientation of the scattered-light disk. The F-v(11.2 mu m) = 49.9 +/- 2.1 mJy flux is significantly above the 28.2 +/- 0.6 mJy photosphere. Subtraction of the stellar point-spread function reveals a bilobed structure with peaks 0.5"-0.6" from the star. The disk is detected out to the sensitivity limit at similar to 1", and the flux in each lobe is symmetric to within 10%. An analysis of the stellar component of the spectral energy distribution ( SED) suggests a spectral type later than A0, in contrast to commonly cited literature values. We fit three-dimensional, single-size grain models of an optically thin dust ring to our image and the SED using a Markov chain Monte Carlo algorithm in a Bayesian framework. The best-fit effective grain sizes are submicron, suggesting the same dust population is responsible for the bulk of the scattered light. The inner boundary of the warm dust is located 0.5"-0.7" (similar to 65AU) from the star, which is approximately cospatial with the outer boundary of the scattered-light asymmetry inward of 0.5". The addition of a separate component of larger, cooler grains that provide a portion of the 60 mu m flux improves both the fidelity of the model fit and consistency with the slopes of the scattered-light brightness profiles. The peak vertical optical depths in our models [similar to(0.3-1) x 10(-2)] imply that grain-grain collisions likely play a significant role in dust dynamics and evolution. Submicron grains can survive radiation pressure blowout if they are icy and porous. Similarly, the inferred warm temperatures (130-200 K) suggest that ice sublimation may play a role in truncating the inner disk.

• 出版日期2007-11-20
• 单位国家自然科学基金委员会