SIMBAD references

2007ApJ...663..543H - Astrophys. J., 663, 543-552 (2007/July-1)

Multispectral observations of lunar occultations. I. Resolving the dust shell around AFGL 5440.

HARVEY P.M. and OLDAG A.

Abstract (from CDS):

We present observations and modeling of a lunar occultation of the dust-enshrouded carbon star AFGL 5440. The observations were made over a continuous range of wavelengths from 1 to 4 µm with a high-speed spectrophotometer designed expressly for this purpose. We find that the occultation fringes cannot be fit by any single-size model. We use the DUSTY radiative transfer code to model a circumstellar shell and fit both the observed occultation light curves and the spectral energy distribution described in the literature. We find a strong constraint on the inner radius of the dust shell, Tmax=950±50 K, and optical depth at 5 µm of 0.5±0.1. The observations are best fit by models with a density gradient of ρ∝r–2 or the gradient derived by Ivezi{cacute} & Elitzur for a radiatively driven hydrodynamic outflow. Our models cannot fit the observed IRAS 60 µm flux without assuming a substantial abundance of graphite or by assuming a substantially higher mass-loss rate in the past.

Abstract Copyright:

Journal keyword(s): Stars: AGB and Post-AGB - stars: individual (AFGL 5440) - Stars: Mass Loss - Techniques: High Anular Resolution

Simbad objects: 5

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