Spatial Variations in the Mid-infrared Spectrum of IRC+10216

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Session 18 -- Stellar Spectra: Individual Objects
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[18.02] Spatial Variations in the Mid-infrared Spectrum of IRC+10216

G.C. Sloan, M.P. Egan (Phillips Lab.), R.F. Shipman (Phillips Lab. and Wyoming)

We have observed the extreme carbon star IRC+10216 with a long-slit mid-infrared spectrometer. Maximum entropy reconstructions of the images, taken with the slit oriented north/south and east/west, reveal three major components. A bright, symmetric central core with a full width at half maximum of two thirds of an arcsecond dominates the total emission from the source. Its spatial and spectral properties are consistent with a full or partial shell of optically thick amorphous carbon dust. An elongated dust shell (4$''$ N/S $\times 3''$ E/W) surrounds the central core and shows strong SiC emission. We have also detected unusually blue radiation from 0$.\negthinspace''$5 south and 1$.\negthinspace''$0-1$.\negthinspace''$5 north of the central core, inside the outer shell. Scattering alone cannot produce this emission because the central star does not radiate strongly enough at 8 $\mu$m. Amorphous carbon dust 0$.\negthinspace''$5-1$.\negthinspace''$0 from the central star would not be hot enough to fully fit the observed spectra, although a combination of thermal emission and scattering might. Other possibilities include flourescent processes or emission in shock fronts in the polar outflows.

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