• Chen, C. H.
• Wyatt, M. C.
• Thebault, P.
• Morlok, A.
• Manoj, P.
• Currie, T. M.
• Lisse, C. M.
• Sheehan, P.

Abstract

We have analyzed the Spitzer IRS 5 - 35 um spectrum of the warm, ~360K circumstellar dust around the nearby MS star η Corvi (F2V, 1.4 ± 0.3 Gyr), a known IRAS excess object with a very high 24um excess luminosity for its age (Fig. 1). The Spitzer spectrum (Fig. 2) shows clear evidence for warm, water- and carbon-rich dust at ~ 3 AU from the central star, uncoupled and in a separate reservoir from the system's extended sub-mm dust ring at 150 ± 20 AU [2,3] (Figs. 1 & 3). Spectral features similar in kind and amplitude to those found for ultra-primitive material in ISO HD100546 spectra were found (water ice & gas, olivines & pyroxenes, amorphous carbon and metal sulfides), in addition to emissions due to impact produced silica and high temperature/pressure carbonaceous phases [4]. A large amount, at least 3 x 1019 kg, of 0.1 - 1000 μm warm dust is present, in a roughly collisional equilibrium distribution with dn/da ~ a-3.5. This is the equivalent of a 140 km radius asteroid of 2.5 g cm-3 density or a "comet" of 260 km radius and 0.40 g cm-3 density. If we allow for particles larger than 1 cm, the mass present increases by (largest particle size/1000 μm)0.5, and the equivalent parent body radius increases by the 0.167th power [4].

Topics

• density
• impedance spectroscopy
• amorphous
• Carbon
• phase
• mass spectrometry