Cooling, Sputtering, and Infrared Emission from Dust Grains in Fast Shocks

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Session 14 -- Interstellar Dust and Extinction
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[14.04] Cooling, Sputtering, and Infrared Emission from Dust Grains in Fast Shocks

Scott M. Foster (University of Maryland, College Park), Eli Dwek (NASA/GSFC), John Raymond, Olaf Vancura (CfA)

We model the dynamics, the destruction by sputtering and the collisional heating of dust grains in fast ($\geq 400 \ km \ s^{-1}$) astrophysical shocks. The effect of grain destruction is to alter the grain size distribution, creating a deficiency of small grains compared to their preshock abundances. The altered grain size distribution depends on shock velocity and the density of the ISM. We calculate the infrared emission from the dust particles using a stochastic dust heating model (Dwek, 1986). In this model, particles with sizes below $\sim 100$ A undergo temperature fluctuations and radiate an excess of near infrared emission ($\lambda \leq 20 \ \mu m$) over that expected for grains in thermal equilibrium. The near infrared excess is a measure of the abundance of small grains in the shock, and the infrared spectrum is, therefore, a powerful diagnostic for the amount of grain destruction in shocks. These studies compliment those that examine the effects of the release of the sputtered refractory elements on the ultraviolet and X-ray emission from shocks (Vancura, et al. 1993).

\bigskip Dwek, E. 1986, ApJ , 302 , 363.

Vancura, O., Raymond, J.C., Dwek, E., Blair, W.P., Long, K.S., and Foster, S., 1993, in preparation.

\bigskip This work is funded by NASA RTOP \#188-44-53-05.

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