NASA Technical Reports Server NTRS 20150007947: Dust Destruction Rates and Lifetimes in the Magellanic CloudsReportar como inadecuado



 NASA Technical Reports Server NTRS 20150007947: Dust Destruction Rates and Lifetimes in the Magellanic Clouds


NASA Technical Reports Server NTRS 20150007947: Dust Destruction Rates and Lifetimes in the Magellanic Clouds - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Descargar gratis o leer online en formato PDF el libro: NASA Technical Reports Server NTRS 20150007947: Dust Destruction Rates and Lifetimes in the Magellanic Clouds
The nature, composition, abundance, and size distribution of dust in galaxies is determined by the rate at which it is created in the different stellar sources and destroyed by interstellar shocks. Because of their extensive wavelength coverage, proximity, and nearly face-on geometry, the Magellanic Clouds MCs provide a unique opportunity to study these processes in great detail. In this paper we use the complete sample of supernova remnants SNRs in the MCs to calculate the lifetime and destruction efficiencies of silicate and carbon dust in these galaxies. We find dust lifetimes of 22+-13 Myr 30+-17 Myr for silicate carbon grains in the LMC, and 54 +- 32 Myr 72 +- 43 Myr for silicate carbon grains in the SMC. The significantly shorter lifetimes in the MCs, as compared to the Milky Way, are explained as the combined effect of their lower total dust mass, and the fact that the dust-destroying isolated SNe in the MCs seem to be preferentially occurring in regions with higher than average dust-to-gas D2G mass ratios. We also calculate the supernova rate and the current star formation rate in the MCs, and use them to derive maximum dust injection rates by asymptotic giant branch AGB stars and core collapse supernovae CCSNe. We find that the injection rates are an order of magnitude lower than the dust destruction rates by the SNRs. This supports the conclusion that, unless the dust destruction rates have been considerably overestimated, most of the dust must be reconstituted from surviving grains in dense molecular clouds. More generally, we also discuss the dependence of the dust destruction rate on the local D2G mass ratio and the ambient gas density and metallicity, as well as the application of our results to other galaxies and dust evolution models.



Autor: NASA Technical Reports Server (NTRS)

Fuente: https://archive.org/







Documentos relacionados