Grain disruption in interstellar hydromagnetic shocks

Journal Article · Mon Aug 01 04:00:00 EDT 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155417· OSTI ID:7297861

Shull, J M

The observed abundance variations of Ca, Fe, Si, and Ti in intermediate-velocity interstellar gas suggest that grains have been disrupted in clouds with velocities as low as 20--50 km s/sup -1/. In this paper, we describe a simplified hydromagnetic shock model for such clouds, derive the dynamical equations for charged grains in the postshock region, including the collisional drag and ''betatron-acceleration'' effect of a magnetic field gradient, and thereby calculate the fraction of grains destroyed in evaporative collisions with other grains. We find that for shocks of 20--50 km s/sup -1/ in which the fractional H-ionization remains low, 3--10% of the grain material may be destroyed: sufficient to explain in part the heavy-element depletion pattern in intermediate velocity clouds and the well-known correlation of N (Ca II)/N (Na I) with cloud velocity.

• Research Organization: Department of Astronomy, University of California, Berkeley
• OSTI ID: 7297861
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 215:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CHEMICAL COMPOSITION
COLLISIONS
COSMIC GASES
FLUID MECHANICS
FLUIDS
GASES
HYDRODYNAMICS
HYDROMAGNETIC WAVES
INTERSTELLAR GRAINS
IONIZATION
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
MOLECULE COLLISIONS
PARTICLES
PLASMA
SHOCK WAVES