Structure and stability of shock waves in a multiphase interstellar medium. II. The effect of a magnetic field, thermal conduction, and viscosity

Journal Article · Mon Dec 01 00:00:00 EST 1975 · Astrophys. J., v. 202, no. 2, pp. 372-388

DOI:https://doi.org/10.1086/153985· OSTI ID:4057116

Mufson, S L

The effect of shock waves on a parcel of gas initially in one phase of a multiphase interstellar medium is studied. Here a model interstellar medium is considered which is heated by a constant flux of low-energy cosmic rays and which includes a magnetic field transverse to the direction of the shock and nonzero coefficients of thermal conductivity and viscosity. As in our previous study, if the shock is sufficiently strong, then gas initially in the hot, intercloud phase undergoes a phase transition and relaxes to the cold, cloud phase. A shock in the cold phase does not instigate a phase change. The stability of the gas in the nonequilibrium conditions behind a shock is investigated in the short wavelength limit. The results show that gas shocked from either the intercloud or cloud phase encounters zones of thermal instability as it moves downstream to equilibrium. Under a wide variety of initial conditions the gas traverses these zones in times long compared with the e-folding time for the instability. The numerical examples demonstrate that shocks in the intercloud gas possess a mechanism to convert intercloud gas to cloud gas and fragment this gas to form clouds and stars. In addition, they show that thermal instability in shocked gas offers one explanation of the fine structure seen in supernova remnants. (AIP)

• Research Organization: National Radio Astronomy Observatory, Green Bank, West Virginia
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-024105
• OSTI ID: 4057116
• Journal Information: Astrophys. J., v. 202, no. 2, pp. 372-388, Other Information: Orig. Receipt Date: 30-JUN-76
• Country of Publication: United States
• Language: English

Related Subjects

N56500* -Physics (Astrophysics & Cosmology)-Galaxies
N56200 -Physics (Astrophysics & Cosmology)-Stars
640105* -Physics Research-Astrophysics & Cosmology- Galaxies
*INTERSTELLAR SPACE- SHOCK WAVES
COSMIC GASES
COSMIC RAY FLUX
INTERSTELLAR MAGNETIC FIELDS
STABILITY
STAR EVOLUTION
SUPERNOVA REMNANTS
THERMAL CONDUCTION
VISCOSITY