Shock-front compression of the magnetic field in the Canis Majoris R1 star-formation region
Results are presented from a linear polarization survey at optical wavelengths of over 140 stars in the direction of the CMa R1 star-formation region; 26 of these are clearly associated with nebulosity within the area. The observations were obtained in order to test the argument of Herbst et al. (1978) that star formation in CMa R1 is driven by a shock wave from a nearby supernova (Herbs and Assousa, 1977 and 1978). The polarizations are found to be consistent with a simple model of the compression by a supernova-induced spherical shock front of an initially uniform interstellar magnetic field. The polarization vectors are inconsistent with a scenario of quiescent cloud collapse along magnetic-field lines. Multicolor polarimetry of the nebular stars provides evidence of grain growth toward increasing cloud optical depth, characterized by a ratio of total-to-selective extinction of R = 3.0 at E(B-V) = 0.23, increasing to R = 4.2 at E(B-V) = 0.7. 15 references.
- Research Organization:
- Naval Observatory, Flagstaff, AZ; Wesleyan Univ., Middletown, CT; Van Vleck Observatory, Middletown, CT
- OSTI ID:
- 6120324
- Journal Information:
- Astrophys. J.; (United States), Vol. 317
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
INTERSTELLAR MAGNETIC FIELDS
COMPRESSION
STAR EVOLUTION
SUPERNOVAE
SHOCK WAVES
COSMIC GASES
MAGNETOHYDRODYNAMICS
NEBULAE
POLARIZATION
STAR CLUSTERS
SUPERNOVA REMNANTS
VISIBLE RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ERUPTIVE VARIABLE STARS
FLUID MECHANICS
FLUIDS
GASES
HYDRODYNAMICS
MAGNETIC FIELDS
MECHANICS
RADIATIONS
STARS
VARIABLE STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 - Astrophysics & Cosmology- Galaxies