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A Search for Shells around Crabs

Published online by Cambridge University Press:  12 April 2016

R.H. Becker  and
D.J. Helfand
R.H. Becker
Affiliation:
Physics Department, University of California, Davis and, Institute of Geophyiscsand Planetary Physics, LLNL
D.J. Helfand
Affiliation:
Astronomy Department, Columbia University, New York, NY

Abstract

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Prior to conducting a survey of the galactic plane at 327 MHz using the VLA, we have imaged four fields near galactic longitude of 20 degrees. Each image will cover a 2.5 degree field with ∼1 arcmin resolution. The fields have been chosen to include the remnants G20.0-0.2, G21.5-0.9, and G24.7+0.6. The first two are isolated Crab-like objects, that is, there is no discernible associated shell. Since such shells have relatively steep spectra, images at 327 MHz will be more sensitive to their presence. The absence of a shell can constrain the density of the ISM in the vicinity of the SNR (Reynolds and Aller 1985 A.J. 90, 2312). Since ∼50% of Crabs are naked, the implications can be extended to a significant fraction of the ISM.

Type
Research Article
Information
International Astronomical Union Colloquium , Volume 101: Supernova Remnants and the Interstellar Medium , 1988 , pp. 335 - 338
Copyright
Copyright © Cambridge University Press 1988

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