VLA OBSERVATIONS OF NEUTRAL HYDROGEN IN THE DIRECTION OF PUPPIS-A

VLA observations in the λ21 cm line of neutral hydrogen in the direction of the supernova remnant (SNR) Puppis A (l≃260.5°, b≃ -3.5°) are presented. The final angular resolution is 90″×90″, and the velocity resolution, 5.2 km s-1. The images were constructed using a mosaicing technique that combined 28 different pointings into one 1.5°×1.5° field. Based on the present data, several absorption and emission H I features associated with Puppis A were identified, mainly at low radial velocities with respect to the systemic velocity of the remnant. The accurate correspondence between the neutral hydrogen λ21 cm distribution and soft x-ray emission, strongly suggests that the interaction of the shock front with the external neutral cloud located to the east of Puppis A is responsible for the enhancement in the x-ray radiation along the eastern border. Based on the associated H I features, a kinematical distance of 2.2±0.3 kpc was estimated for this SNR, in good agreement with earlier determinations. © 1995 American Astronomical Society.