Observations of continuum and recombination-line emission from η carinae at a wavelength of 3 CM

Abstract

We have made 1″ resolution images of η Carinae in both the 3 cm radio continuum and in the H90α and H91α hydrogen recombination lines. The continuum image shows a source with dimensions 10″ × 8″ whose centre coincides with the star, and whose axes of symmetry align approximately, but not exactly, with those of the optical Homunculus. In shape, the image closely resembles infrared images obtained by other authors. The radio emission is unpolarized, and offers no support to models which invoke degenerate stars or more exotic objects within the core of η Carinae. Instead it is consistent with thermal emission from gas flowing away from a 'Luminous Blue Variable' star. The spectrum obtained from the recombination line observations shows two strong peaks, one at -35 km s -1, and the other at -240 km s -1. The former is close to the systemic velocity of η Carinae, the latter must arise from outflowing gas. Imaging shows that these line emissions arise from two small areas, displaced 0.5″ and 1″ respectively, NW of η Carinae. © Universidad Nacional Autónoma de México.