Infrared Spectrum of the Galactic Centre

Abstract

MANY data have recently become available concerning an extended infrared source near the centre of our galaxy^1–4. Although the precise angular extent of this source is not yet certain, a dimension, of ∼1 pc has been suggested for the 10 µm radiation^3,4, and ∼100 pc for the 100 µm radiation². The shape of the infrared spectrum is now fairly well known, particularly over the waveband 5–22 µm. The flux determination at 100 µm is somewhat less certain, while only an upper limit is available for the flux at 1,000 µm. It is readily seen from the data of Low et al.⁴ that the spectrum of the galactic centre source in the range 5–22 µm bears a striking resemblance to that of several Seyfert nuclei⁵. This similarity strongly suggests that similar radiation mechanisms may operate in both cases.