Open AccessAn infrared study of Centaurus A ★
Author(s) -
Bryant J. J.,
Hunstead R. W.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02722.x
Subject(s) - physics , centaurus a , astrophysics , torus , extinction (optical mineralogy) , line of sight , point source , nucleus , infrared , luminous infrared galaxy , astronomy , radio galaxy , optics , galaxy , geometry , mathematics , biology , microbiology and biotechnology
We present J ‐, H ‐ and K ‐band images and 0.9–2.5 μm spectra of the nuclear regions of Centaurus A obtained with IRIS on the AAT. While the K ‐band image has a point source coincident with the nucleus, at H and J we identify diffuse structure extending to the north‐east as a possible ionization cone. By considering the near‐infrared colours, we show that the point‐like K ‐band emission originates not from the nucleus itself, but from dust which has been shock‐heated by nuclear outflows. A J − K image reveals a band of high extinction across the nucleus lying perpendicular to the radio jet axis, as suggested by previous authors. We model the detailed structure of this extinction image with a circumnuclear torus of diameter 240±20 pc, thickness 75±4 pc and tilt 80°±2° to the line of sight, and with the torus and radio jet axes aligned.