Near infrared imaging of a giant red envelope galaxy

Extract

Recently Maccagni et al. (ApJ, 334, L1, 1989) obtained g, r and i images of an X-ray luminous galaxy at the center of a poor cluster of galaxies (1E1111.9-3754). The images showed that the central galaxy was surrounded by a remarkable spatially extended red envelope, visible as a kink in the r¹⁴ surface brightness profile at a radius of 100 kpc. Johnstone & Fabian (MNRAS, 237, 27p, 1989) suggested that the red envelope is composed of low mass stars formed in a cooling flow. This observation sparked considerable interest as the first direct detection of low mass star formation in cooling flows. We have obtained near infrared H-band (1.65 μ images of 1E1111.9-3754 from the Infrared Imaging Spectrometer on the 4-m Anglo-Australian Telescope. Even though low mass stars should be more prominent in the near infrared than at optical wavelengths, the 1.65 μ surface brightness profile shows no deviation from the r¹⁴ profile out to a radius of 100 kpc. This observation argues against the hypothesis that the envelope is composed of low mass stars formed from cooled X-ray gas.