Truncated stellar disks in the near infrared. I. Observations

Abstract

We present NIR surface photometry of 11 edge-on galaxies obtained in the course of a long term project aimed at analysing the occurrence and type of the truncation of the outer disks. Observations were carried out at the 1.5 m CST (Carlos Sánchez Telescope) in Tenerife (Spain) using the CAIN infrared camera. 7 galaxies exhibit clear truncation on their disk profiles and 4 galaxies were observed to be clearly untruncated within observational limits. We describe the truncations as real, smooth and complete (as suggested by extrapolation and in the sense that the measured truncation curve goes into the noise at a truncation radius $R_{tr}$), following a decline proportional to $(R_{tr} -R)^{-n}$ (where $R$ is the radius). Despite its deep photometric reach, the data presented do not permit a detailed exploration of the region where optical data show a second slope. Special care was taken concerning the surface brightness deprojection of edge-on galaxies, which was carried out by two methods, one comprising the inversion of Abel's integral equation and the other following a numerical method. These methods gave nearly identical results. NIR observations of truncations could differ from observations in the optical, since the two domains trace different stellar populations.