V-I Color Index in NGC 1232
265 of 356

(V-I) Color Index in NGC 1232

April 28, 2005
This image is a computer processed "(V-I) colour-index image" of NGC 1232. This technique allows to show the "difference" between images of the galaxy, as seen in different wavebands. Since different types of objects have different brightness in different colours, this method is very useful to locate objects of a particular type and to obtain an overview of their distribution in the galaxy.

The photo is based on two individual images of NGC 1232 obtained by the FORS1 Commissioning Team at the ESO VLT UT1 on 20 September 1998. They were taken through a visual-green filter (V) and a near-infrared-red filter (I). The exposure time was 3 min for both.

Dust lanes in the spiral arms absorb more green light and therefore appear redder than their surroundings. In this differential image, they are seen as dark regions. They are exceptionally sharp and particularly strong in the inner part of the galaxy.

comments powered by Disqus