Galaxy Colours

Galaxy Colours

Filters in HyperSuprimeCame on Subaru

Near-infrared filters on VISTA

When we refer to colours we usually mean a combination of these filters to highlight whether a galaxy (or star) spectrum is "red" or "blue". This is also akin to the HR diagram for stars, which uses colours an an indicator of e.g. Temperature.

Galaxy colour-magnitude diagram

The most common plot in extragalactic astrophysics, is the colour-magnitude diagram, which plots a colour (blue-red filter) against a magnitude in one of the filters. The y-axis is then the colour and the x-axis is the brightness.