Now shift your attention to the longer wavelength IRAS infrared images. Note that this emission is not spherically symmetric like the underlying star cluster itself. This is an artifact resulting from the rectangular shape of the IRAS detectors. Far-infrared light, with wavelengths longer than about 30 microns, is often a product of dust and young stars. The stars emit ultraviolet and visible-light photons that are absorbed by the dust particles.
Globular clusters have no young stars and very little dust.
Therefore, it should not be a surprise to find that there is no measurable far-infrared light from M13. Once again, the cluster itself is virtually invisible. The blue blobs are primarily random electronic noise, similar to static, introduced into the radio receiver. The environment of globular clusters is essentially devoid of strong magnetic fields and fast-traveling electrons, and therefore we should not expect significant synchrotron emission from M13. However, this image alone cannot provide any useful information on the distance to this weak x-ray source, so little can be said about its nature based on this image alone.