Consider two stars in the constellation Pasta. Alpha Tortellini is bright at ultraviolet (UV) wavelenghts and dim in at infrared (IR) wavelengths, while Beta Ziti is dim in the UV and bright in the IR. Which star is hotter?

Beta Ziti is the hotter star.

Infrared is the type of radiation which creates warmth. Atoms and molecules move more and more, and produce infrared radiation, as temperature increases. An object, like a hot clothing iron, which is not hot enough to produce light to the naked eye, emits energy in the infrared.

At the other end of the spectrum is ultraviolet radiation, which is more energetic. It has nothing to do with heat.