What characteristic links the color of newly formed stars to their surface temperature?

Hotter objects emit the vast majority of their light at shorter wavelengths, making them appear bluer.

The relationship between a star's color and its surface temperature is fundamental to astrophysics. Stars that are intrinsically hotter radiate energy across the electromagnetic spectrum, but the peak intensity of their output is shifted towards the shorter, higher-energy wavelengths. Specifically, the most massive, newly formed stars exhibit surface temperatures high enough to emit the vast majority of their observable light in the blue and ultraviolet regions of the spectrum. Conversely, cooler stars, such as our Sun or older, lower-mass stars, have lower surface temperatures and thus emit relatively more light at longer wavelengths, appearing yellow or red.