English to Spanish Science Astronomy & Space cosmic in-betweeners

Hola, necesito ayuda para traducir el siguiente término "cosmic in-betweeners"

Contexto:
Using data from NASA’s Spitzer Space Telescope, scientists have identified the three fastest-spinning brown dwarfs ever found. More massive than most planets but not quite heavy enough to ignite like stars, brown dwarfs are cosmic in-betweeners. And though they aren’t as well-known as stars and planets to most people, they are thought to number in the billions in our galaxy.

¿Sería correcto traducirlo como "series cósmicos intermedios"?