How are Class 0 objects primarily detectable due to their initial embedded stage?

Answer

Only in far-infrared or radio wavelengths

Class 0 objects are the earliest stage, deeply buried within the natal envelope of gas and dust, which makes them invisible in optical light but detectable at the longest wavelengths.

How are Class 0 objects primarily detectable due to their initial embedded stage?
protostarstellar evolutionstar formationastrophysics