Precise records of baby stars' growth caught at millimeter wavelengths
Babies grow up fast, in the blink of an eye, and thus their parents wish to record their growth without missing any moment. This is true not only for human babies but also for baby stars, called protostars, although the recorders are not parents but astronomers. Protostar ages, or evolutionary stages, have been determined from observations at near- and mid-infrared wavelengths. The youngest stage, called Class 0, is defined by non-detection at these wavelengths, corresponding to < 300,000 years old. This definition cannot differentiate younger and older Class 0 protostars. On the other hand, it is expected from studies on even older protostars that they grow up faster at earlier stages than at later stages, as human babies do, implying that many precious moments of their growth are missed.