KMOS study of the mass accretion rate from Class I to Class II in NGC 1333

Context. The mass accretion rate ( Ṁ acc ) is the fundamental parameter to understand process of assembly that results in formation a low-mass star. This has been largely studied Classical T Tauri stars star-forming regions with ages ∼1 − 10 Myr. However, little known about properties young stellar objects (YSOs) younger and early stages star formation, such as Class 0/I phases. Aims. We present new near-infrared spectra 17 I/Flat 35 II sources located (< 1 Myr) NGC 1333 cluster, acquired KMOS instrument at Very Large Telescope. Our goal study whether evolves age, suggested by widely adopted viscous evolution model, comparing members samples older regions. Methods. For our sample, we measured parameters (SpT, A V , L ⋆ through comparison IR grid non-accreting III templates. then computed luminosity using correlation between HI lines (Pa β Br γ ). I where presence large excess makes it impossible use same spectral typing method, applied procedure allowed us measure self-consistent way. Mass rates were once masses radii estimated adopting suitable evolutionary tracks. Results. sample have ∼ −4 ⊙ −11 −7 M yr −1 . find form log = (1.5 ± 0.2)log + 1.0 0.1), (2.6 0.9) (−7.3 0.7). Both correlations are compatible within errors Lupus region, while only latter consistent from Chamaeleon I. shows larger luminosities (∼10 −2 2 −9 −6 respect cloud. derived not sufficiently high build up inferred masses, assuming steady during lifetime. suggests their main phase most already accumulated previous stage and/or an episodic phenomenon. show some targets originally classified Spitzer photometry fact evolved or low accreting objects. evidence can implications for protostellar lifetimes. Conclusions. more embedded YSOs. Further observations needed determine if this general result. In addition, highlight importance spectroscopic surveys YSOs confirm classification perform correct estimate