2011A&A...526L...1C

Strong outbursts in very young and embedded protostars are rare and not yet fully understood. They are believed to originate from an increase in the mass accretion rate ({dot}(M)_acc) onto the source. We report the discovery of a strong outburst in a low-mass embedded young stellar object (YSO), namely 2MASS-J05424848-0816347 or [CTF93]216-2, as well as its photometric and spectroscopic follow-up. Using near- to mid-IR photometry and NIR low-resolution spectroscopy, we monitor the outburst, deriving its magnitude, duration, as well as the enhanced accretion luminosity and mass accretion rate. [CTF93]216-2 increased in brightness by ∼4.6, 4.0, 3.8, and 1.9mag in the J, H, K_s bands and at 24µm, respectively, corresponding to an L_bol increase of ∼20L_☉. Its early spectrum, probably taken soon after the outburst, displays a steep almost featureless continuum, with strong CO band heads and H₂O broad-band absorption features, and Brγ line in emission. A later spectrum reveals more absorption features, allowing us to estimate T_eff∼3200K, M_*∼0.25M_☉, and {dot}(M)_acc∼1.2x10^–6M_☉/yr. This makes it one of the lowest mass YSOs with a strong outburst so far discovered.