2015MNRAS.446.4088T

Near-IR observations from 1993 to 2014 of V723 Carinae confirm this to be a young eruptive variable embedded in the Car I PDR/dust cloud in NGC 3372. In 1993, it was fainter than 16.6 in JHK and went into outburst before 2003, reaching K ≃ 12.9 in 2004. Since then, V723 Car has suffered erratic flux variations of up to ΔK = 2 in time-scales of years. The variations are also evident into the mid-infrared. The H - K index shows correlation with K, though the ratio ΔK/Δ(H - K) differs from that expected from dust extinction. The 1.91 to 2.48 µm spectrum of V723 Car shows emission lines of H2 and also Brγ, as well as 2.3-2.4 µm CO overtone bandheads. The system is extremely red (H - K ≥ 4), with mid- and far-IR colours of a Class I object. The fitted parameters of Robitaille et al.'s model to the 1.6-850 µm spectral energy distribution of V723 Car indicate a system composed of a 10M_☉ central star with a 5.6x10^–3M_☉ disc and a 1.6x10^3M_☉ envelope with AV ∼ 55 of extinction. The total luminosity of the system is about 4x10³L_☉. V723 Car is the most luminous, most massive, most deeply embedded, and possibly the youngest of all the young eruptive variables known. Evidence is provided of a 5000 au-long jet of shocked gas extending to opposite sides of the star. The infrared properties of a nearby 10L_☉ Class I young stellar object, Car I-125, are also described, with variations in K typical of Herbig Ae/Be stars. Its near-IR spectrum is featureless except for bright Brγ line emission.