The Far-ultraviolet Spectrum of FU Ori South | CU Experts

Abstract; The eruptive young stellar object FU Ori is the eponym of its variable class. FU Ori stars are known to undergo outbursts with amplitudes of >4 mag in the V band and durations of several decades. Interaction with a binary companion is one proposed outburst trigger, so understanding both components of the FU Ori system is crucial. A recent Hubble Space Telescope/Space Telescope Imaging Spectrograph observation of the FU Ori system clearly resolves its North and South components. We report here on the spectrum of FU Ori South. We detect near-ultraviolet continuum emission but no far-ultraviolet continuum, although several bright emission lines consistent with those seen in T Tauri stars are present. The presence of the C ii] 2325 multiplet and many H2 lines indicate active accretion. We estimate the extinction to the source and find that the UV spectrum favors A; ; V; < 4, contrary to past estimates based on the near-infrared spectrum.

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