2026ApJ...999..111P

We present Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet (FUV) and Space Telescope Imaging Spectrometer (STIS) optical observations toward the young accreting brown dwarf 2MASS J08440915-7833457 (J0844) from the UV Legacy Library of Young Stars as Essential Standards Director's Discretionary Time program. We analyse hot FUV lines, such C IV, Si IV, and N V, as well as fluorescent emission from H₂. Despite evidence for accretion, the C IV line profiles are narrower than in typical classical T Tauri stars (CTTSs), resembling weak-lined T Tauri stars more closely. Additionally, the C IV integrated line flux does not follow the level expected of an accreting object in the magnetically saturated regime. However, comparing J0844 to appropriate low-mass analogs, J0844 does show excess C IV emission characteristic of accretion, suggesting the magnetic saturation level may need to be redefined for the lowest-mass objects. The C IV/Si IV emission-line ratio is found to be 20, which is higher than for most CTTSs, with a few exceptions (e.g., TW Hya). We fit the STIS optical spectrum to calculate an accretion rate, which we find to be 4.2 × 10^–11M_⊙ yr^–1. The accretion rate found based on the empirical L_CIV-${\dot{M}}_{{\rm{acc}}}$ relationship is 2 orders of magnitude higher, suggesting this relationship may not hold at the lowest masses. We find the H₂ emission appears to originate within the corotation radius, pointing to either disk truncation well inside the corotation radius or additional sources of H₂ emission that we do not consider (e.g., from the accretion flow itself). These data provide an extension of our current understanding of accretion and inner-disk conditions to the relatively unexplored lowest-mass regime.