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TWA 27B (2M1207b) is the first directly-imaged planetary-mass (MP ~ 5 MJ)companion (Chauvin et al. 2004) and was observed at 0.9--5.3 micron withJWST/NIRSpec (Luhman et al. 2023). To understand the accretion properties ofTWA 27B, we search for continuum-subtracted near-infrared helium and hydrogenemission lines and measure their widths and luminosities. We detect the He Itriplet at 4.3 sigma and all Paschen-series lines covered by NIRSpec (Pa alpha,Pa beta, Pa gamma, Pa delta) at 4--5 sigma. The three brightest Brackett-serieslines (Br alpha, Br beta, Br gamma) as well as Pf gamma and Pf delta aretentative detections at 2--3 sigma. We provide upper limits on the otherhydrogen lines, including on H alpha through Hubble Space Telescope archivaldata. Three lines can be reliably deconvolved to reveal an intrinsic widthDelta v = 67+-9 km/s, which is 60% of the surface freefall velocity. The lineluminosities seem significantly too high to be due to chromospheric activity.Converting line luminosities to an accretion rate yields Mdot ~ 5e-9 MJ/yr whenusing scalings relationships for planetary masses, and Mdot ~ 0.1e-9 MJ/yr withextrapolated stellar scalings. Several of these lines represent firstdetections at an accretor of such low mass. The weak accretion rate impliesthat formation is likely over. This analysis shows that JWST can be used tomeasure low line-emitting mass accretion rates onto planetary-mass objects,motivates deeper searches for the mass reservoir feeding TWA 27B, and hintsthat other young directly-imaged objects might -- hitherto unbeknownst -- alsobe accreting.

Revisiting the Helium and Hydrogen Accretion Indicators at TWA 27B: Weak Mass Flow at Near-Freefall Velocity