JWST NIRSpec Spectroscopy of the Triply Lensed z=10.17 Galaxy MACS0647-JD

We present JWST/NIRSpec prism spectroscopy of MACS0647-JD, a triply lensed z similar to 11 candidate discovered in Hubble Space Telescope imaging and spatially resolved by JWST imaging into two components, A and B. Spectroscopy of component A yields a spectroscopic redshift z = 10.17 based on seven detected emission lines: C iii] lambda lambda 1907, 1909, [O ii] lambda 3727, [Ne iii] lambda 3869, [Ne iii] lambda 3968, H delta lambda 4101, H gamma lambda 4340, and [O iii] lambda 4363. These are the second-most distant detections of these emission lines to date, in a galaxy observed just 460 million years after the Big Bang. Based on observed and extrapolated line flux ratios we derive a gas-phase metallicity 12 + log(O/H) similar to 7.5-8.0, or Z similar to (0.06-0.2) Z( circle dot), ionization parameter log(U) = -1.9 +/- 0.2, and an ionizing photon production efficiency log(xi(ion))=25.2 +/- 0.2 erg(-1) Hz. The spectrum has a softened Ly alpha break, evidence for a strong Ly alpha damping wing. The Ly alpha damping wing also suppresses the F150W photometry, explaining the slightly overestimated photometric redshift z = 10.6 +/- 0.3. MACS0647-JD has a stellar mass log(M/M (circle dot)) = 8.1 +/- 0.3, including similar to 6 x 10(7 )M (circle dot) in component A, most of which formed recently (within similar to 20 Myr) with a star formation rate similar to 2 +/- 1 M (circle dot )yr(-1), all within an effective radius 70 +/- 24 pc. Spectroscopy of a fainter companion galaxy C separated by a distance of similar to 3 kpc reveals a Lyman break consistent with z similar to 10.17. MACS0647-JD is likely the most distant galaxy merger known.