SIMBAD references

We present JWST/NIRSpec prism spectroscopy of MACS0647-JD, a triply lensed z ∼ 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] λλ1907, 1909, [O II] λ3727, [Ne III] λ3869, [Ne III] λ3968, Hδλ4101, Hγλ4340, and [O III] λ4363. 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) ∼ 7.5-8.0, or Z ∼ (0.06-0.2) Z_⊙, ionization parameter $\mathrm{log}(U)$ = -1.9 ± 0.2, and an ionizing photon production efficiency $\mathrm{log}({\xi }_{\mathrm{ion}})=25.2\pm 0.2\,$ erg^–1 Hz. The spectrum has a softened Lyα break, evidence for a strong Lyα damping wing. The Lyα 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_⊙) = 8.1 ± 0.3, including ∼6 × 10⁷M_⊙ in component A, most of which formed recently (within ∼20 Myr) with a star formation rate ∼ 2 ± 1 M_⊙ yr^–1, all within an effective radius 70 ± 24 pc. Spectroscopy of a fainter companion galaxy C separated by a distance of ∼ 3 kpc reveals a Lyman break consistent with z ∼ 10.17. MACS0647-JD is likely the most distant galaxy merger known.