article published yes Danielle A. Berg author Rohan P. Naidu author John Chisholm author Hakim Atek author Seiji Fujimoto author Vasily Kokorev author Lukas J. Furtak author Chiaki Kobayashi author Daniel Schaerer author Angela Adamo author Qinyue Fei author Damien Korber author Jorryt J Matthee author 7439a258-f3c0-11ec-9501-9df22fe067200000-0003-2871-127X Rui Marques-Chaves author Zorayda Martinez author Kristen B.W. Mcquinn author Julian B. Muñoz author Pascal A. Oesch author Alberto Saldana-Lopez author Daniel P. Stark author Mabel G. Stephenson author Tiger Yu Yang Hsiao author JoMa department We present the discovery of extreme nitrogen enrichment by Wolf Rayet nitrogen (WN) stars in the metal-poor (∼10%Z⊙), lensed, compact (Reff ∼ 20 pc) galaxy RXCJ2248 at z = 6.1, revealed by unprecedentedly deep JWST/NIRSpec medium-resolution spectroscopy from the GLIMPSE-D Survey. The exquisite signal-to-noise ratio reveals multiple high-ionization nebular lines and broad Balmer and [O III] components (FWHM ∼700–3000 km s −1 ). We detect broadened He II λ1640 and λ4687 (FWHM ∼ 530 km s −1 ) and strong N III λ4642 emission consistent with a population of WN stars, making RXCJ2248 the most distant galaxy with confirmed Wolf Rayet (WR) features to date. We measure the multiphase nebular density across five ions, the direct-method metallicity ( 12 + log(O/H) = 7.753 ± 0.025 ), and a nonuniform elemental enrichment pattern of extreme N/O enhancement ( log(N/O) = 0.391 ± 0.037 from N+, N+2 , and N+3 ) but suppressed C/O relative to empirical C/N trends. We show that this abundance pattern can be explained by enrichment from a dual-burst with a low WR carbon/WN ratio, as expected at low metallicities. Crucially, these signatures can only arise during a brief, rare evolutionary window shortly after a burst (∼3–6 Myr), when WN stars dominate chemical feedback but before dilution by later yields (e.g., supernovae). The observed frequency of strong N emitters at high−z implies a ∼50 Myr burst duty cycle, suggesting that N/O outliers may represent a brief but ubiquitous phase in the evolution of highly star-forming early galaxies. The WN detection in RXCJ2248, therefore, provides the first direct evidence of WR-driven nitrogen enrichment in the first billion years of the Universe and a novel timing argument for the bursty star formation cycles that shaped galaxies at cosmic dawn. https://research-explorer.ista.ac.at/download/21930/21938/2026_AstrophysicalJour_Berg.pdf application/pdfno IOP Publishing2026 eng 0004-637X 1538-4357 2511.1359110.3847/1538-4357/ae5e4c 10032 Berg DA, Naidu RP, Chisholm J, Atek H, Fujimoto S, Kokorev V, Furtak LJ, Kobayashi C, Schaerer D, Adamo A, Fei Q, Korber D, Matthee JJ, Marques-Chaves R, Martinez Z, Mcquinn KBW, Muñoz JB, Oesch PA, Saldana-Lopez A, Stark DP, Stephenson MG, Hsiao TYY. 2026. A fleeting GLIMPSE of N/O enrichment at cosmic dawn: Evidence for Wolf Rayet N stars in a z = 6.1 galaxy. The Astrophysical Journal. 1003(2), 112. Berg, D. A., Naidu, R. P., Chisholm, J., Atek, H., Fujimoto, S., Kokorev, V., … Hsiao, T. Y. Y. (2026). A fleeting GLIMPSE of N/O enrichment at cosmic dawn: Evidence for Wolf Rayet N stars in a z = 6.1 galaxy. <i>The Astrophysical Journal</i>. IOP Publishing. <a href="https://doi.org/10.3847/1538-4357/ae5e4c">https://doi.org/10.3847/1538-4357/ae5e4c</a> D.A. Berg, R.P. Naidu, J. Chisholm, H. Atek, S. Fujimoto, V. Kokorev, L.J. Furtak, C. Kobayashi, D. Schaerer, A. Adamo, Q. Fei, D. Korber, J.J. Matthee, R. Marques-Chaves, Z. Martinez, K.B.W. Mcquinn, J.B. Muñoz, P.A. Oesch, A. Saldana-Lopez, D.P. Stark, M.G. Stephenson, T.Y.Y. Hsiao, The Astrophysical Journal 1003 (2026). Berg DA, Naidu RP, Chisholm J, et al. A fleeting GLIMPSE of N/O enrichment at cosmic dawn: Evidence for Wolf Rayet N stars in a z = 6.1 galaxy. <i>The Astrophysical Journal</i>. 2026;1003(2). doi:<a href="https://doi.org/10.3847/1538-4357/ae5e4c">10.3847/1538-4357/ae5e4c</a> Berg, Danielle A., Rohan P. Naidu, John Chisholm, Hakim Atek, Seiji Fujimoto, Vasily Kokorev, Lukas J. Furtak, et al. “A Fleeting GLIMPSE of N/O Enrichment at Cosmic Dawn: Evidence for Wolf Rayet N Stars in a z = 6.1 Galaxy.” <i>The Astrophysical Journal</i>. IOP Publishing, 2026. <a href="https://doi.org/10.3847/1538-4357/ae5e4c">https://doi.org/10.3847/1538-4357/ae5e4c</a>. Berg, Danielle A., et al. “A Fleeting GLIMPSE of N/O Enrichment at Cosmic Dawn: Evidence for Wolf Rayet N Stars in a z = 6.1 Galaxy.” <i>The Astrophysical Journal</i>, vol. 1003, no. 2, 112, IOP Publishing, 2026, doi:<a href="https://doi.org/10.3847/1538-4357/ae5e4c">10.3847/1538-4357/ae5e4c</a>. D. A. Berg <i>et al.</i>, “A fleeting GLIMPSE of N/O enrichment at cosmic dawn: Evidence for Wolf Rayet N stars in a z = 6.1 galaxy,” <i>The Astrophysical Journal</i>, vol. 1003, no. 2. IOP Publishing, 2026. 219302026-05-31T22:02:12Z2026-06-02T08:46:20Z