A fleeting GLIMPSE of N/O enrichment at cosmic dawn: Evidence for Wolf Rayet N stars in a z = 6.1 galaxy Berg, Danielle A. Naidu, Rohan P. Chisholm, John Atek, Hakim Fujimoto, Seiji Kokorev, Vasily Furtak, Lukas J. Kobayashi, Chiaki Schaerer, Daniel Adamo, Angela Fei, Qinyue Korber, Damien Matthee, Jorryt J ; https://orcid.org/0000-0003-2871-127X Marques-Chaves, Rui Martinez, Zorayda Mcquinn, Kristen B.W. Muñoz, Julian B. Oesch, Pascal A. Saldana-Lopez, Alberto Stark, Daniel P. Stephenson, Mabel G. Hsiao, Tiger Yu Yang ddc:520 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. IOP Publishing 2026 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/21930 https://research-explorer.ista.ac.at/download/21930/21938 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> eng info:eu-repo/semantics/altIdentifier/doi/10.3847/1538-4357/ae5e4c info:eu-repo/semantics/altIdentifier/issn/0004-637X info:eu-repo/semantics/altIdentifier/e-issn/1538-4357 info:eu-repo/semantics/altIdentifier/arxiv/2511.13591 info:eu-repo/semantics/openAccess