A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7 Torralba Torregrosa, Alberto ; https://orcid.org/0000-0001-5586-6950 Matthee, Jorryt J ; https://orcid.org/0000-0003-2871-127X Weibel, Andrea Naidu, Rohan P. Ma, Yilun Cloonan, Aidan P. Desai, Aayush A De Graaff, Anna Greene, Jenny E. Jespersen, Christian Kragh Kramarenko, Ivan ; https://orcid.org/0000-0001-5346-6048 Mascia, Sara Oesch, Pascal A. Sun, Wendy Q. Williams, Christina C. ddc:520 Recent studies at high redshift have revealed an enigmatic class of little red dots (LRDs) with extreme Balmer breaks, stronger than in any stellar atmosphere. However, it is unclear whether such objects exist at lower redshift, especially given the low number of LRDs reported at z ≲ 2. Here, we report the discovery of PAN-BH*-1, an LRD with an extreme Balmer break at z = 1.73, identified from JWST/NIRCam pure-parallel imaging taken by the PANORAMIC survey, and confirmed by deep VLT/X-Shooter spectroscopy. The rest-optical to near-infrared spectral energy distribution of PAN-BH*-1 is consistent with a photospheric continuum with effective temperature Teff ≈ 4800 K. The broad Hα emission line shows remarkably deep absorption, stronger than previously measured in any LRD. The absorption trough spans from −520 to +267 km s−1 with respect to the systemic redshift. The presence of blue- and red-shifted absorption suggests complex dynamics of the obscuring gas along the line of sight. We speculate that the absorption trough can be produced by a thick wind launched from a thick, rotating photospheric disk, the latter being the source of the red optical continuum. While the source is unresolved in the rest-optical JWST data (reff < 47 pc), the rest-near-UV Hubble Space Telescope imaging shows an extended morphology with (formular displayed) kpc, which we interpret as a host galaxy with a stellar mass of ∼10^8 M⊙, in line with the narrow Hα emission. The discovery of this object at cosmic noon highlights the feasibility of systematic searches for extreme LRDs with wide-area facilities such as Euclid and Roman. 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/22263 https://research-explorer.ista.ac.at/download/22263/22274 Torralba Torregrosa A, Matthee JJ, Weibel A, et al. A black hole star at cosmic noon: Extreme Balmer break, photospheric continuum, and broad absorption by thick winds in a Little Red Dot at z = 1.7. <i>The Astrophysical Journal Letters</i>. 2026;1005(2). doi:<a href="https://doi.org/10.3847/2041-8213/ae7bfd">10.3847/2041-8213/ae7bfd</a> eng info:eu-repo/semantics/altIdentifier/doi/10.3847/2041-8213/ae7bfd info:eu-repo/semantics/altIdentifier/issn/2041-8205 info:eu-repo/semantics/altIdentifier/e-issn/2041-8213 info:eu-repo/semantics/altIdentifier/arxiv/2603.28335 https://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess