The eruptive young star IRAS 21204+4913

M. A. Burlak; A. V. Dodin; A. V. Zharova; S. G. Zheltoukhov; N. P. Ikonnikova; S. A. Lamzin; B. S. Safonov; I. A. Strakhov; A. A. Tatarnikov; A. M. Tatarnikov

arXiv · 2602.15157

The eruptive young star IRAS 21204+4913

M. A. Burlak·A. V. Dodin·A. V. Zharova·S. G. Zheltoukhov·N. P. Ikonnikova·S. A. Lamzin·B. S. Safonov·I. A. Strakhov·A. A. Tatarnikov·A. M. Tatarnikov

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Abstract

The results of photometric, polarimetric, and spectroscopic observations are presented for the young star IRAS 21204+4913, whose visible brightness has increased by $\approx 5^{\rm m}$ since October 2025. The star's absorption spectrum in the $0.36 - 0.75 \mu$m range resembles those of A - F giants and supergiants, but it also exhibits molecular TiO bands. The brightening was accompanied by a significant increase in the degree of polarization of the stellar radiation (to $\approx 16 \%$ in the I-band), likely due to scattering by dust in an expanding circumstellar shell. The P Cygni profile of the H$\alpha$ line implies a dusty wind velocity of $\approx 300$ km/s. We believe that the outburst of IRAS 21204+4913 is caused by an increase in the accretion rate of protoplanetary disk's matter onto the young star with a mass of $\lesssim 0.5$ M$_\odot$ to $\gtrsim 3\times 10^{-5}$ M$_\odot$ yr$^{-1}$. Furthermore, IRAS 21204+4913 displays several unusual features: the dependence of the width and radial velocity of absorption lines on the excitation potential, emission in the TiO molecular bands, and a comparably bright outburst that occured in 1948. Several T Tauri stars and a group of Herbig-Haro objects are found in the vicinity of the star.

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M. A. Burlak, A. V. Dodin, A. V. Zharova, S. G. Zheltoukhov, N. P. Ikonnikova, S. A. Lamzin, B. S. Safonov, I. A. Strakhov, A. A. Tatarnikov, A. M. Tatarnikov. 2026-02-16. The eruptive young star IRAS 21204+4913. https://arxiv.org/abs/2602.15157

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