A photometric study in combination with existing stellar models has revealed details of this eclipsing post-mass-transfer binary. The shell star has an equatorial/ polar radius of ~2.60/1.90 Rsun at an equatorial rotational velocity of ~430 km s-1, an effective mean temperature Teff of ~13300 K and a mass of ~3.42 Msun. This former accretor star is surrounded by a large decretion disk of ~47 Rsun. The secondary star is a helium white dwarf precursor with a radius of 0.98 Rsun, a Teff of ~17100 K and a mass of 0.29 Msun. The parameters of this former donor star indicate an age of the binary system of only ~1.8 Myr after the end of mass transfer. The results fit to a sub-solar metallicity of Z = 0.007.
@article{arxiv.2510.19023,
title = {A very young and fast rotating shell star discovered in the eclipsing binary ZTF J200347.63+394429.8},
author = {Norbert Hauck},
journal= {arXiv preprint arXiv:2510.19023},
year = {2026}
}
Comments
6 pages including 2 tables and 4 figures. Accepted for publication in BAV Rundbrief,vol.74, no.4, (2025)