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arXiv · 2510.19023

A very young and fast rotating shell star discovered in the eclipsing binary ZTF J200347.63+394429.8

Norbert Hauck
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Abstract

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.

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Norbert Hauck. 2025-10-21. A very young and fast rotating shell star discovered in the eclipsing binary ZTF J200347.63+394429.8. https://arxiv.org/abs/2510.19023

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