We present an analysis of LAMOST J171013.211+532646.04 (hereafter J1710), a binary system comprising a hot subdwarf B star (sdB) and a white dwarf (WD) companion. Multi-epoch spectroscopy reveals an orbital period of 109.20279 minutes, consistent with TESS and ZTF photometric data, marking it as the sixth detached system known to harbor a WD companion with a period less than two hours. J1710 is remarkably close to Earth, situated at a distance of only \(350.68^{ +4.20}_{ -4.21} \, \mathrm{ pc}\), with a GAIA G-band magnitude of 12.59, rendering it conducive for continuous observations. The spectral temperature is around 25164 K, in agreement with SED fitting results (\(25301^{ +839}_{ -743} \, \mathrm{ K}\)). The TESS light curve displays ellipsoidal variation and Doppler beaming without eclipsing features. Through fitting the TESS light curve using the Wilson-Devinney code, we determined the masses for the sdB (\(M_1 = 0.44^{ +0.06}_{ -0.07} \, M_{ \odot}\)) and the compact object (\(M_2 = 0.54^{ +0.10}_{ -0.07} \, M_{ \odot}\)), with the compact object likely being a WD. Furthermore, MESA models suggest that the sdB, with a helium core mass of 0.431 \(M_{ \odot}\) and a hydrogen envelope mass of \(1.3 \times 10^{ -3}\, M_{ \odot}\), is in the early helium main-sequence phase. The MESA binary evolution shows that the J1710 system is expected to evolve into a double white dwarf system, making it an important source of low-frequency gravitational waves.
Categories: astro-ph.SR