We found that the known spectroscopic binary and variable BU~CMi = HD65241 (V=6.4-6.7 mag, Sp~=~A0~V) is a quadruple doubly eclipsing 2+2 system. Both eclipsing binaries are detached systems moving in an eccentric orbits: pair "A" with the period PA~=~2d.94(e=0.20) and pair "B" with the period PB~=~3d.26 (e=0.22). All four components have nearly equal sizes, temperatures and masses in the range M~=~3.1--3.4 M⊙ and A0 spectra. We derived the mutual orbit of both pairs around the system barycenter with a period of 6.54 years and eccentricity e = 0.71. We detected in pairs "A" and "B" the fast apsidal motion with the periods UA~=~25.0 years and UB~=~25.2 years, respectively. The orbit of each pair shows small nutation-like oscillations in periastron longitude. The age of the system estimated as 200 mln. years. The photometric parallax calculated from the found parameters coincides perfectly with the GAIADR2π=0.00407"±0.00006".
@article{arxiv.2107.09116,
title = {BU CMi as a quadruple doubly eclipsing system},
author = {I. M. Volkov and A. S. Kravtsova and D. Chochol},
journal= {arXiv preprint arXiv:2107.09116},
year = {2021}
}