Abstract Spectroscopic monitoring by our TIGRE telescope with its intermediate-resolution spectrograph revealed the SB2 behaviour of the stellar system HD 46198. An analysis of the radial velocity measurements of the sharp-lined, low-mass (secondary) component yields an orbital period of P = 129.8 days for the system, with a close to circular orbit. We then applied a modified version of our QER20 Package spectral disentangling method to measure the small Doppler shifts of the much more massive and broader-lined (primary) component and obtained the orbital solution of the SB2 system, as well as the disentangled profile of the Hα line for both stellar components. In particular, we find an extremely low mass ratio of q = M2/M1 = 0.083. We revised the TESS photometry data but did not find any indication of eclipses. A determination of the stellar parameters shows that the secondary component is already evolved (log (g) ≈ 1.3), so that the system is definitely not primordial. The system suffers currently no mass-overflow, because the radii are smaller than the distances to the Lagrange point L1, and there is no X-ray emission. However, there must have been a significant exchange and loss of mass and angular momentum in a past, interactive phase of this binary, in which the orbit circularized. Hence, we conclude that HD 46198 is another extreme mass ratio post-mass transfer binary system.
Jack et al. (Wed,) studied this question.