Dynamical masses of 8.39 and 0.81 solar masses derived for AN Col Be-sdOB binary
Preprint reports first dynamical masses for AN Col Be-sdOB binary using interferometry plus spectroscopy. High mass-transfer efficiency and 87.7-day orbit constrain binary evolution models. Evidence strength limited by single-system sample and inclination upper bound.
The analysis separates the dominant 5.1-year disk oscillation cycles from the orbital signal using near-IR time-series astrometry and radial velocities of lines tracing each component. The resulting edge-on compatible orbit is limited to inclination ≤88.4° by the absence of eclipses in TESS photometry, yielding M_Be = 8.39 ± 0.67 M⊙ and M_sdOB = 0.81 ± 0.22 M⊙. This preprint from arXiv:2610.02367 confirms the sdOB companion is a slow rotator near 30 kK. High inferred mass-transfer efficiency aligns with the handful of other known Be + sdOB systems and challenges standard binary-evolution prescriptions that predict lower stripped-star masses. The dynamical parallax provides an independent distance anchor for future disk modeling. Next steps include continued GRAVITY monitoring to tighten the inclination constraint and comparison with population-synthesis runs that incorporate updated mass-transfer efficiency parameters.
Klement et al.: Additional GRAVITY epochs will reduce mass uncertainties below 5% within 18 months.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2610.02367)
- [2]Supporting Source(https://arxiv.org/abs/2305.07645)