2024ApJ...967...64T

We present the results from a complex study of an eclipsing O-type binary (Aa+Ab) with the orbital period of P_A = 3.2254367 days that forms part of a higher-order multiple system in a configuration of (A+B)+C. We derived masses of the Aa+Ab binary of M₁ = 19.02 ± 0.12 and M₂ = 17.50 ± 0.13 M_ ⊙_, the radii of R₁ = 7.70 ± 0.05and R₂ = 6.64 ± 0.06 R_⊙, and temperatures of T₁ = 34,250 ± 500 K and T₂ = 33,750 ± 500 K. From the analysis of the radial velocities, we found a spectroscopic orbit of A in the outer A+B system with P_A+B = 195.8 days (P_A+B/P_A ≈ 61). In the O - C analysis, we confirmed this orbit and found another component orbiting the A+B system with P_AB+C = 2550 days (P_AB+C/P_A+B ≈ 13). From the total mass of the inner binary and its outer orbit, we estimated the mass of the third object, M_B ≳ 10.7 M_⊙. From the light travel time effect fit to the O - C data, we obtained the limit for the mass of the fourth component, M_C ≳ 7.3 M_⊙. These extra components contribute about 20%-30% (increasing with wavelength) to the total system light. From the comparison of model spectra with the multiband photometry, we derived a distance modulus of 18.59 ± 0.06 mag, a reddening of 0.16 ± 0.02 mag, and an R_V of 3.2. This work is part of our ongoing project, which aims to calibrate the surface brightness-color relation for early-type stars.