Presentation #205.12 in the session Binary Stellar System - iPoster Session.
There are only a limited number of black hole high mass X-ray binaries, and in our galaxy only Cygnus X-1 has been confirmed to have a blackhole secondary. HD96670, a new single-line spectroscopic binary in Carina OB2 Association, has been analyzed to possibly have a blackhole companion, and its light curve shows an unexpected “flare” around phase 0.8. In this work, we report more optical observations of HD96670. We collect optical photometry for the system within a long timespan: 10 years of data from 2000 to 2009, 17 non consecutive nights of data in 2016, and most recently 3 months of data in 2019. Periods of all the data are well-constrained around P=5.28388 days. Long-term observations confirm the existence and variability of “excess emission” around the phase of inferior conjunction, which we believe is the signature of a secondary blackhole and leads to a new class of BH-HMXB. Numerical analysis with Wilson-Devinney Code yields a best-fit mass of M1 = 32.57 ± 3.92 M⊙ for the primary and M2 = 6.85 ± 0.45 M⊙ for the secondary. In order to explain the extra flux, we propose a wind model that combines reduction in Kramers opacity and Bremsstrahlung emission from the shock structures in the accretion disk, and the modeling results are consistent with observations. Finally, we do a library search for more SB1 with weak wind O star primary as possible candidates for this new category.