Presented by Ed Budding, Mark Blackford, Roger Butland, (et al.)
We present combined photometric and spectroscopic analyses of the southern close binary systems V454 Car and HX Vel. High-resolution spectra of these systems were taken at the University of Canterbury Mt. John Observatory in the years 2009-15. Absolute parameters for the triple (at least) system V454 Car confirm its young and near-Main-Sequence nature. We find: M1 = 6.30+/-0.20, M2 = 5.86+/-0.18, R1 = 3.12+/-0.05, R2 = 3.04+/-0.04, (all in solar units); T1 ~19000, T2 ~18500 (K); photometric distance ~ 550 (pc).
The close binary is found to be the major component (A) of a multiple star, whose other main component (B) is also probably a binary. The two components are in eccentric orbits about a common centre of gravity with a period of ~ 1900 d. Analysis of the radial velocity curves is strongly suggestive that the mass of component B is greater than that of its visible member, while the measured radial velocities of this visible star show irregularities incompatible with reasonable measurement accuracies. These variations occur on a timescale of days to weeks. For HX Vel we find absolute parameters as follows: M1 = 9.6+/-0.4, M2 = 5.6+/-0.3, R1 = 4.80+/-0.18, R2 = 3.05+/-0.16, (all in solar units); T1 ~25000, T2 ~17000 (K); photometric distance ~ 390+/-30 (pc).
HX Vel, the brighter component of the visual pair CCDM J08423-4806 AB is often considered to be the brightest member of the cluster IC 2395. There appears to be an inconsistency in the distance estimates, however. The ~400 pc distance of our determination would make the system a likely member of the Sco-Cen OB2 Association within Gould’s Belt.