Presentation #128.05 in the session “Understanding the Stars by Watching Them Dance”.
Knowing the age of stars is essential to understanding the planets they host. Orbital analysis of a binary star allows for a precise mass estimate of the system. This mass leads to a model-dependent age which may be extrapolated to the entire moving group. We present new spatially resolved astrometry and photometry of the known binary star system CD-27 11535, a member of the beta Pictoris moving group. By combining new NIRC2 data with earlier GPI and archival NaCo images, we fit the visual orbit. However, the mass deduced from this orbit appeared to be a 2 sigma outlier when compared to theoretical isochrones. We utilised flux ratio data from the visible through the infrared to ascertain the individual component masses which further highlighted the discrepancy between a two star model and the data. We are led to hypothesize a new model - a triple system (AaAbB). This arrangement more accurately matches the flux ratio data and is consistent with the dynamical mass derived from the visual orbit. We predict measured masses of MAa = 0.913 ± 0.023 Msun, MAb = 0.166 ± 0.045 Msun and MB = 0.888 ± 0.022 Msun. While these masses are model dependent, future spectroscopic images of the inner system may give us model independent individual masses.