V928 Tau is a previously known astrometric weak-lined T Tauri binary, with an orbital period inferred to be greater than 58 years (Schaefer et al. 2014). In addition to confirming for the first time that V928 Tau A+B are physically associated on the basis of nearly identical spectra, obtained from adaptive-optics resolved spectroscopy, we report the detection of a single, deep, asymmetric eclipse from K2 data. We suggest this is due to a previously unknown companion at intermediate separation (orbital period > 80 days). From modeling of the eclipse shape we find evidence that the transiting or eclipsing companion is surrounded by a circumsecondary disk or a vast ring system on an eccentric orbit around a single component of the binary. This modeling is done by new software developed specifically for the fitting of inclined and tilted circumsecondary disks or ring systems to light curves. Photometry from ground-based time-domain surveys reveal additional eclipses of the young star system, which provide period constraints, which in turn provide mass and eccentricity constraints of the orbit of the secondary. We find several possible periods and report the corresponding predictions of the next transits, which will be monitored to fully determine the orbital period of the companion. Once this has been done an observing campaign can be organised to fully characterise the physical and chemical properties of the circumsecondary disk allowing us to better understand gas giant formation.
AAS/Division for Extreme Solar Systems Abstracts
- Pub Date:
- August 2019