The Light Curve of V713 Per (HMW 15): Evidence for Gravitational Sculpting by an Object Embedded in the Circumstellar Disk

HMW 15 (V713 Per, H 187, TJ 108, LRLL 35) is a G-type weak-line T Tauri star (WTTS) in the extremely young cluster IC 348. It has an age of about 3 My, a mass of about 1.5 solar mass and a distance of 300 pc. What distinguishes it from other WTTS is a cyclic variation in optical brightness with an amplitude of about 0.8 mag and a period of 1717 d or 4.7 yr (Nordhagen et al. 2006, ApJ 646, 151). The star shows no detectable radial velocity variations to stringent limits (Grinin et al. 2008, A&A 489,1233) indicating that the periodicity is not caused by a stellar companion. Two complete cycles of this variation have now been observed and we present and discuss its form and features. We suggest that the main cause of the periodic variation is a massive embedded planet or protoplanet orbiting at a distance of 3.3 AU from the central (single) star. Other features in the light curve can be seen at the Lagrangian points (L3, L4 and L5) of this system, where we suppose that gravitational sculpting by the planet has been active. Continued monitoring of this unique and potentially important system is obviously warranted and is needed to test our hypothesis. We thank the NASA-Origins program for its support of this work through a grant to WH and the NSF/REU program for supporting the participation of one us (AY).