Radial Velocity Monitoring of the Young Star Hubble 4: Disentangling Star-spot Lifetimes from Orbital Motion*

We studied the weak-lined T Tauri star Hubble 4, a known long-period binary, and its starspot phenomena. used optical radial velocity (RV) data taken over span of 14 years (2004-2010, 2017-2019) at McDonald Observatory 2.7m Harlan J. Smith telescope single epoch imaging from HST/WFC3 instrument. The observed apparent RV variations show contributions, respectively, binary motion as well large spot group on one stars, presumed to be primary. Fitting removing orbital signal RVs, we found lower bound lifetime previously identified surface least 5.1 years. A $\sim5$ year limit is long, but not unprecedented, duration for group. later indicate significant evolution has occurred, placing an upper 12 find that pre-main sequence evolutionary models age Taurus ($\sim2$ Myr), combined with component mass estimates literature, permit us reproduce HST relative photometry binary-induced contribution variations. long-lived 4 implications dynamo in young it adds evidence long lifetimes magnetic field topologies. There are also exoplanet searches coherent signals may spot-induced result planetary motion. (This paper includes University Texas Austin.)