High-Resolution Near-Infrared Images of the T Tauri Binary System XZ Tauri

Abstract

Abstract We present a high-resolution ($\sim $0$.\prime\prime$1 $=$ 14 AU) $H$-band image of XZ Tau, a 0$.\prime\prime$ 3-separated classical T Tauri binary system, taken with the Coronagraphic Imager with Adaptive Optics (CIAO) on the Subaru Telescope. We found a scattered light nebula extending to $\sim $2$.\prime\prime$4 from the secondary, XZ Tau S, in the northeast region of the binary. Its surface brightness is $\sim $16.2 mag arcsec$^{-2}$ in the $H$-band, and decreases as $r^{-1.6 \pm 0.1}$. Combined with the HST/ACS polarimetric images and the [Fe ii] $\lambda$1.644 $\micron$ spectra taken with the Infrared Camera and Spectrograph (IRCS) on the Subaru Telescope, the elongated structure is identified as a wall of a cavity blown by the previously known blueshifted outflow. By a comparison with previous measurements, we estimated that the orbital period is 1010$ \pm $260 yr and the total mass of the binary is 0.62$ \pm $0.36$ M_{\odot}$. The observed $H$-band magnitudes of both the primary and the secondary varied by as much as 1 mag over this decade. These $H$-band inconstancies may arise from a variable accretion rate and changing extinction toward each component.