Calibrating Emission Lines in Near Infrared Spectra of Classical T Tauri Stars with Near Simultaneous Optical Accretion Luminosities.

摘要

Classical T Tauri Stars are cool, young stars surrounded by a disk composed of dust and gas. The material from the inner disk is channeled onto the central star along magnetic field lines with in-fall rates that can vary in a matter of hours. Features in the near-infrared (NIR) observations of these disks indicate the accretion rates; however, these NIR feature strengths have been primarily calibrated using non-simultaneous measurements. We present a study of the NIR features Pa Delta, Pa Gamma, Pa Beta, and Br Gamma for 49 classical T Tauri stars. This study calibrates the strength of NIR features to ultra-violet accretion luminosities determined by Herczeg & Hillenbrand using near-simultaneous observations (separation time < 1 hour). We compare our new calibrations to those previously reported in the literature, while giving particular attention to the residuals of the linear fits to quantify the effects of using non-simultaneous data to calibrate the NIR indicators. We find more scatter in our data than in previous studies indicating that variability is not the dominant factor of the scatter in our data set.