WFPC2 IMAGING OF THE CIRCUMSTELLAR NEBULOSITY OF HL TAURI

摘要

Planetary camera images of HL Tauri have been obtained through V-, R-, and I-band filters using the Wide Field and Planetary Camera 2 aboard the refurbished Hubble Space Telescope. These images show that HL Tauri is entirely reflection nebulosity at optical wavelengths, with no optical star visible to a limiting magnitude of V = 25.5. The optical nebula extends northeast of the stellar position along the direction of HL Tau's optical jet and has an unusual C-shaped morphology. The bright core of the nebula is only 1″ in size and is centered only 1.2″ from the actual stellar position. We estimate that visual extinction toward the unseen point source is at least 22 mag and that the stellar photospheric luminosity must be at least 3 solar luminosity. These findings corroborate other evidence that this star is significantly younger and more embedded than typical T Tauri stars.