Hubble Space Telescope Measurements of the Expansion of NGC 6543: Parallax Distance and Nebular Evolution
Casertano, Stefano; Panagia, Nino; Balick, Bruce; Hajian, Arsen R.; Terzian, Yervant; Reed, Darren S.; Klayton, Tracy L.; Giovanardi, Stefano
United States, Italy
Abstract
The optical expansion parallax of NGC 6543 has been detected and measured using two epochs of Hubble Space Telescope images separated by a time baseline of only 3 years. We have utilized three separate methods of deriving the angular expansion of bright fiducials, with excellent agreement in the results. We combine our angular expansion estimates with spectroscopically obtained expansion velocities to derive a distance to NGC 6543 of 1001+/-269 pc. The deduced kinematic age of the inner bright core of the nebula is 1039+/-259 yr; however, the kinematic age of the polar caps that surround the core is larger-perhaps the result of deceleration or earlier mass ejection. The morphology and expansion patterns of NGC 6543 provide insight into a complex history of axisymmetric, interacting stellar mass ejections.