Ultraviolet spectropolarimetry of three classical novae early in outburst: Evidence for aspherical shells

J. J. Johnson, University of Wisconsin-Madison
C. M. Anderson, University of Wisconsin-Madison
K. S. Bjorkman, University of Wisconsin-Madison
A. D. Code, University of Wisconsin-Madison
G. K. Fox, University of Wisconsin-Madison
A. J. Weitenbeck, University of Wisconsin-Madison
W. Sanders, University of Wisconsin-Madison
B. L. Babler, University of Wisconsin-Madison
M. R. Meade, University of Wisconsin-Madison
N. E.B. Zellner, University of Wisconsin-Madison
R. J. Edgar, University of Wisconsin-Madison
A. M. Magalhães, Universidade de São Paulo
G. C. Clayton, Louisiana State University
R. E. Schulte-Ladbeck, University of Pittsburgh
J. E. Herald, University of Pittsburgh
O. L. Lupie, Space Telescope Science Institute

Abstract

The Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE) was used to obtain the first ultraviolet (1450-3200 Å) spectropolarimetry of three classical novae, all of which had recently gone into outburst (Nova Cir 1995, Nova Aql 1995, and Nova Cen 1995). All three novae appear to have intrinsic polarization, with polarization changes across emission lines or time-variable polarization, indicating that the ejecta were geometrically aspherical. A simple model is used to estimate the level of asphericity of the novae ejecta. Different emission lines exhibit varying amounts of polarization, suggesting that they are formed in regions of differing geometry. In particular, the Mg II resonance line in Nova Cir is more polarized than the continuum. This could be the first time that a polarized resonance line has been observed in a nova. © 1997 American Astronomical Society.