The ejecta from the luminous blue variable star P Cygni |
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Authors: | J Meaburn J A O'connor J A López M Bryce M P Redman A Noriega-Crespo |
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Institution: | Jodrell Bank Observatory, Department of Physics &Astronomy, University of Manchester, Macclesfield, Cheshire SK11 9DL;Instituto de Astronomía, UNAM, Apdo. Postal 877, Ensenada, B.C. 22800, Mexico;Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, California, 91125, USA |
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Abstract: | Further optical observations have been made with the Manchester Occulting Mask Imager and Manchester Echelle Spectrometer of the inner and outer shells of P Cygni, and of the 7-arcmin long giant lobe projecting from this luminous blue variable star. An image in the light of the fluorescently excited Ni ii ] 7378-Å line has revealed the knottiness of the inner shell. Well defined 'velocity ellipses' for the position/velocity arrays across the outer shell indicate that its expansion velocity is 160 km s−1 which is somewhat lower than the previously reported value. The kinematical behaviour of the giant lobe, both in the vicinity of P Cygni, and further away, emphasizes its strange nature, although close association with P Cygni is again suggested by these new observations. One possibility is that this lobe is a 'trail' of collimated ejected material. The observations are compared with a 60-μm IRAS high-resolution map of the region. A variety of possible explanations of the observed phenomena are explored, e.g. radio knots in the outer stellar wind either coalesce or expand to become the Ni ii ]7378-Å emitting knots in the inner shell; that a mass-loaded wind overunning slower moving clumps explains the kinematics of the inner shell; that the one-sided giant lobe could be a 'trail' of ejected material from P Cygni funnelled through the outer shell. |
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Keywords: | circumstellar matter stars: individual: P Cygni stars: variables: other |
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