Properties of the P Cygni wind found using the Self Absorption Curve method

¹ Laboratoire d'Astrophysique de Marseille, 2 place le Verrier, 13248 Marseille Cedex 04, France e-mail: muratorio@observatoire.cnrs-mrs.fr
² Institute of Astronomy and Isaac Newton Institute of Chile Bulgarian Branch, National Astronomical Observatory, PO box 136, 4700 Smoljan, Bulgaria e-mail: rozhen@mbox.digsys.bg
³ Institut d'Astrophysique, 98 bis Boulevard Arago, 75014 Paris, France e-mail: fried@iap.fr
⁴ Instituto de Astrofisica de Canarias, Via Lactea, 38200 La Laguna, Tenerife, Spain e-mail: gil@ll.iac.es

Corresponding author: M. Friedjung, fried@iap.fr

Received: 29 March 2002
Accepted: 13 May 2002

Abstract

We have used the optical lines of N II and Fe III to study the wind of the luminous blue variable P Cyg. This was performed by applying a version of the Self Absorption Curve (SAC) method, involving few assumptions, to lines whose flux can be measured. A rather surprising result was obtained; the lines of more excited multiplets without blue shifted absorption components appear to be optically thick, while the lines of the most excited multiplets may show some indications of being optically thicker than the lines of less excited ones. Explanations of such effects are discussed, including possible inhomogeneities in the wind.