η Carinae: The optical flare-like events during low-excitation passages

¹ Leiden Observatory, Postbus 9513, 2300RA Leiden, The Netherlands
² Astronomy Group, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
³ Alvine Estate, Vintage Lane, RD 3, Blenheim, New Zealand

Corresponding author: A. M. van Genderen, genderen@strw.leidenuniv.nl

Received: 4 November 2002
Accepted: 23 April 2003

Abstract

The 1992.5 and 1998.0 low-excitation events of the possible binary in the core of η Carinae show a conspicuous flare-like event in optical and near-ultraviolet light. These events last a couple of months and have a light amplitude of 01–02 in V. Considering the presence of a dense (bi-polar) stellar wind, one explanation could be that some type of a hot area is created by an increased mass flow from the S Dor primary near the hypothetical periastron. These flare-like events are terminated by sharp dips. The magnitude differences between the underlying light source and the central light (“Component A”) are derived. It turns out that they are fainter than Component A by ~. The luminosity could be of the order of 10. It was possible to derive two new continuum values in the near-UV, reinforcing the impression derived from the HST fluxes that Component A has a very strong radiation peak in the Balmer continuum. This can probably be explained by the strong emission of the stellar wind.