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Session 34 - New Results on the Nature of Eta Carinae.
Oral session, Wednesday, January 07

[34.01] The 1998.0 Spectroscopic Event in \eta Carinae

A. Damineli (JILA-U. Colorado and IAG/USP, Brazil), O. Stahl, A. Kaufer (Landessternwarte Königstuhl, D-69917 Heidelberg, Germany), D. F. Lopes (Obs. Nacional, Brazil)

The luminous star \eta Carinae is undergoing a ''spectroscopic event''. Hundreds of times the Sun's bolometric luminosity is disappearing from the star in the HeI 10830 Å\ emission line every month. Other high excitation lines ([NeIII], [FeIII], [SIII], [ArIII] and [NII]) are also weakening. It is the first time such an event is observed with this star after a prediction and its occurence may demote \eta Car into the ranks of 'normal' stellar objects.

The minimum of the event is expected to occur in January 1998, after which the lines will rapidly strengthen again until May, when it ends. The present data confirm the 5.52 year periodicity in \eta Car discovered by Damineli (1996). The periodicity is highly stable and probably is a strict one, which supports the binary system proposed recently by Damineli, Conti and Lopes (1997). In this picture the object, formerly thought to be peculiar, now fits comfortably in the framework of normal stellar evolution. Many of its characteristics may be explained by a pair of stars in a highly eccentric orbit, the most massive stars thus far known to orbit each other. The dense winds of the components collide with extreme violence, emitting hard X-rays, radio waves and probably injecting fresh dust into the Homunculus.

In this meeting we are discussing the binary model in the light of recent data collected at ESO and LNA observatories.

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Program listing for Wednesday