The Source of the Helium Visible Lines in Eta Carinae

Abstract

We assume that the helium-I lines emitted by the massive binary system Eta Carinae are formed in the acceleration zone of the less-massive secondary star. We calculate the Doppler shift of the lines as a function of orbital phase and of several parameters of the binary system. We find that a good fit is obtained if the helium lines are formed in the region where the secondary wind speed is 430 km/sec. The acceptable binary eccentricity is in the range 0.9-0.95, and the inclination angle (the angle between a line perpendicular to the orbital plane and the line of sight) is in the range 40-55 degrees. Lower values of e require higher values of i, and vice versa. The binary system is oriented such that the secondary star is in our direction (closer to us) during periastron passage. The orbital motion can account in part to the Doppler shift of the peak in X-ray emission.

Accepted by New Astronomy

References in corpus (2)

• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event: III. the He II 4686 Line
• The superimposed photospheric and stellar wind variability of the O-type supergiant alpha Cam

Cited by in corpus (7)

• A multispectral view of the periodic events in eta Carinae
• Possible Implications of Mass Accretion in Eta Carinae
• The Early Spectra of Eta Carinae 1892 to 1941 and the Onset of Its High Excitation Emission Spectrum
• The Orientation of the Eta Carinae Binary System
• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event. V. the Infrared Decline
• A high-velocity transient outflow in Eta Carinae
• Prediction for the He I 10830A Absorption Wing in the Coming Event of Eta Carinae