He II l4686 in h Carinae: The Data and Modeling

A. DAMINELI; M. TEODORO; J. E. STEINER; N. MORRELL; R. BARBÁ; G. SOLIVELLA; R. GAMEN; E. FERNÁNDEZ-LAJÚS; F. GONZALEZ; C. A. O. TORRES; J. GROH; L. FRAGA; C. B. PEREIRA; M. BORGES FERNANDES; M. I. ZEVALLOS; P. MC. GREGOR

Río de Janeiro, Brasil

Jornada; IAU JD 13: Eta Carinae in the Context of the Most Massive Stars; 2009

IAU XXVII th General Assembly

The intrinsic emission of Heii is quite repeatable from cycle to cycle. The Heii l4686line flux rises by a factor of ~10 in the 2 months preceding phase zero. There are twolocal maxima in the monthpreceding the minimum and a secondary maximum ~50daysafter phase zero. The rising before phase zero resembles that seen in X-rays, but withremarkable differences. The Heii line flux increases by a factor of ~10 as compared toonly a few times in X-ray emission. Both light curves collapse before phase zero, butthe collapse of Heii is shifted by 16.5 days relative to the X-ray collapse. The minimumin Heii is reached a week after phase zero. Since the X-ray variability is measured inthe range 2-10 keV, and comes mainly from the vertex of the wind-wind shock cone,it is probably not common to the Heii emitting region, which comes from gas at lowertemperature.TheHeii line indicates ahigh luminosity sourcein the system, butitis notclear whereit comesfrom.Onepossible sourceis the collision of the secondary star wind,since the SED derived from Parkin et al.2009 (MNRAS 394, 1758) models indicates thepresence of 10 times more He+ ionizing photons than those passing through this atomictransition. Recombination of the shocked secondary wind is not the only source for theHe+ ionizing photons. As the shock cone migrates deep in the wind of the primary star,a huge amount of hard photons are free to escape and ionize the inner walls of thewind-wind collision zone.