Detection of high-velocity material from the wind-wind collision zone of Eta Carinae across the 2009.0 periastron passage

Abstract

We report near-IR spectroscopic observations of the Eta Carinae massive binary system during 2008-2009 using VLT/CRIRES. We detect a strong, broad absorption wing in He I 10833 extending up to -1900 km/s across the 2009.0 spectroscopic event. Archival HST/STIS ultraviolet and optical data shows a similar high-velocity absorption (up to -2100 km/s) in the UV resonance lines of Si IV 1394, 1403 across the 2003.5 event. UV lines from low-ionization species, such as Si II 1527, 1533 and C II 1334, 1335, show absorption up to -1200 km/s, indicating that the absorption with v from -1200 to -2100 km/s originates in a region markedly faster and more ionized than the nominal wind of the primary star. Observations obtained at the OPD/LNA during the last 4 spectroscopic cycles (1989-2009) also display high-velocity absorption in He I 10833 during periastron. Based on the OPD/LNA dataset, we determine that material with v < -900 km/s is present in the phase range 0.976 < phi < 1.023 of the spectroscopic cycle, but absent in spectra taken at phi < 0.947 and phi > 1.049. Therefore, we constrain the duration of the high-velocity absorption to be 95 to 206 days (or 0.047 to 0.102 in phase). We suggest that the high-velocity absorption originates from shocked gas in the wind-wind collision zone, at distances of 15 to 45 AU in the line-of-sight to the primary star. Using 3-D hydrodynamical simulations of the wind-wind collision zone, we find that the dense high-velocity gas is in the line-of-sight to the primary star only if the binary system is oriented in the sky so that the companion is behind the primary star during periastron, corresponding to a longitude of periastron of omega ~ 240 to 270 degrees. We study a possible tilt of the orbital plane relative to the Homunculus equatorial plane and conclude that our data are broadly consistent with orbital inclinations in the range i=40 to 60 degrees.

18 pages, 15 figures, accepted for publication in A&A; high-resolution PDF version available also at http://www.mpifr.de/staff/jgroh/etacar.html

References in corpus (20)

• Near-Infrared interferometry of Eta Carinae with high spatial and spectral resolution using the VLTI and the AMBER instrument
• Chemical evolution of galaxies. I. A composition-dependent SPH model for chemical evolution and cooling
• A Blast Wave from the 1843 Eruption of Eta Carinae
• High-excitation emission lines near eta Carinae, and its likely companion star
• The UV Scattering Halo of the Central Source Associated with Eta Carinae
• A multispectral view of the periodic events in eta Carinae
• Modeling the RXTE light curve of $\eta$ Carinae from a 3-D SPH simulation of its binary wind collision
• The Early Spectra of Eta Carinae 1892 to 1941 and the Onset of Its High Excitation Emission Spectrum
• Spectral atlas of massive stars around He I 10830 A
• Episodic Post-Shock Dust Formation in the Colliding Winds of Eta Carinae
• Near-infrared integral field spectroscopy of the Homunculus nebula around Eta Carinae using Gemini/CIRPASS
• Long-Term Optical Monitoring of Eta Carinae. Multiband light curves for a complete orbital period
• The Source of the Helium Visible Lines in Eta Carinae
• The Eta Carinae optical 2009.0 event, a new "eclipse-like" phenomenon
• The Orientation of the Eta Carinae Binary System
• Wind-wind collision in the eta Carinae binary system - III. The HeII 4686 line profile
• Accretion onto the Companion of Eta Carinae During the Spectroscopic Event. V. the Infrared Decline
• A high-velocity transient outflow in Eta Carinae
• Constraining the orbital orientation of Eta Carinae from H Paschen lines
• Prediction for the He I 10830A Absorption Wing in the Coming Event of Eta Carinae

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