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High Velocity Absorption during Eta Car B's Periastron Passage

By H. Hartman, Theodore R. Gull, J. Hillier, A. Damineli, J. H. Groh, G. Weigelt, A. T. Okazaki, S. P. Owocki, M. Teodoro and Krister E. Nielsen

Abstract

Eta Car is one of the most luminous massive stars in the Galaxy, with repeated eruptions with a 5.5 year periodicity. These events are caused by the periastron passage of a massive companion in an eccentric orbit. We report the VLT/CRIRES detection of a strong high-velocity, (<1900 km/s) , broad absorption wing in He I at 10833 A during the 2009.0 periastron passage. Previous observations during the 2003.5 event have shown evidence of such high-velocity absorption in the He I 10833 transition, allowing us to conclude that the high-velocity gas is crossing the line-of-sight toward Eta Car over a time period of approximately 2 months. Our analysis of HST/STlS archival data with observations of high velocity absorption in the ultraviolet Si IV and C IV resonance lines, confirm the presence of a high-velocity material during the spectroscopic low state. The observations provide direct detection of high-velocity material flowing from the wind-wind collision zone around the binary system, and we discuss the implications of the presence of high-velocity gas in Eta Car during periastro

Topics: Astronomy
Year: 2010
OAI identifier: oai:casi.ntrs.nasa.gov:20100002938
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