AffiliationUniv Arizona, Steward Observ
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PublisherIOP PUBLISHING LTD
CitationResolving the H alpha-emitting Region in the Wind of eta Carinae 2017, 841 (1):L7 The Astrophysical Journal
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AbstractThe massive evolved star. Carinae is the most luminous star in the Milky Way and has the highest steady wind mass-loss rate of any known star. Radiative transfer models of the spectrum by Hillier et al. predict that Ha is mostly emitted in regions of the wind at radii of 6-60 au from the star (2.5-25 mas at 2.35 kpc). We present diffraction-limited images (FWHM similar to 25 mas) with Magellan adaptive optics in two epochs, showing that. Carinae consistently appears similar to 2.5-3 mas wider in Ha emission compared to the adjacent 643 nm continuum. This implies that the H alpha line-forming region may have a characteristic emitting radius of 12 mas or similar to 30 au, in very good agreement with the Hillier stellar-wind model. This provides direct confirmation that the physical wind parameters of that model are roughly correct, including the mass-loss rate of M= 10(-3)M(circle dot) yr(-1), plus the clumping factor, and the terminal velocity. Comparison of the Ha images (ellipticity and PA) to the continuum images reveals no significant asymmetries at H alpha. Hence, any asymmetry induced by a companion or by the primary's rotation do not strongly influence the global H alpha emission in the outer wind.
VersionFinal published version
SponsorsNational Science Foundation ; NSF AAG ; NASA Origins of Solar Systems award; TRIF fellowship; NSF [AST-1312221]; NASA Exoplanets Research Program (XRP) [NNX16AD44G]