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arXiv · 2301.00064

The orbital kinematics of eta Carinae over three periastra with a possible detection of the elusive secondary's motion

Emily Strawn·Noel D. Richardson·Anthony F. J. Moffat·Nour Ibrahim·Alexis Lane·Connor Pickett·André-Nicolas Chené·Michael F. Corcoran·Augusto Damineli·Theodore R. Gull·D. John Hillier·Patrick Morris·Herbert Pablo·Joshua D. Thomas·Ian R. Stevens·Mairan Teodoro·Gerd Weigelt
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Abstract

The binary eta Carinae is the closest example of a very massive star, which may have formed through a merger during its Great Eruption in the mid-nineteenth century. We aimed to confirm and improve the kinematics using a spectroscopic data set taken with the CTIO 1.5 m telescope over the time period of 2008-2020, covering three periastron passages of the highly eccentric orbit. We measure line variability of H-alpha and H-beta, where the radial velocity and orbital kinematics of the primary star were measured from the H-beta emission line using a bisector method. At phases away from periastron, we observed the He II 4686 emission moving opposite the primary star, consistent with a possible Wolf-Rayet companion, although with a seemingly narrow emission line. This could represent the first detection of emission from the companion.

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Emily Strawn, Noel D. Richardson, Anthony F. J. Moffat, Nour Ibrahim, Alexis Lane, Connor Pickett, André-Nicolas Chené, Michael F. Corcoran, Augusto Damineli, Theodore R. Gull, D. John Hillier, Patrick Morris, Herbert Pablo, Joshua D. Thomas, Ian R. Stevens, Mairan Teodoro, Gerd Weigelt. 2022-12-30. The orbital kinematics of eta Carinae over three periastra with a possible detection of the elusive secondary's motion. https://doi.org/10.1093/mnras/stad018

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