The Systemic Velocity of Eta Carinae

Abstract

High-resolution spectra of molecular hydrogen in the Homunculus nebula allow for the first direct measurement of the systemic velocity of Eta Carinae. Near-infrared long-slit data for H2 1-0 S(1) lambda 21218 obtained with the Phoenix spectrometer on the Gemini South telescope give Vsys=-8.1pm1 km/s (heliocentric), or VLSR=-19.7pm1 km/s, from the average of the near and far sides of the Homunculus. This measurement considerably improves the precision for the value of -7pm10 km/s inferred from neighboring O-type stars in the Carina nebula. New near-infrared spectra also provide a high-resolution line profile of [Fe II] lambda 16435 emission from gas condensations known as the Weigelt objects without contamination from the central star, revealing a line shape with complex kinematic structure. Previously, uncertainty in the Weigelt knots' kinematics was dominated by the adopted systemic velocity of Eta Car.

4 pages, published in MNRAS

References in corpus (2)

• Latitude-dependent effects in the stellar wind of Eta Carinae
• Dissecting the Homunculus nebula around Eta Carinae with spatially resolved near-infrared spectroscopy

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