Catching the Butterfly and the Homunculus of η Carinae with ALMA

August 2022 • 2022ApJ...935...76Z

Authors • Zapata, Luis A. • Loinard, Laurent • Fernández-López, Manuel • Toalá, Jesús A. • González, Ricardo F. • Rodríguez, Luis F. • Gull, Theodore R. • Morris, Patrick W. • Menten, Karl M. • Kamiński, Tomasz

Abstract • The nature and origin of the molecular gas component located in the circumstellar vicinity of η Carinae are still far from being completely understood. Here, we present Atacama Large Millimeter/submillimeter Array CO(3-2) observations with a high angular resolution (~0.″15) and a great sensitivity that are employed to reveal the origin of this component in η Carinae. These observations reveal much higher velocity (-300 to +270 km s^-1) blue- and redshifted molecular thermal emission than previously reported, which we associate with the lobes of the Homunculus Nebula, and which delineates very well the innermost contours of the red- and blueshifted lobes likely due to limb brightening. The inner contour of the redshifted emission was proposed to be a disrupted torus, but here we reveal that it is at least part of the molecular emission originating from the lobes and/or the expanding equatorial skirt. On the other hand, closer to systemic velocities (±100 km s^-1), the CO molecular gas traces an inner butterfly-shaped structure that is also revealed at near-IR and mid-IR wavelengths as the region in which the shielded dust resides. The location and kinematics of the molecular component indicate that this material has formed after the different eruptions of η Carinae.

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Pat Morris

Senior Scientist