Possible detection of an old bipolar shell associated with η Carinae |
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Authors: | Joaquín Bohigas Mauricio Tapia María Teresa Ruiz † Miguel Roth |
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Institution: | Instituto de Astronomía UNAM, Apdo. Postal 877, 2800 Ensenada BC, Mexico; Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile; Las Campanas Observatory, Carnegie Institution of Washington, Casilla 601, La Serena, Chile |
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Abstract: | Continuum-subtracted dereddened images in the light of several atomic lines show the presence of an extended bipolar nebula surrounding η Carinae with size ∼100×45 arcsec2 (1.3×0.5 pc2). This feature is best delineated in O iii ] 5007. The geometrical disposition and mass of the shell suggest that it was formed by mass ejections from η Carinae. The dynamic age of the nebula is ∼13 000/ V 7 yr, where V 7 is the mean expansion velocity in 100 km s−1, and its mass is between 5 and 10 M⊙. The nebula is photoionized and composed of unprocessed material. The major axes of the nebula and of the Homunculus are nearly perpendicular. We also report the discovery of elongated emission knots prominent in N ii ] located 64 to 100 arcsec away from η Carinae, which implies that they were ejected either centuries ago or at a more recent date but with extremely large velocities. |
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Keywords: | stars: individual: η Carinae stars: variables: other H ii regions ISM: individual: NGC 3372 |
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