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The bipolar structure of the LBV nebula around HR Carinae
* 1, 2,
W.J. Duschl 1, 3,
Y.-H. Chu 2 and
M.D. Joner 4
Received 1 July 1996 / Accepted 12 September 1996
HR Carinae is one of the few Luminous Blue Variables (LBVs) in the Galaxy. It has a nebula that appears bipolar. We have obtained imaging and high-dispersion, long-slit echelle data of the HR Car nebula, and confirmed that it is a bipolar nebula. Its polar axis lies along the position angle of ; each lobe has, at a distance of 5 kpc a diameter of pc and a line-of-sight expansion velocity of .
Beside the expanding bipolar lobes, a number of [N II ]-bright knots are detected. These knots have lower expansion velocities than the lobes and are detected only within the projected boundary of the lobes. These knots are most likely nitrogen-enriched material ejected by HR Car.
On a larger scale, a funnel-shaped nebula is detected at 2 5 northwest of HR Car. The axis of the funnel is roughly aligned with the polar axis of the HR Car nebula, suggesting that HR Car may be responsible for the ionization and shaping of this nebula. Future observations of kinematics and abundances are needed to determine the nature of this nebula.
We propose that the bipolar nebula of HR Car is a more evolved version of the Homunculus Nebula around Car. The recently developed theory of wind-compressed disks may explain the higher density of the equatorial plane and the formation of bipolar nebulae of LBVs.
Key words: stars: evolution stars: individual: HR Car; j Car stars: mass-loss ISM: bubbles: jets and outflows
* Visiting Astronomer, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.
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Online publication: June 30, 1998