THE BIPOLAR STRUCTURE OF THE LBV NEBULA AROUND HR CARINAE

HR Carinae is one of the few Luminous Blue Variables (LBVs) in the Gal axy. It has a nebula that appears bipolar. We have obtained imaging an d high-dispersion, long-slit echelle data of the HR Car nebula, and co nfirmed that it is a bipolar nebula. Its polar axis lies along the pos ition angle of 125 +/- 5 degrees; each lobe has. at a distance of 5 kp c a diameter of similar to 0.65 pc and a line-of-sight expansion veloc ity of 75 - 150 km s(-1). 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 m aterial ejected by HR Car, On a larger scale, a funnel-shaped nebula i s detected at 2.'5 northwest of HR Car. The axis of the funnel is roug hly aligned with the polar axis of the HR Car nebula, suggesting that HR Car may be responsible for the ionization and shaping of this nebul a. Future observations of kinematics and abundances are needed to dete rmine the nature of this nebula. We propose that the bipolar nebula of HR Car is a more evolved version of the Homunculus Nebula around eta Car. The recently developed theory of wind-compressed disks may explai n the higher density of the equatorial plane and the formation of bipo lar nebulae of LBVs.