A massive cool dust torus around η Carinae?

摘要

The star η Carinae, the most luminous known in the Milky Way galaxy, is a puzzling object. It is surrounded by a cloud of glowing gas that shows a distinct 'pinched waist' appearance, whose origin has been controversial. Morris et al.1 proposed that a massive but very compact torus of gas encircles the star, and that this caused the bipolar shape by preventing gas ejected by the star from expanding in the equatorial plane. Here we show that the small size of the torus (diameter of 5 arcsec) is insufficient to produce the observed infrared flux that inspired the conjecture. The dust giving rise to the 17-μm emission must be distributed over an area at least ten times the size of the torus. Such an extended structure of gas, however, would probably be incapable of generating the pinched waist.