Eta Carinae: A Spectacular Show From A Convulsing Massive Star
April 12, 2006 Although the Homunculus Nebula around the massive
star Eta Carinae has been the subject of intense study for many
years, it has always been reluctant to divulge its innermost
secrets. However, an important chapter in the recent evolution
of this unique star was revealed when Nathan Smith (University
of Colorado) used the high-resolution infrared spectrograph
PHOENIX on the Gemini South telescope to observe the bipolar
nebula surrounding Eta Carinae. Multi-slit spectroscopy (see
Figure 1) allowed Smith to reconstruct both the geometry and the
velocity structure of the expanding gas in the nebula based on
the behavior of the molecular line of hydrogen H2 at 2.1218
microns and the atomic line of ionized iron [Fe II] at 1.6435
microns (Figure 2). Figure 1. One of the five PHOENIX
spectrograph long-slit aperture positions superposed on a
2-micron HST/NICMOS image of Eta Carinae. Analysis of the
PHOENIX spectrum shows a very well-defined