A map of the 4680 emission around the central star.

I'm kind of proud of this figure so I wanted to put it up for general consumption. As background, there is a semi-mysterious emission line near to 4680 Angstroms which appeared in the spectrum of Eta Carinae about six months before the mid-2003 spectroscopic event and then abruptly disappeared during the event. The best identification we have for this line is He II 4687 but for various reasons the identification is dubious.

Kris Davidson and I have argued that this emission was unresolved from the central star. This is one of many points in a manuscript we are working on which contradict several assertions made about this feature in the current literature.

These maps are made from the profiles of seven STIS slits observed between MJD 52764 (2003.34) and MJD 52813 (2003.47). The diagonally hatched area is not covered by any slit during that time period. The flux level for each slit was scaled appropriately to compensate for the over-all change in brightness of Eta Carinae and the relative flux scale for both panels is given in the center. The image maps are smeared across the width of the 0.1 arc-second slit (i.e. diagonally from lower left to upper right) because there is no spatial resolution for an individual spectrum in that direction. The right panel is a map of the 4680 \mbox{\AA} emission, the left panel is a map of the 4743 \mbox{\AA} continuum, and the insert at lower left is an HST ACS/HRC image at the same scale and orientation taken with the F330W filter on MJD 52896.

Note that the continuum and the 4680 emission are completely coincident. It is possible that the 4680 emission could be coming from extended areas outside the slit coverage but any model of emission like that would have to be: 1. extremely contrived and/or 2. requiring an energy budget which far exceeds the available energy in the system. It is worth noting that our greatest spatial resolution and coverage is in the equatorial plane of the system so that if the emission moved from one side of the central star to the other (as if it is tied to the motion of the hypothetical binary companion) we would have seen it.

As a side note: the graphic of the orbital motion of the proposed secondary companion to Eta Carinae in the September 2004 issue of Sky & Telescope is backwards in too many ways to simply correct here. Please do not use it to orient yourself with respect to what we are seeing in this diagram.

Last updated 14 Sept 2004