We have discovered a conspicuous unidentified variable feature near 6307 AA in the spectrum of Eta Carinae which is spatially unresolved from the central star and its wind (r < 200--300 AU). It is significant for two reasons: such prominent unidentified lines are now rare in this object, and this feature varies strongly and systematically. It exhibits a combination of characteristics which, so far as we know are unique in Eta Carinae's spectrum. It may provide insights into the recurrent spectroscopic events and the star's long-term brightening.
@article{arxiv.astro-ph/0603168,
title = {Variable Unidentified Emission Near 6307 AA in Eta Carinae},
author = {J. C. Martin and K. Davidson and F. Hamann and O. Stahl and K. Weis},
journal= {arXiv preprint arXiv:astro-ph/0603168},
year = {2009}
}