Variable Unidentified Emission near 6307 Å in η Carinae

Abstract

We have discovered a conspicuous unidentified variable feature near 6307 Å in the spectrum of η Carinae that is spatially unresolved from the central star and its wind (r<~200-300 AU). It is significant for two reasons: first, such prominent unidentified lines are now rare in this object, and second, this feature varies strongly and systematically. It exhibits a combination of characteristics that, so far as we know, are unique in η Carinae's spectrum. It may provide insights into the recurrent spectroscopic events and the star's long-term brightening.

This research is part of the Hubble Space Telescope Treasury Project for η Carinae, supported by grants GO-9420 and GO-9973 from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Partially based on observations obtained with UVES at the ESO Very Large Telescope, Paranal, Chile (proposals 70.D-0607[A], 71.D-0168[A], and 72.D-0524[A]).