Major stellar-wind emission features in the spectrum of η Car have recently decreased by factors of order 2 relative to the continuum. This is unprecedented in the modern observational record. The simplest, but unproven, explanation is a rapid decrease in the wind density.
Digital Object Identifier (DOI)
Mehner, Andrea; Davidson, Kris; Humphreys, Roberta M.; Martin, John C.; Ishibashi, Kazunori; Ferland, Gary J.; and Walborn, Nolan R., "A Sea Change in Eta Carinae" (2010). Physics and Astronomy Faculty Publications. 140.