Mehner, Andrea; Davidson, Kris; Humphreys, Roberta M.; Martin, John C.; Ishibashi, Kazunori; Ferland, Gary J.; Walborn, Nolan R.
The Astrophysical Journal Letters, Volume 717, Issue 1, pp. L22-L25 (2010).
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.