Eta Car's spectroscopic event compared to 2009

ATel #6448; Kris Davidson (U. Minn.), Andrea Mehner (ESO-Chile), Roberta Humphreys (U. Minn), John Martin (U. Ill. - Springfield)
on 5 Sep 2014; 21:21 UT
Credential Certification: Roberta Humphreys (roberta@umn.edu)

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Recent HST/STIS observations of eta Car confirm the forecast in ATEL #6408. On August 31 the He II 4687 had become almost as bright as its first maximum seen in mid-July. This is about twice as strong as the second peak in the 2009 event. Evidently the He II emission, an indicator of soft X-rays, grew much faster after mid-August than it did in the corresponding stage in 2009. -------- If the second 4687 A flash is a leading indicator of hard X-ray recovery as noted by Mehner et al 2011, ApJ 740:80, then the observable X-rays should increase rapidly in the next 5-15 days. (See also Martin et al 2006, ApJ 640, 474.) -------- The FUV-excited N II emission near 4610 A, reported in ATEL #6408, was still conspicuous on August 31. This is evidence that the UV radiation is considerably stronger, and gas densities are lower, than in eta Car's previous periastron events. See Mehner et al 2001, ApJ 737:70.