Explaining the Early Exit of Eta Carinae from its 2009 X-Ray Minimum with the Accretion Model

TL;DR

This paper explains the early exit of Eta Carinae from its 2009 X-ray minimum using an accretion model, highlighting how variations in stellar wind properties affected the duration of the X-ray minimum.

Contribution

It introduces a model linking primary wind fluctuations to the shortened X-ray minimum, providing a new explanation for the 2009 event's early exit.

Findings

Faster, lower mass-loss primary wind led to reduced accretion.

Fluctuations within observed ranges explain the shorter X-ray minimum.

Implications for system recovery from spectroscopic events.

Abstract

We use the accretion model to explain the early exit of Eta Carinae from its 2009 X-ray minimum. In the accretion model the secondary star accretes mass from the primary wind near periastron passage, a process that suppresses the secondary wind. As the shocked secondary wind is responsible for most of the X-ray emission, the accretion process accounts for the X-ray minimum. The early exit from the 2009 X-ray minimum after four weeks, instead of ten weeks as in the two previous minima, is attributed to the primary wind that during the last minimum was somewhat faster and of lower mass loss rate than during the two previous X-ray minima. This results in a much lower mass accretion rate during the X-ray minimum. We show that using fluctuations in these quantities that are within the range deduced from fluctuations in the X-ray flux outside the minimum, can account for the short duration of the last X-ray minimum. The shorter X-ray minimum may have further implications on the recovery of the system from the spectroscopic event.