Does Episodic Mass Loss Dominate the Evolution of Massive Stars?

Evolution of the most massive stars such as eta Carinae is controlled by the effects of mass-loss, possibly dominated by poorly understood stellar eruptions and episodic mass ejections. Copious mass loss leads to circumstellar dust formation, obscuring the star in the optical. But as the light is absorbed and re-emitted by the dust, these objects become very luminous in mid-infrared light. Understanding these stars is challenging because no true analogs of eta Car have been found so far in our or other galaxies. I present the results of our systematic search for eta Car analogs in 7 galaxies utilizing Spitzer, Herschel, HST and other data. While strict eta Car analogs remain to be found, if they exist, we discovered a new class of luminous, heavily dust obscured, massive stars. I will describe the properties of these stars, and discuss the implications of our findings for massive star evolution and their resulting supernovae.

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