The Sanduleak's star in the Large Magellanic Cloud

Rodolfo Angeloni, F. Di Mille, R. Corradi & M. Livio

GEMINI Observatory, Chile

Sanduleak's star is a variable emission-line object in the Large Magellanic Cloud. It was discovered in 1977 and, already in the early 80's, a similarity with eta Carinae and SN 1987A was proposed on the basis on IUE observations which indicated episodic mass outflow, extreme departures from normal cosmic values of nitrogen relative to carbon and oxygen, and an electron temperature which is hard to reconcile with pure photo-ionization models. Sanduleak's star came abruptly back on stage in 2011, when we discovered that it powers a giant, highly-collimated bipolar jet extending over almost 15 pc: to our knowledge, it is the largest stellar jet discovered so far, and the first clearly resolved beyond the Milky Way. In this contribution we present our follow-up observations of Sanduleak's star obtained over the last few years. In particular: HST-WFC3 narrow-band images, that allow us to resolve the spectacular inner nebula; Magellan-FIRE and MMIRS near-infrared spectra, which give insight on the symbiotic character of the central binary; Magellan-MIKE high-resolution optical spectra, that further constraint the kinematics, chemistry and energetics of the overall system. We thus discuss the nature of Sanduleak's star and place it in the general context of the late stages of stellar evolution, by also highlighting some tentative links with the Intermediate-Luminosity Optical Transients.

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