Program: GN-2016A-Q-24

Title:Imaging the Expanding Debris Cloud around Sakurai's Object
PI:Kenneth Hinkle
Co-I(s): Richard Joyce

Abstract

Stellar evolution models predict a common but brief post-AGB episode of helium shell burning as the remnant of a low mass star enters the white dwarf sequence. Over the last century two nearly identical final flash events have been observed. The most recent and by far the best studied is Sakurai's Object=V4334 Sgr. Previously a 21st magnitude central star of an old PN, Sakurai's Object returned to AGB luminosity in 1995 and was obscured in a dust cloud of its own making by 1999. USING NIRI plus Altair we imaged expanding ejecta in 2010 and 2013. Images of the ejectra reveal the mass loss geometry and allow direct measurement of the nebular expansion. The observations of V4334 Sgr and of V605 Aql, which erupted in 1919, strongly disagree with standard predictions. A GNIRS observation in 2013 June revealed a He I and [C I] gas shell five times larger than the dust shell. In 2015 we obtained GMOS and NIFS spectra to determine the excitation and geometry of the gas shell. The key observation, an image of the dust ejecta, was not carried out and is requested here.

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