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V4334 Sgr (Sakurais object) is an enigmatic evolved star that underwent a very late thermal pulse a few years before its discovery in 1996. It ejected a new, hydrogen-deficient nebula in the process. Emission lines from the newly ejected gas were first discovered in 1998 (He I 1083 nm) and 2001 (optical). We have monitored the optical emission spectrum since. From 2001 through 2007 the optical spectrum showed an exponential decline in flux, consistent with a shock that occurred around 1998 and started cooling soon after that. In this paper we show that since 2008 the line fluxes have been continuously rising again. Our preliminary interpretation is that this emission comes from a region close to the central star, and is excited by a second shock. This shock may have been induced by an increase in the stellar mass loss and wind velocity associated with a rise in the stellar temperature.
V4334 Sgr (a.k.a. Sakurais object) is the central star of an old planetary nebula that underwent a very late thermal pulse a few years before its discovery in 1996. We have been monitoring the evolution of the optical emission line spectrum since 200
We investigate the reheating of the very late thermal pulse (VLTP) object V4334 Sgr (Sakurais Object) using radio observations from the Very Large Array, and optical spectra obtained with the Very Large Telescope. We find a sudden rise of the radio f
We present an observation of the very late thermal pulse object V4334 Sgr (Sakurais Object) with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. The emission from 5-38 microns is dominated by the still-cooling dust shell. A number of
The high resolution optical spectra of H-deficient stars, R Coronae Borealis stars and H-deficient carbon stars are analyzed by synthesizing the C2 Swan bands (0,1), (0,0), and (1,0) using our detailed line-list and Uppsala model atmosphere, to deter
We present an analysis of the evolution of circumstellar dust and molecules in the environment of the very late thermal pulse object V4334 Sgr (Sakurais Object) over a $sim20$-year period, drawing on ground-, airborne- and space-based infrared photom