相关论文: V605 Aql: The Older Twin of Sakurai's Object
The "born-again" PNe V605 Aql (A58) and V4344 Sgr (Sakurai) give us the rare chance to follow shell formation and building of the winds in "real-time". The high carbon abundance, and thus the high dust formation rate, enhances the…
New imaging of V605 Aql, was obtained in 2009 with HST/WFPC2, which had a nova-like outburst in 1919, and is located at the center of the planetary nebula (PN), Abell 58. This event has long been ascribed to a final helium shell flash, but…
We derived the properties of V605 Aql before the final helium flash pulse by studying its surrounding PN A58. Photoionizing models of our spectral data together with a new distance estimate and a closer look at the recombination timescales…
The central star V4334 Sgr (Sakurai's Nova) of the planetary nebula PN G010.4+04.4 underwent in 1995-1996 the rare event of a very late helium flash. It represents only one out of two such events during the era of modern astronomy (the…
V4334 Sgr (a.k.a. Sakurai's 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…
The central star V4334 Sgr (Sakurai's Nova) of the planetary nebula PN G010.4+04.4 underwent in 1995-1996 the rare event of a very late helium flash. It is only one of two such events during the era of modern astronomy (the second event was…
The optical photometric evolution of the final helium flash object V4334 Sgr from 1994 to 2000 is described. The rise to optical maximum (1994 - 1996) is characterized by a continuous increase of color indices, indicating a slowly…
The central dust knot V605 Aql (= Nova Aql 1919) in the planetary nebula A58 is the result of a late-helium flash. Previous near infrared (NIR) measurements yield very bright fluxes. This exceeds model predictions, based on other…
We have analysed deep optical spectra of the `born-again' planetary nebula Abell 58 and its hydrogen-deficient knot, surrounding V605 Aql, which underwent a nova-like eruption in 1919. The electron temperature we derive for the central knot…
V4334 Sgr (Sakurai's 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…
``Nova Aquilae No. 4'', discovered in 1919, later renamed V605 Aql, was recognized to be a final helium flash object only in the 1980s. Clayton and De Marco (1997) gave a detailed description of the available spectroscopic and photometric…
We report on the progress of our on-going campaign to monitor the evolution of the VLTP objects V4334 Sgr and V605 Aql, as well as the suspected (V)LTP object CK Vul. V4334 Sgr does not show signs of increased ionization compared to our…
We present stellar evolution calculations from the Asymptotic Giant Branch (AGB) to the Planetary Nebula (PN) phase for models of initial mass 1.2 M\odot and 2.0 M\odot that experience a Late Thermal Pulse (LTP), a helium shell flash that…
CCD UBVRi photometry of the final helium flash object V4334 Sgr (Sakurai's Object), carried out during 1997 - 1999, is presented, and the light curve from its pre-discovery rise to the dust obscuration phase is constructed. The optical…
V605 Aquilae is today widely assumed to have been the result of a final helium shell flash occurring on a single post-asymptotic giant branch star. The fact that the outbursting star is in the middle of an old planetary nebula and that the…
We present a $0.8-2.5\,\mu$m spectrum of the Very Late Thermal Pulse object V4334 Sgr (Sakurai's Object), obtained in 2020 September. The spectrum displays a continuum that rises strongly to longer wavelengths, and is considerably brighter…
The planetary nebula (PN) called the Stingray (PN G331.3$-$12.1) suddenly turned on in the 1980s, and its central star (V839 Ara) started a fast evolution with large amplitudes in magnitude, surface temperature, and surface gravity, perhaps…
Born-again planetary nebulae (PNe) allow investigating stellar evolution, dust production, and nebular shocks in human timescales. Here we present an analysis of multi-epoch optical spectroscopic observations of the born-again PN A 58…
The very late thermal pulse (VLTP) affects the evolution of $\sim$20\% of 1--8\,$\mathrm M_\odot$ stars, repeating the last phases of the red giant within a few years and leading to the formation of a new, but hydrogen-poor nebula within…
Sakurai's object is a born again AGB star of the very late thermal pulse flavor. In this contribution I will discuss new models of stellar evolution and nucleosynthesis models of this phase. Two most intriguing properties of Sakurai's…