Breaking news from the HST: The central star of the Stingray Nebula is now returning towards the AGB

Abstract

SAO244567 is a rare example of a star that allows us to witness stellar evolution in real time. Between 1971 and 1990 it changed from a B-type star into the hot central star of the Stingray Nebula. This observed rapid heating has been a mystery for decades, since it is in strong contradiction with the low mass of the star and canonical post-asymptotic giant branch (AGB) evolution. We speculated that SAO244567 might have suffered from a late thermal pulse (LTP) and obtained new observations with HST/COS to follow the evolution of the surface properties of SAO244567 and to verify the LTP hypothesis. Our non-LTE spectral analysis reveals that the star cooled significantly since 2002 and that its envelope is now expanding. Therefore, we conclude that SAO244567 is currently on its way back towards the AGB, which strongly supports the LTP hypothesis. A comparison with state-of-the-art LTP evolutionary calculations shows that these models cannot fully reproduce the evolution of all surface parameters simultaneously, pointing out possible shortcomings of stellar evolution models. Thereby, SAO244567 keeps on challenging stellar evolution theory and we highly encourage further investigations.

arXiv commentAccepted for publication in MNRAS Letters. 5 pages + appendix

References in corpus (20)

• Ultraviolet Radiation from Evolved Stellar Populations -- I. Models
• Post-Asymptotic Giant Branch Evolution of Low- and Intermediate-Mass Stars. Preliminary Results
• New models for the evolution of Post-Asymptotic Giant Branch stars and Central Stars of Planetary Nebulae
• Evolution, nucleosynthesis and yields of AGB stars at different metallicities (III): intermediate mass models, revised low mass models and the ph-FRUITY interface
• The elemental composition of the Sun II. The iron group elements Sc to Ni
• New evolutionary sequences for extremely low mass white dwarfs: Homogeneous mass and age determinations, and asteroseismic prospects
• The elemental composition of the Sun I. The intermediate mass elements Na to Ca
• Neglecting the porosity of hot-star winds can lead to underestimating mass-loss rates
• A spectroscopic survey of thick disc stars outside the solar neighbourhood
• The timescale of low-mass proto-helium white dwarf evolution
• Hot bottom burning and s-process nucleosynthesis in massive AGB stars at the beginning of the thermally-pulsing phase
• V605 Aql: The Older Twin of Sakurai's Object
• The TP-AGB phase. Lifetimes from C and M star counts in Magellanic Cloud clusters
• Birth and early evolution of a planetary nebula
• Planetary nebulae after common-envelope phases initiated by low-mass red giants
• Stellar archaeology: the evolving spectrum of FG Sge
• The rapid evolution of the exciting star of the Stingray Nebula
• Model Photospheres with Accelerated Lambda Iteration
• FUSE, STIS, and Keck spectroscopic analysis of the UV-bright star vZ 1128 in M3 (NGC 5272)
• RV variable, hot post-AGB stars from the MUCHFUSS project - Classification, atmospheric parameters, formation scenarios

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• The population of hot subdwarf stars studied with Gaia -- IV. Catalogues of hot subluminous stars based on Gaia EDR3
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• Spectral analysis of the hybrid PG 1159-type central stars of the planetary nebulae Abell 43 and NGC 7094
• On the role of reduced wind mass-loss rate in enabling exoplanets to shape planetary nebulae
• The Initial-Final Mass Relation for Hydrogen-Deficient White Dwarfs
• The Class of Jsolated Stars and Luminous Planetary Nebulae in old stellar populations
• Physical properties of the very young PN Hen3-1357 (Stingray Nebula) based on multiwavelength observations
• Chemistry and physical properties of the born-again planetary nebula HuBi 1
• An episodically variable stellar wind in the planetary nebula IC\,4997
• Stellar Neutrino Emission Across The Mass-Metallicity Plane
• The cooling-down central star of the planetary nebula SwSt\,1: a late thermal pulse in a massive post-AGB star?
• The Decline and Fall of the Youngest Planetary Nebula
• Evolution of Hen\,3-1357, the Stingray Nebula
• The Nature of the Stingray Nebula from Radio Observations
• Spatially resolved mid-infrared observations of the circumstellar environment of the born-again object FG Sge
• A primer on the formation and evolution of hydrogen deficient Central Stars of Planetary Nebulæ and Related Objects
• Recombination of hot ionized nebulae: The old planetary nebula around V4334 Sgr (Sakurai's star)
• Long and short term variability of the possible nascent planetary nebula IRAS 22568+6141: A late thermal pulse?
• The post-common-envelope binary central star of the planetary nebula PN G283.7-05.1: A possible post-red-giant-branch planetary nebula central star
• Stars on the ascending helium giant branch I. From white dwarf merger to helium giant: the evolutionary state of the rapidly rotating hot subdwarf HE 1518-0948
• The secular evolution of planetary nebula IC 418 and its implications for carbon star formation