Photometry of the Stingray Nebula (V839 Ara) from 1889-2015 Across the Ionization of Its Planetary Nebula

Abstract

Up until around 1980, the Stingray was an ordinary B1 post-AGB star, but then it suddenly sprouted bright emission lines like in a planetary nebula (PN), and soon after this the Hubble Space Telescope (HST) discovered a small PN around the star, so apparently we have caught a star in the act of ionizing a PN. We report here on a well-sampled light curve from 1889 to 2015, with unique coverage of the prior century plus the entire duration of the PN formation plus three decades of its aftermath. Surprisingly, the star anticipated the 1980's ionization event by declining from B=10.30 in 1889 to B=10.76 in 1980. Starting in 1980, the central star faded fast, at a rate of 0.20 mag/year, reaching B=14.64 in 1996. This fast fading is apparently caused by the central star shrinking in size. From 1994-2015, the V-band light curve is almost entirely from the flux of two bright [OIII] emission lines from the unresolved nebula, and it shows a consistent decline at a rate of 0.090 mag/year. This steady fading (also seen in the radio and infrared) has a time scale equal to that expected for ordinary recombination within the nebula, immediately after a short-duration ionizing event in the 1980s. We are providing the first direct measure of the rapidly changing luminosity of the central star on both sides of a presumed thermal pulse in 1980, with this providing a strong and critical set of constraints, and these are found to sharply disagree with theoretical models of PN evolution.

ApJ accepted, 54 pages, 4 figures, one long data table

References in corpus (4)

• Accelerated post-AGB evolution, initial-final mass relations, and the star-formation history of the Galactic bulge
• The onset of photoionization in Sakurai's Object (V4334 Sgr)
• The rapid evolution of the exciting star of the Stingray Nebula
• ATCA observations of the very young Planetary Nebula SAO 244567

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• The Decline and Fall of the Youngest Planetary Nebula
• Evolution of Hen\,3-1357, the Stingray Nebula
• A primer on the formation and evolution of hydrogen deficient Central Stars of Planetary Nebulæ and Related Objects
• Long and short term variability of the possible nascent planetary nebula IRAS 22568+6141: A late thermal pulse?