NSV 11749, an elder sibling of the born again stars V605 Aql and V4334 Sgr?

TL;DR

This paper presents evidence that NSV 11749 experienced a very late thermal pulse, making it a rare example of a born again star, and compares it with known VLTP objects and models to support this claim.

Contribution

The study identifies NSV 11749 as a potential VLTP event, expanding the sample of known born again stars and providing observational and model-based comparisons.

Findings

NSV 11749's lightcurve resembles other VLTP objects.

The object is not enshrouded in thick dust, unlike similar stars.

No planetary nebula detected at the eruption site.

Abstract

We argue that NSV 11749, an eruption observed in the early twentieth century, was a rare event known as "very late thermal pulse" (VLTP). To support our argument we compare the lightcurve of NSV 11749 with those of the two bonafide VLTP objects known to date, V4334 Sgr and V605 Aql, and with those predicted by state of the art stellar evolution models. Next, we explore the IPHAS and 2MASS catalogues for possible counterparts of the eruption. Our analysis shows that the VLTP scenario outperforms all other proposed scenarios as an explanation of NSV 11749. We identify an IPHAS/2MASS source at the eruption location of NSV 11749. The derived colors suggest that the object is not enshrouded in a thick dust shell as V605 Aql and V4334 Sgr. Also the absence of an apparent planetary nebula (PN) at the eruption location suggests differences with known VLTP objects which might be linked to the intensity of the eruption and the mass of the object. Further exploration of this source and scenario seems desirable. If NSV 11749 was a born again star, it would be the third event of its kind to have been observed and will strongly help us to increase our understanding on the later stages of stellar evolution and violent reactive convective burning.