Surviving planet around a white dwarf?

Echoes of a decaying planetary system: the gaseous and dusty disks surrounding three white dwarfs

Excerpt from arXiv preprint: an interesing point about the white dwarf Ton 345. Emphasis mine.

Quote :

Why does this method fail for Ton 345? A clue comes from considering the agreement ofSDSS1228’s gravitational redshifts as measured from the two different methods. As modeledby G¨ansicke et al. (2006, 2008a), the gas disk orbiting SDSS1228 has negligible eccentricitywhile for Ton 345 the disk eccentricity is large (e=0.2−0.4). In the case of a large diskeccentricity it is understandable that measuring the peak midpoint velocity as describedin Section 3.2 would provide an inaccurate estimate of the systemic velocity. As such, weinstead take the discrepancy between the gravitational redshifts as computed through thetwo different methods for Ton 345 as additional evidence for the large eccentricity of thegaseous disk (e=0.2-0.4, Gansicke et al. 2008a). It is noted that these high eccentricityvalues in Ton 345’s disk persist over long time-spans. Ton 345’s disk is likely pumped up to(and maintained at) high eccentricity by a surviving planet (Lubow 1991; Kley & Dirksen2006).