Hidden Companions to Intermediate-mass Stars. XX. Discovery of a 0.58M ⊙, 7.4 au Companion to p Puppis

Abstract

p Puppis is a nearby 3.1M ⊙ B8V star with astrometric evidence for a close companion in addition to its two wide companions at 1.3 kau (a white dwarf (WD)) and 38.7 kau (an F2V astrometric binary). Here we report on a VLTI/GRAVITY observation that revealed the close companion to be a 0.58M ⊙ star at a projected separation ρ = 100.2 mas ↔ 7.4 au, confirming the system to be a quintuple. The discovered companion explains the X-ray emission of p Pup detected by eROSITA. Moreover, we also find that the isochrone age of 100−20+50  Myr of p Pup is incompatible with the minimum cooling age of 350 Myr for the 1.3 kau wide WD companion, suggesting that either they are not coeval or that the WD was formed through a non-trivial channel.