Cosmic Fireworks: Simulating the Red Nova Eruption in Andromeda

Luminous Red Novae (LRNe) are explosive transients with optical luminosities that fall between those of classical novae and supernovae, with durations ranging from tens to hundreds of days. LRNe are believed to arise from binary star interactions involving mass transfer between a donor star and its companion. One notable LRN occurred in the Andromeda Galaxy in 2015, providing an opportunity to investigate how binary interactions trigger such outbursts. A pre-outburst image of the donor star allows constraints to be placed on its mass and evolutionary state, while the observed light curve provides an estimate of the total mass ejected during the event.

To investigate the nature of the companion star, I performed 1D hydrodynamic simulations of the binary interaction and compared the results with observations. Three simulations were conducted with varying mass ratios (companion mass to donor mass) to examine how the companion mass influences the amount of mass ejected. The simulations indicate that the closest match to observations occurs at a mass ratio of 0.2, producing an ejected mass of 0.44 M⊙. Although this value is somewhat larger than the observed estimate of 0.3 solar masses, the results provide insight into the range of companion masses capable of reproducing the event. Future work will extend these simulations by including radiation transport and exploring a wider range of companion and donor star masses consistent with the photometric constraints.