http://arxiv.org/abs/1904.11331
We study the formation of intermediate luminosity optical transients (ILOTs) from the merger of two cool giant stars. For the two stars to merge when both are in their giant phases the stars must have close masses at their zero age main sequence, and the orbital separation must be in the right range. After the two giants merge, the two cores spirals-in toward each other within a common envelope. This process ejects mass that powers radiation by recombination and by collision with previously ejected mass. Using the stellar evolution numerical code MESA for two binary systems with stellar masses of (15,15.75Mo) and (31,31.5Mo), we find that the merger of the two cores releases gravitational energy that marginally ejects the entire common envelope. This implies that in many cases the two cores merge, i.e., a fatal common envelope evolution, leading to a somewhat more luminous ILOT. Overall, we estimate that a typical ILOT from merger of two cool giant stars lasts for several months to several years and has a typical average luminosity of L(ILOT)=10^6(M(CE)/10Mo)Lo, where M(CE) is the common envelope mass. Due to the merger-driven massive outflow, we expect dust formation and a very red ILOT, possibly even an infrared luminous and undetectable in the visible. As the giants cannot launch jets, we expect the descendant nebula formed by the merger process to have an elliptical morphology but with no bipolar lobes.
R. Segev, E. Sabach and N. Soker
Fri, 26 Apr 19
69/69
Comments: Will be submitted in two days to allow comments from readers
You must be logged in to post a comment.