2024/08/03 by Bhawna Mukhija, Mukhija, Bhawna, Amit Kashi +1 · 3 citations
Physics and Astronomy · Engineering · #Stellar, planetary, and galactic studies #Astronomy and Astrophysical Research #Astronomical Observations and Instrumentation
paper · pdf · doi:10.48550/arxiv.2408.01718
Giant eruptions (GE) in Luminous blue variables (LBVs) are years to decades-long episodes of enhanced mass loss from the outer layers of the star during which the star undergoes major changes in its physical and observed properties. We use the mesa stellar evolution code to model the evolution of a 70~M\odot star that undergoes a GE. We let the star evolve to the termination of the main sequence (MS) and when it reaches T≃ 19 400 K we emulate a GE by removing mass from its outer layers, at a rate of 0.15~ M\odot~\rm yr-1 for 20 years. As mass is being lost, the star contracts and releases a substantial amount of gravitational energy. The star undergoes an initial ≃ 3 days of expansion followed by years of contraction. During that time the star tries to reach an equilibrium state and as a result of loss in gravitational energy, its luminosity drops about one order of magnitude. As the GE terminates, we let the star continue to evolve without any further mass loss and track its recovery as it regains its equilibrium by adjusting its internal structure. After ≃ 87 years it reaches a state very close to the one where the GE was first initiated. We suggest that at this point another GE or a cycle of GEs may occur.