Luminous blue variables and the fates of very massive stars

Abstract

Luminous blue variables (LBVs) had long been considered massive stars in transition to the Wolf-Rayet (WR) phase, so their identification as progenitors of some peculiar supernovae (SNe) was surprising. More recently, environment statistics of LBVs show that most of them cannot be in transition to the WR phase after all, because LBVs are more isolated than allowed in this scenario. Additionally, the high-mass H shells around luminous SNe IIn require that some very massive stars above 40 die without shedding their H envelopes, and the precursor outbursts are a challenge for understanding the final burning sequences leading to core collapse. Recent evidence suggests a clear continuum in pre-SN mass loss from super-luminous SNe IIn, to regular SNe IIn, to SNe II-L and II-P, whereas most stripped-envelope SNe seem to arise from a separate channel of lower-mass binary stars rather than massive WR stars.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'.

Accuracy of inference on the physics of binary evolution from gravitational-wave observations

“…During the luminous blue variable (LBV) phase (Humphreys & Davidson 1994), extremely massive stars undergo a relatively short episode of rapid mass loss which strongly impact the binary's future evolutionary trajectory (e.g., Mennekens & Vanbeveren 2014); observational constraints on the physics of LBV stars are currently uncertain (Smith 2017). 2 Following Belczynski et al (2010), we parametrise this rate in terms of a multiplicative factor fLBV used to modify the basic prescription, so that the rate becomeṡ…”

Cosmic Ray Production in Supernovae

“…A superluminous SN event may occur in the case of a dense enough circumstellar medium around the SN which provides a radiation-dominated shock propagating through the envelope (e.g., Falk & Arnett 1977, Chugai & Danziger 1994, Chevalier & Irwin 2011, Chevalier 2012, Blinnikov 2016b,a, Sorokina et al 2016). Pre-supernova activity of a massive progenitor star during some evolutionary phases may have a very large mass-loss rate in the form of a dense slow wind that produces dense circumstellar envelopes (Smith 2017, Morozova et al 2017. Multiple envelopes may be formed if outbursts occur at different progenitor star evolutionary stages prior to the SN event.…”

Titanium hidden in dust

“…It is well observed that some of the superluminous supernovae are bright because their ejecta are interacting with the dense CSM (Chugai & Danziger 1994;Smith et al 2010;Smith 2017). Moreover, some parts of the ejected nucleosynthesis products condense into dust grains quite early after the explosion (on time scales of ∼ 40 -240 days).…”