Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars

“Since massive stars have short lifetimes, their ultraviolet (UV) radiation (reprocessed in various forms) is the most observable tracer of star formation and is used to calculate the star formation rates (Kennicutt 1998, Kennicutt & Evans 2012).”

“Perhaps new open-source codes like MESA (Paxton et al. 2011) will facilitate this.”

“This single-star paradigm then permitted one to extend even further, to compute models for the collective radiative output of entire stellar populations as a function of age (e.g., codes like starburst99; Leitherer et al. 1999).”

“Later, estimates for the solar wind (Parker 1958) powered by hot gas pressure had such low mass-loss rates that winds would not matter much in stellar evolution.”

“Since massive stars have short lifetimes, their ultraviolet (UV) radiation (reprocessed in various forms) is the most observable tracer of star formation and is used to calculate the star formation rates (Kennicutt 1998, Kennicutt & Evans 2012).”

“They leave behind exotic corpses such as black holes, neutron stars, pulsars, magnetars, and all the bizarre high-energy phenomena that occur when compact objects remain bound in a binary system (e.g., Remillard & McClintock 2006).”

“The fact that GRB progenitors have shed most of their envelopes while still retaining a great deal of angular momentum (MacFadyen & Woosley 1999) would seem to strongly favor their origin in binary evolution with mass transfer to spin up the star, or even a merger.”

“…very massive, and they made the first SNe, the first stellar mass black holes, the first dust, ejected the first metals back into the ISM, enhanced or dominated reionization, and probably triggered the formation of the earliest generations of low-mass stars (Bromm & Larson 2004, Heger et al. 2003).”

“…from several young clusters suggest that, when corrected for obervational bias, the fraction of massive stars in binary systems whose orbital period is so short that the stars must exhange mass or merge is something like 3/4 (Kiminki & Kobulnicky 2012, Kobulnicky & Fryer 2007, Sana et al. 2012).”

“There are many ways M & 8 M stars can end their lives 3 (e.g., Woosley et al. 2002; Smartt 2009; Meynet et al. 2010; Langer 2012; Nomoto et al. 2013; Smith 2014).”

“It is frequently cited as one of the most uncertain ingredients in stellar evolution, and is thought to play a crucial role in the advanced stages of stellar evolution for low-mass stars and in all phases of evolution for massive stars (see Smith 2014 for a recent review on this topic).”

“…the formation of the dense molecular clouds and stars (Heyer & Dame 2015); the evolution of stellar populations, their winds and energetic feedback (Smith 2014); the explosions of supernovae (Nomoto, Kobayashi & Tominaga 2013); the formation of supermassive black holes and the interaction of…”

“Their strengths depend on stellar properties, but cannot be derived from first principles; instead they are empirically derived and calibrated based on observations (for a review, see Smith 2014).”

“…amount of their mass through line-driven stellar winds and that the mass-loss rates show a simple scaling law with the metallicity (Castor, Abbott & Klein 1975; Kudritzki & Puls 2000; Nugis & Lamers 2000; Vink, de Koter & Lamers 2000, 2001; Muijres et al. 2012b; Crowther 2007; Smith 2014).”

“The collapse of a massive star (Smith 2014), or the collision of two neutron stars (Abbott et al. 2017a), injects massive amounts of energy and material into the surrounding environment, producing heavy elements and seeding further star formation in galaxies.”

“…velocities of about 1000–3000 km s−1, are presumably driven by atomic line opacity, with Doppler shifts in the wind acceleration zone strongly increasing the effective line width (see, e.g., Owocki 2010; Smith 2014; Puls et al. 2015, for recent reviews on mass-loss mechanisms in massive stars).”

“For recent studies and reviews of the evolution of massive stars and the mechanisms of corecollapse supernovae we refer to [402, 78, 316, 875, 212, 714].”

“…main sequence lifetimes, evolutionary stages, end states, and chemical yields from massive stars all depend on the details of mass loss (e.g., Smith 2014), which itself depends on the initial chemical composition (e.g., Puls et al. 2008; Kudritzki & Puls 2000; Cantiello et al. 2007; Eldridge…”

“We vary η between 0.1 and 1.0 (Smith 2014), with our fiducial wind being the (H) rate with η=0.1 (Yoon et al. 2010).”

“The current understanding of mass-loss from massive stars is encompassed in the review of Smith (2014), which includes a discussion of recent SN studies that favour the majority of SE SNe arising from binaries, with single, very massive Wolf– Rayet stars contributing a small fraction at most.”

“The effective radius of a massive star could be increased just prior to its explosion by envelope inflation or enhanced mass loss timed with stellar death, as observed in a variety of SNe (e.g., Smith 2014).”

“The physics and rates of mass loss are generally not well understood, and the rates used in stellar evolution models are quite uncertain (Langer 2012; Smith 2014).”

“Massive stars may lose large fractions of their hydrogenrich envelopes via steady line-driven winds, via stable or unstable binary mass transfer, or, possibly, through pulsational instabilities and eruptions (see, e.g., Smith 2014 for a recent review).”

“At the same time, there has been increasing evidence of SNe interacting with dense circumstellar material (CSM) that requires strong mass loss shortly before core collapse (see Smith 2014, and references therein).”

“These are taken from the recent review by Smith (2014); see the caption for definitions.”

“2 in Smith 2014, and references therein).”

“They are also available for the high-mass end where stripped stars are indistinguishable from Wolf-Rayet stars (Gräfener et al. 2002), which can also be formed from single stars stripped by stellar winds (Conti 1976; Smith 2014; Shenar et al. 2016).”

“Two main mechanisms have been suggested to produce SE SNe: either binary mass transfer (e.g., Iben & Tutukov 1985; Yoon et al. 2010; Claeys et al. 2011; Dessart et al. 2012; Yoon 2015) or strong line-driven winds from massive Wolf-Rayet (WR) stars (e.g., Conti 1976; Groh et al. 2013; Smith 2014).”

“…theory shows that single stars below a certain initial mass are unable to strip their outer envelopes, given that their line-driven winds are not strong enough to sustain large mass-loss rates for enough time (see e.g., Smith 2014, for a recent review on mass loss of massive stars).”

“…Crowther & Hadfield 2006) The amount of EUV flux which passes through these winds to power nebular emission is decreased substantially by high-density winds and difficult to calibrate directly, especially beyond the He+ ionizing edge (e.g. Smith et al. 2002; Crowther & Hadfield 2006; Smith 2014).”

“The mass-loss rate by stellar winds as well as eruptive events is uncertain, in particular for the late phases and the most massive stars (Smith 2014).”

“• SN 2014C adds to the complex picture of mass loss in massive stars that recent observations are painting (Smith 2014) and demonstrates that the ejection of massive H-rich material is not a prerogative of very massive H-rich stars (M ∼ 60M , like the progenitor of SN 2009ip, Smith et al. 2010,…”

“Type IIn SNe and SN Impostors Type IIn SNe are hydrogen-rich SNe that exhibit narrow lines in their spectrum — indicative of dense circumstellar material surrounding the progenitor at the time of explosion (see, e.g., Filippenko 1989; Schlegel 1990; Chugai 1991; Smith 2014).”

“…not yet discussed how the envelope may be removed by a brief period of enhanced mass-loss, e.g. via binary envelope stripping or a short phase of enhanced mass-loss in the decades or centuries before explosion (e.g. Yoon & Cantiello 2010; Quataert & Shiode 2012; Smith 2014; Smith & Arnett 2014).”

“…have LBV-like mass-loss rates and in four cases progenitors are known, e.g., SN 1961V (Smith et al., 2011b; Kochanek, Szczygiel, & Stanek, 2011), 2005gl (GalYam & Leonard, 2009), 2010jl (Smith et al., 2011b), and 2009ip (Smith et al. 2010, Foley et al. 2011; see also Smith (2014) for a review).”

“…the most massive ones produce copious amounts of ionising photons (Doran et al. 2013), emit powerful stellar winds (e.g., Kudritzki & Puls 2000; Smith 2014) and in their final explosions are suspected to produce the most energetic and spectacular stellar explosions, as pairinstability…”

“The narrow and intermediate-width emission lines are often assumed to result from the SN ejecta interacting with slowly-moving massive CSM (e.g., Chugai & Danziger 1994; Smith 2014).”

“Such massive stars often experience mass loss from their outer layers, due to stellar winds, binary interaction, or eruptive mass-loss events (see, e.g., Smith 2014 and references within).”

“SNe IIn contribute a fraction of 8–9% of all core-collapse SNe (Smith et al. 2011a) in a volume-limited sample of large star-forming galaxies, and there are hints that they are as common or possibly more common at lower metallicity (see Smith 2014).”

“The radiative and mechanical energy output from massive stars are important feedback mechanisms regulating star formation and the structure of the interstellar medium in galaxies (Kennicutt 2005; Smith 2014).”

“There is recent observational evidence that mass-loss rates may be overestimated for certain evolutionary phases (e.g., Smith 2014; Beasor & Davies 2018; Sander et al. 2020; Miller-Jones et al. 2021; Neijssel et al. 2021).”

“Moreover, as pointed out by Yungelson et al. (2006), because mass-loss rates from massive stars are uncertain, it is possible that for a different set of mass-loss assumptions the range of CE survivors at the solar metallicity would extend to MZAMS > 20 M as well (Smith 2014; Renzo et al. 2017).”

“Throughout their lives, stars affect their surroundings via the immense energy radiated across the electromagnetic spectrum (e.g., Conroy 2013; Eldridge & Stanway 2022) and the nuclearprocessed material emitted as a stellar wind (e.g., Kudritzki & Puls 2000; Smith 2014).”

“This is discussed further in Appendix E. Stellar wind mass loss is also an important uncertainty for the evolution of massive stars (Smith 2014; Renzo et al. 2017).”

“Furthermore, uncertain mass loss rates (Smith 2014) and internal mixing processes (Bressan et al. 1981; Langer 1991; Schaller et al. 1992; Yoon et al. 2006) are more important the more massive the stars.”

“They are also available for the high-mass end where stripped stars are indistinguishable from Wolf-Rayet stars (Gräfener et al. 2002), which can also be formed from single stars stripped by stellar winds (Conti 1976; Smith 2014; Shenar et al. 2016).”

“…Vink et al. 2001; Wellstein et al. 2001; Puls et al. 2008; Yoon et al. 2010), but the details behind the precise physical mechanisms that are involved and the stages that this mass loss takes place are not well constrained (see Eldridge et al. 2008; Langer 2012; Smith 2014 and references therein).”

“It is possible for this to be larger than what we have in our current sample, but our models do not include mass loss during LBV phases or other forms of pulsational and eruptive mass loss from massive stars (see e.g. Smith 2014), which likely limits BH masses from single stars.”

“…driven winds is thought to be reduced at low metallicity, mass loss via LBV eruptions is likely to still be very significant also at low metallicity (e.g., Smith 2014; Sanyal et al. 2017; Kalari et al. 2018; Davies et al. 2018; Higgins & Vink 2020; Sabhahit et al. 2021; Gilkis et al. 2021).”

“…do not say anything about the other possibly existing mass loss channels (e.g., binary interactions and/or impulsive phenomena, see, for example, Smith 2014; Smith & Arnett 2014; Morozova et al. 2015; Margutti et al. 2017) that are usually neglected in stellar evolution calculations, or…”

“Note that the mass-loss rate of O7 and later stars is a factor of 10 to 102 lower than theoretically expected (Puls et al. 2008; Smith 2014).”

“…of massive stars, affecting their luminosities, chemical surface abundances, rotational velocities, and nuclear burning lifetimes, as well as ultimately determining which type of supernova the star explodes as and which type of remnant it leaves behind (Meynet et al. 1994; Langer 2012; Smith 2014).”

“When the stellar luminosity exceeds this limit, 5 These have densities of order ∼10−20 g cm−3 and temperatures of order ∼10 K. high mass-loss rates are expected (e.g., Owocki & Shaviv 2012; Smith 2014).”

“However, we can probe these terminal phases of stellar evolution prior to the core-collapse of massive stars >8Me by understanding the composition and origin of the high-density, circumstellar material (CSM) surrounding these stars at the time of explosion (Smith 2014).”

“We refer the reader to Smith et al. (2011b) and Smith (2014) for further discussion of this diverse class of transients.”

“Prior to core collapse, massive stars can undergo mass loss via steady winds or eruptive episodes (Smith 2014).”

“Recent observations of a number of SNe show eruptions in the centuries prior to explosion (e.g., Margutti et al. 2014a, 2017a; Smith 2014; Milisavljevic et al. 2015), and AT 2018cow shows a similarly steep density profile (Margutti et al. 2019) to CSS161010.”

“LBVs are the most dramatic manifestation of episodic mass loss in massive stars (see, e.g., Davidson & Humphreys 2012; Smith 2014 for reviews).”

“The agreement between our models and the Chandra data is overall quite good, particularly accounting for uncertainties in massive star mass-loss rates (e.g. Smith 2014).”

“However, there is now mounting evidence (see e.g. Smith 2014 and discussion below) that a significant fraction SE-SNe arise from lower mass progenitors where the envelope stripping is achieved through interaction with a close binary companion (e.g. Podsiadlowski et al. 1992).”

“The main open questions concern the role of stellar wind mass loss (e.g., Smith 2014; Renzo et al. 2017), and interior mixing (e.g., Maeder & Meynet 2000), which affect the final core masses and radial evolution.”

“According to standard stellar evolutionary models, massive stars ( M30> ) are thought to have very little hydrogen at the time of supernova explosion (Georgy et al. 2012; Langer 2012; Smith 2014).”

“It was only later, with the realization that massive stars can drive significant winds, that stripping through winds or eruptions associated with single stars became a viable alternative (Conti 1976; Abbott & Conti 1987; Smith 2014).”

“Mass loss immediately before the SN explosion has a major impact on the SN properties (see Smith 2014) and has been investigated in SN IIn using spectroscopy and photometry several days after their discoveries (e.g., Smith et al. 2007; Pastorello et al. 2007; Kiewe et al. 2012; Ofek et al. 2014;…”

“Though some SNe IIn have been associated with luminous blue variables (e.g., SN 2005gl; Gal-Yam & Leonard 2009, SN 2010jl; Smith et al. 2011b, and SN 2009ip; Foley et al. 2011), the exact nature of their progenitors is still debated (see Smith 2014 for a review).”

“Names like SN impostors, Type V SNe, or η Carinae variables were often taken to be synonyms of LBVs (Humphreys & Davidson 1994; Humphreys, Davidson & Smith 1999; Van Dyk et al. 2000; Smith 2014).”

“Various lines of evidence show that interacting SNe require eruptive pre-SN mass loss that is reminiscent of luminous blue variable (LBV) stars, like η Car, although observations indicate a wide range of mass-loss properties (e.g., see the review by Smith 2014).”

“Therefore, similar to the case of massive stars (Smith 2014), radiation acceleration via the iron opacity bump has the potential to drive significant outflow, even though the normal Eddington ratio is smaller than 1.”

“…yr−1, where vCSM is the velocity of the CSM. Wolf–Rayet stars or red supergiant stars have difficulty in producing such intense ejections; while binary interaction can possibly be responsible for mass ejection of 10−3– 10−1 M yr−1 (see Smith 2014; Bhirombhakdi et al. 2019, and references therein).”

“These are hydrogen-rich SNe that show strong and narrow Balmer emission lines for an extended period of time and do not develop broad hydrogen features, characteristic of the high expansion velocity of the SN ejecta around peak light (Schlegel 1990; Filippenko 1997; Kiewe et al. 2012; Smith 2014).”

“It also experienced pronounced mass loss prior to explosion, which may not comport with the emerging understanding of stellar mass loss (Smith 2014).”

“However, a diverse range of observations dictate that close binary interaction (Sana et al. 2012; Moe & Di Stefano 2017) and asymmetric CSM (Smith 2014) are the norm among massive stars, not the exception.”

“In the ejecta–CSM interaction case, this separation roughly coincides with where the estimated mass-loss rate of the progenitor star roughly matches typical LBV mass-loss rates (M 10 3~ -˙ M yr−1; Smith 2014), and where many identified SNe IIn lie.”

“One key factor that significantly affects the evolution and fate of massive stars is wind mass-loss (Smith 2014).”

“The wide range of light-curve properties shown by SNe IIn indicates significant variety in both CSM and ejecta properties (e.g. Moriya & Maeda 2014), suggesting that different mechanisms and progenitor channels lead to the SNe IIn we observe (Smith 2014).”

“Given the abundance of W-R stars in the Local Group (Hainich et al. 2014; Rosslowe & Crowther 2015) and a lifetime of 106 yr in this phase (Smith 2014), the predicted W-R death rate is 3%–20% of the CCSN rate (Maoz & Badenes 2010), at least an order of magnitude in excess of what we inferred in…”

“There are theoretical reasons to expect that the fates of massive stars could be determined in part by metallicity (e.g., Langer 2012; Smith 2014; Yoon 2015) or SFR conditions (e.g., because galaxies with high sSFRs may have altered IMFs or because they may possess dense clusters with a high number…”

“It is well known that massive stars occasionally produce giant eruptions during which they can largely increase their luminosity for months to years, and experience major mass loss (e.g. Smith 2014).”

“Towards the end of the lives of some massive stars, nonterminal, discrete mass loss events are detected as supernova type IIn or supernova imposters (see Section 4 of Smith 2014).”

“On the other hand, the WR star progenitors of SNe Ic lose mass through relatively steady, strong stellar winds (Crowther 2007; Smith 2014).”