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).”

“This scenario is also in line with the growing consensus that most stripped-envelope SNe are created via binary interaction, as opposed to single star mass loss (e.g. Smith 2014; De Marco & Izzard 2017).”

“We also run a subset of models for the q = 0.18 case (M1 = 17 M ) using the “van Loon” formula (van Loon et al. 2005) suggesting stronger winds during the RSG phase (Smith 2014) in order to investigate the effect of mass–loss on the final surface rotation rate.”

“…evolution (Arnett & Meakin 2011; Smith & Arnett 2014), and revisions to our understanding of mass loss and observations of a high binary fraction among O-type stars (Smith 2014) suggest circumstellar environments that are not spherically symmetric (Schwarz & Pringle 1996; Ryder et al. 2004).”

“The mass-loss rate we deduce including the deviation from equipartition is on the higher end of the mass-loss rate in stripped envelope SN, but not in any extreme way (Smith 2014).”

“Theoretically, enhanced mass loss (above steady line-driven winds) is expected from binary interactions (e.g. Smith 2014) or from additional energy injection such was wave energy dissipation (Quataert & Shiode 2012; Quataert et al. 2016; Fuller 2017; Fuller & Ro 2018).”

“14 Carnegie-Princeton Fellow. standard reference for understanding episodic mass-loss in very massive stars (e.g., Smith 2014), LBVs (e.g., Humphreys & Davidson 1994), supernova (SN) impostors (e.g., Humphreys et al. 1999; Van Dyk et al. 2002; Maund et al. 2006; Smith et al. 2011; Kochanek et al.…”

“For stars in the mass range 8–30M⊙, OB star winds on the main sequence are weak (Smith 2014).”

“This lower limit is higher than the typical Ṁ of almost all massive stars in the local Universe, except for selected LBVs such as Eta Car (Groh et al. 2012) and others during S-Dor type outbursts (Smith 2014).”

“All massive stars are expected to lose mass, however the properties of mass loss (e.g. density, radial extent, physical location) vary for different progenitors (Smith 2014).”

“Furthermore, all stellar winds’ mass loss from massive stars, binary interactions, and their ionizing effects are ignored (e.g., Dray et al. 2003; Smith 2014; Götberg et al. 2020; Doughty & Finlator 2021; Farmer et al. 2021; Goswami et al. 2022).”

“Similar speeds are seen in the CSM of Type IIn supernovae (see Smith 2014).”

“…mass loss exhibited by luminous blue variables (LBVs) is thought to be an important ingredient in stellar evolution (see, e.g., Smith & Owocki 2006; Smith 2014), but the way LBVs actually figure in this evolution and the physical mechanisms of their outbursts remains challenging to understand.”

“…nebulae of evolved massive stars, such as fast-rotating luminous blue variables, typically have a bipolar morphology because equatorial gravity darkening will lead to a higher mass-loss rate and faster wind speed along the poles of the star (Dwarkadas & Owocki 2002; Lobel et al. 2013; Smith 2014).”

“Predictions of the elemental yield of a massive star and the nature of its remnant are sensitive to many processes including convection [5], winds [6], nuclear reaction rates [7], and numerical algorithms [8].”

“For type II (hydrogen rich) SLSN the leading mechanism for its radiated energy, instead, is thought to come from the interaction of a SN explosion ejecta with a dense circumstellar medium (CSM; e.g., see Smith et al. 2007; Smith 2014).”

“For example, while some LBV eruptions show bluer continua and H lines with strong P Cygni profiles (e.g., NGC 3432 OT; Pastorello et al. 2010), others are indistinguishable from ILRTs (Smith et al. 2010, 2011; Rest et al. 2012; Prieto et al. 2014).”

“Therefore, it has been actively investigated from both observational and theoretical points of view (e.g., Smith 2014).”

“A few percent of core-collapse SNe exhibit narrow lines from dense circumstellar interaction, indicating intense phases of pre-SN mass loss (Smith et al. 2011; Kiewe et al. 2012; Smith 2014; Moriya et al. 2014).”

“The SN can be powered either entirely by radioactive 56Ni → 56Co decay or by CSM interaction (or both).”

“Even without this, we find that both spectra and LC-based estimates of the mass-loss rate are very high, in the region associated with eruptive mass-loss in massive stars (Smith 2014).”

“However, it is likely that this group also exists at solar metallicity given evidence that winds are weaker than previously assumed (Smith 2014; Yoon et al. 2017, see also discussion in Section 6.2 in paper I).”

“Thus, the shell corresponds to a high mass-loss rate of the progenitor system of (3– 5) × 10−2 M⊙ yr −1, which is much higher than those of linedriven winds (Smith 2014).”

“In many cases, episodic eruptions, rather than continuous line-driven winds, are the dominant source of massloss from these stars (Smith 2014).”

“Once the star explodes, the radiation, shock wave, and (at later times) ejecta can interact with the material lost prior to explosion, producing observational signatures such as narrow emission lines, enhanced luminosity, and blue colors (Smith 2014).”

“Mass loss Mass loss is one of the dominant uncertainties in evolutionary models of massive stars (Smith 2014).”

“While there is ample evidence for strong pre-SN episodic mass loss from SNe IIn (for a review, see Smith 2014), there is currently no prescription for including that mass loss in evolutionary models.”

“…as a dwarf (i.e., luminosity class V) and its luminosity L is less than logL/L ≈ 5.2, since below this luminosity threshold observations show much weaker than expected winds for OB dwarfs (this is known as the weak wind problem; for a recent review of mass loss in massive stars, see Smith 2014).”

“Eruptions of LBVs produce M>−16 mag optical transients with similar optical spectra to SNe IIn, referred to as SN impostors (e.g., Van Dyk et al. 2000; Maund et al. 2006; Smith et al. 2011b; Smith 2014; de Jaeger et al. 2015).”

“The most likely mechanism for such shrinking is a common envelope phase after the formation of the compact object (e.g., Dominik et al. 2012; Bogomazov 2014; Belczynski et al. 2016; van den Heuvel et al. 2017; Bogomazov et al. 2018; Giacobbo et al. 2018).”

“Extensive mass loss has been associated with both Wolf-Rayet stars and luminous blue variables (LBVs; Smith 2014).”

“It is, however, necessary to appreciate that the ambient gas density and the mass-loss rate associated with massive stars (or AGNs) are not spherically symmetric because they exhibit a strong angular dependence relative to the rotation axis of the central object (Puls et al. 2008; Smith 2014).”

“…and explosive mass-loss events during the late nuclear burning stages before core-collapse (e.g., Kotak & Vink 2006; Smith et al. 2007; Pastorello et al. 2007; Gal-Yam & Leonard 2009; Fraser et al. 2013; Gal-Yam et al. 2014; Smith 2014; Groh 2014; Fuller 2017; Yaron et al. 2017; Boian & Groh 2018).”

“The OCs that survive the initial gas expulsion phase end up suffering mass loss due to: (a) stellar evolution (e.g., Vink et al. 2001; Smith 2014), (b) internal interactions, which ?”

“It has been proposed that the progenitor systems of SNe IIn undergo massloss episodes preceding their terminal SN explosion (Smith 2014).”

“The YSG and LBV phases last on the order of 104 or 105 yr in single star evolution models (Neugent et al. 2012; Smith 2014), while the WR phase lasts a few times 105 yr (Crowther 2007).”

“…and location in the Hertzsprung-Russell (HR) diagram are of importance to calibrate stellar evolutionary models for massivetars and to understand their further evolution toward WR stars and SNe, a topic that has seen an increased interest (e.g., Dessart et al. 2013; Smith 2014; Meynet et al. 2015).”

“This is inconsistent with the properties of SNe Ic-BL, which have typical mass-loss rate ∼ 10−6M yr−1 (Smith 2014).”

“…S Doradus LBVs have traditionally been suggested to be transitional objects (Humphreys & Davidson 1994; Lamers et al. 1998), in the last decade, they have been proposed as direct core-collapse supernovae SNe progenitors (Kotak & Vink 2006; Gal-Yam & Leonard 2009; Groh et al. 2013; Smith 2014).”

“The evolution of such SNe is indicative of the progenitor stars having been stripped of all but a minute amount of hydrogen ( 0.1M⊙) and, as such, these SNe and their progenitors provide exquisite probes of the mass loss processes that massive stars may undergo (Smith 2014).”

“This radiation, along with strong winds produced by massive stars, are important feedback mechanisms that regulate star formation and the structure of the interstellar medium in galaxies (Kennicutt 2005; Smith 2014).”

“As noted by Offner & Arce (2015), these mass-loss rates are 2–3 orders of magnitudes larger than predicted by theoretical models of linedriven winds from main-sequence B stars (e.g., Smith 2014, Figure 3).”

“However, these mass-loss rates are orders of magnitude higher than those that can be explained by stellar winds, outflows (considering outflows are collimated; Bally 2016), or ionization or radiation pressure from the stars observed in Taurus (Smith 2014).”

“Lastly, in standard stellar mass-loss models (which likely overestimate the effects of winds; Smith 2014), the momentum from stellar winds is at most comparable to that of photons.”

“Hydrogen-rich SLSNe exhibit strong narrow Balmer emission lines within their spectra, but are more luminous than standard type IIn supernovae (SNe IIn), achieving luminosities typically with M −20 at peak brightness (Gal-Yam 2012; Smith 2014; Gal-Yam 2019).”

“Type IIn supernovae (SNe IIn; see Filippenko 1997 and Smith 2017 for reviews) are characterised by relatively narrow emission lines (Schlegel 1990) which are not associated with the SN explosion itself, but rather with dense circumstellar material (CSM) produced by pre-SN mass loss (Smith 2014).”

“However, the circumstellar material (CSM) created by this mass loss can have an impact on both the light curve and spectra of SNe II at very early times (Smith 2014).”

“1 − 100 yr before the explosion [3, 30, 31].”

“Smith (2014) notes that for both red supergiants and Wolf-Rayet stars with solar metallicity, the massloss rates do not extend much past 10−5 M☉ yr −1, and the mass loss from line-driven winds scales as (Z/Z☉) 0.5, so maximum mass-loss rates will be further reduced in the low-metallicity…”

“Type IIn SNe and SN impostors are related to the unsolved problems in stellar mass loss, and it is important to understand their origins (e.g., Smith 2014; Langer 2012).”

“It has long been known that abundances affect both the momentum transfer and mass loss in the stellar winds of massive stars (e.g., Vink et al. 2001; Kudritzki 2002), though the situation is complicated (Smith 2014).”

“1, where a quantity ∝ m × dLNT/dm is shown, stars with masses significantly below 40M⊙ do not contribute significantly to the non-thermal luminosity; and the weak-wind problem would start to be significant for stars of spectral type O7O8, which have masses of ∼ 25 − 28M⊙ (Smith 2014).”

“During and shortly after the main sequence phase, mass loss rates are at their lowest (Puls et al. 2008; Smith 2014), and the geometries of their circumstellar media (CSM) are at their simplest (e.g., Garcia-Segura et al. 1996; Gvaramadze et al. 2018).”

“The typical mass-loss rates in RSGs, yellow hypergiants and luminous blue variables (LBVs) are found to have a range of 10−6 – 10−4 M yr−1, 10−4 – 10−3 M yr−1 and 0.1 – 10 M yr−1, respectively (see Smith 2014).”

“Since the most radiatively efficient collisions occur with CSM located near the progenitor, the interacting SNe reveal the mass-loss history of massive stars shortly before the collapse of the core (e.g., Smith & McCray 2007; Smith 2014; Stritzinger et al. 2012).”

“However, in spite of the fact that most massive stars are found in binary systems (Smith 2014), that most Type Ib/c SNe occur in binary systems (Smith et al. 2011), and that SNe associated with long GRBs are indeed of Type Ib/c (Della Valle 2011), the effects of binarity on long GRBs have been for…”

“Galactic analogs with such mass-loss rates include anything from extreme self-obscured red supergiants (RSGs) to luminous blue variables (LBVs), each of which present further questions of their own (see Smith 2014 for a review).”

“The exact details of the mass loss mechanism remain poorly understood (Smith 2014).”

“Such a collapsar model does not address some observational facts: 1) most massive stars are found in binary systems (Smith 2014), 2) most type Ib/c SNe occur in binary systems (Smith et al. 2011) and 3) the SNe associated to long GRBs are indeed of type Ib/c (Della Valle 2011).”

“…down as a result of angular momentum conservation and may be further reduced by, e.g. mass loss due to stellar winds (e.g. Maeder & Meynet 2000; Smith 2014), possibly inward convective transport of angular momentum (e.g. Brun & Toomre 2002; Brun & Palacios 2009), and magnetic braking (Mestel…”

“Recent estimates of mass-loss rates have been revised downward, lower than mass-loss rates adopted in most models (see Smith 2014 for a recent review).”

“However, recently evidence has been mounting that many massive stars experience highly variable stellar winds and eruptive mass-loss in the period before the explosion (see Smith 2014, for a review).”

“This implies that the progenitor of SN 1978K suffered heavy mass loss, with rate at least comparable to type-IIn SN progenitors with the highest mass loss rates (Kiewe et al. 2012) and the averaged mass loss rate in the events of LBV giant eruptions (Smith 2014).”

“MS stars at these luminosities are predominantly observed with emission-line spectra of the WNh sub-type, typically with Ṁ & 5 × 10−6M yr−1 derived using detailed spectroscopic modelling (Martins et al. 2008; Martins & Palacios 2013; Crowther et al. 2010; Smith 2014).”

“Drout et al. (2011) show that SNe Ib/c have relatively low ejecta masses; stellar winds are generally too weak to remove the entire outer envelope on their own (Smith 2014), except perhaps in the most massive (and rare) stars.”

“Reviews of massive star winds and mass loss include Kudritzki & Puls (2000), Puls et al. (2008), and Smith (2014).”

“…times, for values of ÛM lower than ∼ 10−5M⊙/yr (being 2 × 10−5M⊙/yr our benchmark value), while for higher values it safely attains the PeVatron phase up to ∼ 100 yr MNRAS 000, 1–10 (2017) (see Smith 2014 for a comprehensive review on the mass loss rates in different types of progenitor stars).”