Mass loss of massive stars
Fabrice Martins
LUPM (Laboratoire Univers et Particules de Montpellier)
Mass loss, evolution and fate of massive stars
Mass loss affects
● evolutionary paths and end-points of stellar evolution (together with rotation, metallicity, binarity...)
Meynet+15
● type of SN resulting from core-collapse event - SN progenitor - environment in which explosion occurs
Evolution of massive stars
LBV
Red supergiant
Wolf- Rayet
OB star
Yellow hypergiant
OB stars
3 Myr
13 Myr
OB phase (~ main sequence): 85-90% of lifetime Winds:
M=15 Msun T = 13 Myr (lifetime = 15 Myr) Mass loss rates: 10-10 to 10-5 Msun/yr MS
M=60 Msun T = 3.5 Myr (lifetime = 4 Myr) Wind velocity: ~500 to 4000 km/s MS OB stars
Radiatively driven winds
- Photons absorbed through metallic lines - Momentum redistributed to bulk material Fe through collisional coupling
Lucy & Solomon (1970) CNO Castor, Abbott & Klein (1975) H He Pauldrach et al. (1986) Vink et al. (2001)
. M ∝ L1/α
α V = V ∞ esc√1-α
Vink+01 OB stars
Mokiem+07
● 1.5-2.0 ● M ∝ L M ∝ Z0.83 Martins+04
Garcia+14
Observational trends confirm theoretical predictions
OB stars
Instabilities:
g dv/dr + = f <> line cl +=density in overdense structures f = clumping factor (~ 3) cl
Runacres & Owocki 02
Red supergiants
0.3-3 Myr
0.2-0.5 Myr
Red supergiant phase: ~5-10% of lifetime Winds:
M=9 Msun T = 2.5 Myr (lifetime = 30 Myr) Mass loss rates: 10-7 to 10-4 Msun/yr RSG M=15 Msun T = 1 Myr (lifetime = 15 Myr) RSG Wind velocity: 10-40 km/s M=25 Msun T = 0.3 Myr (lifetime = 7 Myr) RSG Red supergiants
Mauron & Josselin (2011) Large dispersion
Assumptions in methods to determine Mdot (gas-to-dust ratio, opacity...)
Red supergiants
Credit: P. Kervella
Origin of mass loss:
Radiation pressure on dust inefficient (compared to AGBs) since dust forms further out No pulsations like in AGBs Dust nucleation seeds unidentified
Convection may trigger surface motions
Subsequent radiation pressure on molecules? Red supergiants
Smith+01 Inhomogeneities Multiple ejections? Luminous Blue Variables (LBV)
Few 0.1 Myr
LBV phase: <1% of lifetime (104 to 105 yr) Winds:
Unstable phase Mass loss rates: 10-5 to ~1 Msun/yr Occurs only above M~40 Msun Observational limit (Humphreys-Davidson) related Wind velocity: 100-500 km/s to Eddington limit Luminous Blue Variables (LBV)
η Car
Clarke+05
LBV phase: 2 types of variability
● S Dor varialitity: magnitude changes by 1-2 units Associated to variations of Teff / R, at constant L
● Violent eruptions: only ηCar and P Cygni in Galaxy Short, episodic eruptions (e.g. Great eruption of ηCar) Luminous Blue Variables (LBV)
Owocki 14
Stahl+01 1990-1995 (brightening) Vink & de Koter 02 1995-1999 (dimming)
LBV phase: origin of mass loss
● partly due to change in ionization structure and radiative acceleration (S Dor phase) ● still unknown for eruptions: continuum driving in clumped material (Owocki+04)? Role of radiation pressure, rotation, binarity, pulsations... ? → Great Eruption of Eta Car: more than 10 Msun in about 10 years Luminous Blue Variables (LBV)
F658N filter
Morse+01 Wolf-Rayet (WR)
Few 0.1 Myr
WR phase: ~5% of lifetime Winds:
WR stars above ~25 Msun in the Galaxy Mass loss rates: few 10-6 to 10-4 Msun/yr
M=40 Msun T = 0.2 Myr (lifetime = 5 Myr) WR Wind velocity: 800-2500 km/s Wolf-Rayet (WR)
□w/ H ▪w/o H
Crowther 07
● Current understanding: radiation driven winds (multiple scattering) ● Hints of metallicity dependence (Mdot Z0.8) Wolf-Rayet (WR)
Clumped material in motion
Co-rotatind interaction regions (CIRs)
Pinwheel structures
Lépine & Moffat 99 Tuthill+06 Summary
WR
RSG
Clark+12
RSG 15 M OB sun OB LBV WR 40 M sun