The Winds of the Hot Massive Stars in I Zw 18

Dorottya Szécsi

Collaborators: Norbert Langer (Bonn, Germany), Carolina Kehrig (Granada, Spain), Frank Tramper (Madrid, Spain), Takashi Moriya (Tokyo, Japan) Jíři Kubát (Ondrejov, Czech Rep.)

Grant: 13-10589S GA ČR Quy Nhon, Vietnam, 11th August 2016 The night-sky and beyond The night-sky and beyond The night-sky and beyond The night-sky and beyond The night-sky and beyond The night-sky and beyond The night-sky and beyond The night-sky and beyond The night-sky and beyond The night-sky and beyond What is a star? surface? hot, dense plazma photons escape →"photosphere" What is inside? →← theoretical modelling of the stellar structure

equilibrium: pressure gradient gravity

What is a star? surface? photons escape →"photosphere" What is inside? →← theoretical modelling of the stellar structure

equilibrium: pressure gradient gravity

What is a star?

hot, dense plazma surface? photons escape →"photosphere" What is inside?

theoretical modelling of the stellar structure

What is a star?

hot, dense plazma

→←

equilibrium: pressure gradient gravity photons escape →"photosphere" What is inside?

theoretical modelling of the stellar structure

What is a star?

surface? hot, dense plazma

→←

equilibrium: pressure gradient gravity What is inside?

theoretical modelling of the stellar structure

What is a star?

surface? hot, dense plazma photons escape →"photosphere" →←

equilibrium: pressure gradient gravity What is inside?

theoretical modelling of the stellar structure

What is a star?

surface? hot, dense plazma photons escape →"photosphere" →←

equilibrium: pressure gradient gravity theoretical modelling of the stellar structure

What is a star?

surface? hot, dense plazma photons escape →"photosphere" What is inside? →←

equilibrium: pressure gradient gravity What is a star?

surface? hot, dense plazma photons escape →"photosphere" What is inside? →← theoretical modelling of the stellar structure

equilibrium: pressure gradient gravity mass conservation

momentum conservation

energy conservation

transport of energy

composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation.

Theoretical modelling of the stellar structure

Guilera et al. 2011 momentum conservation

energy conservation

transport of energy

composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation.

Theoretical modelling of the stellar structure

mass conservation

Guilera et al. 2011 energy conservation

transport of energy

composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation.

Theoretical modelling of the stellar structure

mass conservation

momentum conservation

Guilera et al. 2011 transport of energy

composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation.

Theoretical modelling of the stellar structure

mass conservation

momentum conservation

energy conservation

Guilera et al. 2011 composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation.

Theoretical modelling of the stellar structure

mass conservation

momentum conservation

energy conservation

transport of energy

Guilera et al. 2011 ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation.

Theoretical modelling of the stellar structure

mass conservation

momentum conservation

energy conservation

transport of energy

Guilera et al. 2011 composition change due to nuclear burning ?! + Rotation.

Theoretical modelling of the stellar structure

mass conservation

momentum conservation

energy conservation

transport of energy

Guilera et al. 2011 composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , Theoretical modelling of the stellar structure

mass conservation

momentum conservation

energy conservation

transport of energy

Guilera et al. 2011 composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation. Theoretical modelling of the stellar structure

mass conservation

momentum conservation

energy conservation

transport of energy

Guilera et al. 2011 composition change due to nuclear burning ?! ∂Xi Ai mu = ( Σj k ri j k + Σk l rk l i ) (13) ∂t ρ − , , , , , , + Rotation. • nuclear reactions, ﬁnal composition • number of stars: massive stars are rare • lifetime: massive stars have shorter lives • ﬁnal fate

Massive vs. low-mass stars

Massive stars: & 9 times the Sun (& 9 M )

• number of stars: massive stars are rare • lifetime: massive stars have shorter lives • ﬁnal fate

Massive vs. low-mass stars

Massive stars: & 9 times the Sun (& 9 M )

• nuclear reactions, ﬁnal composition • lifetime: massive stars have shorter lives • ﬁnal fate

Massive vs. low-mass stars

Massive stars: & 9 times the Sun (& 9 M )

• nuclear reactions, ﬁnal composition • number of stars: massive stars are rare • ﬁnal fate

Massive vs. low-mass stars

Massive stars: & 9 times the Sun (& 9 M )

• nuclear reactions, ﬁnal composition • number of stars: massive stars are rare • lifetime: massive stars have shorter lives Massive vs. low-mass stars

Massive stars: & 9 times the Sun (& 9 M )

• nuclear reactions, ﬁnal composition • number of stars: massive stars are rare • lifetime: massive stars have shorter lives • ﬁnal fate Wolf–Rayet stars (i.e. optically thick winds)

Massive stars with solar composition

Hertzsprung–Russell diagram

Groh et al. 2013 Massive stars with solar composition

Hertzsprung–Russell diagram

Wolf–Rayet stars (i.e. optically thick winds)

Groh et al. 2013 Hertzsprung–Russell diagram

Wolf–Rayet stars (i.e. optically thick winds)

Massive stars with solar composition

Groh et al. 2013 – my thesis ,

Low Metallicity Massive Stars Low Metallicity Massive Stars – my thesis , I Zwicky 18

• Blue Compact Dwarf Galaxy • 60 million lightyears local 12+log(O/H)=7.17 → • star formation rate: Z=1/50 Z↓ 0.0002 0.1 M /yr ≈

• ionized gas • low metallicity!

IZw18 SMC LMC SUN

0 Z 0.0002 0.0021 0.0047 0.0134

Compact Dwarf Galaxies

Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13 12+log(O/H)=7.17

Z=1/50 Z↓ 0.0002 ≈

IZw18 SMC LMC SUN

0 Z 0.0002 0.0021 0.0047 0.0134

Compact Dwarf Galaxies

I Zwicky 18

• Blue Compact Dwarf Galaxy • 60 million lightyears local → • star formation rate: 0.1 M /yr

• ionized gas • low metallicity!

Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13 IZw18 SMC LMC SUN

0 Z 0.0002 0.0021 0.0047 0.0134

Compact Dwarf Galaxies

I Zwicky 18

• Blue Compact Dwarf Galaxy • 60 million lightyears local 12+log(O/H)=7.17 → • star formation rate: Z=1/50 Z↓ 0.0002 0.1 M /yr ≈

• ionized gas • low metallicity!

Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13 Compact Dwarf Galaxies

I Zwicky 18

• Blue Compact Dwarf Galaxy • 60 million lightyears local 12+log(O/H)=7.17 → • star formation rate: Z=1/50 Z↓ 0.0002 0.1 M /yr ≈

• ionized gas • low metallicity!

IZw18 SMC LMC SUN

0 Z 0.0002 0.0021 0.0047 0.0134

Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13 7 7 294 M⊙ 294 M ⊙ 6.5 150 M 6.5 150 M ⊙ ⊙ 77 M 6 77 M ⊙ 6 ⊙ ) ) ⊙ ⊙ 5.5 5.5 39 M ⊙ ⊙ log(L/L log(L/L 2020 M M⊙ 5 5 ⊙

4.5 4.5 10 M 10 M⊙⊙ coreZAMS H-burn 4 ZAMS 4 0 ZAMSkm/s 2000 ZAMSkm/s0 km/s 2003500200 ZAMSkm/s km/s 2003505000350 km/s km/s 3.5 500 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6 5 4.8 4.6 4.4 4.2 4 3.8 3.6 log(Teff/K) log(Teff/K)

Low Metallicity Massive Stars

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 294 M ⊙

6.5 150 M ⊙

77 M 6 ⊙ ) ⊙ 5.5 39 M ⊙

log(L/L 20 M 5 ⊙

4.5 10 M ⊙ 4

0 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6

log(Teff/K) 7 7 294 M⊙ 294 M ⊙ 6.5 150 M 6.5 150 M ⊙ ⊙ 77 M 6 77 M ⊙ 6 ⊙ ) ) ⊙ ⊙ 5.5 5.5 39 M ⊙ ⊙ log(L/L log(L/L 2020 M M⊙ 5 5 ⊙

4.5 4.5 10 M 10 M⊙⊙ coreZAMS H-burn 4 ZAMS 4 0 ZAMSkm/s 2000 ZAMSkm/s0 km/s 2003500200 km/s km/s 200350500350 km/s km/s 3.5 500 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6 5 4.8 4.6 4.4 4.2 4 3.8 3.6 log(Teff/K) log(Teff/K)

Low Metallicity Massive Stars

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 294 M ⊙

6.5 150 M ⊙

77 M 6 ⊙ ) ) ⊙ ⊙ 5.5 39 M ⊙ log(L/L log(L/L 20 M 5 ⊙

4.5 10 M ⊙ 4

ZAMS 0 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6

log(Teff/K) 7 7 294 M⊙ 294 M ⊙ 6.5 150 M 6.5 150 M ⊙ ⊙ 77 M 6 77 M ⊙ 6 ⊙ ) ) ⊙ ⊙ 5.5 5.5 39 M ⊙ ⊙ log(L/L log(L/L 2020 M M⊙ 5 5 ⊙

4.5 4.5 10 M 10 M⊙⊙ coreZAMS H-burn 4 ZAMS 4 0 ZAMSkm/s 2000 km/s0 km/s 200350200 km/s km/s 350500350 km/s km/s 3.5 500 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6 5 4.8 4.6 4.4 4.2 4 3.8 3.6 log(Teff/K) log(Teff/K)

Low Metallicity Massive Stars

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 294 M ⊙

6.5 150 M ⊙

77 M 6 ⊙ ) ) ⊙ ⊙ 5.5 39 M ⊙ log(L/L log(L/L 20 M 5 ⊙

4.5 10 M ⊙ 4 ZAMS 0 ZAMSkm/s 2000 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6

log(Teff/K) 7 7 294 M⊙ 294 M ⊙ 6.5 150 M 6.5 150 M ⊙ ⊙ 77 M 6 77 M ⊙ 6 ⊙ ) ) ⊙ ⊙ 5.5 5.5 39 M ⊙ ⊙ log(L/L log(L/L 2020 M M⊙ 5 5 ⊙

4.5 4.5 10 M 10 M⊙⊙ coreZAMS H-burn 4 ZAMS 4 0 km/s 200 km/s0 km/s 350200 km/s km/s 500350 km/s km/s 3.5 500 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6 5 4.8 4.6 4.4 4.2 4 3.8 3.6 log(Teff/K) log(Teff/K)

Low Metallicity Massive Stars

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 294 M ⊙

6.5 150 M ⊙

77 M 6 ⊙ ) ) ⊙ ⊙ 5.5 39 M ⊙ log(L/L log(L/L 20 M 5 ⊙

4.5 10 M ⊙

4 ZAMS 0 ZAMSkm/s 2000 ZAMSkm/s 2003500 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6

log(Teff/K) 7 294 M⊙

6.5 150 M⊙

77 M 6 ⊙ ) ⊙ 5.5 39 M⊙

log(L/L 20 M⊙ 5

4.5 10 M ⊙ core H-burn ZAMS 4 0 km/s 200 km/s 350 km/s 500 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6

log(Teff/K)

Low Metallicity Massive Stars

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 294 M ⊙

6.5 150 M ⊙

77 M 6 ⊙ ) ) ⊙ ⊙ 5.5 39 M ⊙ log(L/L log(L/L 20 M 5 ⊙

4.5 10 M ⊙ ZAMS 4 0 ZAMSkm/s 2000 ZAMSkm/s 2003500 ZAMSkm/s 2003505000 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6

log(Teff/K) Low Metallicity Massive Stars

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 7 294 M⊙ 294 M ⊙ 6.5 150 M 6.5 150 M ⊙ ⊙ 77 M 6 77 M ⊙ 6 ⊙ ) ) ) ⊙ ⊙ ⊙ 5.5 5.5 39 M ⊙ ⊙ log(L/L log(L/L log(L/L 2020 M M⊙ 5 5 ⊙

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 7 294 M⊙ 294 M ⊙ 6.5 150 M 6.5 150 M ⊙ ⊙ 77 M 6 77 M ⊙ 6 ⊙ ) ) ) ⊙ ⊙ ⊙ 5.5 5.5 39 M ⊙ ⊙ log(L/L log(L/L log(L/L 2020 M M⊙ 5 5 ⊙

Szécsi et al. 2015 (Astronomy & Astrophysics, v.581, A15)

7 7 294 M⊙ 294 M ⊙ 6.5 150 M 6.5 150 M ⊙ ⊙ 77 M 6 77 M ⊙ 6 ⊙ ) ) ) ⊙ ⊙ ⊙ 5.5 5.5 39 M ⊙ ⊙ log(L/L log(L/L log(L/L 2020 M M⊙ 5 5 ⊙

• stellar ’wind’: accelerated particle ﬂow • hot stars at solar Z: Wolf–Rayet (WR) stars • opaque wind strong emission lines → • hot stars at low Z? Core-H-burning lifetime: wind optical depth is τ . 1

7.5 τ<0.05 τ 7 ⊙ 0.05< <1 294 M 1<τ<2 ⊙ 6.5 150 M 2<τ<3

) 6 77 M ⊙ ⊙ 5.5 39 M ⊙

log(L/L 5 Transparent Wind 20 M ⊙ 4.5 Ultraviolet INtense 4 (TWUIN) stars 10 M ⊙ 3.5 4.95 4.9 4.85 4.8 4.75 4.7 4.65 4.6 4.55 4.5 4.45 4.4

log(Teff/K)

Hot stars at low Z: transparent wind! Core-H-burning lifetime: wind optical depth is τ . 1

Transparent Wind Ultraviolet INtense (TWUIN) stars

Hot stars at low Z: transparent wind!

7.5 τ<0.05 τ 7 ⊙ 0.05< <1 294 M 1<τ<2 ⊙ 6.5 150 M 2<τ<3

) 6 77 M ⊙ ⊙ 5.5 39 M ⊙

log(L/L 5

20 M ⊙ 4.5

4 10 M ⊙ 3.5 4.95 4.9 4.85 4.8 4.75 4.7 4.65 4.6 4.55 4.5 4.45 4.4

log(Teff/K) Transparent Wind Ultraviolet INtense (TWUIN) stars

Hot stars at low Z: transparent wind!

Core-H-burning lifetime: wind optical depth is τ . 1

7.5 τ<0.05 τ 7 ⊙ 0.05< <1 294 M 1<τ<2 ⊙ 6.5 150 M 2<τ<3

) 6 77 M ⊙ ⊙ 5.5 39 M ⊙

log(L/L 5

20 M ⊙ 4.5

4 10 M ⊙ 3.5 4.95 4.9 4.85 4.8 4.75 4.7 4.65 4.6 4.55 4.5 4.45 4.4

log(Teff/K) Hot stars at low Z: transparent wind!

Core-H-burning lifetime: wind optical depth is τ . 1

7.5 τ<0.05 τ 7 ⊙ 0.05< <1 294 M 1<τ<2 ⊙ 6.5 150 M 2<τ<3

) 6 77 M ⊙ ⊙ 5.5 39 M ⊙

log(L/L 5 Transparent Wind 20 M ⊙ 4.5 Ultraviolet INtense 4 (TWUIN) stars 10 M ⊙ 3.5 4.95 4.9 4.85 4.8 4.75 4.7 4.65 4.6 4.55 4.5 4.45 4.4

log(Teff/K) Photoionization Q(HeII)obs = 1.33 1050 photons s 1 · − + 9 WC stars

(Kehrig+15, Crowther+06)

Back to I Zw 18

I Zwicky 18

• Blue Compact Dwarf Galaxy • 60 million lightyears local → • star formation rate: 0.1 M /yr

• ionized gas • low metallicity: Z=1/50 Z

Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13 Back to I Zw 18

I Zwicky 18

• Blue Compact Dwarf Photoionization Galaxy • 60 million lightyears Q(HeII)obs = local 50 1 → 1.33 10 photons s− • star formation rate: · 0.1 M /yr + 9 WC stars

• ionized gas (Kehrig+15, Crowther+06) • low metallicity: Z=1/50 Z

Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13 Photoionizationobs = 1 − Q(HeII) 50 photons s 10 1.33 · + 9 WC stars 7 Thank you 257 M⊙ 172 M for your 6.5 ⊙ 8 WC stars 131 M⊙ attention!

88 M 6 ⊙

) 67 M⊙ ⊙ 59 M⊙

5.5 45 M⊙ log(L/L simulated stellar population of I Zw 18 5 (including post-MS phase): 26 M⊙ 23 M⊙ sim 50 1 20 M Q(He II) =1.65 10 photons s− ⊙ 4.5 core H-burn · 50 1 TWUIN stars ZAMSHeII ﬂux of I Zw 18 (10 s− ) core He-burn→ corenumber C-burn of WC stars (8-9) 13 M⊙ 4 →core Ne-burn Transparent Wind 5.4Ultraviolet IN 5.2tense 5 4.8 4.6 4.4 log(Teff/K)

Photoionization in I Zw 18

Photoionizationobs = 1 − Q(HeII) 50 photons s 10 1.33 · + 9 WC stars 7 294 M⊙

6.5 150 M⊙

77 M 6 ⊙ ) ⊙ 5.5 39 M⊙

log(L/L 20 M⊙ 5

4.5 10 M ⊙ core H-burn ZAMS 4 0 km/s 200 km/s 350 km/s 500 km/s 3.5 5 4.8 4.6 4.4 4.2 4 3.8 3.6

log(Teff/K) Thank you for your 8 WC stars attention!

simulated stellar population of I Zw 18 (including post-MS phase): sim 50 1 Q(He II) =1.65 10 photons s− TWUIN stars HeII ﬂux of I Zw 18· (1050 s 1) → − number of WC stars (8-9) → Transparent Wind Ultraviolet INtense

Photoionization in I Zw 18

Photoionizationobs = 1 − Q(HeII) 50 photons s 10 1.33 · + 9 WC stars 7 294 M⊙ 257 M⊙ 6.5 150 M 172 M 6.5 ⊙ ⊙ 131 M⊙ 77 M 6 ⊙ 88 M 6 ⊙ ) ) 67 M⊙ ⊙ ⊙ 59 M 5.5 39 M⊙ ⊙

5.5 45 M⊙ log(L/L log(L/L 20 M⊙ 5

5 26 M⊙ 4.5 23 M⊙ 10 M 20 M ⊙ core H-burn ⊙ 4.5 core H-burn ZAMS 4 ZAMS 0 km/s core He-burn 200 km/s core C-burn 350 km/s 13 M⊙ 4 core Ne-burn 500 km/s 3.5 5 5.4 4.8 5.24.6 4.4 5 4.2 4.8 4 4.6 3.8 3.64.4

log(Teff/K) Thank you for your 8 WC stars attention!

TWUIN stars HeII ﬂux of I Zw 18 (1050 s 1) → − number of WC stars (8-9) → Transparent Wind Ultraviolet INtense

Photoionization in I Zw 18

Photoionizationobs = 1 − Q(HeII) 50 photons s 10 1.33 · + 9 WC stars 7 294 M⊙ 257 M⊙ 6.5 150 M 172 M 6.5 ⊙ ⊙ 131 M⊙ 77 M 6 ⊙ 88 M 6 ⊙ ) ) 67 M⊙ ⊙ ⊙ 59 M 5.5 39 M⊙ ⊙

5.5 45 M⊙ log(L/L log(L/L 20 M⊙ 5 simulated stellar population of I Zw 18 5 (including post-MS phase): 26 M⊙ 4.5 23 M⊙ sim 1050 M 1 20 M Q(He II) =1.65 10 ⊙photons s− core H-burn ⊙ 4.5 core H-burn · ZAMS 4 ZAMS 0 km/s core He-burn 200 km/s core C-burn 350 km/s 13 M⊙ 4 core Ne-burn 500 km/s 3.5 5 5.4 4.8 5.24.6 4.4 5 4.2 4.8 4 4.6 3.8 3.64.4

log(Teff/K) Thank you for your attention!

TWUIN stars HeII ﬂux of I Zw 18 (1050 s 1) → − number of WC stars (8-9) → Transparent Wind Ultraviolet INtense

Photoionization in I Zw 18

Photoionizationobs = 1 − Q(HeII) 50 photons s 10 1.33 · + 9 WC stars 7 294 M⊙ 257 M⊙ 6.5 150 M 172 M 6.5 ⊙ ⊙ 8 WC stars 131 M⊙ 77 M 6 ⊙ 88 M 6 ⊙ ) ) 67 M⊙ ⊙ ⊙ 59 M 5.5 39 M⊙ ⊙

log(Teff/K) Thank you for your attention!

Photoionization in I Zw 18

5.5 45 M⊙ log(L/L log(L/L 20 M⊙ 5 simulated stellar population of I Zw 18 5 (including post-MS phase): 26 M⊙ 4.5 23 M⊙ sim 1050 M 1 20 M Q(He II) =1.65 10 ⊙photons s− core H-burn ⊙ 4.5 50 1 TWUIN starscore H-burnHeII ﬂux of I Zw 18· (10 s ) ZAMS 4 ZAMS − 0 km/s core He-burn→ 200 km/s corenumber C-burn of WC stars (8-9) 350 km/s 13 M⊙ 4 core Ne-burn 500 km/s 3.5 → Transparent5Wind 5.4Ultraviolet4.8 IN 5.2tense4.6 4.4 5 4.2 4.8 4 4.6 3.8 3.64.4 log(Teff/K) Photoionization in I Zw 18

Photoionizationobs = 1 − Q(HeII) 50 photons s 10 1.33 · + 9 WC stars 7 294 M⊙ Thank you 257 M ⊙ for your 6.5 150 M 172 M 6.5 ⊙ ⊙ 8 WC stars 131 M⊙ attention! 77 M 6 ⊙ 88 M 6 ⊙ ) ) 67 M⊙ ⊙ ⊙ 59 M 5.5 39 M⊙ ⊙