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The Life and Death of Massive Starsin the
Starburst Galaxy I Zw18
Dorottya SzécsiNorbert Langer
Stellar Explosions in an Ever-Changing Environment(IAU General Assembly FM 10)
11-13. August 2015, Honolulu, Hawaii
Life and Death of Massive Stars
Collapsar→ lGRB
Massive stars
?
Yoon&Langer’05; Woosley&Heger’06; Yoon+06; Yoon+12
Life and Death of Massive Stars
Collapsar→ lGRBMassive stars
?
Yoon&Langer’05; Woosley&Heger’06; Yoon+06; Yoon+12
Meet I Zw 18!
• Blue Compact DwarfGalaxy
• 18 Mpc→ local
• SFR: 0.1-1 M�/yr
• ionized gas
• low metallicity:12+log(O/H)=7.17↓Z=1/50 Z� ≈ 0.0002
I Zwicky 18
Z0
IZw18
0.0002
SMC
0.0021
LMC
0.0047
SUN
0.0134
Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13
Meet I Zw 18!
• Blue Compact DwarfGalaxy
• 18 Mpc→ local
• SFR: 0.1-1 M�/yr
• ionized gas
• low metallicity:12+log(O/H)=7.17↓Z=1/50 Z� ≈ 0.0002
I Zwicky 18
Z0
IZw18
0.0002
SMC
0.0021
LMC
0.0047
SUN
0.0134
Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators
"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators
"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
Stellar evolution in I Zw 18
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.6 3.8 4 4.2 4.4 4.6 4.8 5
log(
L/L ⊙
)
log(Teff/K)
ZAMS0 km/s
200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
3.5
4
4.5
5
5.5
6
6.5
7
3.63.844.24.44.64.85
log(
L/L ⊙
)
log(Teff/K)
core H-burnZAMS
0 km/s200 km/s350 km/s500 km/s
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Z=1/50 Z� models fromSzécsi et al. 2015 (A&A)
No enhanced mixing→Normal Evolution→
RSGs→SN Type IIp
Slow rotators
Rotational mixing→Chemically Homogeneous
Evolution→’Wolf-Rayet’ stars (?) →
lGRB
Fast rotators"angular momentum in the core is
higher than the critical limit for the
formation of an accretion disc
around a rotating black hole"
Collapsar→ lGRB
MS lifetime of the lGRB progenitors
3.5
4
4.5
5
5.5
6
6.5
7
7.5
4.4 4.45 4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95
log(
L/L ⊙
)
log(Teff/K)
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙294 M⊙
τ<0.050.05<τ<11<τ<22<τ<3
Main sequence lifetime: wind optical depth is τ . 1
Transparent WindUltraviolet INtense
(TWUIN) stars
MS lifetime of the lGRB progenitors
3.5
4
4.5
5
5.5
6
6.5
7
7.5
4.4 4.45 4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95
log(
L/L ⊙
)
log(Teff/K)
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙294 M⊙
τ<0.050.05<τ<11<τ<22<τ<3
Main sequence lifetime: wind optical depth is τ . 1
Transparent WindUltraviolet INtense
(TWUIN) stars
MS lifetime of the lGRB progenitors
3.5
4
4.5
5
5.5
6
6.5
7
7.5
4.4 4.45 4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95
log(
L/L ⊙
)
log(Teff/K)
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙294 M⊙
τ<0.050.05<τ<11<τ<22<τ<3
Main sequence lifetime: wind optical depth is τ . 1
Transparent WindUltraviolet INtense
(TWUIN) stars
MS lifetime of the lGRB progenitors
3.5
4
4.5
5
5.5
6
6.5
7
7.5
4.4 4.45 4.5 4.55 4.6 4.65 4.7 4.75 4.8 4.85 4.9 4.95
log(
L/L ⊙
)
log(Teff/K)
10 M⊙
20 M⊙
39 M⊙
77 M⊙
150 M⊙294 M⊙
τ<0.050.05<τ<11<τ<22<τ<3
Main sequence lifetime: wind optical depth is τ . 1
Transparent WindUltraviolet INtense
(TWUIN) stars
Back to I Zw 18
• Blue Compact DwarfGalaxy
• 18 Mpc→ local
• SFR: 0.1-1 M�/yr
• ionized gas
• low metallicity:12+log(O/H)=7.17↓Z=1/50 Z� ≈ 0.0002
I Zwicky 18
Q(HeII)obs =1.3 · 1050 photons s−1
+ weak WR features
(Kehrig+15, Crowther+06 )
Photoionization
Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13
Back to I Zw 18
• Blue Compact DwarfGalaxy
• 18 Mpc→ local
• SFR: 0.1-1 M�/yr
• ionized gas
• low metallicity:12+log(O/H)=7.17↓Z=1/50 Z� ≈ 0.0002
I Zwicky 18
Q(HeII)obs =1.3 · 1050 photons s−1
+ weak WR features
(Kehrig+15, Crowther+06 )
Photoionization
Legrand+07, Aloisi+09, Annibali+13, Kehrig+13, Lebouteiller+13
Photoionization in I Zw 18
He II photon number
5
5.5
6
6.5
7
4.3 4.4 4.5 4.6 4.7 4.8 4.9
log
(L/L
⊙)
log(Teff)
0
2e+48
4e+48
6e+48
8e+48
1e+49
1.2e+49
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Q(HeII)obs =
1.3 · 1050 photons s−
1
+ weak WR features
Photoio
nization
Z=1/50 Z� models fromSzécsi et al. 2015
+ Black body radiation
simulated stellar population ofI Zw 18:
Q(He II)sim=1.6·1050 photons s−1
TWUIN stars→ HeII flux of I Zw 18 �Transparent Wind Ultraviolet INtense
Cowther+06, Shirazi+12, Kehrig+15, Heap+15
Photoionization in I Zw 18
He II photon number
5
5.5
6
6.5
7
4.3 4.4 4.5 4.6 4.7 4.8 4.9
log
(L/L
⊙)
log(Teff)
0
2e+48
4e+48
6e+48
8e+48
1e+49
1.2e+49
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Q(HeII)obs =
1.3 · 1050 photons s−
1
+ weak WR features
Photoio
nization
Z=1/50 Z� models fromSzécsi et al. 2015
+ Black body radiation
simulated stellar population ofI Zw 18:
Q(He II)sim=1.6·1050 photons s−1
TWUIN stars→ HeII flux of I Zw 18 �Transparent Wind Ultraviolet INtense
Cowther+06, Shirazi+12, Kehrig+15, Heap+15
Photoionization in I Zw 18
He II photon number
5
5.5
6
6.5
7
4.3 4.4 4.5 4.6 4.7 4.8 4.9
log
(L/L
⊙)
log(Teff)
0
2e+48
4e+48
6e+48
8e+48
1e+49
1.2e+49
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Q(HeII)obs =
1.3 · 1050 photons s−
1
+ weak WR features
Photoio
nization
Z=1/50 Z� models fromSzécsi et al. 2015
+ Black body radiation
simulated stellar population ofI Zw 18:
Q(He II)sim=1.6·1050 photons s−1
TWUIN stars→ HeII flux of I Zw 18 �Transparent Wind Ultraviolet INtense
Cowther+06, Shirazi+12, Kehrig+15, Heap+15
Photoionization in I Zw 18
He II photon number
5
5.5
6
6.5
7
4.3 4.4 4.5 4.6 4.7 4.8 4.9
log
(L/L
⊙)
log(Teff)
0
2e+48
4e+48
6e+48
8e+48
1e+49
1.2e+49
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Q(HeII)obs =
1.3 · 1050 photons s−
1
+ weak WR features
Photoio
nization
Z=1/50 Z� models fromSzécsi et al. 2015
+ Black body radiation
simulated stellar population ofI Zw 18:
Q(He II)sim=1.6·1050 photons s−1
TWUIN stars→ HeII flux of I Zw 18 �Transparent Wind Ultraviolet INtense
Cowther+06, Shirazi+12, Kehrig+15, Heap+15
Photoionization in I Zw 18
He II photon number
5
5.5
6
6.5
7
4.3 4.4 4.5 4.6 4.7 4.8 4.9
log
(L/L
⊙)
log(Teff)
0
2e+48
4e+48
6e+48
8e+48
1e+49
1.2e+49
39 M⊙
77 M⊙
150 M⊙
294 M⊙
Q(HeII)obs =
1.3 · 1050 photons s−
1
+ weak WR features
Photoio
nization
Z=1/50 Z� models fromSzécsi et al. 2015
+ Black body radiation
simulated stellar population ofI Zw 18:
Q(He II)sim=1.6·1050 photons s−1
TWUIN stars→ HeII flux of I Zw 18 �Transparent Wind Ultraviolet INtense
Cowther+06, Shirazi+12, Kehrig+15, Heap+15
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64
Takeaway message
lGRBs(Levesque’10, Niino’11 )
Death of Massive Stars
He II photons(Shirazi+12, Kehrig+15 )
Life of Massive Stars
Hot stars with weak winds
Explanation
Chemically Homogeneous Evolution
Theory
TransparentWind UVINtense(TWUIN) stars
!
Thank you
for your
attention!
A&A: Szécsi et al. 2015
[arXiv:1506.09132]
?
Poster: FM 7 p. 64