Metallicity dependence of winds from red supergiants and asymptotic giant branch stars
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Metallicity Dependence of Winds from Red SuperGiants and Asymptotic Giant Branch Stars. Jacco van Loon Keele University. Jacco van Loon Keele University. Dust wind structure. Radiative equilibrium + continuity equation:. Spectral Energy Distribution. Spectral Energy Distribution.

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Metallicity dependence of winds from red supergiants and asymptotic giant branch stars

Metallicity Dependence of Winds from Red SuperGiants and Asymptotic Giant Branch Stars


Jacco van loon keele university
Jacco van LoonKeele University


Jacco van loon keele university1
Jacco van LoonKeele University


Dust wind structure
Dust wind structure

Radiative equilibrium + continuity equation:



Spectral energy distribution1
Spectral Energy Distribution

  • Integral luminosity


Spectral energy distribution2
Spectral Energy Distribution

  • Integral luminosity

  • Shape optical depth


Spectral energy distribution3
Spectral Energy Distribution

  • Integral luminosity

  • Shape optical depth

… but measuring mass-loss rate requires:

  • Dust-to-gas ratio


Spectral energy distribution4
Spectral Energy Distribution

  • Integral luminosity

  • Shape optical depth

… but measuring mass-loss rate requires:

  • Dust-to-gas ratio

  • Wind speed


Dust wind structure1
Dust wind structure

Momentum equation:

Gail & Sedlmayr (1986)





Wind speed from OH masers

Wood et al. (1992)




Wind speed1
Wind speed

For oxygen-rich stars


Lmc versus the milky way
LMC versus the Milky Way

Van Loon (2000)



Mass loss rate1
Mass-loss rate

For oxygen-rich stars



Superwind mass loss rates
Superwind mass-loss rates

Conversion of radiative momentum:


Superwind mass loss rates1
Superwind mass-loss rates

Conversion of radiative momentum:

Multiplescattering:

Gail & Sedlmayr (1986)


Superwind mass loss rates2
Superwind mass-loss rates

Multiple scattering limit predicts:


Superwind mass loss rates3
Superwind mass-loss rates

Multiple scattering limit predicts:


Lmc versus galactic bulge
LMC versus galactic bulge

Alard et al. (2001)


Temperature and evolution
Temperature and evolution

Galactic bulge observations:

Alard et al. (2001)


Temperature and evolution1
Temperature and evolution

Galactic bulge observations:

Alard et al. (2001)

Hydrodynamic models (carbon stars):

Arndt, Fleischer & Sedlmayr (1997)

Wachter et al. (2002)


Superwind stars in the lmc
Superwind stars in the LMC

Cluster superwind carbon star LI-LMC 1813:

luminosity, metallicity (20-25% solar), mass

Van Loon et al. (2003)


Superwind stars in the lmc1
Superwind stars in the LMC

Cluster superwind carbon star LI-LMC 1813:

luminosity, metallicity (20-25% solar), mass

Van Loon et al. (2003)

Compare with solar metallicity model:

Wachter et al. (2002)


Superwind stars in the lmc2
Superwind stars in the LMC

Van Loon et al. (2005)


Superwind stars in the lmc3
Superwind stars in the LMC

For oxygen-rich stars


LMC prediction applied to Milky Way

Van Loon et al. (2005)





Mass loss rate2
Mass-loss rate

For oxygen-rich and carbon stars




Z independent mass loss rate1
Z-independent mass-loss rate?

(above ~0.1 solar metallicity)


Z independent mass loss rate2
Z-independent mass-loss rate?

(above ~0.1 solar metallicity)

WHY ?


Pulsation in lmc superwind stars
Pulsation in LMC superwind stars

Whitelock et al. (2003)


Pulsational energy
Pulsational energy

Absolute maximum = 0.5


Pulsation during the superwind
Pulsation during the superwind

Similar limit for Milky Way, LMC, SMC


Pulsation during the superwind1
Pulsation during the superwind

Similar limit for Milky Way, LMC, SMC


Pulsation during the superwind2
Pulsation during the superwind

Similar limit for Milky Way, LMC, SMC

Hence similar (maximum) mass-loss rates?


Molecule formation
Molecule formation

Van Loon et al. (1998)


Molecule formation1
Molecule formation

  • LMC: AGB up to M10; RSG up to M7


Molecule formation2
Molecule formation

  • LMC: AGB up to M10; RSG up to M7

  • SMC: AGB up to M8; RSG up to M5

Groenewegen & Blommaert (1998)




Magellanic carbon stars1
Magellanic carbon stars

Van Loon, Zijlstra & Groenewegen (1999)

Matsuura et al. (2002, 2005)


Magellanic carbon stars2
Magellanic carbon stars

Large(r?) molecular abundances at low Z


Magellanic carbon stars3
Magellanic carbon stars

Large(r?) molecular abundances at low Z

Especially C2 and C2H2 (not CN and HCN)


Magellanic carbon stars4
Magellanic carbon stars

Large(r?) molecular abundances at low Z

Especially C2 and C2H2 (not CN and HCN)

Due to lower O (and N) abundances


Metal poor carbon star winds
Metal-poor carbon star winds

What if in metal-poor carbon stars...


Metal poor carbon star winds1
Metal-poor carbon star winds

What if in metal-poor carbon stars...

… the dust-to-gas ratio were higher...


Metal poor carbon star winds2
Metal-poor carbon star winds

What if in metal-poor carbon stars...

… the dust-to-gas ratio were higher...

… their winds would be faster...


Metal poor carbon star winds3
Metal-poor carbon star winds

What if in metal-poor carbon stars...

… the dust-to-gas ratio were higher...

… their winds would be faster...

… but their mass-loss rates the same (?)



Molecules in magellanic winds
Molecules in magellanic winds

Spitzer GO programme 3505 (Peter Wood)


Co in magellanic winds
CO in magellanic winds

  • measure dust-to-CO ratio

  • measure carbon star wind speed


Conclusions to be continued
Conclusions (to be continued)

above ~0.1 solar metallicity:


Conclusions to be continued1
Conclusions (to be continued)

above ~0.1 solar metallicity:

  • mass-loss rates independent of Z


Conclusions to be continued2
Conclusions (to be continued)

above ~0.1 solar metallicity:

  • mass-loss rates independent of Z

  • metal-poor O-rich stars are less dusty


Conclusions to be continued3
Conclusions (to be continued)

above ~0.1 solar metallicity:

  • mass-loss rates independent of Z

  • metal-poor O-rich stars are less dusty

  • slower winds of metal-poor O-rich stars


Conclusions to be continued4
Conclusions (to be continued)

above ~0.1 solar metallicity:

  • mass-loss rates independent of Z

  • metal-poor O-rich stars are less dusty

  • slower winds of metal-poor O-rich stars

  • … smaller momentum injection rate


Conclusions to be continued5
Conclusions (to be continued)

above ~0.1 solar metallicity:

  • mass-loss rates independent of Z

  • metal-poor O-rich stars are less dusty

  • slower winds of metal-poor O-rich stars

  • … smaller momentum injection rate

  • are metal-poor carbon stars less dusty?


Conclusions to be continued6
Conclusions (to be continued)

above ~0.1 solar metallicity:

  • mass-loss rates independent of Z

  • metal-poor O-rich stars are less dusty

  • slower winds of metal-poor O-rich stars

  • … smaller momentum injection rate

  • are metal-poor carbon stars less dusty?

  • wind speed of metal-poor carbon stars: ?


Conclusions to be continued7
Conclusions (to be continued)

above ~0.1 solar metallicity:

  • mass-loss rates independent of Z

  • metal-poor O-rich stars are less dusty

  • slower winds of metal-poor O-rich stars

  • … smaller momentum injection rate

  • are metal-poor carbon stars less dusty?

  • wind speed of metal-poor carbon stars: ?

Below ~0.1 solar metallicity: ?


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