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Effect of Radiative Levitation on Calculations of Accretion Rates in White Dwarfs

Effect of Radiative Levitation on Calculations of Accretion Rates in White Dwarfs. Gemini Observatory Illustration by Jon Lomberg. Pierre Chayer 1 and Jean Dupuis 2 1 STScI, 2 CSA 17 th European White Dwarf Workshop Tübingen, Germany August 16−20, 2010.

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Effect of Radiative Levitation on Calculations of Accretion Rates in White Dwarfs

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  1. Effect of Radiative Levitation on Calculations of Accretion Rates in White Dwarfs Gemini Observatory Illustration by Jon Lomberg Pierre Chayer1 and Jean Dupuis2 1STScI, 2CSA 17th European White Dwarf Workshop Tübingen, Germany August 16−20, 2010

  2. Two methods exist for computing accretion rates • Steady state approximation • Time-dependent diffusion calculations

  3. Silicon and aluminum are supported Teff = 20,000 K, log g = 8.0 Radiative acceleration as a function of depth

  4. Silicon is supported in DA with Teff < 17,500 K Log g = 8.0 Radiative acceleration as a function of depth for Si

  5. Evolution of Si in a DA in presence of accretion but without radiative levitation Log [dM/dt]Si = 102 g/s, Teff = 20,000 K, log g = 8.0

  6. Evolution of Si in a DA in presence of accretion and radiative levitation Log [dM/dt]si = 102 g/s, Teff = 20,000 K, log g = 8.0

  7. Evolution of Si in a DA in presence of accretion and radiative levitation Log [dM/dt]si = 106 g/s, Teff = 20,000 K, log g = 8.0

  8. The radiative levitation has an impact on the determination of accretion rates Teff = 20,000 K Log g = 8.0 Silicon abundance as a function of depth

  9. In summary, the abundance of elements supported by the radiative levitation may not be related to the accretion rate Log g = 8.0 25,000 K 22,500 K 20,000 K 17,500 K

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