Astron. Astrophys. 344, 282-288 (1999)

Computing radiative equilibria with Monte Carlo techniques

L.B. Lucy

Space Telescope - European Coordinating Facility, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany

Received 7 September 1998 / Accepted 9 December 1998

Abstract

Monte Carlo techniques are used iteratively to compute the radiative equilibrium temperature stratification of a non-grey, spherically-extended stellar atmosphere in LTE. The derived temperature distribution agrees well with that predicted by Castor's (1974) code, as also does the emergent spectrum. However, in contrast to such conventional codes, the adopted Monte Carlo techniques and associated temperature-correction procedure are in no way restricted to 1-D stratifications. Accordingly, this successful test indicates that realistic 2- and 3-D radiative equilibria can be similarly computed.

Key words: radiative transfer methods: numerical stars: atmospheres

Present address: Astrophysics Group, Blackett Laboratory, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BZ, UK

Send offprint requests to: L.B. Lucy

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Contents

• 1. Introduction
• 2. Test problems
• 3. Monte Carlo procedures
  • 3.1. Energy packets and radiative equilibrium
  • 3.2. Initiation
  • 3.3. Trajectories
  • 3.4. Monte Carlo estimators
  • 3.5. Temperature corrections
• 4. Numerical results
  • 4.1. Parameters
  • 4.2. Temperature corrections
  • 4.3. Grey atmospheres
  • 4.4. Emergent spectrum
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: March 10, 1999
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