Consistent simulations of substellar atmospheres and nonequilibrium dust cloud formation

Christiane Helling, Matthias Dehn, Peter Woitke, Peter H. Hauschildt

Research output: Contribution to journalArticlepeer-review

101 Citations (Scopus)

Abstract

We aim to understand cloud formation in substellar objects. We combined our nonequilibrium, stationary cloud model DRIFT ( seed formation, growth, evaporation, gravitational settling, element conservation) with the general-purpose model atmosphere code PHOENIX (radiative transfer, hydrostatic equilibrium, mixing-length theory, chemical equilibrium) in order to consistently calculate cloud formation and radiative transfer with their feedback on convection and gas-phase depletion. We calculate the complete 1D model atmosphere structure and the chemical details of the cloud layers. The DRIFT-PHOENIX models enable the first stellar atmosphere simulation that is based on the actual cloud formation process. The resulting (T, P)-profiles differ considerably from the previous limiting PHOENIX cases DUSTY and COND. A tentative comparison with observations demonstrates that the determination of effective temperatures based on simple cloud models has to be applied with care. Based on our new models, we suggest a mean T-eff = 1800 K for the L dwarf twin-binary system DENIS J0205-1159, which is up to 500 K hotter than suggested in the literature. We show transition spectra for gas-giant planets which form dust clouds in their atmospheres and evaluate photometric fluxes for a WASP-1 type system.

Original languageEnglish
Pages (from-to)L105-L108
Number of pages4
JournalAstrophysical Journal Letters
Volume675
Issue number2
DOIs
Publication statusPublished - 10 Mar 2008

Keywords

  • astrochemistry
  • methods : numerical
  • stars : atmospheres
  • LATE M-DWARFS
  • EXTRASOLAR PLANET
  • BROWN DWARFS
  • SECONDARY ECLIPSE
  • PHOTOSPHERIC ENVIRONMENT
  • ULTRACOOL DWARFS
  • PHOTOMETRY
  • JUPITER
  • SPECTRA
  • GRAINS

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