A self-consistent determination of the temperature profile and the magnetic field geometry in winds of late-type stars

Aline De Almeida Vidotto, D. Falceta-Goncalves, V. Jatenco-Pereira

Research output: Contribution to journalArticlepeer-review

Abstract

Cool giant and supergiant stars generally present low velocity winds with high mass-loss rates. Several models have been proposed to explain the acceleration process of these winds. Although dust is known to be present in these objects, the radiation pressure on these particles is uneffective in reproducing the observed physical parameters of the wind. The most promising acceleration mechanism cited in the literature is the transference of momentum and energy from Alfven waves to the gas. Usually, these models consider the wind to be isothermal. We present a stellar wind model in which the Alfven waves are used as the main acceleration mechanism, and determine the temperature profile by solving the energy equation taking into account both the radiative losses and the wave heating. We also determine, self-consistently, the magnetic field geometry as the result of the competition between the magnetic field and the thermal pressure gradient. As the main result, we show that the magnetic geometry presents a super-radial index in the region where the gas pressure is increasing. However, this super-radial index is greater than that observed for the solar corona.

Original languageEnglish
Pages (from-to)181-188
Number of pages8
JournalSpace Science Reviews
Volume122
Issue number1-4
DOIs
Publication statusPublished - Feb 2006
Event2nd World Space Environment Forum (WSEF 2005) - Schloss Seggau, Austria
Duration: 2 May 20056 May 2005

Keywords

  • stars : mass loss
  • stars : magnetic fields
  • MHD
  • waves
  • COOL STARS
  • FLUX TUBE
  • MASS-LOSS
  • SOLAR
  • ENERGY
  • MODEL

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