Magnetic flares on asymptotic giant branch stars

Noam Soker*, Joel H. Kastner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

We investigate the consequences of magnetic flares on the surface of asymptotic giant branch (AGB) and similar stars. In contrast to the solar wind, in the winds of AGB stars the gas cooling time is much shorter than the outflow time. As a result, we predict that energetic flaring will not inhibit, and may even enhance, dust formation around AGB stars. If magnetic flares do occur around such stars, we expect some AGB stars to exhibit X-ray emission; indeed, certain systems including AGB stars, such as Mira, have been detected in X-rays. However, in these cases, it is difficult to distinguish between potential AGB star X-ray emission and, e.g., X-ray emission from the vicinity of a binary companion. Analysis of an archival ROSATX-ray spectrum of the Mira system suggests an intrinsic X-ray luminosity ∼2 × 1029 ergs s-1 and temperature ∼107 K. These modeling results suggest that magnetic activity, either on the AGB star (Mira A) or on its nearby companion (Mira B), is the source of the X-rays, but do not rule out the possibility that the X-rays are generated by an accretion disk around Mira B.

Original languageEnglish
Pages (from-to)498-503
Number of pages6
JournalAstrophysical Journal
Volume592
Issue number1 I
DOIs
StatePublished - 20 Jul 2003

Keywords

  • Stars: AGB and post-AGB
  • Stars: magnetic fields
  • Stars: mass loss stars: winds, outflows
  • X-rays: stars

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