Deriving the geometry of Be star circumstellar envelopes from continuum spectropolarimetry : The case of zeta Tauri

Kenneth Wood, KS Bjorkman, JE Bjorkman

Research output: Contribution to journalArticlepeer-review

82 Citations (Scopus)

Abstract

We present a general scheme for determining the circumstellar geometry of Be stars from modeling of optical continuum spectropolarimetry. Our modeling scheme utilizes a Monte Carlo radiation transfer code that determines the polarization due to multiple photon scattering, including the effects of continuous hydrogen absorption and emission from a disklike circumstellar envelope. We show that by matching the polarization level on either side of the Balmer jump, one can determine the opening angle of the disk. In general, there are only two solutions, either a geometrically thin or a geometrically thick. disk.

Applying our analysis techniques to observations of the Be star zeta Tauri, we find that the two solutions for the disk have half-opening angles of either 2 degrees.5 or 52 degrees. The geometricaly thick disk can be excluded based on recent interferometric imaging of Be star disks, including zeta Tau. The thin disk solution is consistent with either a Keplerian or a wind-compressed dish; both models predict small disk opening angles at small radii. In addition to matching the continuum polarization, our thin disk model reproduces the continuum spectral energy distribution from the UV through IRAS wavelengths, providing convincing evidence that Be circumstellar disks are geometrically thin.

Original languageEnglish
Pages (from-to)926-939
Number of pages14
JournalAstrophysical Journal
Volume477
Publication statusPublished - 10 Mar 1997

Keywords

  • circumstellar matter
  • polarization
  • radiative transfer
  • stars, emission-line, Be
  • stars, individual (xi Tauri)
  • PHOTO-POLARIMETER EXPERIMENT
  • MASS-LOSS RATES
  • LINEAR-POLARIZATION
  • STELLAR ENVELOPES
  • IRAS OBSERVATIONS
  • B-STARS
  • DISKS
  • WINDS
  • CONSTRAINTS

Fingerprint

Dive into the research topics of 'Deriving the geometry of Be star circumstellar envelopes from continuum spectropolarimetry : The case of zeta Tauri'. Together they form a unique fingerprint.

Cite this