2007/10/22 by A. C. Carciofi, A. M. Magalhães, N. V. Leister +3 · 3 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/524772
16 pages, 5 figures, Accepted to ApJ
arxiv created 2007/10/22 · openalex publication_date 2007/11/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present the results of a high-accuracy (σ ≈ 0.005%) polarization monitoring of the Be star Achernar that was carried out between 2006 July 7 and November 5. Our results indicate that after a near-quiescent phase from 1998 to 2002, Achernar is currently in an active phase and has built a circumstellar disk. We detect variations both in the polarization level and position angle on timescales as short as 1 hr and as long as several weeks. Detailed modeling of the observed polarization strongly suggests that the short-term variations originate from discrete mass ejection events which produce transient inhomogeneities in the inner disk. Long-term variations, on the other hand, can be explained by the formation of an inner ring following one or several mass ejection events.