First detection of surface magnetic fields in Post-AGB stars : the cases of U Monocerotis and R Scuti
arXiv:1410.6224 · doi:10.1093/mnras/stu2227
Abstract
While several observational investigations have revealed the presence of magnetic fields in the circumstellar envelopes, jets and outflows of post-Asymptotic Giant Branch stars (PAGBs) and planetary nebulae (PNe), none has clearly demonstrated their presence at the stellar surface. The lack of information on the strength of the surface magnetic fields prevents us from performing any thorough assessment of their dynamic capability (i.e. material mixing, envelope shaping, etc). We present new high resolution spectropolarimetric (Stokes V ) observations of a sample of PAGB stars, realised with the instruments ESPaDOnS and Narval, where we searched for the presence of photospheric magnetic fields. Out of the seven targets investigated the RV Tauri stars U Mon and R Sct display a clear Zeeman signature and return a definite detection after performing a least squares deconvolution (LSD) analysis. The remaining five PAGBs show no significant detection. We derived longitudinal magnetic fields of 10.2 +/- 1.7 G for U Mon and 0.6 +/- 0.6 G for R Sct. In both cases the Stokes profiles point towards an interaction of the magnetic field with the atmosphere dynamics. This first discovery of weak magnetic fields (i.e. ~10 gauss level) at the stellar surface of PAGB stars opens the door to a better understanding of magnetism in evolved stars.
11 pages, 4 figures and 4 tables. Accepted for publication in MNRAS
References in corpus (11)
- Keplerian discs around post-AGB stars: a common phenomenon?
- Imaging the circumstellar envelopes of AGB stars
- A magnetically collimated jet from an evolved star
- Isolated vs. Common Envelope Dynamos in Planetary Nebula Progenitors
- An evolutionary catalogue of Galactic post-AGB and related objects
- Magnetic fields in planetary nebulae and post-AGB nebulae
- Weak magnetic fields in central stars of planetary nebulae?
- Post-AGB stars as testbeds of nucleosynthesis in AGB stars
- Kinematic structure of the atmosphere and envelope of the post-AGB star HD56126
- From the ashes: JVLA observations of water fountain nebula candidates show the rebirth of IRAS 18455+0448
- Magnetic Fields around (post-)AGB stars and (Pre-)Planetary Nebulae
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