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| Paper: |
The Circumstellar Environment of Rigel Probed at High Spatial and Spectral Resolution |
| Volume: |
464, Circumstellar Dynamics at High Resolution |
| Page: |
35 |
| Authors: |
Kaufer, A.; Chesneau, O.; Stahl, O.; Colvinter, C.; Spang, A.; Dessart, L.; Prinja, R.; Kaufer, a. R. C.; Chesneau, A.; Stahl, O.; Colvinter, O.; Spang, C.; Dessart, A.; Prinja, L.; Chini, R.; R. |
| Abstract: |
The presence of highly structured circumstellar environments in late B- and
early A-type supergiants is well established through extensive spectroscopic,
photometric, and polarimetric time series observations. The circumstellar
structures are located within a few stellar radii in the transition zone from
the stellar photosphere to the inner wind region of the expanding envelopes of
the stars. The physical mechanisms that generate the observed circumstellar
structures remain subject of debate. Coupling of stellar surface structures
into the inner wind regions combined with rotational modulation is generally
favoured with the surface structure being results of multi-mode non-radial
pulsation patterns or complex magnetic fields structures. However, little
observational evidence is available to narrow down the underlying mechanisms.
Optical and near-IR interferometry at high spectral resolution has high
potential to shed new light on the circumstellar environments of massive
supergiants. We present first results from spectro-interferometric studies of
the prototypical late-B supergiant Rigel (β Orionis, B8 Ia). Rigel has
for the first time been monitored over several rotational cycles with the AMBER 3-beam combiner instrument at the VLTI in 2006–2007 and
2009–2010. The observations targeted the photosphere- and wind-sensitive
Brγ line at a resolving power of R=12 000. The analysis of the
measured interferometric visibilities provides constraints on the extension of
the line-forming region in photosphere and wind; the observed variability of
the differential phases across the line profile gives indications on the
dynamics and the geometry of the circumstellar structures of Rigel. A possible
link between high-velocity absorptions (HVA) and the observed S-shaped signals
in the differential phases is discussed. |
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