Bibcode
Aldoretta, E. J.; St-Louis, N.; Richardson, N. D.; Moffat, A. F. J.; Eversberg, T.; Hill, G. M.; Shenar, T.; Artigau, É.; Gauza, B.; Knapen, J. H.; Kubát, J.; Kubátová, B.; Maltais-Tariant, R.; Muñoz, M.; Pablo, H.; Ramiaramanantsoa, T.; Richard-Laferrière, A.; Sablowski, D. P.; Simón-Díaz, S.; St-Jean, L.; Bolduan, F.; Dias, F. M.; Dubreuil, P.; Fuchs, D.; Garrel, T.; Grutzeck, G.; Hunger, T.; Küsters, D.; Langenbrink, M.; Leadbeater, R.; Li, D.; Lopez, A.; Mauclaire, B.; Moldenhawer, T.; Potter, M.; dos Santos, E. M.; Schanne, L.; Schmidt, J.; Sieske, H.; Strachan, J.; Stinner, E.; Stinner, P.; Stober, B.; Strandbaek, K.; Syder, T.; Verilhac, D.; Waldschläger, U.; Weiss, D.; Wendt, A.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 460, Issue 3, p.3407-3417
Advertised on:
8
2016
Citations
15
Refereed citations
14
Description
During the summer of 2013, a 4-month spectroscopic campaign took place
to observe the variabilities in three Wolf-Rayet stars. The
spectroscopic data have been analysed for WR 134 (WN6b), to better
understand its behaviour and long-term periodicity, which we interpret
as arising from corotating interaction regions (CIRs) in the wind. By
analysing the variability of the He II λ5411 emission line, the
previously identified period was refined to P = 2.255 ± 0.008
(s.d.) d. The coherency time of the variability, which we associate with
the lifetime of the CIRs in the wind, was deduced to be 40 ± 6 d,
or ˜18 cycles, by cross-correlating the variability patterns as a
function of time. When comparing the phased observational grey-scale
difference images with theoretical grey-scales previously calculated
from models including CIRs in an optically thin stellar wind, we find
that two CIRs were likely present. A separation in longitude of
Δφ ≃ 90° was determined between the two CIRs and we
suggest that the different maximum velocities that they reach indicate
that they emerge from different latitudes. We have also been able to
detect observational signatures of the CIRs in other spectral lines (C
IV λλ5802,5812 and He I λ5876). Furthermore, a DAC
was found to be present simultaneously with the CIR signatures detected
in the He I λ5876 emission line which is consistent with the
proposed geometry of the large-scale structures in the wind. Small-scale
structures also show a presence in the wind, simultaneously with the
larger scale structures, showing that they do in fact co-exist.