2007A&A...470.1105S -
Astronomy and Astrophysics, volume 470, 1105-1109 (2007/8-2)
Radio observations of candidate magnetic O stars.
SCHNERR R.S., RYGL K.L.J., VAN DER HORST A.J., OOSTERLOO T.A., MILLER-JONES J.C.A., HENRICHS H.F., SPOELSTRA T.A.T. and FOLEY A.R.
Abstract (from CDS):
Some O stars are suspected to have to have (weak) magnetic fields because of the observed cyclical variability in their UV wind-lines. However, direct detections of these magnetic fields using optical spectropolarimetry have proven to be very difficult. Non-thermal radio emission in these objects would most likely be due to synchrotron radiation. As a magnetic field is required for the production of synchrotron radiation, this would be strong evidence for the presence of a magnetic field. Such non-thermal emission has already been observed from the strongly magnetic Ap/Bp stars. We have performed 6 and 21cm observations using the WSRT and use these, in combination with archival VLA data at 3.6cm and results from the literature, to study the radio emission of 5 selected candidate magnetic O stars. Out of our five targets, we have detected three: ξ Per, which shows a non-thermal radio spectrum, and α Cam and λ Cep, which show no evidence of a non-thermal spectrum. In general we find that the observed free-free (thermal) flux of the stellar wind is lower than expected. This is in agreement with recent findings that the mass-loss rates from O stars as derived from the Hα line are overestimated because of clumping in the inner part of the stellar wind.
Abstract Copyright:
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Journal keyword(s):
stars: magnetic fields - stars: early-type - stars: general - stars: mass-loss - radio continuum: stars - radiation mechanisms: non-thermal
CDS comments:
Table 1 association Lac OB1 not in Simbad.
Simbad objects:
18
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