منابع مشابه
Radio observations of candidate magnetic O stars
A number of O stars are suspected to have (weak) magnetic fields because of the observed cyclical variability in their UV wind-lines. However, direct detections of these magnetic fields with optical spectropolarimetry have proven to be very difficult. We have searched for non-thermal radio emission, which would be a strong indication for the presence of a magnetic field. Of our 5 selected candi...
متن کاملRadio observations of stellar winds from early type stars
FifteenO andB supergiants have been observedwith the Very Large Array (VLA) at 4.85, 8.45, and 14.95 GHz in order to make a detailed comparative study of the mass loss rates evaluated from Hα and radio continuum observations and reveal and quantify possible departures from standardwind conditions. We detected 12 sources, 7 of which for the first time, thus increasing by 30% the total number of ...
متن کاملNon-thermal radio emission from O-type stars
HD 167971 is a triple system consisting of a 3.3-day eclipsing binary (O5–8 V + O5–8 V) and an O8 supergiant. It is also a well known non-thermal radio emitter. We observed the radio emission of HD 167971 with the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA). By combining these data with VLA archive observations we constructed a radio lightcurve covering a 20-yr time-...
متن کاملObservations of convection in A-type stars
Convection and turbulence in stellar atmospheres have a significant effect on the emergent flux from A-type stars. The recent theoretical advancements in convection modelling have proved a challenge to the observers to obtain measurements with sufficient precision and accuracy to allow discrimination between the various predictions. A discussion of the current observational techniques used to e...
متن کاملSpectroscopic observations of D - type symbiotic stars ? , ? ?
Observations of five D-type symbiotics are presented: three oxygen Mira (He2-38, H2-38 and H1-36) and two carbon Mira symbiotics (AS 210 and SS 38). The observations in the spectral range between 3200Å and 7400Å show the presence of several emission lines in various states of excitation. A line list is provided with their suggested identifications. Several parameters were derived for each objec...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 1981
ISSN: 0252-9211
DOI: 10.1017/s0252921100094781