Radio observations of candidate magnetic O stars
Context: 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.Aims: Non-thermal radio emission in th...
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| Format: | Journal Article |
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EDP Sciences
2007
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| Online Access: | http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...470.1105SFUL http://hdl.handle.net/20.500.11937/24456 |
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| author | Schnerr, R. Rygl, K. van der Horst, A. Oosterloo, T. Miller-Jones, James Henrichs, H. Spoelstra, T. Foley, A. |
| author_facet | Schnerr, R. Rygl, K. van der Horst, A. Oosterloo, T. Miller-Jones, James Henrichs, H. Spoelstra, T. Foley, A. |
| author_sort | Schnerr, R. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Context: 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.Aims: 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.Methods: We have performed 6 and 21 cm observations using the WSRT and use these, in combination with archival VLA data at 3.6 cm and results from the literature, to study the radio emission of 5 selected candidate magnetic O stars.Results: Out of our five targets, we have detected three: ? Per, which shows a non-thermal radio spectrum, and a Cam and ? 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 Ha line are overestimated because of clumping in the inner part of the stellar wind. |
| first_indexed | 2025-11-14T07:52:40Z |
| format | Journal Article |
| id | curtin-20.500.11937-24456 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:52:40Z |
| publishDate | 2007 |
| publisher | EDP Sciences |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-244562017-02-28T01:47:57Z Radio observations of candidate magnetic O stars Schnerr, R. Rygl, K. van der Horst, A. Oosterloo, T. Miller-Jones, James Henrichs, H. Spoelstra, T. Foley, A. radiation mechanisms: non-thermal stars: general stars: mass-loss stars: magnetic fields radio continuum: stars stars: early-type Context: 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.Aims: 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.Methods: We have performed 6 and 21 cm observations using the WSRT and use these, in combination with archival VLA data at 3.6 cm and results from the literature, to study the radio emission of 5 selected candidate magnetic O stars.Results: Out of our five targets, we have detected three: ? Per, which shows a non-thermal radio spectrum, and a Cam and ? 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 Ha line are overestimated because of clumping in the inner part of the stellar wind. 2007 Journal Article http://hdl.handle.net/20.500.11937/24456 http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...470.1105SFUL EDP Sciences restricted |
| spellingShingle | radiation mechanisms: non-thermal stars: general stars: mass-loss stars: magnetic fields radio continuum: stars stars: early-type Schnerr, R. Rygl, K. van der Horst, A. Oosterloo, T. Miller-Jones, James Henrichs, H. Spoelstra, T. Foley, A. Radio observations of candidate magnetic O stars |
| title | Radio observations of candidate magnetic O stars |
| title_full | Radio observations of candidate magnetic O stars |
| title_fullStr | Radio observations of candidate magnetic O stars |
| title_full_unstemmed | Radio observations of candidate magnetic O stars |
| title_short | Radio observations of candidate magnetic O stars |
| title_sort | radio observations of candidate magnetic o stars |
| topic | radiation mechanisms: non-thermal stars: general stars: mass-loss stars: magnetic fields radio continuum: stars stars: early-type |
| url | http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...470.1105SFUL http://hdl.handle.net/20.500.11937/24456 |