Clark, J. S.; Fender, R. P.; Waters, L. B. F. M.; Dougherty, S. M.; Koornneef, J.; Steele, I. A. and van Blokland, A.
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|DOI (Digital Object Identifier) Link:||http://doi.org/10.1046/j.1365-8711.1998.02038.x|
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We present 10 ?m, ISO-SWS and Australia Telescope Compact Array observations of the region in the cluster Wd1 in Ara centred on the B[e] star Ara C. An ISOSWS spectrum reveals emission from highly ionised species in the vicinity of the star, suggesting a secondary source of excitation in the region.We find strong radio emission at both 3.5cm and 6.3cm, with a total spatial extent of over 20 arcsec. The emission is found to be concentrated in two discrete structures, separated by 14'. The westerly source is resolved, with a spectral index indicative of thermal emission. The easterly source is clearly extended and nonthermal (synchrotron) in nature. Positionally, the B[e] star is found to coincide with the more compact radio source, while the southerly lobe of the extended source is coincident with Ara A, an M2 I star. Observation of the region at 10?m reveals strong emission with an almost identical spatial distribution to the radio emission. Ara C is found to have an extreme radio luminosity in comparison to prior radio observations of hot stars such as O and B supergiants and Wolf-Rayet stars, given the estimated distance to the cluster. An origin in a detatched shell of material around the central star is therefore suggested; however given the spatial extent of the emission, such a shell must be relatively young (103yrs). The extended non thermal emission associated with the M star Ara A is unexpected; to the best of our knowledge this is a unique phenomenon. SAX (2-10keV) observations show no evidence of X-ray emission, which might be expected if a compact companion were present.
|Item Type:||Journal Article|
|Keywords:||stars; emission-line; Be stars; Ara C Individuals|
|Academic Unit/Department:||Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||Users 9108 not found.|
|Date Deposited:||16 Jul 2009 11:33|
|Last Modified:||06 Aug 2016 10:35|
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