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Numrering	Referens	Omslagsbild	Hitta
1.	Saha, Anindya, et al. (författare) Search for particle acceleration in two massive Wolf-Rayet stars using uGMRT observations 2023 Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 526:1, s. 750-757 Tidskriftsartikel (refereegranskat)abstract Large wind kinetic power of Wolf-Rayet (WR) stars make them ideal targets in low radio frequencies to search for non-thermal emission due to relativistic particle acceleration. In this paper, we present observations of two WR stars, WR 114 and WR 142, in Band 4 (550-950 MHz) and Band 5 (1050-1450 MHz) using the upgraded Giant Meterwave Radio Telescope. Neither star is detected in the observed frequency bands, nor extended emission associated with them. The upper limit to the free-free radio emission from the stellar wind enables us to constrain the mass-loss rate of WR 114 to; this is a factor three smaller than previously estimated using spectroscopic modelling. If we further assume that the WR stars are binaries, the non-detection of synchrotron emission from the putative wind collision region implies that the stars are either in very wide binary systems away from periastron, or that the stars are in close binary systems with an orbital separation <70 AU for WR 114 and <20 AU for WR 142. The non-detection of low-frequency radio emission from these two systems thus provides evidence that narrows their nature, though it does not rule them out as bona fide particle-accelerating colliding-wind binaries.

Saha, Anindya, et al. (författare)
Search for particle acceleration in two massive Wolf-Rayet stars using uGMRT observations
2023
Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 526:1, s. 750-757
Tidskriftsartikel (refereegranskat)abstract
- Large wind kinetic power of Wolf-Rayet (WR) stars make them ideal targets in low radio frequencies to search for non-thermal emission due to relativistic particle acceleration. In this paper, we present observations of two WR stars, WR 114 and WR 142, in Band 4 (550-950 MHz) and Band 5 (1050-1450 MHz) using the upgraded Giant Meterwave Radio Telescope. Neither star is detected in the observed frequency bands, nor extended emission associated with them. The upper limit to the free-free radio emission from the stellar wind enables us to constrain the mass-loss rate of WR 114 to; this is a factor three smaller than previously estimated using spectroscopic modelling. If we further assume that the WR stars are binaries, the non-detection of synchrotron emission from the putative wind collision region implies that the stars are either in very wide binary systems away from periastron, or that the stars are in close binary systems with an orbital separation <70 AU for WR 114 and <20 AU for WR 142. The non-detection of low-frequency radio emission from these two systems thus provides evidence that narrows their nature, though it does not rule them out as bona fide particle-accelerating colliding-wind binaries.

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