Megahertz emission of massive early-type stars in the Cygnus region

Massive, early-type stars have been detected as radio sources for many decades. Their thermal winds radiate free–free continuum and in binary systems hosting a colliding-wind region, non-thermal emission has also been detected. To date, the most abundant data have been collected from frequencies hig...

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Detalles Bibliográficos
Autores principales: Benaglia, Paula, De Becker, M., Ishwara-Chandra, C. H., Intema, Huib, Isequilla, Natacha Laura
Formato: Articulo Preprint
Lenguaje:Inglés
Publicado: 2020
Materias:
Astronomía
radio continuum: stars
radiation mechanisms: non-thermal
stellar associations: individual: Cyg OB2
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/132353
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-132353
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Astronomía
radio continuum: stars
radiation mechanisms: non-thermal
stellar associations: individual: Cyg OB2
spellingShingle Astronomía
radio continuum: stars
radiation mechanisms: non-thermal
stellar associations: individual: Cyg OB2
Benaglia, Paula
De Becker, M.
Ishwara-Chandra, C. H.
Intema, Huib
Isequilla, Natacha Laura
Megahertz emission of massive early-type stars in the Cygnus region
topic_facet Astronomía
radio continuum: stars
radiation mechanisms: non-thermal
stellar associations: individual: Cyg OB2
description Massive, early-type stars have been detected as radio sources for many decades. Their thermal winds radiate free–free continuum and in binary systems hosting a colliding-wind region, non-thermal emission has also been detected. To date, the most abundant data have been collected from frequencies higher than 1 GHz. We present here the results obtained from observations at 325 and 610 MHz, carried out with the Giant Metrewave Radio Telescope, of all known Wolf-Rayet and O-type stars encompassed in area of ∼15 sq degrees centred on the Cygnus region. We report on the detection of 11 massive stars, including both Wolf-Rayet and O-type systems. The measured flux densities at decimeter wavelengths allowed us to study the radio spectrum of the binary systems and to propose a consistent interpretation in terms of physical processes affecting the wide-band radio emission from these objects. WR 140 was detected at 610 MHz, but not at 325 MHz, very likely because of the strong impact of free–free absorption (FFA). We also report—for the first time—on the detection of a colliding-wind binary system down to 150 MHz, pertaining to the system of WR 146, making use of complementary information extracted from the Tata Institute of Fundamental Research GMRT Sky Survey. Its spectral energy distribution clearly shows the turnover at a frequency of about 600 MHz, that we interpret to be due to FFA. Finally, we report on the identification of two additional particle-accelerating colliding-wind binaries, namely Cyg OB2 12 and ALS 15108 AB.
format Articulo
Preprint
author Benaglia, Paula
De Becker, M.
Ishwara-Chandra, C. H.
Intema, Huib
Isequilla, Natacha Laura
author_facet Benaglia, Paula
De Becker, M.
Ishwara-Chandra, C. H.
Intema, Huib
Isequilla, Natacha Laura
author_sort Benaglia, Paula
title Megahertz emission of massive early-type stars in the Cygnus region
title_short Megahertz emission of massive early-type stars in the Cygnus region
title_full Megahertz emission of massive early-type stars in the Cygnus region
title_fullStr Megahertz emission of massive early-type stars in the Cygnus region
title_full_unstemmed Megahertz emission of massive early-type stars in the Cygnus region
title_sort megahertz emission of massive early-type stars in the cygnus region
publishDate 2020
url http://sedici.unlp.edu.ar/handle/10915/132353
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