Multi-epoch Very Long Baseline Array Observations of the Compact Wind-collision Region in the Quadruple System Cyg OB2 #5

Authors
Dzib, Sergio A.; Rodríguez, Luiis Felipe; Loinard, laurent; Mioduszewski, Amy J.; Ortiz Leon, Gisela N.; Araudo, Anabella Teresa
Publication Year
2013
Language
English
Format
article
Status
Published version
Description
We present multi-epoch Very Long Base Array observations of the compact wind-collision region in the Cyg OB2 #5 system. These observations confirm the arc-shaped morphology of the emission reported earlier. The total flux as a function of time is roughly constant when the source is "on," but falls below the detection limit as the wind-collision region approaches periastron in its orbit around the contact binary at the center of the system. In addition, at one of the "on" epochs, the flux drops to about a fifth of its average value. We suggest that this apparent variation could result from the inhomogeneity of the wind that hides part of the flux rather than from an intrinsic variation. We measured a trigonometrical parallax, for the most compact radio emission of 0.61 ± 0.22 mas, corresponding to a distance of 1.65 +0.96 –0.44 kpc, in agreement with recent trigonometrical parallaxes measured for objects in the Cygnus X complex. Using constraints on the total mass of the system and orbital parameters previously reported in the literature, we obtain two independent indirect measurements of the distance to the Cyg OB2 #5 system, both consistent with 1.3-1.4 kpc. Finally, we suggest that the companion star responsible for the wind interaction, yet undetected, is of spectral type between B0.5 and O8.
Fil: Dzib, Sergio A.. Universidad Nacional Autonoma de Mexico. Centro de Radiostronomía y Astrofísica; México
Fil: Rodríguez, Luiis Felipe. Universidad Nacional Autonoma de Mexico. Centro de Radiostronomía y Astrofísica; México. King Abdulaziz University. Astronomy Department, Faculty of Science; Arabia Saudita
Fil: Loinard, laurent. Universidad Nacional Autonoma de Mexico. Centro de Radiostronomía y Astrofísica; México. Max-Planck-Institut fur Radioastronomie; Alemania
Fil: Mioduszewski, Amy J. . National Radio Astronomy Observatory; Estados Unidos
Fil: Ortiz Leon, Gisela N.. Universidad Nacional Autonoma de Mexico. Centro de Radiostronomía y Astrofísica; México
Fil: Araudo, Anabella Teresa. Universidad Nacional Autonoma de Mexico. Centro de Radiostronomía y Astrofísica; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto Argentino de Radioastronomia (i); Argentina
Subject
Astrometry
Non-thermal mechanisms
Cyg OB2 #5
Winds
outflows
Radiation mechanisms
Stars
Astronomía
Ciencias Físicas
CIENCIAS NATURALES Y EXACTAS
Access level
Restricted access
License
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repository
CONICET Digital (CONICET)
Institution
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identifier
oai:ri.conicet.gov.ar:11336/5841