Gisela N. Ortiz–León,1 Luis F. Rodríguez,1,2 and Mauricio Tapia3
1 Centro de Radiostronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 3–72, (Xangari), 58089 Morelia, Michoacán, México. (g.ortiz@crya.unam.mx, l.rodriguez@crya.unam.mx).
2 Astronomy Department, Faculty of Science, King Abdulaziz University, Saudi Arabia.
3 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, Ensenada, Baja California, CP 22830, México. (mt@astrosen.unam.mx).
Received 2011 January 11. ]]> Accepted 2011 November 28
RESUMEN
Cyg OB2 #5 es un sistema binario de contacto (O6.5–7+O5.5–6) con emisión de radio asociada. Dos fuentes compactas (<0."3.") de radiocontinuo han sido reportadas anteriormente: la primaria está asociada con la binaria de contacto y la secundaria es una fuente con forma de arco proyectada a ~0."8 al NE de la primaria. Esta fuente con forma de arco resulta de la interaction de los vientos de la binaria de contacto y de una estrella tipo B en la región. En este artículo reportamos la detección de una componente extendida (~30") y no–termica al NE de las componentes compactas. Proponemos que esta emision extendida podría ser una fuente de fondo (i.e. una radiogalaxia), emisión galactica extendida, o emisión no–termica relacionada con electrones relativistas que se producen en el choque entre la binaria de contacto y la estrella tipo B y que son arrastrados a grandes distancias por el viento de la binaria de contacto.
ABSTRACT
Cyg OB2 #5 is a contact binary system (O6.5–7+O5.5–6) with associated radio continuum emission. Two compact (<0."3) radio continuum components have been reported previously: the primary is associated with the contact binary and the secondary is an arc–like source ~0."8 to the NE of the primary. This arc–like source results from the interaction of the winds of the contact binary and a B–type star in the region. In this paper we report the detection of an extended (~30"), nonthermal component to the NE of the compact components. We propose that this extended emission could be an unresolved background source (i.e. a radio galaxy), extended galactic emission, or non–thermal emission related to the relativistic electrons that are produced in the shock between the contact binary and the B–type star and that are carried away to large distances by the wind from the contact binary.
Key Words: radio continuum: stars — stars: individual (Cyg OB2 #5).
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