Luis F. Rodríguez,1,2 Sergio A. Dzib,1 Laurent Loinard,1,3 Luis A. Zapata,1 Alejandro C. Raga,4 Jorge Cantó,5 and Angels Riera6
1 Centro de Radiostronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal, 3–72, Xangari, 58089 Morelia, Michoacán, México (s.dzib@crya.unam.mx, l.rodriguez@crya.unam.mx, l.zapata@crya.unam.mx).
2 Astronomy Department, Faculty of Science, King Abdulaziz University, Saudi Arabia.
3 Max–Planck–Institut fur Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany (l.loinard@crya.unam.mx).
4 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70–543, 04510, D. F., México (raga@nucleares.unam.mx).
5 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70–264, CP. 04510, D. F., México.
]]> 6 Departament de Física i Enginyeria Nuclear, EUETIB, Universitat Politècnica de Catalunya, Compte d'Urgell 187, 08036 Barcelona, Spain (angels.riera@upc.edu).
Received 2012 May 7.
Accepted 2012 June 25.
RESUMEN
DG Tau B es un objeto estelar joven de Clase I que produce el chorro bipolar asimétrico HH 159. En longitudes de onda visibles está oscurecido por material circunestelar ópticamente grueso. Usando observaciones del VLA y el JVLA determinamos por primera vez los movimientos propios de esta fuente y los encontramos consistentes, dentro del error, con los de la estrella cercana DG Tau. También discutimos un evento de eyección que es evidente en los datos del VLA de 1994. Al igual que los flujos óptico y molecular, esta eyección observada en el radiocontinuo es marcadamente asimétrica y se detectó sólo hacia el noroeste de la estrella. Proponemos que este nudo, que ya no es detectable en el radio, podría ser observado en futuras imágenes ópticas de DG Tau B. Las posiciones de la fuente VLA y de un objeto infrarrojo cercano no son coincidentes espacialmente y sugerimos que es la fuente VLA la que traza al objeto excitador, mientras que la fuente infrarroja podría ser un lóbulo de reflexión.
ABSTRACT
DG Tau B is a Class I young stellar source that drives the asymmetric HH 159 bipolar jet. At optical wavelengths it is obscured by circumstellar optically–thick material. Using VLA and JVLA observations, we determine for the first time the proper motions of this source and find them to be consistent, within error, with those of the nearby young star DG Tau. We also discuss an ejection event that is evident in the 1994 VLA data. As the optical and molecular outflows, this ejection traced in the radio continuum is markedly asymmetric and was detected only to the NW of the star. We propose that this knot, no longer detectable in the radio, could be observed in future optical images of DG Tau B. The positions of the VLA source and of a nearby infrared object are not coincident and we suggest that the VLA source traces the exciting object, while the infrared source could be a reflection lobe.
]]> Key Words: ISM: jets and outflows — radio continuum: stars — stars: individual (DG Tau B).
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ACKNOWLEDGMENTS
L.F.R., S.A.D., L.A.Z., A.C.R. and J.C. are thankful for the support of DGAPA, Universidad Nacional Autónoma de México, and of Conacyt (México). A.R. is partially supported by Spanish MCI grants AYA2008-06189-C03 and AYA2011- 30228-C03, and FEDER funds. L.L. is indebted to the Alexander von Humboldt Stiftung and the Guggenheim Memorial Foundation for financial support. This research made use of the SIMBAD database, operated at CDS, Strasbourg, France. The Digitized Sky Survey image used in this paper was produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions. This paper is partially based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof´ısica de Canarias.
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