The neutral counterpart of an uncatalogued nebula and a probable interstellar bubble around wr 53 in the centaurus region
M. C. Martín,1 C. E. Cappa,1,2 and J. C. Testori1
1 Instituto Argentino de Radioastronomía, CONICET, Argentina.
2 Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Argentina.
M. C. Martín, C. E. Cappa, and J. C. Testori: Instituto Argentino de Radiostronomía, Parque Pereyra Iraola Km 40, Apdo. Postal 1894 (Villa Elisa), Provincia Buenos Aires, Argentina (cmartin@iar.unlp.edu.ar).
]]> Received 2006 November 03
Resumen
La inspección de imágenes ópticas hacia l = 307° permitió encontrar una nebulosa no catalogada de 9' de radio, que denominamos G307.27+0.27. El análisis de la distribución de la emisión de HI reveló la presencia de una cascara en expansión que rodea a la nebulosa. Sugerimos que la cascara, a una distancia cinemática de 4±1 kpc, es la contraparte atómica neutra de la nebulosa. Observaciones de CO en la banda de radio y datos de la emisión en el infrarrojo lejano y medio nos permitieron detectar gas molecular y polvo interestelar asociados a las estructuras.
La presencia de una estrella O6 a una distancia compatible con la de la cascara de Hi sugiere que la estructura es una región HII o una burbuja interestelar.
Reportamos también el descubrimiento de una probable burbuja interestelar de HI relacionada a la estrella Wolf–Rayet WR53. Sus parámetros físicos son similares a los de otras burbujas interestelares asociadas a estrellas masivas.
Abstract
From the inspection of optical images at l = 307° we have found an uncata–logued nebula of about 9' in radius, which we named G307.27+0.27. The analysis of the HI–21cm line emission distribution revealed an expanding HI shell that encircles the optical emission region. The shell, placed at a kinematical distance of 4±1 kpc, is suggested to be the Hi counterpart of the optical nebula. CO observations at radio wavelengths, and far and mid IR data, allowed us to detect molecular gas and interstellar dust associated with the structures.
]]> The presence of an O6 star at a spectrophotometric distance compatible with that of the shell supports a stellar wind/HII region origin for the whole structure.We also report a probable Hi interstellar bubble related to the Wolf–Rayet star WR 53. Its physical parameters are similar to the parameters of other Hi bubbles around massive stars.
Key Words: ISM: bubbles rayet—ISM:HII regions—stars: wolf–rayet
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Acknowledgement
We thank R. Barba for helpful comments on the paper and T. Dame for making his CO data available to us. We also thank P. Thutill, Q. Parker, P. Benaglia, and G. Solivella. We acknowledge the anonymous referee for valuable comments. This project was partially financed by the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) of Argentina under project PIP 5886/05, FCAG, UNLP, under project 11/G072, and Agencia de Promoción Científica under project PICT 14018. The Digitized Sky Survey (DSS) was produced at the Space Telescope Science Institute under US Government grant NAGW–2166.
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