Estudio del remanente de supernova CTB 80 y su entorno

CASTELLETTI G., DUBNER G.

Tafí del Valle, Tucumán, Argentina, 18 al 22 de septiembre

Congreso; 44a Reunión Anual de la Asociación Argentina de Astronomía; 2000

The galactic supernova remnant (SNR) CTB 80 (G69.0+2.7) is a nonthermal radio source of unusual morphology. At radio frequencies the remnant presents a complex structure formed by three long arcs (about half a degree each) which extend to the north, east and southwest. It is one of the very few known SNR associated with a fast pulsar (PSR 1951+32) with a period of 40 ms which is interacting with the rest of the remnant forming a bright radio nebula around it. This compact region, ~ 30´´ in diameter, is located on the western end of a plateau-like feature of size ~ 10´ X 6´, where the three wings intersect. At present there are not satisfactory explanations for the origin of this singular morphology. The present work report on radioastronomical observations of the SNR CTB 80 obtained at 330 and 1365 MHz with high angular resolution using the Very Large Array (VLA, NRAO) in its C and D configurations, respectively. This is the first study at low frequencies covering the remnant in all its extension. Since both images at 330 and 1365 MHz have been obtained with similar resolution and sensitivity we have compared them to study the spectral index distribution in the different components of CTB 80 with the aim of understanding the physical nature of the source. A preliminary spectral study reveals a mean value between -0.3 and -0.4 for the spectral index alpha of the extended components with a tendence in the northeast wing towards a flatter spectrum of -0.1 to -0.2. In these calculations we have added a typical 30 % of flux to the image at 330 MHz since the information of extended structures is lacking. With the addition of the D-array data it will be possible to accurately estimate the spectral variations. For the nebula of the pulsar a flat spectral index of ~ 0 has been confirmed. In addition, the surrounding neutral gas around CTB 80 has been analized from the combination of VLA and Dwingeloo 25 m radiotelescope data (Hartmann, D., Burton, W.B., 1997 Atlas of Galactic Neutral Hydrogen, Cambridge University Press., Cambridge, UK.). Gas aligned with the southeast arc of the remnant between 8 and 17 km/s has been identified which has a density ~1.5 higher than the unperturbed gas.