Radio continuum emission from the central stars of M20 and the detection of a new supernova remnant near M20

F. Yusef-Zadeh, Mark Shure, Mark Wardle, N. Kassim

Published 2000-03-20Version 1

The Trifid nebula (M20) is a well-known prominent optical HII region trisected by obscuring dust lanes. Radio continuum VLA observations of this Nebula show free-free emission at lambda 3.6 and 6cm from three stellar sources lying close to the O7V star at the center of the nebula. We argue that neutral material associated with these stars are photoionized externally by the UV radiation from the hot central star. We also report the discovery of a barrel-shaped SNR G7.06--0.12 at the northwest rim of the nebula and two shell-like features G6.67--0.42 and G6.83--0.21 adjacent to W28 and M20. We discuss the nature of these features and their possible relationship to the pulsar PSR 1801-2306 and W28 OH (1720 MHz) masers.