Kinetic energies and the possible origin of HI supershells

SUAD LAURA A.; ARNAL E. MARCELO; CAIAFA CESAR; CICHOWOLSKI SILVINA

Bariloche

Conferencia; Massive stars and Supernovae; 2018

The Milky Way, when viewed in the neutral hydrogen (HI) line emission, presents large structures called galactic supershells (GSs). The origin of these structures is still a subject of debate. The most common scenario invoked is the combined action of strong winds from massive stars and their subsequent explosion as supernova.The aim of this work is to determine the origin of 490 GSs that belong to the "Catalog of HI supershell candidates in the outer part of the Galaxy"of Suad et al. 2014 (A&A 564A 116S).To know the physical processes that took place to create these expanding structures, it is necessary to determine their kinetic energies. To obtain all the GSs masses, we have developed and used an automatic algorithm. We found that the kinetic energies are between 0.2 to 67.4x10^{50} ergsand that the 95% of the GSs have energies lower than 4x10^{50} erg, which, for a stellar origin, implies that a wind energy greater than 2x10^{51} erg is required. This amount of energycan be easily supplied by OB associations.According to the interval of energies obtained, a stellar origin is possible for most of the GSs. However, more than one star is needed and, in most of the cases, given their high ages, more than one stellar generation, including several SN explosions.