Galactic star formation with NIKA2: the GASTON large programme
Over the last decade, Herschel observations of the Galactic interstellar medium have transformed our understanding of the early stages of star formation. At the low-mass end of the stellar initial mass function (IMF), a paradigm has emerged in which low-mass cores – the progenitors of stars with masses from ~0.1 to a couple of solar masses – are thought to form as the result of gravitational instabilities developing along gravitationally bound filaments, providing a compact and fixed mass reservoir for the protostars forming inside them. However, on either side of that mass range, processes that lead to the formation of massive stars on the one hand, and to the formation of brown-dwarfs on the other, remain elusive. Indeed, it is well known that thermal Jeans-type fragmentation cannot explain the formation of cores more massive than a few solar masses, and there are strong indications that the dynamical evolution of the larger-scale mass reservoirs in star-forming regions play a key role in the formation of high-mass stars. Furthermore, the formation mechanism of brown dwarfs is also controversial, and in particular it is unknown whether a continuation of the filamentary paradigm at even lower masses could be an important formation pathway. The GASTON large programme at the IRAM 30m telescope is exploiting the high angular resolution of the 30m telescope at 1.2 mm, and the high mapping speed of the NIKA2 camera to scrutinise the formation mechanisms of stars across all mass ranges in unprecedented detail. Specifically, GASTON is aimed at bridging the divides between the brown dwarf, the low-mass, and the high-mass star-formation regimes. An additional goal to the project is to constrain the evolution of dust properties – upon which so much of our understanding of ISM physics is based – as a function of environment. In the context of this talk, we will present the current status of the GASTON project, mostly focussing on our deep NIKA2 survey of the Galactic plane, and the first statistical results on the link between intermediate-mass and high-mass core populations.