Massive Star Formation with New Generation Interferometers

Over the last 25 years, large improvements in the detection capabilities of current telescopes in the infrared (IR) and radio parts of the spectrum of light, have allowed us to carry out systematic studies of the population of stars present in clusters deeply embedded in molecular dark clouds across our Galaxy. These clusters, which remain hidden behind large amounts of interstellar molecular gas and dust, cannot be accessed by telescopes operating at optical wavelengths because the radiation emitted by young stars is absorbed by interstellar cold dust, which re-emits it afterwards at infrared and radio wavelengths. These IR and radio studies have revealed that most stars in our Galaxy form in clusters, and that these clusters typically show a wide distribution of masses that range from brown dwarfs, with 13-80 times the mass of Jupiter, to the most massive stars, with over a hundred times the mass of the Sun (or Mo). This mass distribution is called the Initial Mass Function (IMF) and peaks broadly between 0.1-0.5 Mo indicating that most stars forming in our Galaxy are low-mass stars. Massive stars - stars with masses larger than 8 Mo - are therefore rare. However, they dominate the energetics and feedback of galaxies, since they inject vast amounts of energy in the form of winds, strong ultraviolet (UV) radiation and supernovae explosions. Despite their short life times, massive stars dramatically modify the dynamical, thermal and chemical properties of the interstellar medium (ISM), shaping the structure of galaxies and largely impacting on galaxy evolution. Massive stars are also a key source of heavy elements, enriching the ISM for future generations of stars and for their associated solar systems. Understanding the physical processes that lead to the formation of massive stars is therefore crucial to establish their role in galaxy formation and evolution, and in the origin of life. However, in contrast with low-mass stars whose formation mechanisms are relatively well-known, the processes that lead to massive star birth still remain unclear. Observational studies of massive star forming regions are indeed challenging in modern astronomy because these regions are located at distances very far from us (further away than 1 kpc or 3000 light years), they show a complex morphology and structure with a high level of confusion, and they remain hidden behind large amounts of molecular gas and dust. The unprecedented capabilities of the new generation synthesis imaging radio telescopes such as the Submillimeter Array (SMA) on Mauna Kea (Hawaii), the Northern Extended Millimeter Array (NOEMA) located in the french Alps, and the Atacama Large Millimeter Array (ALMA) located in the Atacama desert in Chile, will represent a breakthrough in radio astronomy since they will allow us to image massive star forming regions with much higher detail (angular resolution), sensitivity (to discover new and fainter features), and at wavelength ranges never explored before. Molecules, which are very abundant in these regions, will be used as probes because they are very sensitive to the different physical processes (UV photon illumination or shock waves) taking place in the ISM. In this proposal, I will therefore combine the detailed information provided by the observations with these telescopes, with theoretical models of the chemistry of the ISM to understand the physical processes involved in the formation of the most massive stars in our Galaxy.