Unveiling the stellar nurseries with MORFEO-SHARP

What are the physical processes intervening in star formation within molecular clouds ?

What are the effects of the local environment on the properties of the forming stars ?

Is the stellar initial mass function dependent on the environment ?

The formation of stars and planetary systems is one of the most complex processes in the Universe. Over the last decades, astronomers have studied extensively the star forming regions in the Solar neighborhood at short heliocentric distances (within 500 pc). These regions are made of a few tens to a few hundreds of stars. Nevertheless,  the vast majority of stars form in the deep interior of giant molecular clouds which dominate the star formation rate of the entire Galaxy. As an example, the Carina Nebula at a distance of 2 kpc from the Sun, is currently forging new stars at a rate of nearly 0.02 MSun per year (Roccatagliata et al. 2013), while the star formation rate of the local clouds (within 500 pc) is between 2 and 4 orders of magnitude lower (e.g., Lada et al. 2010).

The unprecedented observing capabilities of the ELT will soon allow us to sneak into the darkest interior of the most massive molecular clouds of the outer Galaxy and of the Magellanic Clouds. In particular, MORFEO-SHARP with its two facilities (NEXUS and VESPER) will be able for the first time to spatially resolve the individual spectra of young stellar objects (YSOs). From the near-infrared spectra we will determine the physical properties of the newly formed stars (e.g., their mass, temperature, gravity and metallicity) as well as the rate of mass accretion and mass loss (from hydrogen recombination lines, H2 and CO ro-vibrational transitions and forbidden lines of e.g. [FeII]) in star forming regions never explored before. With SHARP we will be able to study the role of environmental effects, such as external photoevaporation, stellar feedback, and metallicity on the formation of stars and planetary systems and to derive the initial mass function in star forming regions very different from those of the Solar neighborhood .

The dark age of star formation with MORFEO-SHARP

What are the properties and the mass accretion rate of a protostar ?

What are the properties of the ejected gas and outflows ? 

Most of what we know about the formation of stars and planets relies on the observations of the so-called Class II stage when the pre-main-sequence stars and the protoplanets have already formed, the infalling envelope is mostly dissipated and a naked protoplanetary disk is visible at multiple wavelengths. Nevertheless, there is growing evidence that the bulk of the gas mass is fueled into the protostar during the earlier Class 0 and Class I stages when the Young Stellar Object (YSO) is heavily enshrouded in the cold dust. The mass accretion rate is expected to be more than 2 orders of magnitudes higher compared to the Class II stage and to have episodic and non-constant behaviors (e.g., Stamatellos et al. 2011). At this epoch, powerful jets are also ejected. Notably, recent high angular resolution observations with ALMA of Class II protoplanetary disks, also point to an early start of the planet formation process. Most of the Class II disks are indeed characterized by substructures in the gas and dust distribution, hinting at the presence of embedded protoplanets. Moreover, the dust mass budget of Class II disks is too low compared to the mass of planetary systems (Tychoniec et al. 2020). All of these indicate that planet formation should start early on, again during the Class I (and maybe class 0) stage.  

The angular resolution and sensitivity of the ELT is best suited to peer into the heavily dust obscured protostars. The wide field coverage offered by MORFEO-SHARP with NEXUS (multi objects) and VESPER (multi-IFU) will allow us to simultaneously study, on one hand, the protostar (e.g. stellar properties and mass accretion rate) and possible forming planets and, on the other, the jet and outflows properties (e.g. mass loss rate, jet rotation, ejection radius) as they interact with the surrounding medium.