The Formation of Stars -- From Filaments to Cores to Protostars and Protoplanetry Disks

Abstract: Star formation involves the flow of gas and dust within molecular clouds into protostars and young stellar objects (YSOs) due to gravity. Along the way, these flows are shaped significantly by many other mechanisms, including pressure, turbulent motions, magnetic fields, stellar feedback, jets, and angular momentum. How all these mechanisms interact nonlinearly with each other on various length scales leads to the formation and evolution of substructures within clouds, including filaments, clumps, cores, disks, outflows, the protostars/YSOs themselves, and planets. In this white paper, prepared for the 2020 Long Range Plan panel which will recommend Canada's future directions for astronomy, we describe the observational and theoretical leadership in the star formation field that Canada's vibrant community has demonstrated over the past decade. Drawing from this extensive background, we identify five key questions that must be addressed for further progress to be made in understanding star formation in the next decade. Addressing these questions will improve our understanding of the dynamics of the dense gas and the role of the magnetic field in star formation, the optical properties of the dust used to trace mass and magnetic fields, the sources of variability in star-forming objects on short timescales, and the physical processes that specifically promote the clustering of stars. We further highlight key facilities in which Canada should become involved to continue making progress in this field. Single-dish facilities we recommend include LSST, trans-atmospheric far-infrared telescopes like BLAST-TNG and SPICA, and ground-based telescopes like JCMT, GBT, and CCAT-p. Interferometric facilities we recommend include ALMA, ngVLA, and SKA1.

• The paper shows that gravitational collapse, turbulence, and magnetic fields collectively drive the evolution from filaments to protostellar cores and disks.
• It utilizes state-of-the-art observatories like ALMA and JCMT to capture high-resolution data on gas dynamics and protostellar outflows.
• The study outlines future research avenues, emphasizing enhanced simulations and Canadian facility collaborations to refine star formation models.

Overview of "The Formation of Stars - From Filaments to Cores to Protostars and Protoplanetary Disks"

The paper "The Formation of Stars - From Filaments to Cores to Protostars and Protoplanetary Disks" provides a comprehensive analysis of the mechanisms and processes involved in star formation, specifically focusing on the contributions and future prospects of Canadian research in this domain. The research emphasizes the multipartite nature of star formation processes, acknowledging that gas and dust within molecular clouds evolve into protostars through interactions shaped by gravity, turbulence, magnetic fields, and other astrophysical forces.

Key Aspects of Star Formation

1. Mechanisms in Star Formation: The authors discuss how gravitational forces, coupled with other physical factors including turbulent motions, magnetic fields, and angular momentum, drive the evolution of molecular clouds into dense cores and eventually young stellar objects (YSOs). This transformation is characterized by complex interactions across varying spatial scales within star-forming regions.
2. Role of Filaments and Clumps: Filaments in molecular clouds serve as material highways channeling gas into denser structures like clumps and cores, setting the stage for star formation. This progression from filamentary structures to protostars is pivotal, showing how gas fragmentation and accretion processes operate in a hierarchical manner within the interstellar medium.
3. Observational and Theoretical Advances: The paper articulates the use of state-of-the-art observational technologies and theoretical simulations in understanding star formation. The authors detail how facilities such as ALMA and JCMT have provided high-resolution insights into the dynamics within star-forming regions, allowing for the study of protostellar outflows, magnetic fields, and variability in YSOs.
4. Magnetic Fields: The investigation into magnetic fields, using polarized emissions, reveals their significant role in shaping molecular clouds and aiding the star formation process. The study of field strengths and morphologies across different scales helps elucidate their influence on core collapse and disk formation, paving the way for fine-tuned star formation models.
5. Evolving Concepts in Star Formation: The authors outline critical areas where further exploration could yield significant insights, including the flow dynamics of dense gas into stars, the precise interaction of magnetic fields during star formation, and the variability of star-forming processes on observationally accessible timescales.

Implications and Future Directions

The findings underscore the importance of continued investment in both observational and theoretical frameworks to advance the understanding of star formation processes. The authors argue for strengthening collaborations and involving Canadian facilities in upcoming large-scale projects like the LSST and ngVLA to remain at the forefront of astrophysical research. The integration of upcoming technologies could facilitate exploring the interstellar medium at unprecedented resolutions, providing clearer insights into not only star formation but its consequential impact on galaxy evolution.

This paper sets a strategic course for future research, encouraging the development of a coherent star formation theory that encompasses a broad range of astrophysical conditions and scales. The authors emphasize the need for high-resolution observational campaigns and sophisticated modeling to address unresolved questions about the clustering of stars, variability in protostars, and the interplay of different physical forces during star formation.

In conclusion, "The Formation of Stars - From Filaments to Cores to Protostars and Protoplanetary Disks" serves as a pivotal reference, laying out a roadmap for advancing our understanding of one of astrophysics' most fundamental phenomena through a combination of past experiences and future ambitions.