Letters of Intent received in 2016

LoI 2018-1930
GA Symposium --- The Interstellar Star Formation Cycle: Clouds, Stars, and Feedback

Topics

(1) Formation of molecular clouds out of the diffuse ISM. Impact of galactic environments (e.g., spiral arms, shear, galaxy mergers) on this process.

(2) Evolution of molecular clouds towards star formation. Connection between cloud properties and star formation activity.

(3) Disruption of molecular clouds by star formation feedback and other processes. Role of feedback in triggering the formation of the next generation of molecular clouds and stars.

(4) Development of observational methods that allow to explore the evolutionary processes listed above. Focus on approaches that can be utilized in both galactic and extragalactic environments.

Rationale

Galactic and extragalactic research both provide critical constraints on our understanding of the star formation (SF) process. Molecular clouds form out of diffuse atomic gas, they evolve towards star formation, and the resulting stars impact the ISM via the injection of mass and energy by so–called "feedback". This produces a dynamic and structurally complex multi–scale ISM in which star formation is linked to a wide variety of processes occurring at a range of spatial scales. These connections have been known for some time, but instrumental limitations made it difficult to research them observationally.

Observations of the Milky Way and galaxies now provide fresh and critical data to study the dynamic ISM. To give examples, ALMA can now resolve individual molecular clouds in nearby galaxies while Herschel provides wide–field views of entire nearby molecular clouds. This means that we can now study star formation on similar spatial scales in the Milky Way and nearby galaxies.

This meeting seeks to strengthen the collaborations between researchers on galactic and extragalactic star formation that are needed to make further progress. Scheduled in 2018, this IAU symposium will discuss progress based on the following timely developments in the field.

(1) ALMA–based studies will have researched individual extragalactic star–forming clouds in molecular species tracing dense gas and star formation (e.g., HCN and N2H+) on spatial scales approaching as small as 1pc. Studies of [CII] on SOFIA will constrain the hot and diffuse matter in galaxies. MUSE on the VLT will provide comprehensive information on extragalactic star–forming regions at excellent spatial and spectral resolution.

(2) Comprehensive research programs combining data from a variety of surveys (e.g., VIALACTEA) will have produced a detailed multi–scale and multi–tracer perspective of molecular clouds and star formation in the Milky Way. The combination of FCRAO and APEX data will provide the first view of CO–traced gas covering all of the central part of the Galaxy. MeerKAT will be in the process of surveying the atomic and ionized diffuse gas in the Milky Way.

(3) Numerical simulations will provide comprehensive predictions on how stellar feedback influences the ISM in galaxies on spatial scales ranging from individual molecular clouds to kpc–sized sectors of galaxies (e.g., FIRE and SILCC collaborations). Other sets of ongoing calculations will greatly improve our understanding of the formation of spiral arms in galaxies.

(4) The research community will actively prepare observation programs for the James Webb Space Telescope (JWST), which will launch two months after the GA. Gaia data on spectral types and parallaxes released in 2018 will offer new ways to study the young stellar population of the Milky Way. This meeting offers a platform to discuss and fine–tune ideas for these important opportunities.

In combination these observational and theoretical efforts will massively improve our understanding of the complex processes that control how galaxies form stars and evolve over cosmic time.