Star formation is one of the most active areas of both theoretical astrophysics and observational astronomy. The formulation of a theory of star formation is essential not only for understanding the origin of our own solar system and, ultimately, of life itself, but also for the development of a theory of galaxy formation and evolution. Stars are observed to form inside interstellar gas clouds consisting primarily of molecular hydrogen. Although molecular clouds are very massive (up to 106 solar masses), they are not observed to be globally collapsing; instead they fragment into high-density cores, which collapse to form stars while most of the cloud remains. The process of star formation thus has a very low efficiency. While thermal-pressure forces are small, since molecular cloud temperatures are observed to be very low (~10K), supersonic turbulence and magnetic fields are observed in molecular clouds and may both play a role in their dynamics. However, the relative importance of each in opposing gravity remains an open question and a subject of heated debate in the field. The reason is that physical conditions in molecular clouds are difficult to extract from observable quantities, because each observable is typically affected by multiple factors that are nontrivial to deconvolve.
A most promising way to make progress is to concentrate on the earliest phases of star formation, i.e. prestellar molecular cloud cores, which will ultimately from stars and planets. Models of these cores need to be developed that simultaneously and self-consistently follow all processes affecting interstellar gas probes, such as molecular spectral lines, dust continuum emission and absorption; to vary all uncertain parameters within limits allowed by observations; to produce theoretical predictions of various observable quantities; and to identify which diagnostics feature minimal degeneracies between different dynamical models and, as a result, maximal potential for discrimination between theories of star formation.
Although the necessity of such a comprehensive study has long been recognized in the field, its implementation is complicated for two reasons. First, it requires combined expertise in molecular cloud dynamics [both hydrody- namic and magnetohydrodynamic (MHD) models of core formation and collapse], interstellar chemistry, and radiative processes; as a result it requires cross-disciplinary collaborations to ensure its successful conclusion. Second, due to the large number of models and parameter variations that have to be examined, such a study is computationally expensive and it requires a well-thought-out scheme for dissemination of the results to the observational community; as a result, it requires a substantial commitment in resources (both computational and human). It is such a study that we undertake with this program.
We combine dynamical, chemical, and radiative-transfer modeling of prestellar cores. Our aim is to produce a comprehensive database of observational signatures of a variety of prestellar molecular cloud core models, as manifested in molecular line profiles, and continuum emission maps and spectra. We will make this database publicly available to the community through a web interface designed to disseminate the predictions of any specific dynamical model for hundreds of molecular species, for user-selected cloud physical properties, line-of-sight geometry, and observatory capabilities.
These results are especially timely as current and future facilities, such as ALMA and SKA, will be able to measure these quantities and contribute to the resolution of long-standing questions in star formation.