Abstract:
Stellar multiplicity is common at all evolutionary stages and mass ranges. Multiple stellar systems produce a myriad of phenomena, such as complex planetary nebulae, cataclysmic variables, type Ia supernovae, and inspirialing binary systems that generate gravitational waves. Observations of star forming regions reveal that a significant fraction of stars form in multiple protostellar systems. Even more interesting is the occurrence of protostellar cloud cores that host systems with four or more protostellar components. Many questions arise, from how these systems form and evolve to whether they will survive as gravitationally bound multiple stellar systems. A systematic study that takes a global view of these objects is needed to answer many of the questions related with multiple stellar system formation. The first step is the identification of the physical factors that influence the formation of multiple protostellar systems.
Fragmentation, of the natal cloud core or protostellar disk, is generally agreed to be the main formation mechanism of multiple protostellar systems. However, the factors that determine the degree of multiplicity and system structure produced by fragmentation have not been observationally constrained. To do so, physical conditions (e.g., temperature, density, mass, and kinematics) around protostellar sources need to be measured and compared with system properties (location in the star forming region, multiplicity, luminosity, outflows, and chemical inventory).
In order to gain observational insight into the molecular gas environment around protostellar systems, a survey of the Perseus Molecular cloud was carried out. An observing campaign with the Nobeyama 45m Radio Observatory (>5000 AU scales), APEX (5000 to 8000 AU), and ALMA ACA (< 3000 AU) targeted molecular species that trace cold and warm gas from molecular cloud scales down to inner envelope scales. The targeted molecular species provide several independent measurements of temperature, molecular hydrogen density, column densities, gas masses, and gas kinematics at different scales. Dust continuum, polarization data and chemical inventories down to scales of a few 100 AU from previous surveys compliment the Perseus molecular gas survey, providing an almost complete view of star formation in the region, and allowing the factors that influence multiple star formation to be identified. In this presentation I will provide an overview of the available data, current results, and future projects, as well as related research.
