Astrophysics
SEREN was designed with solving astrophysical problems such as star formation and planet formation in mind. Although SEREN can be used as a generic SPH code to simulate different types of astrophysical phenomena, the incorporated algorithms are specialist routines to investigate a particular facit or star formation. We briefly discuss the kinds of simulations performed using SEREN, the physics and algorithms used in each simulation, and the relevance of the simulations to astrophysics.
Turbulent Molecular Cloud Cores
Observations of the morphology and line-width profiles of star-forming regions suggest that the motion the gas is turbulent, rather than quiescent (e.g. Larson 1981). While the origin of astrophysical turbulence is hotly debated (e.g. hydrodynamical instabilities, magneto-hydrodynamic instabilities, radiative and mechanical feedback, etc..), the effects of turbulence in molecular clouds can be studied using hydrodynamical simulations. Various authors have studied various instances of turbulence in star formation using SPH such as driven turbulence in molecular clouds and undriven turbulence in star-forming cores.
Planetary Disks
Planets are believed to form from dusty gas disks that condense from the ambient material the protostar itself is being formed. Prestellar cores typically have a small amount of angular momentum. As the prestellar core collapses, angular momentum must be conserved unless there is some mechanism that can transfer some angular momentum to external material (e.g. jets). Low angular momentum gas will form the central protostar. High angular momentum gas cannot collapse and forms a centrifugally supported disk. Depending on various factors, this disk may fragment to form secondary objects such as lower mass companion stars, brown dwarfs or planets, or simply disperse slowly due to accretion onto the central protostar and evaporation.
Triggered Star Formation
Star formation is a complicated non-linear process where feedback from the formation of other stars can, depending on many factors, either trigger the formation of a new generation of stars or supress any subsequent formation by destroying the natal cloud. Feedback in star formation can be due to i) winds from the atmospheres of new protostars, ii) highly collomated bipolar jets, iii) ionizing UV radiation from high-mass protostars.
SEREN uses the HEALPix algorithm to model the ionizing flux from high-mass stars (Bisbas et al. 2009).