10978(  1) - 04/03/06 11:19  - [  1]

                  HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 10978

Version: 1    Check-in Time: 03-Apr-2006 15:19:39

Title
Modeling the Transition from Pop III to Pop II Star Formation in the Early Universe
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Type             Cycle     Parallel Pointing Tolerance
AR               15        <none>
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Investigators
                                                                                     Contact?
    PI: Prof. Steinn Sigurdsson           The Pennsylvania State University
   CoI: Mr. Britton Devon Smith           The Pennsylvania State University             N

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Abstract

We will study the physical conditions necessary to shift from very high-mass,
population III star formation to low-mass, population II star formation. We will
model the critical chemical abundances needed to enhance radiative cooling
efficiency at temperatures below 10000 K. This added cooling will allow the
collapsing protostar to fragment, thereby forming multiple low-mass stars, as
opposed to the metal-free case where a single star of a few hundred solar masses is
formed. This will be accomplished by adding the treatment of metal cooling to an
established cosmological hydrodynamic simulation code. Our technique allows us
freely vary abundance patterns for all elemental species up through Zinc, giving us
the ability to identify the specific elements responsible for the transition to
modern-day star formation. We will, then, be able to predict the initial mass
function for stars formed in the wake of population III supernova, as well as the
evolution to the currently observed stellar mass function. This information will be
highly beneficial to those who will use the HST to study star formation at high
redshift. In addition, this study will be of particular use to those who will use
the JWST to observe the environment of population III stars, their supernovae, and
the stars that form after their deaths. The JWST will be able to directly observe
the period in the history of the universe when population II stars are formed for
the very first time, verifying the predictions made by our study.
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