CAREER: Structure Formation and Support by Magnetized, Supersonic Turbulence in the Interstellar Medium and Star-Forming Regions

American Museum Natural History, New York NY

Investigators

Abstract

AST-9985392 MAC LOW The appointment of Dr. Mordecai-Mark Mac Low to a position as Assistant Curator of Astrophysics at the American Museum of Natural History presents an extraordinary opportunity to combine public education using the assets of a state-of-the-art planetarium with fundamental research on the birth of stars and the structure of the interstellar gas. Stars are formed from huge clouds of interstellar gas that collapse under the force of their own gravity. The gas observed in our own and other galaxies would all collapse into stars in a small fraction of the lifetimes of the galaxies if it were not somehow supported. Supersonic random motions (turbulence) are observed in the interstellar gas, and in the denser star-forming clouds observed in that gas. These supersonic motions appear to support the clouds against immediate collapse, yet shock waves from these supersonic motions sweep gas up into extremely dense sheets and filaments. In the interstellar gas, these dense regions may be the progenitors of the star-forming clouds, while within the clouds, these regions appear to evolve into the even denser cores in which the very youngest stars are observed. Understanding how the balance between support and collapse caused by the supersonic motion works will open the way to understanding the evolution of star-forming galaxies and the origins of stars including our own Sun Dr. Mac Low is computing three-dimensional models of supersonic turbulence in magnetized gas in order to study how star-forming clouds are swept up in the interstellar gas and how protostellar cores are in turn swept up in the clouds. He includes realistic descriptions of the supernova explosions and protostellar outflows that drive the supersonic motions in the gas, as well as the heating and cooling of the gas. He also models how ionizing radiation is transferred through the modeled density structure to understand how the gas in our own and other galaxy is ionized at enormous distances from hot stars, as well as how molecular clouds emit and are radiatively cooled. The Rose Center for Earth and Space Sciences at the Museum includes two permanent exhibition halls---the Hall of the Universe and the Hall of Planet Earth---and a new Hayden Planetarium. The new Planetarium has both a Zeiss star projector incorporating the latest developments in analog projection technology, and a Digital Dome that allows the projection of nine megapixels of computer-generated graphics in real time. Dr. Mac Low incorporates the results of his research, as well as his general knowledge of modern astrophysics, into the Space Shows produced for the Planetarium, into other exhibits in the Planetarium and the Hall of the Universe, and into their associated web sites. He also works with pre-college teachers to incorporate the spirit and results of modern research into their teaching. This project is supported by funds from the Division of Astronomical Sciences. ***