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

AST-9985392MAC LOW任命末底改-马克·洛博士为美国自然历史博物馆天体物理学助理馆长提供了一个非同寻常的机会，可以利用最先进的天文馆的资产将公共教育与恒星的诞生和星际气体结构的基础研究结合起来。恒星是由巨大的星际气体云形成的，这些气体在自身引力的作用下坍塌。如果没有某种支持，在我们自己的星系和其他星系中观察到的气体都会在星系寿命的一小部分内坍塌成恒星。在星际气体中观察到超音速随机运动(湍流)，并在该气体中观察到密度更大的恒星形成云。这些超音速运动似乎支持云层防止立即坍塌，但这些超音速运动产生的冲击波将气体向上扫射成极其致密的薄片和细丝。在星际气体中，这些致密区域可能是恒星形成云的前身，而在星云中，这些区域似乎演变成更密集的核心，在那里可以观察到最年轻的恒星。了解超音速运动造成的支撑和坍塌之间的平衡是如何工作的，将为理解恒星形成星系的演化和恒星的起源(包括我们自己的太阳系)开辟了道路。Mac Low正在计算磁化气体中超音速湍流的三维模型，以研究恒星形成的云是如何在星际气体中卷起的，以及原恒星核心是如何在云层中卷起的。他对推动气体中超音速运动的超新星爆炸和原恒星外流，以及气体的加热和冷却进行了逼真的描述。他还对电离辐射如何通过模拟的密度结构进行了建模，以了解我们自己和其他星系中的气体是如何在距离热恒星很远的地方被电离的，以及分子云是如何发射和辐射冷却的。博物馆的玫瑰地球和空间科学中心包括两个永久性的展厅-宇宙大厅和地球大厅-以及一个新的海登天文馆。新的天文馆既有蔡司的恒星投影仪，融入了模拟投影技术的最新发展，也有数字穹顶，可以实时投影900万像素的计算机生成的图形。Mac Low博士将他的研究成果以及他对现代天体物理学的一般知识融入到为天文馆制作的太空展览中，纳入天文馆和宇宙大厅的其他展品，以及它们的相关网站。他还与大学预科教师合作，将现代研究的精神和成果融入到他们的教学中。这个项目得到了天文科学部的资金支持。

AST-9985392MAC LOWThe 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 SunDr. 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.***