Title: 超新星与宇宙起源
Speaker: Richard McCray
美国科罗拉多大学教授
美国科学院院士
美国Dannie S. Heinemann奖获得者
时间： 2016年4月20日晚7点
地点： 清华大学建筑馆报告厅
主办单位： 清华大学天体物理中心
支持单位： 清华大学物理系
清华大学-国家天文台联合天体物理中心
清华大学高等研究院
清华大学科普基地管理办公室
清华大学学生天文协会
Abstract:
A supernova is the explosion that marks the death of a massive star. For a few months, the exploding star is more luminous than one billion suns. Such supernovae are responsible for creating the heavy elements in the universe, including the material of which the Earth is composed. In fact, the iron in our blood and the calcium in our bones were created in a supernova explosion that occurred about 5 billion years ago.
During the past 2000 years, about 20 supernovae have been bright enough to see with the naked eye. Chinese astronomers provided the earliest detailed records of supernovae, giving their locations in the sky and the evolution of their brightness. Today, astronomers can point modern telescopes toward these ancient supernovae and see expanding shells of hot gas caused by the explosions.
Supernovae manifest some of the most extreme environments in the physical universe, with temperatures ranging from 109 K to < 100 K and densities ranging from 1015 g cm-3 to 10-23 g cm-3. They produce neutron stars and black holes. To probe the conditions in supernovae and their remnants, astronomers use telescopes spanning the entire electromagnetic spectrum, ranging from radio to gamma rays.
With modern telescopes, astronomers are now discovering hundreds of supernovae each year and learning what kinds of stars explode as supernovae, what factors determine their behavior, and their influence on the evolution of the cosmos. We now understand that supernovae are essential to the origin of life in the universe. Because of supernovae, the universe has found a way to create (at least one) intelligent civilization. We can regard civilizations as devices whereby the universe becomes conscious of itself.
