NASA

报告摘要:
Pulsars (neutron stars) have been discovered four decades ago, but to date the radiation mechanism remains a mystery. In this paper I will abandon the usual assumption that the observed pulsar radio emissions with high brightness temperatures, must be from coherent processes and I will also abandon one of the golden rules of stellar structure, that radiative equilibrium is maintained inside neutron stars. I will start by constructing more realistic neutron star models, with a neutron dominant core and a more realistic envelope, including the presence of intense magnetic fields which have been shown to prevail in neutron stars. In the neutron dominant core of my models, neutrons are in equilibrium with protons and electrons. Outside the core where neutron equilibrium cannot be maintained, the composition switches to that of neutron rich super trans-uranium elements (STUE). On top of this STUE shell is an atmosphere where beamed radio emission originates. It is shown that the transition from the predominantly neutron core to the neutron rich STUE shell is very abrupt, and this STUE shell, if exists, will likely be very thin. Then I will show that one of the golden rules of stellar structure, radiative equilibrium, might be severely limited throughout the neutron star including the surface region where pulsar radio emission takes place. I will also show that, because of the presence of intense magnetic fields (0.1 T to as high as $10^4$ T), radiations will be beamed along field lines and the radiation pattern is in the shape of a narrow angular cone. Similar cone shaped radiation patterns prevail along all field lines, but only one such cone is observable by an observer along the line of sight of the cone. This produces an illusion that to an observer on Earth the pulsar will only emit a cone shaped pulse in his/her direction, while in fact, pulsar radiations are more or less isotropic in most directions. This geometric effect will be explained in this paper. Finally, my theoretical model will be compared with pulsar data..

报告人简介：
Hong-Yee Chiu (Chinese: 丘宏義) was born in Shanghai in October 1932. Chiu graduated from National Taiwan University and later received his PhD in Astrophysics from Cornell University. After graduation, he was a member at the Institute for Advanced Study in Princeton, New Jersey. He served as a Space Astrophysics Scientist for NASA for over 35 years. In 1969, Chiu was the first Chinese-American scientist to receive the NASA Exceptional Scientific Achievement Medal. He was also the first scientist to officially use the term "quasar," in 1964. After his retirement from NASA, Chiu started the EHanism Group and developed an EHGBooks micropublishing app with some notable Chinese computer scientists in order to promote Chinese culture and Sinology memory. With his niece and assistant Nonny Hsueh, the family helped the National Central Library of the Republic of Taiwan, R.O.C. to participate in the World Digital Library organization under the auspices of UNESCO in 2008. Later on, Chiu led the EHanism Group to develop the first Amazon Micropublishing Chinese Solution in 2012. Chiu is the host of the 2013 Taiwan Reunion Program for NTU Early Graduates in commemoration of the 85th anniversary of National Taiwan University

联 系 人：傅琦（82649469）