The Milky Way Galaxy at the Center: A Talk Summary by David G. Penney, Ph.D.

Description

In this presentation, Dr. Penney will talk mainly about the core of the Milky Way and how it can affect us. The core is contained in the central bulge, at the center of our galaxy. This structure is found in millions of other galaxies. Thankfully, we are 25-28,000 lightyears away from our core. It cannot be seen by the naked eye or even by visible light with the most powerful telescopes. This is because of the distance, the gas and dust clouds in the way, our perspective, and the fact that we are inside our galaxy. The core has low surface brightness, so a night sky must be very dark for details of the Milky Way to be seen. The core is a place totally unlike our own. At our stage of science it is a mysterious place. It is highly congested by stars, large and small, old and young. In the core, instead of the sky being dark as it is at night on earth, it is ablaze as if it were daytime, with millions of stars shining brightly. The levels of radiation of all types, magnetic fields, stray particles, star debris, etc., and danger in general, is very much higher. Lurking at the center of the galactic core is a supermassive black hole (SMBH), equal in mass to 4.1 million suns. This black hole is capable of “eating” stars - even hundreds of stars. It cannot be seen by any current technology, but can be inferred from the violent effect it has on nearby stars. Dr. Penney will talk about the woman astronomer at UCLA (Adrea Ghez) who has done brilliant work in investigating this black hole (he will also talk about a second leading woman astronomer [Heidi Jo Newberg] in NY). Although smaller than the orbit of the planet Mercury, when the SMBH is “feeding” it can emit radiation equal to that of millions of supernovae simultaneously exploding. Fortunate for us, it is not feeding right now. Enormous levels of radiation (visible light to X-rays) flow through and out from the core, even in quiet (“starving”) periods. It is not a place where life would or could develop and flourish. Many of the stars move in random orbits, unlike our sun that regularly circles the galaxy every 240 million years. This fact alone is dangerous for life. Most of the core stars are very old, what are called Population II stars. They contain little metal and are unable to form planets or support life. Other star types there are huge, very energetic, and hence have extremely short lives, which end in supernovae (bang!), that kill any life that exists. Dr. Penney earned his Bachelors of Science Degree from Wayne State University and Masters from the University of California. He is a former full professor of physiology at the School of Medicine and adjunct professor of occupational and environmental health at the School of allied Health Professionals at Wayne State University, as well as Director of General Surgical Research at Providence Hospital in Southfield, Michigan. As a young child, his interest in science began with astronomy. Because of his lifelong passion, he is a member of Grand Traverse Astronomical Society in Michigan. Dr. Penny enjoys sharing his knowledge with school groups, science clubs, societies, and library groups.