Why stellar astronomers should be interested in the sun

Abstract

By all accounts, the Sun is a garden-variety star with an average age, a standard size, a regular temperature, norormal mass, an ordinary structure, and a typical chemical composition. Only one feature makes it special - the Sun is our star. It is located in the center of our solar system, and therefore, is responsible for all life on Earth. Astronomically speaking, the Sun is the only star in the sky that we can study up-close and personal. The unaided human eye does a better job of resolving the Sun than the finest telescope does for any other star. Stellar astronomers issue a press release whenever they can lay a few pixels of some state-of-the-art instrument across a nearby supergiant. The resolution of the Sun, however, is something we can see routinely in the magnificent images that are downloaded every day from the Transition Region and Coronal Explorer (TRACE) spacecraft. In a very real sense, the Sun is the Rosetta Stone of the Stars. Observations of the Sun deflecting starlight ushered in a new way of thinking about gravity. Zeeman effect observations of the Sun showed that stellar atmospheres were controlled by magnetic fields. The discovery of solar helium founded the science of stellar spectroscopy. Measurements of the solar mass, radius, and temperature allowed scientists to probe the interiors of stars for the first time. tim ancient age of the Sun implied that stars shine as a result of thermonuclear fusion. Observations of solar flares flamulated developments in rapid magnetic reconnection theory. The study of solar coronal holes led to a deeper understanding of the role that mass loss plays in the evolution of stars. Detailed analysis of the solar activity cycle inspired the development of Magneto-Hydrodynamic (MHD) dynamo theory. The detection and understanding; of the solar corona uncovered one of the longest unsolved mysteries in all of astrophysics — the coronal-heating problem. And the list goes on. The Sun is indeed a Laboratory for Astrophysics, but it is more than that. The Sun is a Laboratory for all of Physics. This paper describes 20th century physics discoveries that are directly attributable to solar observations. It is in the form of a Top Ten List, and was inspired originally by a talk given by Dr. Eugene N. Parker; subsequent discussions with Dr. Parker have molded it into its present form.