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November 2004 Meeting Report

Around 50 members and guests attended our meeting on 1st November 2004. Our first speaker was Philip Baxter who demonstrated how to measure angular distance in the night sky.

Philip Baxter showing young member how to measure angular distance

Our chairman, Mr John McConnell welcomed Mr Neill McKeown as the main speaker for the evening. This was Neill McKeown's first lecture to the EAAS, and his lecture was was entitled "Extrasolar Planets - A New Age of Planetary Discovery". Neill began by involving the audience and getting them to come up with a definition of what an extrasolar planet is and then offering his own definition. Next on the agenda was outlining various statistics about extrasolar planets including the number of planets, the number of other stars with planets and interesting facts like the oldest and youngest planets so far found. He also outlined interesting concepts like planets orbiting around irregular type stars including pulsars and brown dwarfs and, planets which exist without a star companion (planetary mass objects). Planetary migration theory was also outlined to explain the presence of large gas giants in orbits around their stars tighter than that of Mercury around the Sun.

Neill McKeownNeill then briefly moved onto to describe the main individuals involved in the field of planet hunting. He then went on to describe the four main methods of finding extrasolar planets used by the planet hunters. These were the Radial Velocity or Doppler Spectroscopy method, Astrometry, the Transit method and Optical detection.

The next section of the lecture involved looking at three specific systems containing extrasolar planets. These systems were 51 Pegasi, Upsilon Andromedae and 55 Cancri. For each system, their position in the night sky was demonstrated using star charts. Data about the star itself was then revealed such as the type of star, the distance from the Earth, its apparent magnitude as viewed from the Earth, its mass relative to the Sun, what constellation the star was in, the number of planets in the system and the star's approximate age. Planetary data was then revealed about each of the systems including the planets' relative masses as compared to planets in the solar system, their orbital radii and periods again being compared in relation to the planets of the solar system, what type of planets these bodies are and how and when they were discovered. This section of the lecture allowed Neill to expand on the concepts first explored in the statistical section including planetary migration and to outline the different theories currently being discussed in this relatively new area of astronomy in relation to planetary system formation.

The talk was concluded by outlining the various space missions that NASA and ESA will be undertaking in the next ten to fifteen years in order to further understand these new worlds. Examples of such missions include Kepler, Darwin and Terrestrial Planet Finder.

An exceptional question and answer session followed with many varied questions, which showed the level of interest of the audience in the topic. Without doubt, Neill did not get an easy time but he managed to answer each question well which showed his own interest and the extensive research he has carried out on this topic.

EAAS member asking a question

If you have any questions about this lecture or would like to learn more, try posting your question on the EAAS Forum where Neill, and the other Forum members, will be only too glad to answer any questions.

Thanks go to Mr Neill McKeown for sending us this report.

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