Description of August 20th radio show: Extrasolar Planets

Much detailed, for which I apologize, is a detailed description of the August 20th radio show available here. On this program, I discussed:

• News: Phoenix Mars Lander takes first photograph of a Martian dust particle using an atomic force microscope (link); Cassini spacecraft starts transmitting data from flyby over Saturn's moon Enceladus, famous for its geysers (link) - information from this flyby determines these geysers originate from fractures in its surface (link); ESA spacecraft Rosetta tracks asteroid (2867) Steins for upcoming rendezvous; NASA moves up milestones for final Hubble Space Telescope servicing mission; NASA's IBEX mission fueled and testing continues for October 5th launch; series of key tests for a components of the J-2X engine on NASA's Ares rocket (successor to the space shuttle) completed; psychologists outline personal challenges astronauts might face on longer space missions (link); NASA astronaut Greg Chamitoff on board the International Space Station answering questions on a weekly basis (link); congratulations to students at Ohio State University who successfully built and launched a balloon-born cosmic ray detector to the edge of space (link); survey of supernovae (bright flashes of light caused by either the explosion of a white dwarf or the collapse of the core of a massive star) shows that ones which are further away get dimmer slower than ones which are nearer - as expected from general relativity; PAMELA satellite which measures the ratio of positrons to electrons at high energy might (only might) have detected indirect evidence for the existence of dark matter; swimsuit used by Michael Phelps and others at Beijing Olympics to break swimming records tested at NASA's Langley Research Center (link).
• Wednesday Morning Astronomer: (an astronomer's take on the Astronomy content of Gregg Easterbrook's ESPN column "Tuesday Morning Quaterback", available here) While "smithereens" isn't very technical, it does make sense to use it in a press release. And "bizarre" is a term astronomers often use to describe what they see...
• Astronomy Calender of upcoming Astronomy and science events in the greater New York City/Poughkeepsie area.
• Extrasolar Planets: While, as discussed on August 13th, a lot of work is going into discovering new extrasolar planets, a lot of science can be done by studying known systems. One major question is what role does the chemical composition of a star play in the formation of a planet. For example, it appears that stars with a higher concentration of elements heaving than Hydrogen and Helium (which astronomers lump together as "metals") are more likely to have a planet orbiting them. A recent discovery of a planet orbiting a metal rich star that drifted away from the Hyades cluster bolsters this claim (link). Additionally, astronomers are very interested in the properties of the extrasolar planets themselves, and not just the stars they orbit. For extrasolar planets which pass between their central star and the Earth, the so-called "transiting planets", the atmospheres of these planets absorb some of the light emitted by the central star. Since atoms absorb light at particular frequencies, one can use these "absorption lines" in the spectrum to determine the chemical composition of the planet's atmosphere. Also, the width and depth of these lines gives you an estimate of the velocity and amount of this particular elements in the atmosphere. A recent analysis of the spectrum of extrasolar planet HD 209458b discovered broad Hydrogen absorption lines - implying that fast moving Hydrogen is being ejected from this planet's atmosphere. It is thought that this is the result of the solar wind from the central star interacting with this planet's atmosphere - similar to the interaction between the Sun and the Earth. Also, using this technique methane has been detected in the atmosphere of another extrasolar planet, HD 189733b - the first time this has happened. It is possible to use Solar System meteorites to estimate the properties of the Solar System when planets formed because they were also formed during this time, and have not undergone the chemical changes planets have. A recent chemical analysis of meteorites suggest that the dust cloud if which the Earth and other planets formed was denser than previously thought (link). A major goal of extrasolar planet research is to detect Earth-like planets, a method to do this is being developed by astronomers at Penn State and University of Hawaii (link). What is not known is how common a Solar System like ours is (rocky planets close to the Sun, larger gaseous planets further away) since we currently can't detect Solar Systems like our own. As a result, almost all of the other Solar Systems we known of are very different, with large gas giants orbiting close to their central star. A recent computer simulation of the formation of a solar system suggests that our Solar System is rare indeed (link, article). This affects the odds of finding extraterresterial intelligent life, which a recent analysis predicts to be quite rare (link). Last, but not least, stars are expected to swell as they age, and swallow the surrounding planets. This process might already have been observed.

Thank you for listening. Hope you enjoyed, and as always, any and all feedback is appreciated.