Extrasolar planetary systems

The search for signs of life, present or past, is an important goal of NASA s robotic solar system exploration programs and, ultimately, for its astronomical programs designed to probe the gross characteristics of extrasolar planetary systems. To date, that search has been governed by a model of life that is based on the life that we know on Earth—terran life. Several features of terran life have attracted particular focus ... 

One mechanism to consider might be planetary migration (Lin et al., 1996 Murray et al., 1998). Observations of extrasolar planets provide strong evidence that planets migrate after their formation (Lin et al, 1996). Resonances are observed in extrasolar planetary systems possessing multiple Jupiter-like planets. These resonances can only be explained if the planets migrated after ffieir formation (Murray et al, 1998). Two kinds of models can be considered. 

Okamoto, Y.K. and 9 others, 2004. An early extrasolar planetary system revealed by planetesimal belts in /3 Pictoris. Nature, 431, 660-3. 

The restricted three-body problem Two bodies of finite masses, called primaries, revolve around their common center of mass in circular orbits and a third body with negligible mass moves under their gravitational attraction, but does not affect the orbits of the two primaries. In most astronomical applications the second primary has a small mass compared to the first primary, and consequently the motion of the third, massless, body is a perturbed Keplerian orbit. This is a model for the study of an asteroid (Jupiter being the second primary), a trans-Neptunian object (Neptune being the second primary) or an Earth-like planet in an extrasolar planetary system. 

The general three-body problem Three bodies with finite masses moving under their gravitational attraction. This is a model for a triple stellar system. In many astronomical applications one of the three bodies has a large mass and the other two bodies have small, but not negligible masses. This is a model for an extrasolar planetary system, or a system of two satellites moving around a major planet. In the latter two cases the two small bodies move in perturbed Keplerian orbits. 

Hadjidemetriou, J. (2002). Resonant periodic motion and the stability of extrasolar planetary systems. Cel. Mech. Dynam. Astron. 83, 141-154. 

Hadjidemetriou, J. D. and Psychoyos, D. (2003), Dynamics of extrasolar planetary systems 2/1 resonant motion. In Galaxies and chaos (G. Contopoulos and N. Voglis, eds.). Lectures Notes in Physics, Springer, 412-432. 

The results of 21st century space exploration are truly impossible to imagine. The Wright brothers flew for 2 8 seconds in 1903 and less than a century later there were tangible plans to establish a permanent base on the Moon in preparation for a manned landing on Mars. It was only in 1995 that the first extrasolar planet was identified definitively. As of January 2006, 153 extrasolar planetary systems have been identified including a total of at least... 

Mammana, Dennis L., and Donald W. McCarthy, Jr. Other Suns, Other Worlds The Search for Extrasolar Planetary Systems. New York St. Martin s Press, 1996. Mandelbrot, B. B. Fractals and Multifractals Noise, Turbulence, and Galaxies. New York Springer-Verlag, 1990. Mann, Charles, and Mark Plummer. The Aspirin Wars Money, Medicine and 100 Years of Rampant Competition. New York Knopf, 1991. 

The solar system is not unique in the universe, in the beginning of 2010 about 400 extrasolar planetary systems were known. The formation of such systems seems to be a normal process. 

Observations of extrasolar planetary systems have shown also that when the metallicity of the star becomes too high more massive planets orbiting close to the stars are likely. These could have destroyed Earth-sized objects there. 

Before the first extrasolar planets were detected, the observational evidence of dust around stars was a first hint to the existence of extrasolar planetary systems. 

Maser detection in the interstellar medium was described by Elitzur, 1987 [118]. Water maser emission at 22 GHz may be a hint for cometary impacts that occur in extrasolar planetary systems. Such radiosignatures were proposed by Cos-movici et al., 2001 [79]. During the impact of comet Shoemaker-Levy 1994 on Jupiter observations made with the 32-m dish Medicina radiotelescope (Bolgna, Italy) revealed the delivery of water and for the first time also a water maser in the solar system. After the comet s nucleus exploded in the upper part of Jupiter s atmosphere, this maser was produced. 

Water is one of the basic elements for life. It is even assumed that the evolution of life is only possible if there is liquid water present. A water molecule has some remarkable properties that make it quite unique in the universe. In the first chapter of this book we will review these basic properties of water and the role of water on Earth. All ancient civilizations realized the importance of water and their cities were constructed near great reservoirs of water. But is water unique on Earth Do we find water elsewhere in the solar system, on extrasolar planetary systems or in distant galaxies We will start the search for the presence of extraterrestrial water in our solar system. Surprisingly enough it seems that water in some form and sometimes in only minute quantities is found on any object in the solar system. Even on the planet nearest to the Sun, Mercury, there may be some water in the form of ice near its poles where never the light of Sun heats the surface. And there are objects in the solar system that are made up of a large quantity of water in terms of their mass, like comets and several satellites of the giant planets. 

Now, since the first extrasolar planetary systems have been detected, the search for water on such objects has just started. Because from observations it is very difficult to measure the spectroscopic signatures of the atmospheres of such planets, we have to wait for the newly planned observational facilities (both in space and on ground) some of them will be in operation very soon. 

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