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Posted on 09/08/2008 7:16:52 PM PDT by SunkenCiv
The ensemble of now more than 250 discovered planetary systems displays a wide range of masses, orbits and, in multiple systems, dynamical interactions. These represent the end point of a complex sequence of events, wherein an entire protostellar disk converts itself into a small number of planetary bodies. Here, we present self-consistent numerical simulations of this process, which produce results in agreement with some of the key trends observed in the properties of the exoplanets. Analogs to our own solar system do not appear to be common, originating from disks near the boundary between barren and (giant) planet-forming.
(Excerpt) Read more at sciencemag.org ...
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Uncommon Earth...a new computer simulation... described in the Aug. 8 Science, is the first to trace from beginning to end how planetary systems form from an initial gas disk encircling a baby star. "The really striking result of the new model is how chaotic and even violent the average story of a planet's birth is," says Edward Thommes, an astrophysicist now at the University of Guelph in Ontario, Canada. The process is typically a big mess. "Planets get into each others' 'personal space,' gravitationally scattering each other. They compete with each other for gas from the disk that gives birth to them and lots of planets are lost along the way," he says. "It's almost like reality TV." ... "An amount of gas in between those two is where there's a relatively narrow range where systems like ours are the end result," Thommes says. But, he cautions, although analogues to the solar system are less common, the team did still see a handful of them after 100 simulations. "Although we may be weird, we're by no means unique," he says.
by Ashley Yeager
August 30th, 2008
that’s the
“diversity of extrasolar planets and planetary systems”?
PRECISELY!
The Architecture of Exoplanetary SystemsAre all planetary systems coplanar? Concordance cosmogony makes that prediction. It is, however, a prediction of extrasolar planetary system architecture as yet untested by direct observation for main sequence stars other than the Sun. To provide such a test, we propose to carry out FGS astrometric studies on four stars hosting seven companions. Our understanding of the planet formation process will grow as we match not only system architecture, but formed planet mass and true distance from the primary with host star characteristics for a wide variety of host stars and exoplanet masses. We propose that a series of FGS astrometric observations with demonstrated 1 millisecond of arc per-observation precision can establish the degree of coplanarity and component true masses for four extrasolar systems: HD 202206 {brown dwarf+planet}; HD 128311 {planet+planet}, HD 160691 = mu Arae {planet+planet}, and HD 222404AB = gamma Cephei {planet+star}. In each case the companion is identified as such by assuming that the minimum mass is the actual mass. For the last target, a known stellar binary system, the companion orbit is stable only if coplanar with the AB binary orbit.
NASA Hubble Space Telescope Daily Report #4685
Friday, August 29, 2008
SpaceRef
[Comments: Report of the Exoplanet Task Force to the Astronomy and Astrophysics Advisory Committee]Worlds Beyond: A Strategy for the Detection and Characterization of ExoplanetThis is a scientific strategy for the detection and characterization of extrasolar planets; that is, planets orbiting other stars. As such, it maps out over a 15-year horizon the techniques and capabilities required to detect and measure the properties of planets as small as Earth around stars as large as our own Sun.
Jonathan I. Lunine et al
Thursday, August 21, 2008
It shows how the technology pieces and their development fit together to achieve the primary goal of the strategy: if planets like Earth exist around stars within some tens of light years of our own Solar System, those planets will be found and their basic properties characterized. Essential to this strategy is not only the search for and examination of individual planets, but also a knowledge of the arrangement, or architecture, of planetary systems around as large a number of stars as possible; this is the second goal of the strategy.
The final goal of the strategy is the study of disks around stars, important both to understand the implications of the variety of exoplanet systems for planet formation, and to determine how many nearby stars have environments around them clean enough of debris that planets may be sought and, if found, characterized.
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Yeah, it’s not as if “goldilocks theorem” was dreamed up because it’s a nice sound byte and dinosaur media catchphrase or anything... ;’)
For tomorrow.
The Chaotic Genesis of Planets [ FREE PREVIEW ]
Scientific American | April 2008 | Douglas N. C. Lin
Posted on 05/01/2008 9:35:33 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/2009765/posts
Planets Were Formed From A Giant Mix, Suggests New AnalysisParticularly significant was the discovery of calcium aluminium inclusions, which are amongst the oldest solids in the Solar System and are thought to have formed close to the young Sun. This discovery suggests that components of the comet came from all over the early Solar System, with some dust having formed close to the Sun and other material coming from the asteroid belt between Mars and Jupiter. Since Wild-2 originally formed in the outer Solar System, this means that some of its composite material has travelled great distances.
Science News
Dec. 19, 2006
Comets Throw Light On Solar System's BeginningsA new picture of the composition of comets is emerging with the help of 21st century technology available at Diamond, the UK's national synchrotron light source, in Oxfordshire... Most of the icy, small planetary bodies that otherwise became comets went into forming the gas giant planets... a fraction ended up in the inner Solar System bringing water and biogenic elements of interest to Earth. Without this cometary transport, life on Earth may never have had a chance to start... Dr John Bridges, from the Space Research Centre, explains the results, "Comets are starting to look a lot more complicated than the old dusty iceball idea. For one thing Wild-2 contains material, like chromium oxides, from the hot inner Solar System -- so how did that material get mixed in with a comet which has spent most of its life beyond Neptune? ...we have also been finding X-ray signatures of iron oxides. These are important because they show that on the Wild-2 nucleus there could have been small trickles of water that deposited these minerals. Similar grains are found in carbonaceous chondrite meteorites. This might mean that there have been localised heating events perhaps caused by impact on the Wild-2 nucleus that melted some of its ice." ...Dr Bridges adds, "It's now becoming clear that not all comets are the same..."
Science Daily
Monday, September 8, 2008
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