http://oklo.org/2005/12/21/i-wish-i-had-an-evil-twin/ characterizing planetary systems Wed, 18 Apr 2012 18:53:22 +0000 hourly 1 http://wordpress.org/?v=3.3.1 http://oklo.org/2005/12/21/i-wish-i-had-an-evil-twin/comment-page-1/#comment-373 systemic - extrasolar trojans Wed, 11 Oct 2006 20:44:50 +0000 http://oklo.org/?p=24#comment-373 [...] Last week, during my visit to Harvard CfA, I talked to Eric Ford, who has been exploring the idea searching for trojan companions to extrasolar planets. He pointed out that the discovery of a body in a trojan configuration with a known extrasolar planet would provide an important test of theories of hot Jupiter formation. [...] [...] Last week, during my visit to Harvard CfA, I talked to Eric Ford, who has been exploring the idea searching for trojan companions to extrasolar planets. He pointed out that the discovery of a body in a trojan configuration with a known extrasolar planet would provide an important test of theories of hot Jupiter formation. [...]

]]> http://oklo.org/2005/12/21/i-wish-i-had-an-evil-twin/comment-page-1/#comment-363 systemic - and inside the second envelope… Mon, 09 Oct 2006 00:34:46 +0000 http://oklo.org/?p=24#comment-363 [...] [For more about 1:1 resonances, see this post and this post. For a discussion about the audio wave forms that they produce, see this post.] [...] [...] [For more about 1:1 resonances, see this post and this post. For a discussion about the audio wave forms that they produce, see this post.] [...]

]]> http://oklo.org/2005/12/21/i-wish-i-had-an-evil-twin/comment-page-1/#comment-19 Centauri Dreams » Blog Archive » Systemic: Working with Extrasolar Data Thu, 29 Dec 2005 14:58:26 +0000 http://oklo.org/?p=24#comment-19 [...] Be aware, too, that the Systemic site contains an ongoing weblog laced not only with gorgeous photography but Laughlin’s insightful posts, the most recent of which discusses, in addition to the Lagrangian points associated with Jupiter and the Sun, the question of whether a stable orbit exists on the opposite side of the Sun from the Earth and in the Sun’s habitable zone — a twin of Earth, in other words. The intriguing result is that such an orbit is nonlinearly stable. Laughlin describes the scenario this way: As one planet tries to pass the other one up, it receives a forward gravitational pull. This forward pull gives the planet energy, which causes it to move to a larger-radius orbit, which causes its orbital period to increase, which causes it to begin to lag behind. Likewise, the planet which is about to be passed up receives a backward gravitational pull. This backward pull drains energy from the orbit, causes the semi-major axis to decrease, and causes the period to get shorter. The two planets are thus able to toss a bit of their joint orbital energy back and forth like a hot potato, and orbit in a perfectly stable variety of a 1:1 orbital resonance, known as a horseshoe configuration. The horseshoe orbit is an example of the negative heat capacity of self-gravitating systems, which is one of the most important concepts in astrophysics: If you try to drain heat away from a self gravitating object, it gets hotter. [...] [...] Be aware, too, that the Systemic site contains an ongoing weblog laced not only with gorgeous photography but Laughlin’s insightful posts, the most recent of which discusses, in addition to the Lagrangian points associated with Jupiter and the Sun, the question of whether a stable orbit exists on the opposite side of the Sun from the Earth and in the Sun’s habitable zone — a twin of Earth, in other words. The intriguing result is that such an orbit is nonlinearly stable. Laughlin describes the scenario this way: As one planet tries to pass the other one up, it receives a forward gravitational pull. This forward pull gives the planet energy, which causes it to move to a larger-radius orbit, which causes its orbital period to increase, which causes it to begin to lag behind. Likewise, the planet which is about to be passed up receives a backward gravitational pull. This backward pull drains energy from the orbit, causes the semi-major axis to decrease, and causes the period to get shorter. The two planets are thus able to toss a bit of their joint orbital energy back and forth like a hot potato, and orbit in a perfectly stable variety of a 1:1 orbital resonance, known as a horseshoe configuration. The horseshoe orbit is an example of the negative heat capacity of self-gravitating systems, which is one of the most important concepts in astrophysics: If you try to drain heat away from a self gravitating object, it gets hotter. [...]

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