Comments on: 436 again http://oklo.org/2008/01/22/436-again/ characterizing planetary systems Wed, 18 Apr 2012 18:53:22 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: thiessen http://oklo.org/2008/01/22/436-again/comment-page-1/#comment-4443 thiessen Sun, 03 Feb 2008 08:15:13 +0000 http://oklo.org/?p=266#comment-4443 There's another transit curve on the AXA site dated February 1 2008. These are the numbers I'm getting to put into the TDS file. I'll add an error estimate of 0.001 to the two transits that lack numbers. 2454222.616 0.001 2454238.47926 2454251.6993 2454280.78149 0.00016 2454465.8498 0.00179 2454497.5790 0.0025 Are these the correct numbers? I'll admit I'm not sure about the distinction between JD and HJD or mid and ephem numbers. Chris There’s another transit curve on the AXA site dated February 1 2008. These are the numbers I’m getting to put into the TDS file. I’ll add an error estimate of 0.001 to the two transits that lack numbers.

2454222.616 0.001
2454238.47926
2454251.6993
2454280.78149 0.00016
2454465.8498 0.00179
2454497.5790 0.0025

Are these the correct numbers? I’ll admit I’m not sure about the distinction between JD and HJD or mid and ephem numbers.

Chris

]]> By: greg http://oklo.org/2008/01/22/436-again/comment-page-1/#comment-4394 greg Wed, 23 Jan 2008 21:30:35 +0000 http://oklo.org/?p=266#comment-4394 Hi Andy, Indeed. I see no indication that this claimed planet is real, but it'll be interesting to see whether the self-consistent fit has both resonant arguments librating. Occams razor works against the idea that Butler et al. missed the transit which then, amazingly, precessed into view. The Butler et al. photometry was based on phase-folded data, which, when low-amplitude signals are present, is notoriously tough to deal with. In all likelihood, the transit signal is actually present in the clump of low points on the Butler et al. plot, muddled perhaps by long-term systematic errors in the time series. The timing data collected to date shows no evidence of planet-planet induced timing variations. That said, Gliese 436 has surprised us in the past.... (Comment edited slightly 1/24/08. The original version was overly harsh.) Hi Andy,

Indeed. I see no indication that this claimed planet is real, but it’ll be interesting to see whether the self-consistent fit has both resonant arguments librating.

Occams razor works against the idea that Butler et al. missed the transit which then, amazingly, precessed into view. The Butler et al. photometry was based on phase-folded data, which, when low-amplitude signals are present, is notoriously tough to deal with. In all likelihood, the transit signal is actually present in the clump of low points on the Butler et al. plot, muddled perhaps by long-term systematic errors in the time series.

The timing data collected to date shows no evidence of planet-planet induced timing variations.

That said, Gliese 436 has surprised us in the past….

(Comment edited slightly 1/24/08. The original version was overly harsh.)

]]> By: Centauri Dreams » Blog Archive » A ‘Super Earth’ Around GJ 436? http://oklo.org/2008/01/22/436-again/comment-page-1/#comment-4393 Centauri Dreams » Blog Archive » A ‘Super Earth’ Around GJ 436? Wed, 23 Jan 2008 20:20:59 +0000 http://oklo.org/?p=266#comment-4393 [...] The radial velocity data on this system is consistent with a planet that matches up with these properties (but see systemic for a more detailed look, and reservations on this), and may indicate still more planets: Indeed, the system around GJ 436 shows striking resemblances to that around the M-type star Gl 581 (Udry et al. 2007), and thus its planets may experience changes in the orbital elements, perhaps eventually undergoing transits in spite of a previously null result… Our study provides yet another illustration of the variety of exoplanet systems and highlights the potential for complex dynamical histories that imply sizeable variations of the planets’ orbital elements, like the eccentricity, over timescales of decades. [...] [...] The radial velocity data on this system is consistent with a planet that matches up with these properties (but see systemic for a more detailed look, and reservations on this), and may indicate still more planets: Indeed, the system around GJ 436 shows striking resemblances to that around the M-type star Gl 581 (Udry et al. 2007), and thus its planets may experience changes in the orbital elements, perhaps eventually undergoing transits in spite of a previously null result… Our study provides yet another illustration of the variety of exoplanet systems and highlights the potential for complex dynamical histories that imply sizeable variations of the planets’ orbital elements, like the eccentricity, over timescales of decades. [...]

]]> By: andy http://oklo.org/2008/01/22/436-again/comment-page-1/#comment-4383 andy Wed, 23 Jan 2008 13:50:54 +0000 http://oklo.org/?p=266#comment-4383 Hmmm... it seems that the ~5-day planet is hard to find. However quite a few of the fits uploaded contain a 53-day planet of around 12-13 Earth masses. Would such a planet be able to cause the observed perturbations and maintain the eccentricity of planet "b"? Hmmm… it seems that the ~5-day planet is hard to find. However quite a few of the fits uploaded contain a 53-day planet of around 12-13 Earth masses. Would such a planet be able to cause the observed perturbations and maintain the eccentricity of planet “b”?

]]> By: andy http://oklo.org/2008/01/22/436-again/comment-page-1/#comment-4348 andy Tue, 22 Jan 2008 12:59:35 +0000 http://oklo.org/?p=266#comment-4348 This system is a good example of why the top two peaks in the 1-10 day range should be displayed in the periodograms. I get a peak at 1.1997 days which is much stronger than the ~5 day peak, which is visible in the graph but sufficiently narrow to be quite hard to hit. This system is a good example of why the top two peaks in the 1-10 day range should be displayed in the periodograms. I get a peak at 1.1997 days which is much stronger than the ~5 day peak, which is visible in the graph but sufficiently narrow to be quite hard to hit.

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