Two planets at HD 191760

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Two planets at HD 191760

Post by Sirius_Alpha on 18th November 2008, 9:09 pm

Exoplanets from the CHEPS: Discovery of the Double Planet System HD191760
http://arxiv.org/abs/0811.2975

Jenkins et al. wrote:We report the discovery of planetary companions around HD191760 with orbital periods of 8.64+/-0.02 and 86.83+/-0.50 days, semimajor axes of 0.09 and 0.42 AU and masses of 0.29+/-0.05 and 7.20+/-0.44 MJ respectively. The star has a spectral type of G3IV/V and a metallicity of 0.29 dex. HD191760 adds to the list of metal-rich multiple planet systems. The periods indicate the planets are located at the 10:1 mean motion resonance points. The outer planet exerts a large reflex velocity of 322.17+/-18.98 m/s on HD191760, whereas the inner planet's amplitude is found to be 24.22+/-2.86 m/s. The best fit to the Doppler data suggest a low eccentricity of 0.04+/-0.12 for the inner planet and a somewhat larger eccentricity of 0.49+/-0.07 for the outer planet. Dynamical simulations show the system to be stable, at least for the next 100,000 years. However, the eccentricity of the inner planet is found to oscillate with a frequency of around 140 years which may be measurable with more epochs of high quality radial-velocity data. In addition we also refine the orbits found for HD48265b, HD143361b and HD154672b. These systems have been announced by the Magellan Planet Search.

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Re: Two planets at HD 191760

Post by Lazarus on 19th November 2008, 8:27 am

Interesting that they used the Systemic software to do the analysis of the orbits.
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Re: Two planets at HD 191760

Post by Edasich on 19th November 2008, 8:50 am

It's always nice to see a multi-planets system Very Happy

The innermost planet has the same mass of Saturn. Due to its extreme closeness to host star, its structure may likely resemble that of HD 149026 b (i.e 2/3rds of its mass being solid).
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Re: Two planets at HD 191760

Post by Lazarus on 26th November 2008, 12:36 pm

It has been withdrawn... for now...

(In fact, having entered the data into systemic, it seems that a single ~35 Jupiter mass brown dwarf on an eccentric orbit gives a better fit to the data than the two planet configuration; let's see how the additional data point affects things...)
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Re: Two planets at HD 191760

Post by Sirius_Alpha on 26th November 2008, 1:54 pm

expletive!

Well, let's wait for that data point... I sure hope this doesn't turn into a Gliese 317 c sort of thing.

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Re: Two planets at HD 191760

Post by Lazarus on 5th December 2008, 12:09 pm

What happened with GJ 317c?
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Re: Two planets at HD 191760

Post by Sirius_Alpha on 5th December 2008, 12:55 pm

It was retracted a day or two after it both planets were announced, and currently rests as unconfirmed, if I recall correctly.

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Re: Two planets at HD 191760

Post by Lazarus on 5th December 2008, 1:03 pm

Was it? It may have got shuffled around a bit on EPE, but there only seems to be one version of the paper on arXiv, and that states that the parameters are uncertain...
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Re: Two planets at HD 191760

Post by Lazarus on 27th May 2009, 6:02 pm

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Re: Two planets at HD 191760

Post by Sirius_Alpha on 27th May 2009, 6:53 pm

Good catch. I failed to remember HD 191760 had two unconfirmed planets when I read the abstract for this back when it came out.

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Re: Two planets at HD 191760

Post by Edasich on 28th May 2009, 6:41 am

Last week issue.

It seems there is no new detection since a month or more.
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