OGLE-GD-ECL-11388 (AB)b

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OGLE-GD-ECL-11388 (AB)b

Post by Edasich on 22nd December 2016, 12:06 pm

A new possible circumbinary planet in Galactic Disk.

Photometric Properties of the HW Vir-type Binary OGLE-GD-ECL-11388

We present the first extensive photometric results for the eclipsing binary OGLE-GD-ECL-11388 with a period of about 3.5 hours located in the Galactic disk. For the photometric solutions, we obtained the BVI light curves from both the KMTNet observations in 2015 and the OGLE-III survey data from 2001-2009, which show striking reflection effects and very sharp eclipses. The light curve synthesis indicates that the eclipsing system is a HW Vir-type binary with a mass ratio of q = 0.289, an orbital inclination of i = 81.9 deg, and a temperature ratio between both components of T 2/T 1 = 0.091. A frequency analysis was applied to the light residuals from our binary model; however, no pulsating periodicity from the subdwarf B-type primary component was detected under signal-to-noise amplitude ratios larger than 4.0. A total of 27 minimum epochs spanning 15 yr were used to analyze the eclipse timing variations of OGLE-GD-ECL-11388. It was found that the orbital period has varied due to a continuous period decrease at a rate of dP/dt = -1.1 ื 10-8 day yr-1 or a sinusoidal oscillation with a semiamplitude of K = 35 s and a cycle of P 3 = 8.9 yr. The period decrease may be explained by an angular momentum loss via magnetic stellar wind braking or may be only a part of the sinusoidal variation. We think the most likely interpretation of the orbital period change, at present, is the light-time effect via the presence of a third body with a mass of {M}3\sin {i}3=12.5 M Jup, putting it in the boundary zone between planets and brown dwarfs.

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Re: OGLE-GD-ECL-11388 (AB)b

Post by Lazarus on 22nd December 2016, 2:24 pm

Judging by eye from figure 4, the sine wave fit looks rather contrived. Phase coverage looks pretty bad, I wouldn't be entirely surprised if the conclusions about the third body get substantially revised when more data is available.

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Re: OGLE-GD-ECL-11388 (AB)b

Post by Shellface on 22nd December 2016, 6:58 pm

Did this seriously get through peer review?!

The observations are so tightly clustered together that the long-period variability is basically unresolved, so the data effectively consists of 5 datapoints. Attempting to fit anything more than a parabola to this is overfitting.

I decided to quickly throw this into systemic. While their solution does converge on a fit (chi2 = 5.43), the parameter space is so poorly resolved (because of the crap sampling) that this is entirely meaningless; for example, a fit with sinusoid period = 1.30 days provides chi2 = 4.82. Meanwhile, a simple parabola has a chi2 of 8.21, which is not all that much worse.

There may or may not be a signal hidden in here, but this data is nowhere near good enough to find out.

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Re: OGLE-GD-ECL-11388 (AB)b

Post by Edasich on 24th December 2016, 4:50 am

Despite our skepticism both this candidate and DW UMa (AB)b too have been listed in EPE:  Rolling Eyes

http://exoplanet.eu/catalog/ogle-gd-ecl-11388_b/
http://exoplanet.eu/catalog/dw_uma_b/

I wish they were as much prompt in adding validated transiting exopanets, there are tens unlisted from Kepler and K2.

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Re: OGLE-GD-ECL-11388 (AB)b

Post by qubit on 1st January 2017, 8:58 am

Edasich wrote:Despite our skepticism both this candidate and DW UMa (AB)b too have been listed in EPE:  Rolling Eyes

I wish they were as much prompt in adding validated transiting exopanets, there are tens unlisted from Kepler and K2.

Just a thought... maybe people who maintain exoplanet databases can simply do it in Wikipedia instead?
(1) no need to maintain a separate website.
(2) whenever one maintainer of the database loses interest or ability to keep it updated, there will be others willing to step up.

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Re: OGLE-GD-ECL-11388 (AB)b

Post by Sirius_Alpha on 1st January 2017, 11:09 am

The problem with Wikipedia is that anybody can edit it. I'm finding NASA's Exoplanet Archive is pretty decent. It features links to both summary pages on the planets as well as photometry and spectroscopy data.
http://exoplanetarchive.ipac.caltech.edu/

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Re: OGLE-GD-ECL-11388 (AB)b

Post by Stalker on 1st January 2017, 3:16 pm

I'm creating a new version of my website, it will still be in french (for the moment) but I will try to make a "submit an update" application. If my website is good enough I will make the code public and I hope we can create an internationnal collaborative catalog.

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Re: OGLE-GD-ECL-11388 (AB)b

Post by qubit on 2nd January 2017, 4:29 am

Sirius_Alpha wrote:The problem with Wikipedia is that anybody can edit it.

Practice shows that this is not a huge problem. There are millions of articles there, vast majority of them are quite good.
Edit wars are a problem for politically sensitive topics and such. It's unlikely that there will often be heated discussions about a particular exoplanet; but if there will be, Wikipedia already has ways of dealing with this problem.

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Re: OGLE-GD-ECL-11388 (AB)b

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