KOI-94 - Four transiting Planets

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Re: KOI-94 - Four transiting Planets

Post by Sirius_Alpha on 21st September 2012, 12:30 am

Planet-Planet Eclipse and the Rossiter-McLaughlin Effect of a Multiple Transiting System: Joint Analysis of the Subaru Spectroscopy and the Kepler Photometry
KOI-94 is found to be well-aligned with its star and coplanar.

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Re: KOI-94 - Four transiting Planets

Post by Lazarus on 21st September 2012, 6:07 pm

A planet-planet eclipse? Very nice. Not sure that has been observed in any of the other multi-transit systems.
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Re: KOI-94 - Four transiting Planets

Post by Sirius_Alpha on 21st September 2012, 9:26 pm

I don't believe it has.

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Re: KOI-94 - Four transiting Planets

Post by tommi59 on 22nd September 2012, 4:27 am

Why you do not believe?
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Re: KOI-94 - Four transiting Planets

Post by Edasich on 22nd September 2012, 10:30 am

tommi59 wrote:Why you do not believe?

I suppose Sirius isn't sure the planet-planet eclipse has been observed before KOI-94's case. Rolling Eyes
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Re: KOI-94 - Four transiting Planets

Post by tommi59 on 22nd September 2012, 12:29 pm

Was not observed but might be this case
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Re: KOI-94 - Four transiting Planets

Post by Sirius_Alpha on 22nd September 2012, 4:59 pm

Lazarus was stating
Not sure that has been observed in any of the other multi-transit systems.
And I was agreeing with him, to the best extent of my memory.

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KOI-94 - Four transiting Planets

Post by pochimax on 23rd September 2012, 3:42 am

And the paper shows that the farther from the star the easier to detect the rossiter effect (well, in comparison with the orbital RV). good news to confirm superearth planets in the HZ.
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Re: KOI-94 - Four transiting Planets

Post by Sirius_Alpha on 11th March 2013, 8:37 pm

The Mass of KOI-94d and a Relation for Planet Radius, Mass, and Incident Flux
http://arxiv.org/abs/1303.2150

We measure the mass of a modestly irradiated giant planet, KOI-94d. We wish to determine whether this planet, which is in a 22-day orbit and receives 2700 times as much incident flux as Jupiter, is as dense as Jupiter or rarefied like inflated hot Jupiters. KOI-94 also hosts 3 smaller transiting planets, all of which were detected by the Kepler Mission. With 26 radial velocities of KOI-94 from the W. M. Keck Observatory and a simultaneous fit to the Kepler light curve, we measure the mass of the giant planet and determine that it is not inflated. Support for the planetary interpretation of the other three candidates comes from gravitational interactions through transit timing variations, the statistical robustness of multi-planet systems against false positives, and several lines of evidence that no other star resides within the photometric aperture. The radial velocity analyses of KOI-94b and KOI-94e offer marginal (>2\sigma) mass detections, whereas the observations of KOI-94c offer only an upper limit to its mass. Using the KOI-94 system and other planets with published values for both mass and radius (138 exoplanets total, including 35 with M < 150 Earth masses), we establish two fundamental planes for exoplanets that relate their mass, incident flux, and radius from a few Earth masses up to ten Jupiter masses. These equations can be used to predict the radius or mass of a planet.

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Re: KOI-94 - Four transiting Planets

Post by Lazarus on 12th March 2013, 2:13 pm

KOI-94b looks like it could be quite a dense planet (though the error bar is large, as noted the mass detection is marginal). Haven't checked where the proposed parameters lie on the composition diagram though.
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Re: KOI-94 - Four transiting Planets

Post by Lazarus on 23rd October 2013, 1:23 pm

Also relevant to KOI-94: this post

Characterization of the KOI-94 System with Transit Timing Variation Analysis: Implication for the Planet-Planet Eclipse
http://arxiv.org/abs/1310.5771

Some points from the conclusion:
  1. Although the RV analysis results in a fairly large eccentricity for KOI-94c (ec = 0.43 0.23), the TTVs indicate a significantly smaller value. In fact, the stability analysis of the system favors the TTV result.
  2. The TTV best-fit value of md differs from the RV result md = 106 11M by ∼ 4σ level. If the TTV value is correct, KOI-94d may be inflated, in contrast to the conclusion obtained by Weiss et al. (2013).
  3. The TTV of the outermost planet KOI-94e is not well reproduced in the current modeling with the three planets. This might suggest the presence of additional planets and/or minor bodies that have evaded the detection so far.
Next planet-planet eclipse is predicted to occur in April 2026.
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