Kepler News and Results (Thread 2)

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Re: Kepler News and Results (Thread 2)

Post by Edasich on 16th June 2017, 4:06 am

Additional companions to Kepler-448 and Kepler-693 from TTV. The latter turns out hosting both a Hot Jupiter both a close, eccentric stellar companion (mB = 0.143 MSol a = 2.8 or 5.8 AUs e =0.47), so that Kepler-693 b becomes Kepler-693 Ab.

Eccentric Companions to Kepler-448b and Kepler-693b: Clues to the Formation of Warm Jupiters

I report the discovery of non-transiting close companions to two transiting warm Jupiters (WJs), Kepler-448/KOI-12b (orbital period P=17.9days, radius Rp=1.23+0.06−0.05RJup) and Kepler-693/KOI-824b (P=15.4days, Rp=0.91±0.05RJup), via dynamical modeling of their transit timing and duration variations (TTVs and TDVs). The companions have masses of 22+7−5MJup (Kepler-448c) and 150+60−40MJup (Kepler-693c), and both are on eccentric orbits (e=0.65+0.13−0.09 for Kepler-448c and e=0.47+0.11−0.06 for Kepler-693c) with periastron distances of 1.5au. Moderate eccentricities are detected for the inner orbits as well (e=0.34+0.08−0.07 for Kepler-448b and e=0.2+0.2−0.1 for Kepler-693b). In the Kepler-693 system, a large mutual inclination between the inner and outer orbits (53+7−9deg or 134+11−10deg) is also revealed by the TDVs. This is likely to induce a secular oscillation of the inner WJ's eccentricity that brings its periastron close enough to the host star for tidal star-planet interactions to be significant. In the Kepler-448 system, the mutual inclination is weakly constrained and such an eccentricity oscillation is possible for a fraction of the solutions. Thus these WJs may be undergoing tidal migration to become hot Jupiters (HJs), although the migration via this process from beyond the snow line is disfavored by the close-in and massive nature of the companions. This may indicate that WJs can be formed in situ and could even evolve into HJs via high-eccentricity migration inside the snow line.
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Re: Kepler News and Results (Thread 2)

Post by Daniel on 19th June 2017, 1:05 pm



THe final Kepler catalog 2017
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Re: Kepler News and Results (Thread 2)

Post by Daniel on 19th June 2017, 1:24 pm



The New planets candidates in the HZ in the final catalog KOI-8012.01 seems similar in someway with TRAPPIST-1 planets.
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Re: Kepler News and Results (Thread 2)

Post by Led_Zep on 11th July 2017, 3:15 pm

https://www.nasa.gov/feature/jpl/hidden-stars-may-make-planets-appear-smaller

Hidden Stars May Make Planets Appear Smaller

« …In the new study, Furlan and Howell focused on 50 planets in the Kepler observatory's field of view whose masses and radii were previously estimated. These planets all orbit stars that have stellar companions within about 1,700 astronomical units. For 43 of the 50 planets, previous reports of their sizes did not take into account the contribution of light from a second star. That means a revision to their reported sizes is necessary.
In most cases, the change to the planets' reported sizes would be small. Previous research showed that 24 of the 50 planets orbit the bigger, brighter star in a binary pair. Moreover, Furlan and Howell determined that 11 of these planets would be too large to be planets if they orbited the fainter companion star. So, for 35 of the 50 planets, the published sizes will not change substantially.
But for 15 of the planets, they could not determine whether they orbit the fainter or the brighter star in a binary pair. For five of the 15 planets, the stars in question are of roughly equal brightness, so their densities will decrease substantially regardless of which star they orbit… »
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Re: Kepler News and Results (Thread 2)

Post by Sirius_Alpha on 13th July 2017, 3:29 pm

Is there a list of the 219 new planet candidates?
Also I'm a bit concerned about some of the planetary radii being reported in the newest update to the KOI catalogue -- some of the planets have reported radii above that of the Sun.

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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 27th July 2017, 12:26 pm

Teachey, Kipping & Schmitt "HEK VI: On the Dearth of Galilean Analogs in Kepler and the Exomoon Candidate Kepler-1625b I"
https://arxiv.org/abs/1707.08563

The occurrence rate of Galilean-analogs appears to be less than 0.38 to 95% confidence. The case of Kepler-1625 would be a ~Neptune-size satellite orbiting a 10 Jupiter-mass planet. They note that they are cautious about the reality of this system but have secured Hubble Space Telescope observations for the October 2017 transit.
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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 28th July 2017, 6:59 am

Also worth reading this blogpost on Scientific American by Alex Teachey: apparently someone was going to do a media release based on the Hubble proposal which made them decide to publish Kepler-1625 before actually doing the Hubble observations.

They consider the population statistics to be the more important and solid result (David Kipping's Twitter feed).
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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 22nd August 2017, 4:51 am

Possible comets around the F2V star KIC 3542116, plus a similarly-shaped transit around KIC 11084727, also an F2V.

Rappaport et al. "Likely Transiting Exocomets Detected by Kepler"
https://arxiv.org/abs/1708.06069

Seem to be better candidates for comets than the infamous Boyajian's Star.
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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 18th October 2017, 3:31 am

Update on the exomoon candidate around Kepler-1625b:

René Heller "The nature of the giant exomoon candidate Kepler-1625 b-i"
https://arxiv.org/abs/1710.06209

A Neptune-mass exomoon around a giant planet or low-mass BD would not be compatible with the common mass scaling relation of the solar system moons about gas giants. The case of a mini-Neptune around a high-mass BD or a VLMS, however, would be located in a similar region of the satellite-to-host mass ratio diagram as Proxima b, the TRAPPIST-1 system, and LHS 1140 b. The capture of a Neptune-mass object around a 10 MJup planet during a close binary encounter is possible in principle. The ejected object, however, would have had to be a super-Earth object, raising further questions of how such a system could have formed. In summary, this exomoon candidate is barely compatible with established moon formation theories. If it can be validated as orbiting a super-Jovian planet, then it would pose an exquisite riddle for formation theorists to solve.
VLMS = very low mass star
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Re: Kepler News and Results (Thread 2)

Post by Sirius_Alpha on 6th November 2017, 9:48 pm

Validation of small Kepler transiting planet candidates in or near the habitable zone
https://arxiv.org/abs/1711.01267

A main goal of NASA's Kepler Mission is to establish the frequency of potentially habitable Earth-size planets (eta Earth). Relatively few such candidates identified by the mission can be confirmed to be rocky via dynamical measurement of their mass. Here we report an effort to validate 18 of them statistically using the BLENDER technique, by showing that the likelihood they are true planets is far greater than that of a false positive. Our analysis incorporates follow-up observations including high-resolution optical and near-infrared spectroscopy, high-resolution imaging, and information from the analysis of the flux centroids of the Kepler observations themselves. While many of these candidates have been previously validated by others, the confidence levels reported typically ignore the possibility that the planet may transit a different star than the target along the same line of sight. If that were the case, a planet that appears small enough to be rocky may actually be considerably larger and therefore less interesting from the point of view of habitability. We take this into consideration here, and are able to validate 15 of our candidates at a 99.73% (3 sigma) significance level or higher, and the other three at slightly lower confidence. We characterize the GKM host stars using available ground-based observations and provide updated parameters for the planets, with sizes between 0.8 and 2.9 Earth radii. Seven of them (KOI-0438.02, 0463.01, 2418.01, 2626.01, 3282.01, 4036.01, and 5856.01) have a better than 50% chance of being smaller than 2 Earth radii and being in the habitable zone of their host stars.

Magellan II/PFS Radial Velocity Mass Measurements of the Super-Earth Planets Transiting GJ 9827 at 30 Parsecs
https://arxiv.org/abs/1711.01359

The Kepler mission showed us that planets with sizes between that of Earth and Neptune appear to be the most common type in our Galaxy. These "super-Earths" continue to be of great interest for exoplanet formation, evolution, and composition studies. However, the number of super-Earths with well-constrained mass and radius measurements remains small (40 planets with σmass< 25 %), due in part to the faintness of their host stars causing ground-based mass measurements to be challenging. Recently, three transiting super-Earth planets were detected by the K2 mission around the nearby star GJ 9827/HIP115752, at only 30 pc away. The radii of the planets span the "radius gap" detected by Fulton et al. (2017), and all orbit within ~6.5 days, easing follow-up observations. Here we report radial velocity (RV) observations of GJ 9827, taken between 2010 and 2016 with the Planet Finder Spectrograph on the Magellan II Telescope. We employ two different RV analysis packages, SYSTEMIC and RadVel, to derive masses and thus densities of the GJ 9827 planets. Our RV observations are not able to place strong mass constraints on the two outer planets (c & d) but do indicate that planet b, at 1.64 R⊕ and ~8 M⊕, is one of the most massive (and dense) super-Earth planets detected to date.

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