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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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 27th November 2017, 9:20 am

Lazarus wrote:The KIC 7177553 system is an SB4 system containing an eclipsing binary and a second binary pair. The eclipse timing of this system suggests the presence of a ~5 Jupiter mass planet in an eccentric orbit around the eclipsing pair.

Lehmann et al. "KIC 7177553: a quadruple system of two close binaries"
http://arxiv.org/abs/1601.02926

The details of the planetary companion can be found in an earlier paper (see table 6):

Borkovits et al. "A Comprehensive Study of the Kepler Triples via Eclipse Timing"
http://arxiv.org/abs/1510.08272
Another update to the system:

MacDonald & Mullan "The Age of the KIC 7177553 System"
https://arxiv.org/abs/1609.00942

Evolutionary models predict that the system is very young, age around 33–36 Myr. The stars would then be in the pre-main sequence stage. If so, the planet may resemble the HR 8799 planets, but direct detection would be much more difficult.
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Re: Kepler News and Results (Thread 2)

Post by Sirius_Alpha on 13th December 2017, 9:32 pm

Ugh...

Robo-AO Kepler Survey IV: the effect of nearby stars on 3857 planetary candidate systems
https://arxiv.org/abs/1712.04454

We present the overall statistical results from the Robo-AO Kepler planetary candidate survey, comprising of 3857 observations with 0.1"-resolution of planetary candidate systems with Robo-AO, an automated laser adaptive optics system. These observations reveal previously unknown nearby stars blended with the planetary candidate host star which alter the derived planetary radii or may be the source of an astrophysical false positive transit signal. In the first three papers in the survey, we detected 440 nearby stars around 3313 planetary candidate host stars. In this paper, we present observations of 532 planetary candidate host stars, detecting 94 companions around 88 stars; 84 of these companions have not previously been observed in high-resolution. We also report 50 more-widely-separated companions near 715 targets previously observed by Robo-AO. We derive corrected planetary radius estimates for the 814 planetary candidates in systems with a detected nearby star. If planetary candidates are equally likely to orbit the primary or secondary star, the radius estimates for planetary candidates in systems with likely bound nearby stars increase by a factor of 1.54, on average. We find that 35 previously-believed rocky planet candidates are likely not rocky due to the presence of nearby stars. From the combined datasets from the complete Robo-AO KOI survey, we find that 14.5\pm0.5% of planetary candidate hosts have a nearby star with 4", while 1.2% have two nearby stars and 0.08% have three. We find that 16% of Earth-sized, 13% of Neptune-sized, 14% of Saturn-sized, and 19% of Jupiter-sized planet candidates have stars close enough to affect their radius estimates.

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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 19th December 2017, 8:10 pm

Progress update on Kepler-1625: https://www.youtube.com/watch?v=vDXJAtLLiyw
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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 21st December 2017, 4:51 pm

Update for the evaporating planet KOI-2700:

Garai "Light-curve analysis of KOI 2700b: the second extrasolar planet with a comet-like tail"
https://arxiv.org/abs/1712.07461
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Re: Kepler News and Results (Thread 2)

Post by Led_Zep on 8th February 2018, 4:53 pm

Press release about GJ 9827 :

https://carnegiescience.edu/news/are-you-rocky-or-are-you-gassy-carnegie-astronomers-help-unlock-mysteries-super-earths

"...teams of Carnegie scientists including co-authors Steve Shectman, Sharon Wang, Paul Butler, Jeff Crane, and Ian Thompson, have been monitoring GJ 9827 with their Planet Finding Spectrograph (PFS), so they were able to constrain the masses of the three planets with data in hand, rather than having to scramble to get many new observations of GJ 9827..."
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Re: Kepler News and Results (Thread 2)

Post by Sirius_Alpha on 26th February 2018, 9:41 pm

Validation and Initial Characterization of the Long Period Planet Kepler-1654 b
https://arxiv.org/abs/1802.08945

Fewer than 20 transiting Kepler planets have periods longer than one year. Our early search of the Kepler light curves revealed one such system, Kepler-1654 b (originally KIC~8410697b), which shows exactly two transit events and whose second transit occurred only 5 days before the failure of the second of two reaction wheels brought the primary Kepler mission to an end. A number of authors have also examined light curves from the Kepler mission searching for long period planets and identified this candidate. Starting in Sept. 2014 we began an observational program of imaging, reconnaissance spectroscopy and precision radial velocity measurements which confirm with a high degree of confidence that Kepler-1654 b is a {\it bona fide} transiting planet orbiting a mature G2V star (Teff=5580K, [Fe/H]=-0.08) with a semi-major axis of 2.03 AU, a period of 1047.84 days and a radius of 0.82±0.02 RJup. Radial Velocity (RV) measurements using Keck's HIRES spectrometer obtained over 2.5 years set a limit to the planet's mass of <0.5 (3σ) MJup. The bulk density of the planet is similar to that of Saturn or possibly lower. We assess the suitability of temperate gas giants like Kepler-1654b for transit spectroscopy with the James Webb Space Telescope since their relatively cold equilibrium temperatures (Tpl∼200K) make them interesting from the standpoint of exo-planet atmospheric physics. Unfortunately, these low temperatures also make the atmospheric scale heights small and thus transmission spectroscopy challenging. Finally, the long time between transits can make scheduling JWST observations difficult---as is the case with Kepler-1654b.

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Re: Kepler News and Results (Thread 2)

Post by Sirius_Alpha on 27th February 2018, 9:52 pm

30% of sun-like stars have Kepler-like systems, but no evidence for the so-called "Kepler dichotomy."

About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of their Intrinsic Architecture
https://arxiv.org/abs/1802.09526

We constrain the intrinsic architecture of Kepler planetary systems by modeling the observed multiplicities of the transiting planets (tranets) and their transit timing variations (TTVs). We robustly determine that the fraction of Sun-like stars with Kepler-like planets, ηKepler, is 30±3%. Here Kepler-like planets are planets that have radii Rp≳R⊕ and orbital periods P<400~days. Our result thus significantly revises previous claims that more than 50\% of Sun-like stars have such planets. Combining with the average number of Kepler planets per star (∼0.9), we obtain that on average each planetary system has 3.0±0.3 planets within 400 days. We also find that the dispersion in orbital inclinations of planets within a given planetary system, σi,k, is a steep function of its number of planets, k. This can be parameterized as σi,k∝kα and we find that −4<α<−2 at 2-σ level. Such a distribution well describes the observed multiplicities of both tranets and TTVs with no excess of single tranets. Therefore we do not find evidence supporting the so-called "Kepler dichotomy." Together with a previous study on orbital eccentricities, we now have a consistent picture: the fewer planets in a system, the hotter it is dynamically. We discuss briefly possible scenarios that lead to such a trend. Despite our Solar system not belonging to the Kepler club, it is interesting to notice that the Solar system also has three planets within 400 days and that the inclination dispersion is similar to Kepler systems of the same multiplicity.

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Re: Kepler News and Results (Thread 2)

Post by Sirius_Alpha on 25th March 2018, 9:16 pm

An accurate mass determination for Kepler-1655b, a moderately-irradiated world with a significant volatile envelope
https://arxiv.org/abs/1803.08820

We present the confirmation of a small, moderately-irradiated (F = 155 +/- 7 Fearth) Neptune with a substantial gas envelope in a P=11.8728787+/-0.0000085-day orbit about a quiet, Sun-like G0V star Kepler-1655. Based on our analysis of the Kepler light curve, we determined Kepler-1655b's radius to be 2.213+/-0.082 Rearth. We acquired 95 high-resolution spectra with TNG/HARPS-N, enabling us to characterize the host star and determine an accurate mass for Kepler-1655b of 5.0+3.1/-2.8 Mearth via Gaussian-process regression. Our mass determination excludes an Earth-like composition with 98\% confidence. Kepler-1655b falls on the upper edge of the evaporation valley, in the relatively sparsely occupied transition region between rocky and gas-rich planets. It is therefore part of a population of planets that we should actively seek to characterize further.

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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 26th March 2018, 3:54 pm

Insolation 155 times that of the Earth. "Moderately-irradiated". You've got to love exoplanets...
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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 30th March 2018, 6:32 am

Constraints on the occurrence of rings around transiting planets from the Kepler mission

Aizawa et al. "Systematic Search for Rings around Kepler Planet Candidates: Constraints on Ring Size and Occurrence Rate"
https://arxiv.org/abs/1803.09114
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Re: Kepler News and Results (Thread 2)

Post by Sirius_Alpha on 1st April 2018, 8:51 pm

Doubts cast on Kepler-452b.

Kepler's Earth-like Planets Should Not Be Confirmed Without Independent Detection: The Case of Kepler-452b
https://arxiv.org/abs/1803.11307

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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 26th April 2018, 5:08 pm

A study of the infamous HD 188753 triple system with Kepler asteroseismology data.

Marcadon et al. "Asteroseismic and orbital analysis of the triple star system HD 188753 observed by Kepler"
https://arxiv.org/abs/1804.09296
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Re: Kepler News and Results (Thread 2)

Post by Lazarus on 27th April 2018, 5:58 pm

Latest update from David Kipping on the Kepler-1625 exomoon candidate:

https://twitter.com/david_kipping/status/989647243908034560

A lot of you may be wondering what’s going on with @HEK_Project #exomoon candidate K1625. @alexteachey & I are really doing overtime on this but by geeze is the analysis complicated! Don’t fret we’re close but there is some serious unpacking to explain about this one. Stay tuned!

I read that as leaning towards the potential for a nastily subtle false positive, but will have to wait and see.
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Re: Kepler News and Results (Thread 2)

Post by Led_Zep on 2nd May 2018, 4:24 am

https://arxiv.org/abs/1805.00231

Revised Radii of Kepler Stars and Planets using Gaia Data Release 2

A critical bottleneck for stellar astrophysics and exoplanet science using data from the Kepler mission has been the lack of precise radii and evolutionary states of the observed target stars. Here we present revised radii of 186,813 Kepler stars derived by combining parallaxes from Gaia Data Release 2 with the DR25 Kepler Stellar Properties Catalog. The median radius precision is ≈ 8%, a factor 4-5 improvement over previous estimates for typical Kepler stars. We find that ≈ 65% (≈ 128,000) of all Kepler targets are main-sequence stars, ≈ 23% (≈ 40,600) are subgiants, and ≈ 12% (≈ 23,000) are red giants, demonstrating that subgiant contamination is less severe than previously thought and that the Kepler parent population mostly consists of unevolved main-sequence stars. Using the revised stellar radii, we recalculate the radii for 2218 confirmed and 1958 candidate exoplanets. Our results confirm the presence of a gap in the radius distribution of small, close-in planets, but yield evidence that the gap is mostly limited to incident fluxes > 200F earth and may be located closer to 2R earth . We furthermore find several confirmed exoplanets which occupy the "hot super-Earth desert", detect direct evidence for a correlation of gas-giant planet inflation with increasing incident flux, and establish a bona-fide sample of 8 confirmed planets and 34 planet candidates with <2R earth in the habitable zone. The results presented here demonstrate the enormous potential for the precise characterization of stellar and exoplanet populations using the transformational dataset provided by Gaia
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