Kepler News and Results (Thread 2)

Lazarus wrote:

Supermassive? Hardly. At a mere 3k solar masses it would be a far more exotic beast, one of those elusive intermediate-mass black holes.

According to the KOI overview, it should be 2.335.

Even with "only" 3.3 Solar masses it's really a massive A-type star for a transiting exoplanet host.

Using the "super-stacking" strategy that had previously been used for exomoons to look for Trojans in the Kepler data.

Hippke & Angerhausen "A statistical search for a population of Exo-Trojans in the Kepler dataset"
http://arxiv.org/abs/1508.00427

No individual candidates found, but some tentative hints that Trojans may be more common for planets with orbital periods longer than about 60 days.

Spotted in A&A forthcoming...

Planetary candidates around the pulsating sdB star KIC5807616 considered doubtful
J. Krzesinski
Received: 17 April 2015 / Accepted: 12 June 2015
DOI: http://dx.doi.org/10.1051/0004-6361/201526346

KIC 5807616 = KOI-55 = Kepler-70

I'm not terribly surprised. When it was announced, I remember thinking that I could come up with about a million* alternative explanations.

*two or three.

The KIC 5807616 paper is now available via Latest Articles Free. Interesting arguments.

Boyajian et al. "Planet Hunters X. KIC 8462852 - Where's the Flux?"
http://arxiv.org/abs/1509.03622

Perplexing data from KIC 8462852, possibly a family of exocomets passing in front of the star?

I hadn't heard about this star before, but wow - those are some violent variations. On a simple level, they do look quite like transits of diffuse, irregular objects.

With such large variations and a fairly bright star, ground-based observation of the events should be possible, though the lack of predictability in the time of the events makes that challenging. As so much flux is blocked during the events, they ought to leave a detectable spectroscopic signature, if the star is observed during transit.

An interesting implication here is that transiting comets can leave large photometric signatures, depending (presumably) on the mass loss rate. Transiting comets around Beta Pictoris have been identified spectroscopically, so logically they should be observable photometrically, too, though how large a transit they leave is an open question. That seems like an interesting endeavour…

Numerical and Analytical Modelling of Transit Time Variations
http://arxiv.org/abs/1510.02476

Quote :

We develop and apply methods to extract planet masses and eccentricities from observed transit time variations (TTVs). First, we derive simple analytic expressions for the TTV that include the effects of both first- and second-order resonances. Second, we use N-body Markov chain Monte Carlo (MCMC) simulations, as well as the analytic formulae, to measure the masses and eccentricities of ten planets discovered by Kepler that have not previously been analyzed. Most of the ten planets have low densities. Using the analytic expressions to partially circumvent degeneracies, we measure small eccentricities of a few percent or less.

As they say in the abstract, this work presents masses and densities for some Kepler planets (Kepler-307 b and c, Kepler-128 b and c, Kepler-26 b and c, Kepler-33 c, d, e and f). Most are low-density mini-Neptunes. For one of them, the maximum likelihood value of the mass is 0.8 Earth-masses, representing a sub-Earth-mass low density planet, but the 1-sigma range extends all the way to 3.3 Earth-masses. The two planets at Kepler-128 appear to be much more terrestrial, with masses, radii and densities comparable to Earth.

I wonder how such low-density sub-Earth mass planets could form :?

Several eclipsing binaries with candidate planetary/substellar circumbinary companions

A Comprehensive Study of the Kepler Triples via Eclipse Timing

Quote :

We produce and analyze eclipse time variation (ETV) curves for some 2600 Kepler binaries. We find good to excellent evidence for a third body in 222 systems via either the light-travel-time (LTTE) or dynamical effect delays. Approximately half of these systems have been discussed in previous work, while the rest are newly reported here. Via detailed analysis of the ETV curves using high-level analytic approximations, we are able to extract system masses and information about the three-dimensional characteristics of the triple for 62 systems which exhibit both LTTE and dynamical delays; for the remaining 160 systems we give improved LTTE solutions. New techniques of preprocessing the flux time series are applied to eliminate false positive triples and to enhance the ETV curves. The set of triples with outer orbital periods shorter than ∼2000 days is now sufficiently numerous for meaningful statistical analysis. We find that (i) there is a peak near i_m~40 deg in the distribution of the triple vs. inner binary mutual inclination angles that provides strong confirmation of the operation of Kozai-Lidov cycles with tidal friction; (ii) the median eccentricity of the third-body orbits is e_2=0.35; (iii) there is a deficit of triple systems with binary periods <1 day and outer periods between ~50 and 200 days which might help guide the refinement of theories of the formation and evolution of close binaries; and (iv) the substantial fraction of Kepler binaries which have third-body companions is consistent with a very large fraction of all binaries being part of triples

Mass constrains for several Kepler giant planets from SOPHIE

SOPHIE velocimetry of Kepler transit candidates XVII. The physical properties of giant exoplanets within 400 days of period

Quote :

While giant extrasolar planets have been studied for more than two decades now, there are still some open questions such as their dominant formation and migration process, as well as their atmospheric evolution in different stellar environments. In this paper, we study a sample of giant transiting exoplanets detected by the Kepler telescope with orbital periods up to 400 days. We first defined a sample of 129 giant-planet candidates that we followed up with the SOPHIE spectrograph (OHP, France) in a 6-year radial velocity campaign. This allow us to unveil the nature of these candidates and to measure a false-positive rate of 54.6 +/- 6.5 % for giant-planet candidates orbiting within 400 days of period. Based on a sample of confirmed or likely planets, we then derive the occurrence rates of giant planets in different ranges of orbital periods. The overall occurrence rate of giant planets within 400 days is 4.6 +/- 0.6 %. We recover, for the first time in the Kepler data, the different populations of giant planets reported by radial velocity surveys. Comparing these rates with other yields, we find that the occurrence rate of giant planets is lower only for hot jupiters but not for the longer period planets. We also derive a first measurement on the occurrence rate of brown dwarfs in the brown-dwarf desert with a value of 0.29 +/- 0.17 %. Finally, we discuss the physical properties of the giant planets in our sample. We confirm that giant planets receiving a moderate irradiation are not inflated but we find that they are in average smaller than predicted by formation and evolution models. In this regime of low-irradiated giant planets, we find a possible correlation between their bulk density and the Iron abundance of the host star, which needs more detections to be confirmed.

Bad omens for Kepler-86 b which could turn out a triple system rather a transiting planet.

Placek et al. "Characterization of Kepler-91b and the Investigation of a Potential Trojan Companion Using EXONEST"
http://arxiv.org/abs/1511.01068

Seems likely the "Trojan planet" is a false positive, the derived daytime temperature is hotter than the star. But still not conclusive as to what is going on.

https://aas.org/meetings/dps47/schedule_events

Abstract from 47th DPS meeting this week :(page 636)

An Exo-Venus Around a Cool, Nearby Star
I. Angelo; 1, 2; J. F. Rowe; 2, 3; S. B. Howell; 2;
1. Physics and Astronomy, UC Berkeley, Los Angeles, CA, United States.
2. NASA Ames Research Center, Moffett Field, CA, United States.
3. SETI Institute, Mountain View, CA, United States.

Abstract (2,250 Maximum Characters):

We present the discovery and planetary confirmation of KOI-3138, a likely Earth-sized (1.08 Earth radii ) planet in a 9-day orbit around a nearby M Dwarf star. A planet transit was detected around KOI-3138 with the Kepler spacecraft and confirmed via false positive analysis using data from the UK Infrared telescope, Digital Sky Survey, and DSSI Speckle imaging. The planet’s short orbital period places it close to its host star, making it an interesting Venus analog around a cool star.
It remains possible, although unlikely, that KOI-3138.01 instead orbits a bound, undetected binary companion to KOI-3138. Under these conditions, the planet becomes a mini-Neptune-sized planet orbiting a brown dwarf with a mass of ~0.05 solar mass. Follow-up radial velocity measurements on the host star are required in order to accurately assess the likelihood of this possibility. Specifically, detection of a significant radial velocity ( ~725 m/s) upon observation of KOI-3138 will indicate the presence of a bound companion that was not detected by our false positive analysis procedures. Such a companion, if detected, cannot be ruled out as the host star around which KOI-3138.01 orbits.
KOI-3138.01 is too small to induce a detectable “wobble" in its host star. We therefore make no conclusions about mass or composition. However, there is reasonable incentive to determine these properties in the hopes of understanding the nature of habitable zones around M-type stars. Kepler-186f, a previously discovered Earth-like exoplanet, is similar in size to KOI-3138.01 and orbits the outer reaches of its star’s conservative habitable zone. KOI-3138.01, also Earth-sized, orbits a similar star but resides much closer in. The two planets together span the range of distances within the habitable zones of M Dwarfs. Determining the composition and atmosphere of KOI-3138.01 is therefore useful in understanding the nature of habitable zone boundaries of such star types. This task may in fact be possible with the James Webb Space Telescope (JWST), which will characterize atmospheric compositions of nearby Earth-sized planets like KOI-3138.01 and thereby provide insight into the habitability of both known and to-bediscovered exoplanets.

http://arxiv.org/pdf/1510.02776v1.pdf
Laplace resonance in Kepler 60

Investigation of the Kepler "habitable" planet host stars, including detection of a superflare on Kepler-438.

Armstrong et al. (2015) "The Host Stars of Keplers Habitable Exoplanets: Superflares, Rotation and Activity"
http://arxiv.org/abs/1511.05306

0.166 AU from host is not that close to loose whole atmosphere we have example in case of Kepler 138d which density suggest thick atmosphere despite being closer and less irradiated than k 438b

The density of Kepler-138 d is not well constrained and Kepler 138 is not a flare star. And if you have a very thick atmosphère it will beter survive flares than tha atmosphère of a earth like planet, look at Mars for a (bad) example.

Well even if density of k-138d will be better constrained it still looks like surrounded by thick atmosphere What I wanted to say is simply we should not be sure kepler 438 is uninhabitable despite flaring star

With some updated Kepler planets, exoplanet count has just exceeded 2K! (2001)

http://exoplanet.eu/catalog/

http://arxiv.org/pdf/1401.7275v1.pdf
Kepler-413b: a slightly misaligned, Neptune-size transiting circumbinary
planet

Very old news

Over the last few weeks some kepler updates on mass and radius have updated at exoplanet.eu.  http://exoplanet.eu/catalog/http://phl.upr.edu/projects/habitable-exoplanets-catalog/calculators

I calculated the density with the calculator


Kepler 100b 1.305 radi/7.34 mass = 18.22g/cm^3 density  
Kepler 100c 2.22 radi/.86 mass = .4335 g/cm^3 density
Kepler 100d 1.514 radi/3 mass = 4.767 g/cm^3 density
Kepler 103b 3.476 radi/9.9 mass = 1.3g/cm^3 density
Kepler 103c 5.319 radi/36.2 mass = 1.327 g/cm^3 density
Kepler 106b .82 radi/.15 mass = 1.501 g/cm^3 density
Kepler 106c 2.5 radi/10.44 mass = 3.685 g/cm^3 density
Kepler 106d .95 radi/7.9 mass = 50.81g/cm^3 density
Kepler 106e 2.56 radi/11.17 mass = 3.672 g/cm^3 density
Kepler 109b 2.338 radi/1.3 mass = .5608 g/cm^3 density
Kepler 109c 2.63 radi/2.22 mass = 1.326 g/cm^3 density
Kepler 60c 2.5 radi/6 mass = 2.118 g/cm^3 density
Kepler 60b 2 radi/3 mass = 2.068 g/cm^3 density
Kepler 60d 2.6 radi/3.5 mass = .3344 g/cm^3 density
Kepler 37b .32 radi/2.78 mass = 467.9 g/cm^3 density
Kepler 37c .75 radi/10  mass = 130.7 g/cm^3 density
Kepler 37d 1.94 radi/12.2 mass = 9.215 g/cm^3 density
Kepler 113b 1.82 radi/11.7 mass = 10.7 g/cm^3 density
Kepler 113c 2.17 radi/8.6 mass = 4.641 g/cm^3 density
Kepler 131b 2.41 radi/16.13 mass = 6.353 g/cm^3 density
Kepler 131c .84 radi/8.3 mass = 77.21 g/cm^3 density
Kepler 406b 1.43 radi/6 mass = 11.32 g/cm^3 density
Kepler 406c .85 radi/2.71 mass = 24.34 g/cm^3
Kepler 93b 1.483 radi/4 mass = 6.761 g/cm^3 density
Kepler 10b 1.473 radi/3.33 mass = 5.746 g/cm^3 density
Kepler 10c 2.323 radi/17.2 mass = 7.566 g/cm^3 density
Kepler 23b 1.694 radi/15.2 mass = 17.24 g/cm^3 density
Kepler 23d 2.236 radi/17 mass = 8.388 g/cm^3 density
Kepler 23c 3.12 radi/60.1 mass = 10.91 g/cm^3 density
Kepler 25c 5.154 radi/14 mass = .5642 g/cm^3 density
Kepler 25d 89.9 mass

I think this was a classic case of EPE taking upper limits as true values. I read over the paper EPE claims to get its numbers from and that does appear to be the case. This explains some of the extreme densities in your table.

Upper limit for some cases like kepler 23 , 37 planets and k-106 d, k-131c, k-406 c.k-25 d