Kepler News and Results (Thread 2)

Good to see yet more small HZ candidates.

Concerning KOI 4032 which now has 5 candidates, I notice that the entire system is very tightly packed, with all period ratios being less than 1.5 - particularly .04 - .03, with a period ratio of ~1.1748. The 5 seem to be clear of resonances, so this system looks to be dynamically complex.

More about Kepler-91 and new entry for KOI-1894:

Precise Radial Velocity Measurements for Kepler Giants Hosting Planetary Candidates: Kepler-91 and KOI-1894

Quote :

We present results of radial-velocity follow-up observations for the two Kepler evolved stars Kepler-91 (KOI-2133) and KOI-1894, which had been announced as candidates to host transiting giant planets, with the Subaru 8.2m telescope and the High Dispersion Spectrograph (HDS). By global modeling of the high-precision radial-velocity data taken with Subaru/HDS and photometric ones taken by Kepler mission taking account of orbital brightness modulations (ellipsoidal variations, reflected/emitted light, etc.) of the host stars, we independently confirmed that Kepler-91 hosts a transiting planet with a mass of 0.66 M_Jup (Kepler-91b), and newly detected an offset of ~20 m s$^{-1}$ between the radial velocities taken at ~1-yr interval, suggesting the existence of additional companion in the system. As for KOI-1894, we detected possible phased variations in the radial velocities and light curves with 2--3 sigma confidence level which could be explained as a reflex motion and ellipsoidal variation of the star caused by the transiting sub-saturn-mass (~0.18 M_Jup) planet.

See also: the Kepler-91 thread.

If the parameters for KOI-1894 are accurate, then the companion has an unusually low mass for a Hot Jupiter…

http://arxiv.org/list/astro-ph.EP/new

Planetary Candidates Observed by \ik V: Planet Sample from Q1-Q12 (36 Months)

The Kepler mission discovered 2842 exoplanet candidates with 2 years of data. We provide updates to the Kepler planet candidate sample based upon 3 years (Q1-Q12) of data. Through a series of tests to exclude false-positives, primarily caused by eclipsing binary stars and instrumental systematics, 855 additional planetary candidates have been discovered, bringing the total number known to 3697. We provide revised transit parameters and accompanying posterior distributions based on a Markov Chain Monte Carlo algorithm for the cumulative catalogue of Kepler Objects of Interest. There are now 130 candidates in the cumulative catalogue that receive less than twice the flux the Earth receives and more than 1100 have a radius less than 1.5 Rearth. There are now a dozen candidates meeting both criteria, roughly doubling the number of candidate Earth analogs. (…)



From "Validation of 12 small Kepler planets in HZ" :
KOI 3255 is K-437b
KOI 3284 is K-438b
KOI 4087 is K-440b
but sizes are different...

http://arxiv.org/abs/1502.02038

Planetary Candidates Observed by Kepler VI: Planet Sample from Q1-Q16 (47 Months)

We present the sixth catalog of Kepler candidate planets based on nearly 4 years of high precision photometry. This catalog builds on the legacy of previous catalogs released by the Kepler project and includes 1493 new Kepler Objects of Interest (KOIs) of which 554 are planet candidates, and 131 of these candidates have best fit radii <1.5 R_earth. This brings the total number of KOIs and planet candidates to 7305 and 4173 respectively. We suspect that many of these new candidates at the low signal-to-noise limit may be false alarms created by instrumental noise, and discuss our efforts to identify such objects. We re-evaluate all previously published KOIs with orbital periods of > 50 days to provide a consistently vetted sample that can be used to improve planet occurrence rate calculations. We discuss the performance of our planet detection algorithms, and the consistency of our vetting products. The full catalog is publicly available at the NASA Exoplanet Archive

Kepler-447b: a hot-Jupiter with an extremely grazing transit

Quote :

We present the radial velocity confirmation of the extrasolar planet Kepler-447b, initially detected as a candidate by the Kepler mission. In this work, we analyze its transit signal and the radial velocity data obtained with the Calar Alto Fiber-fed Echelle spectrograph (CAFE). By simultaneously modeling both datasets, we obtain the orbital and physical properties of the system. According to our results, Kepler-447b is a Jupiter-mass planet ($M_p=1.37^{+0.48}_{-0.46} M_{\rm Jup}$), with an estimated radius of $R_p=1.65^{+0.59}_{-0.56} R_{\rm Jup}$ (uncertainties provided in this work are $3\sigma$ unless specified). This translates into a sub-Jupiter density. The planet revolves every $\sim7.8$ days around a G8V star with detected activity in the Kepler light curve. Kepler-447b transits its host with a large impact parameter ($b=1.076^{+0.112}_{-0.086}$), being one of the few planetary grazing transits confirmed so far and the first in the Kepler large crop of exoplanets. We estimate that only around 20% of the projected planet disk occults the stellar disk. The relatively large uncertainties in the planet radius are due to the large impact parameter and short duration of the transit. Within the transit time interval, we find the presence of large (somehow modulated) outliers during the transit. We propose and analyze different scenarios that could explain these brighter data points, including instrumental effects, additional perturbing bodies, stellar pulsations, rotation of a non-spherical planet, and spot-crossing events. However, short-cadence photometric data (at the 1 minute level) is still needed to unveil the nature of this observational effect.

http://www.sciencedaily.com/releases/2015/02/150212114243.htm
Kepler 432 b almost 8g/cm3 very nice

Kepler 447 grazing transits http://arxiv.org/pdf/1502.03267.pdf

tommi59 wrote:

Kepler 447 grazing transits  http://arxiv.org/pdf/1502.03267.pdf

Already posted...

In paper below 1 planet is quite interesting kepler 57 c it has 1.55 earth radius and mass 5.4 density 8.0 g/cm3  with temp smaller than 700 K
http://arxiv.org/pdf/1502.03605.pdf

tommi59 wrote:

http://www.sciencedaily.com/releases/2015/02/150212114243.htm
Kepler 432 b almost 8g/cm3 very nice

8g/cm3 ?

http://kepler.nasa.gov/Mission/discoveries/

tommi59 wrote:

In paper below 1 planet is quite interesting kepler 57 c it has 1.55 earth radius and mass 5.4 density 8.0 g/cm3  with temp smaller than 700 K
http://arxiv.org/pdf/1502.03605.pdf

There seem to be several mass estimates for Kepler-57 floating around, they are all highly uncertain. TTV estimated masses are likely not representative for the Kepler-57 system as there are indications that the orbits are eccentric.

RV I guess by steffen 2013 reference for kepler 57 .In this system planet k57 b seems to be very dense also. In case of kepler 432b recently on sciencedaily they gave mass 5.84j and 1.0j radius

Disintegrating super mercury planet
http://arxiv.org/pdf/1502.04612.pdf

tommi59 wrote:

Disintegrating super mercury planet  
http://arxiv.org/pdf/1502.04612.pdf

Old one

Stalker wrote:

Old one

The paper doesn't assert it's a new planet, it presents simultaneous multi-colour photometry of the debris tail to show it to be consistent with micron-sized dust, confirming the nature of the object as a disintegrating exoplanet.

On the Detection of Exomoons
http://arxiv.org/abs/1502.05033

Very fascinating paper. By stacking up transit light curves of whole groups of planets, they find tentative evidence for exomoons orbiting intermediate-period giant planets. Furthermore, they find exomoon candidates around several specific Kepler planets. Almost all of them are better explained by systematics or stellar activity, but an exomoon candidate around Kepler-264b seems to pass all of these tests. The moon is a super-Earth-sized object orbiting a Neptune-sized planet, so the author has been cautious about asserting any sort of confirmation.

The concept of stacking many transits from different sources together to make a "super-transit" is again very interesting - its previous application being to the average albedo of small Kepler planets. Its apparent success here is perhaps not a surprise.

The paper also notes the impact of approximating an exomoon signal with a single moon when it could be due to several moons. Indeed, I suspect that the divide seen in the solar system (Jupiter-like systems with several large moons, or Saturn-like systems with one (or two) moons that contain most of the mass of the moon system) may be rather applicable here, because such large moons are less feasible than multiple small ones.

Ultimately, searching for moons in Kepler data is exceptionally difficult and unlikely to be successful. However, a strong successful identification would be extraordinarily valuable, and so the continued searches are very justified. But I expect that it will be a generation or two of telescopes until exomoons are as readily identifiable via photometry as planets are today.

Interesting if confirmed. Well greater than the 1/81 mass ratio of Earth-Moon system.

Additional exomoon candidates for Kepler-241 b & c and KOI-367.01 too.

Mass ratio for kepler 264b and potential moon will be around 1/8 or even less knowing now what density can have objects with radii 3.3 and 1.6 earth

About the Hunt for Exomoons with Kepler (HEK) project :

http://www.nas.nasa.gov/publications/articles/feature_exomoons_kipping.html

Another update from the HEK project, still no exomoons though ever-more-stringent limits, plus some indications of an additional planet in the Kepler-10 system.

Kipping et al. "The Hunt for Exomoons with Kepler (HEK): V. A Survey of 41 Planetary Candidates for Exomoons"
http://arxiv.org/abs/1503.05555

The Kepler discovery list of planets has been updated to 1022 from 1019. What ones are the 3 new ones???

http://kepler.nasa.gov/Mission/discoveries/

Not sure. I have all of the Kepler-#'s already in my notes except Kepler-72 and Kepler-73, which this page promises exist but aren't published. So maybe they added new planets in known systems.... or just finally updated to catch up with the available literature.