Kepler News and Results (Thread 2)

SOPHIE velocimetry of Kepler transit candidates XII. KOI-1257 b: a highly-eccentric 3-month period transiting exoplanet

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In this paper we report a new transiting warm giant planet: KOI-1257 b. It was first detected in photometry as a planet-candidate by the Kepler space telescope and then validated thanks to a radial velocity follow-up with the SOPHIE spectrograph. It orbits its host star with a period of 86.647661 d ± 3 s and a high eccentricity of 0.772 ± 0.045. The planet transits the main star of a metal-rich, relatively old binary system with stars of mass of 0.99 ± 0.05 Msun and 0.70 ± 0.07 Msun for the primary and secondary (respectively). This binary system is constrained thanks to a self-consistent modelling of the Kepler transit light curve, the SOPHIE radial velocities, line bisector and full-width half maximum (FWHM) variations as well as the spectral energy distribution. However, future observations are needed to confirm it. The PASTIS fully-Bayesian software was used to validate the nature of the planet and to determine which star of the binary system is the transit host. By accounting for the dilution from the binary both in photometry and in radial velocity, we find that the planet has a mass of 1.45 ± 0.35 Mjup, and a radius of 0.94 ± 0.12 Rjup, and thus a bulk density of 2.1 ± 1.2 g.cm−3. The planet has an equilibrium temperature of 511 ± 50 K, making it one of the few known membre of the warm-jupiter population. The HARPS-N spectrograph was also used to observe a transit of KOI-1257 b, simultaneously with a joint amateur and professional photometric follow-up, with the aims at constraining the orbital obliquity of the planet. However, the Rossiter-McLaughlin was not clearly detected, resulting in poor constraints on the orbital obliquity of the planet.

Wait a minute, the preferred model is a giant planet orbiting the primary of a 5.3 AU binary??? What the...

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A more detailed study is necessary to uncover the effects of its high eccentricity on its evolution, and the role of the outer binary KOI-1257 B on the formation of such an object. Such study is out of the scope of this paper.

Yes, well...

Exoplanets in close binary systems seem even less a minority.

Yeah, I… very much doubt this is possible. How could it both orbits be misaligned by ~70 degrees after the entire lifetime of the system, much less a single orbit? Where could the planet have formed? Why?


Hedging my bet here that the trend is due to a substellar companion. Or something. Definitely not a star at 5 AU.

page 20 :
"...The Gaia astrometric observatory is expected
to reach an astrometric precision at the level of the as. This
precision will be, by far, enough to detect and confirm the
presence of KOI-1257 B..."

Why not?

Well it's not an impossible configuration, e.g. if the system underwent some kind of dynamical interaction that shrunk the binary after the formation of the planet, but it is in an entirely new region of parameter space for exoplanets.

I dream about a binary system with planets for each star PLUS circumbinary planets… (and satellites of course !)

KOI-1474 = Kepler-419.
http://exoplanetarchive.ipac.caltech.edu./cgi-bin/DisplayOverview/nph-DisplayOverview?objname=Kepler+419+b&type=CONFIRMED_PLANET

KOI-1257 = Kepler-420
http://exoplanetarchive.ipac.caltech.edu./cgi-bin/DisplayOverview/nph-DisplayOverview?objname=Kepler+420+b&type=CONFIRMED_PLANET

Revision of Earth-sized Kepler Planet Candidate Properties with High Resolution Imaging by Hubble Space Telescope
http://arxiv.org/abs/1407.1057

Kepler-296 turns out to be binary (~80 AU projected). Component A contributes 80% of the light in Kp band. So the planets (including the HZ candidate) are all larger. KOI-2626 and KOI-3049, which also have HZ candidate planets, are found to be multiple.

And now with the MMT :

http://arxiv.org/abs/1407.1848

Adaptive Optics Images III: 87 Kepler Objects of Interest

The Kepler mission has revolutionized our understanding of exoplanets, but some of the planet candidates identified by Kepler may actually be astrophysical false positives or planets whose transit depths are diluted by the presence of another star. Adaptive optics images made with ARIES at the MMT of 87 Kepler Objects of Interest place limits on the presence of fainter stars in or near the Kepler aperture. We detected visual companions within 1" for five stars, between 1" and 2" for seven stars, and between 2" and 4" for 15 stars. For those systems, we estimate the brightness of companion stars in the Kepler bandpass and provide approximate corrections to the radii of associated planet candidates due to the extra light in the aperture. For all stars observed, we report detection limits on the presence of nearby stars. ARIES is typically sensitive to stars approximately 5.3 Ks magnitudes fainter than the target star within 1" and approximately 5.7 Ks magnitudes fainter within 2", but can detect stars as faint as delta Ks = 7.5 under ideal conditions

Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry
http://arxiv.org/abs/1407.2245

BEER analysis of Kepler and CoRoT light curves: II. Evidence for emission phase shift due to superrotation in four Kepler hot Jupiters
http://arxiv.org/abs/1407.2361

A couple of papers showing phase offsets for numerous hot Jupiters in the Kepler dataset.

Most 1.6 Earth-Radius Planets are not Rocky
http://arxiv.org/abs/1407.4457

http://www.noao.edu/news/2014/pr1406.php

NOAO: Half of all Exoplanet Host Stars are Binaries

Co-author of the study, Dr. Steve B. Howell (NASA Ames Research Center), commented, “An interesting consequence of this finding is that in the half of the exoplanet host stars that are binary we can not, in general, say which star in the system the planet actually orbits.”

"For the majority of the Kepler stars, this means companion stars with a true separation of a few to about 100 times the Sun-Earth distance"

Interesting range of implied separations there, other surveys have suggested that planet formation is suppressed in intermediate-separation binaries. Of course, could be in a few cases the radial component of the separation is much larger.

This looks like the paper.

Most Sub-Arcsecond Companions of Kepler Exoplanet Candidate Host Stars are Gravitationally Bound
http://arxiv.org/abs/1409.1249

On Kepler-47d

Predicting a third planet in the Kepler-47 circumbinary system
http://arxiv.org/abs/1409.1349

The new paper about Kepler-47 should be compared to whatever this was. The results are not inconsistent, though a look to the stability diagrams indicate that a 190-day planet is not in the most stable region. However, this new work uses fixed masses for b and c which are significantly different to those from that other thing, so comparisons must be qualitative especially when considering the peculiar calculated mass for c.

Lissauer, Dawson & Tremaine "Advances in exoplanet science from Kepler"
http://arxiv.org/abs/1409.1595

Was skimming through it, the following caught my eye as something useful to remember about the Kepler results so far.

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Just as important as the discoveries made by Kepler are its non-discoveries. So far Kepler has found no co-orbital planets, planets sharing the same average semi-major axis like the Trojan asteroids found accompanying Jupiter and the Saturnian satellites Janus and Epimetheus. It has found neither exomoons nor “binary” planets orbiting one another (Kipping et al. 2012a, 2013).

Good to be reminded of the non-discoveries from time to time...

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Just as important as the discoveries made by Kepler are its non-discoveries. So far Kepler has found no co-orbital planets, planets sharing the same average semi-major axis like the Trojan asteroids found accompanying Jupiter and the Saturnian satellites Janus and Epimetheus. It has found neither exomoons nor “binary” planets orbiting one another (Kipping et al. 2012a, 2013).

Given the difficulty Kepler has in detecting earth sized planets at distances of 1 AU+ around normal G-K types stars, is this much of a surprise? (it seems as though more and more 'super-earths' are now 'min-Neptune's'.) Would Kepler even be capable of spotting a Io or Titan sized moon around a exo-Jupiter or Saturn?

Lazarus wrote:

Lissauer, Dawson & Tremaine "Advances in exoplanet science from Kepler"
http://arxiv.org/abs/1409.1595

Was skimming through it, the following caught my eye as something useful to remember about the Kepler results so far.

Quote :

Just as important as the discoveries made by Kepler are its non-discoveries. So far Kepler has found no co-orbital planets, planets sharing the same average semi-major axis like the Trojan asteroids found accompanying Jupiter and the Saturnian satellites Janus and Epimetheus. It has found neither exomoons nor “binary” planets orbiting one another (Kipping et al. 2012a, 2013).

Good to be reminded of the non-discoveries from time to time...

That's one of the few thing's I hate about exo-planetary science; some of the discoveries, or some lack thereof, can be an incredibly big downer, moreso if one has a mind for fantastical science fiction or science fantasy.

Kane, Kopparapu & Domagal-Goldman "On the Frequency of Potential Venus Analogs from Kepler Data"
http://arxiv.org/abs/1409.2886

Define a "Venus Zone", the outer boundary is at the runaway greenhouse limit, the inner boundary is set by atmospheric erosion, value used is 25 times Earth's incident flux based on the flux to place Venus at the "cosmic shoreline" based on the divide of objects with and without atmospheres in the solar system.

43 potential Venus analogues identified, with fairly high estimates of the rate of such planets around M and GK dwarfs (~0.32 and ~0.45 respectively).

Wolfgang & Lopez "How Rocky Are They? The Composition Distribution of Kepler's Sub-Neptune Planet Candidates within 0.15 AU"
http://arxiv.org/abs/1409.2982

Looking at the fraction of the planet's mass that is in the gaseous envelope:

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the following summary provides a reasonable rule-of-thumb when interpreting the composition of planets based on their radii: planets with R_pl < 2 R_⊕ have f_env < 1%, planets with 2 < R_pl < 3 R_⊕ have f_env ~ 1%, and planets with R_pl > 3 R_⊕ have f_env ~ a few %.

Consistent with prior findings (Rogers 2014) that the rocky-gaseous transition occurs at 1.5 R_⊕.

Characterization of the four new transiting planets KOI-188b, KOI-195b, KOI-192b, and KOI-830b
http://arxiv.org/abs/1409.8554

KOI-188 is Kepler-425
KOI-195 is Kepler-426
KOI-192 is Kepler-427
KOI-830 is Kepler-428

http://exoplanetarchive.ipac.caltech.edu/docs/exonews_archive.html

Looking for more evaporating planets...

Garai et al. "Search for a circum-planetary material and orbital period variations of short-period Kepler exoplanet candidates"
http://arxiv.org/abs/1410.1290