ALL SIX PLANETS KNOWN TO ORBIT KEPLER-11 HAVE LOW DENSITIES

By Jack J. Lissauer, D. Jontof-Hutter, J. Rowe, D. Fabrycky, E. Lopez, E. Agol, G. Marcy, K. Deck, Debra A. Fischer, Jon Fortney and 7 more. 2013

146 citations recorded by the source corpus.

The Kepler-11 planetary system contains six transiting planets ranging in size from 1.8 to 4.2 times the radius of Earth. Five of these planets orbit in a tightly packed configuration with periods between 10 and 47 days. We perform a dynamical analysis of the system based upon transit timing variations observed in more than three years of Kepler photometric data. Stellar parameters are derived using a combination of spectral classification and constraints on the star's density derived from transit profiles together with planetary eccentricity vectors provided by our dynamical study. Combining masses of the planets relative to the star from our dynamical study and radii of the planets relative to the star from transit depths together with deduced stellar properties yields measurements of the radii of all six planets, masses of the five inner planets, and an upper bound to the mass of the outermost planet, whose orbital period is 118 days. We find mass–radius combinations for all six planets that imply that substantial fractions of their volumes are occupied by constituents that are less dense than rock. Moreover, we examine the stability of these envelopes against photoevaporation and find that the compositions of at least the inner two planets have likely been significantly sculpted by mass loss. The Kepler-11 system contains the lowest mass exoplanets for which both mass and radius have been measured.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/a3000ab0152bb545c19b201338a26aafdaa3a293

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Citations in the corpus

TRANSIT TIMING OBSERVATIONS FROM KEPLER. IX. CATALOG OF THE FULL LONG-CADENCE DATA SET (2016, unknown): “…(9) Kipping et al. (2014), (10) Holman et al. (2010), (11) Masuda (2014), (12) Fabrycky et al. (2012), (13) Jontof-Hutter et al. (2014), (14) Lissauer et al. (2013), (15) Sanchis-Ojeda et al. (2012), (16) Diamond-Lowe et al. (2015), (17) Ragozzine & Kepler Team (2012), (18) Yang et al.…”
THE MASS–RADIUS RELATION FOR 65 EXOPLANETS SMALLER THAN 4 EARTH RADII (2013, background): “A T-test comparing the residual masses from the RVs to the TTVs results in a two-tailed P-value of 0.03, indicating the two samples, if drawn from the same distribution, would be this discrepant 3% of the time.”
UNDERSTANDING THE MASS–RADIUS RELATION FOR SUB-NEPTUNES: RADIUS AS A PROXY FOR COMPOSITION (2013, methodology): “For CoRoT-7b, the five inner Kepler-11 planets, and 55 Cancri e we used masses and radii from Hatzes et al. (2011), Lissauer et al. (2013), and Dragomir et al. (2013), respectively.”
Compositional Imprints in Density–Distance–Time: A Rocky Composition for Close-in Low-mass Exoplanets from the Location of the Valley of Evaporation (2017, background): “Most of the low-mass exoplanets in the right panel are from the Kepler satellite (Marcy et al. 2014; Lissauer et al. 2013).”
Kepler Planet Masses and Eccentricities from TTV Analysis (2016, background): “TTV analyses of the Kepler-11 system have been conducted by number of authors (Lissauer et al. 2011a; Migaszewski et al. 2012; Lissauer et al. 2013; Borsato et al. 2014), and our results agree well with previous work.”
The Gaia–Kepler Stellar Properties Catalog. I. Homogeneous Fundamental Properties for 186,301 Kepler Stars (2020, background): “Our results (purple, center) appear to be in better agreement with the photodynamical analysis of the Kepler -11 lightcurve, and hence also with the prediction of the stellar density computed in Lissauer et al. (2013).”
MAKE SUPER-EARTHS, NOT JUPITERS: ACCRETING NEBULAR GAS ONTO SOLID CORES AT 0.1 AU AND BEYOND (2014, background): “Bodenheimer & Lissauer (2014) focus on Kepler-11f, and find that a solid core of mass Mcore ' 2M⊕ at 0.5 AU can safely avoid runaway, accreting an atmosphere for which Mgas/Mcore ∼ 2%, so long as the disk disperses in 2 Myr.”
The Occurrence and Architecture of Exoplanetary Systems (2014, background): “Also noteworthy is that many planets in compact systems have very low densities ( <∼ 1 g cm−3; see, e.g., Lissauer et al. (2013), Wu & Lithwick (2013), Masuda (2014), which have mainly been revealed through the transit-timing method.”
THE MASS OF Kepler-93b AND THE COMPOSITION OF TERRESTRIAL PLANETS (2014, background): “Some low-mass worlds with very low densities are known, notably the Kepler-11 system (Lissauer et al. 2013) and KOI-314c (Kipping et al. 2014).”
VALIDATION OF KEPLER'S MULTIPLE PLANET CANDIDATES. II. REFINED STATISTICAL FRAMEWORK AND DESCRIPTIONS OF SYSTEMS OF SPECIAL INTEREST (2014, background): “All six candidates in KOI-157 pass our validation tests, but as these candidates have already been verified as Kepler-11 b–g by Lissauer et al. (2011a) and analyzed more extensively by Lissauer et al. (2013), we do not consider them further herein.”
DENSITIES AND ECCENTRICITIES OF 139 KEPLER PLANETS FROM TRANSIT TIME VARIATIONS (2013, methodology): “Inverting the analytical formula is not only much faster than the more typically used Nbody inversion (Holman et al. 2010; Lissauer et al. 2011b; Cochran et al. 2011; Lissauer et al. 2013), but it also allows one to break the strong degeneracy between mass and eccentricity in a statistical way.”
Core-powered mass-loss and the radius distribution of small exoplanets (2017, background): “A commonly suggested structure that explains the low densities of these planets is a rocky core engulfed by a voluminous gas atmosphere of several percent in mass (e.g. Lopez et al. 2012; Lissauer et al. 2013; Wolfgang & Lopez 2015).”
THE KEPLER-10 PLANETARY SYSTEM REVISITED BY HARPS-N: A HOT ROCKY WORLD AND A SOLID NEPTUNE-MASS PLANET (2014, background): “The masses derived from TTVs eventually led to densities ranging from 1.7 down to 0.58 g cm−3 (Lissauer et al. 2013), much less than the Earth’s bulk density of 5.5 g cm−3, presumably due to extended atmospheres of hydrogen and helium.”
SUPER-EARTH ATMOSPHERES: SELF-CONSISTENT GAS ACCRETION AND RETENTION (2015, background): “Such atmospheres are necessary in order to explain some of the recently discovered Kepler lowdensity super Earths (see, e.g., Lopez et al. 2012; Lissauer et al. 2013).”
REVISED STELLAR PROPERTIES OF KEPLER TARGETS FOR THE QUARTER 1–16 TRANSIT DETECTION RUN (2013, background): “For multi-planet systems in particular, transit-derived stellar densities reach uncertainties comparable to asteroseismology and are often preferred over constraints on log g from spectroscopy (Lissauer et al. 2013; Jontof-Hutter et al. 2013).”