A search for transit timing variations and orbital decay in WASP-46b

A search for transit timing variations and orbital decay in WASP-46b 

Authors:

Petrucci et al

Abstract:

We present 12 new transit observations of the exoplanet WASP-46b obtained with the 1.54-m telescope at Estación Astrofísica de Bosque Alegre (EABA, Argentina) and the 0.40-m Horacio Ghielmetti and 2.15-m Jorge Sahade telescopes at Complejo Astronómico El Leoncito (CASLEO, Argentina). We analyse them together with 37 light curves from the literature to re-determine the physical parameters and search for additional planets via transit timing variations (TTVs). We consider the 31 transits with uncertainties in their mid-transit times (eT0 eT0) less than 1 minute, to perform the first homogeneous study of TTVs for the system, finding a dispersion of σ = 1.66 minutes over a 6 year baseline. Since no periodic variations are found, our interpretation for this relatively high value of σ is that the stellar activity could be affecting the measured mid-transit times. This value of dispersion allows us to rule out the presence of additional bodies with masses larger than 2.3, 4.6, 7, and 9.3 M⊕ M⊕ at the first-order mean-motion resonances 2:1, 3:2, 4:3, and 5:4 with the transiting planet, respectively. Despite the 6 year baseline and a typical light curve precision of 2 × 10−3, we find that we cannot significantly demonstrate a slow decrease of the orbital period of WASP-46b. We place a lower limit of Q⋆ greater than 7 × 103 on the tidal quality factor and determine that an additional 6 year baseline is required to rule out Q⋆ less than 105.

Kepler-30: the Cesar of TTV variations

Kepler-30: the Cesar of TTV variations


Authors:

Panichi et al

Abstract:
We study the orbital architecture, physical character of planets, formation and long-term evolution of the Kepler-30 planetary system, detected and announced in 2012 by the KEPLER team. We show that it belongs to a particular class of very compact and quasi-resonant, yet long-term stable planetary systems. We re-analyzed light-curves of the host star spanning Q1-Q17 quarters. A huge variability of the Transit Timing Variations (TTV) exceeding 2 days is induced by a massive Jovian planet located between two Neptune-like companions. The innermost pair is near to the 2:1 mean motion resonance (MMR), and the outermost pair is close to the 19:8 MMR. Our re-analysis of photometric data allows us to constrain better than before the orbital elements, planets' radii and masses, which are 9.2±0.1, 536±5, and 23.7±1.3 Earth masses for Kepler-30b, Kepler-30c and Kepler-30d, respectively. The masses of the inner planets are determined within ∼1% uncertainty. We inferred the internal structures of the Kepler-30 planets and their bulk densities in a wide range from ∼0.19±0.01 g⋅cm−3 for Kepler-30d, ∼0.96±0.15 g⋅cm−3 for Kepler-30b, to ∼1.71±0.13 g⋅cm−3 for Jovian planet Kepler-30c, respectively. We attempt to explain the origin of this unique planetary system and a deviation of the orbits from exact MMRs by the planetary migration scenario. We anticipate that the Jupiter-mass planet plays an important role in determining the present dynamical state of this system.

Transit Timing and Duration Variations for the Discovery and Characterization of Exoplanets

Transit Timing and Duration Variations for the Discovery and Characterization of Exoplanets

Authors:

Agol et al

Abstract:

Transiting exoplanets in multi-planet systems have non-Keplerian orbits which can cause the times and durations of transits to vary. The theory and observations of transit timing variations (TTV) and transit duration variations (TDV) are reviewed. A watershed since the last review is that the Kepler spacecraft has detected several hundred perturbed planets. In a few cases, these data have been used to discover additional planets, which has historical resonance with how Neptune was discovered in our own Solar System. However, the more impactful aspect of TTV and TDV studies has been characterization of planetary systems in which multiple planets transit. After addressing the equations of motion and parameter scalings, the main dynamical mechanisms for TTV and TDV are described, with citations to the observational literature for real examples. We describe parameter constraints, particularly how the mass/eccentricity degeneracy comes about and is overcome by the high-frequency component of the signal. On the observational side, derivation of timing precision and introduction to the timing diagram are given. Science results are reviewed, with an emphasis on mass measurements of transiting sub-Neptunes and super-Earths, which allows access to the mass-radius diagram and hence inference of bulk compositions.

Transiting Exoplanet Monitoring Project (TEMP). II. Refined System Parameters and Transit Timing Analysis of HAT-P-33b

Transiting Exoplanet Monitoring Project (TEMP). II. Refined System Parameters and Transit Timing Analysis of HAT-P-33b

Authors:

Wang et al

Abstract:

We present ten R-band photometric observations of eight different transits of the hot Jupiter HAT-P-33b, which has been targeted by our Transiting Exoplanet Monitoring Project (TEMP). The data were obtained by two telescopes at the Xinglong Station of National Astronomical Observatories of China (NAOC) from 2013 December through 2016 January, and exhibit photometric scatter of 1.6−3.0mmag. After jointly analyzing the previously published photometric data, radial-velocity (RV) measurements, and our new light curves, we revisit the system parameters and orbital ephemeris for the HAT-P-33b system. Our results are consistent with the published values except for the planet-to-star radius ratio (RP/R∗), the ingress/egress duration (τ) and the total duration (T14), which together indicate a slightly shallower and shorter transit shape. Our results are based on more complete light curves, whereas the previously published work had only one complete transit light curve. No significant anomalies in Transit Timing Variations (TTVs) are found, and we place upper mass limits on potential perturbers, largely supplanting the loose constraints provided by the extant RV data. The TTV limits are stronger near mean-motion resonances, especially for the low-order commensurabilities. We can exclude the existence of a perturber with mass larger than 0.6, 0.3, 0.5, 0.5, and 0.3M⊕ near the 1:3, 1:2, 2:3, 3:2, and 2:1 resonances, respectively.

Spin dynamics of close-in planets exhibiting large TTVs

Spin dynamics of close-in planets exhibiting large TTVs

Authors:

Delisle et al

Abstract:
We study the spin evolution of close-in planets in compact multi-planetary systems. The rotation period of these planets is often assumed to be synchronous with the orbital period due to tidal dissipation. Here we show that planet-planet perturbations can drive the spin of these planets into non-synchronous or even chaotic states. In particular, we show that the transit timing variation (TTV) is a very good probe to study the spin dynamics, since both are dominated by the perturbations of the mean longitude of the planet. We apply our model to KOI-227b and Kepler-88b, which are both observed undergoing strong TTVs. We also perform numerical simulations of the spin evolution of these two planets. We show that for KOI-227b non-synchronous rotation is possible, while for Kepler-88b the rotation can be chaotic.

Kepler Planet Masses and Eccentricities from TTV Analysis

Kepler Planet Masses and Eccentricities from TTV Analysis

Authors:

Hadden et al

Abstract:
We conduct a uniform analysis of the transit timing variations (TTVs) of 145 planets from 55 Kepler multiplanet systems to infer planet masses and eccentricities. Eighty of these planets do not have previously reported mass and eccentricity measurements. We employ two complementary methods to fit TTVs: Markov chain Monte Carlo simulations based on N-body integration, and an analytic fitting approach. Mass measurements of 49 planets, including 12 without previously reported masses, meet our criterion for classification as robust. Using mass and radius measurements, we infer the masses of planets' gaseous envelopes for both our TTV sample and transiting planets with radial velocity observations. Insight from analytic TTV formulae allows us to partially circumvent degeneracies inherent to inferring eccentricities from TTV observations. We find that planet eccentricities are generally small, typically a few percent, but in many instances are nonzero.

Kepler Planet Masses and Eccentricities from Transit TIming Variation Analysis

Kepler Planet Masses and Eccentricities from TTV Analysis

Authors:

Hadden et al

Abstract:

We conduct a uniform analysis of the transit timing variations (TTVs) of 145 planets from 55 Kepler multiplanet systems to infer planet masses and eccentricities. Eighty of these planets do not have previously reported mass and eccentricity measurements. We employ two complementary methods to fit TTVs: Markov chain Monte Carlo simulations based on N-body integration and an analytic fitting approach. Mass measurements of 49 planets, including 12 without previously reported masses, meet our criterion for classification as robust. Using mass and radius measurements, we infer the masses of planets' gaseous envelopes for both our TTV sample as well as transiting planets with radial velocity observations. Insight from analytic TTV formulae allows us to partially circumvent degeneracies inherent to inferring eccentricities from TTV observations. We find that planet eccentricities are generally small, typically a few percent, but in many instances are non-zero.

Kepler-421b may be Alone in its System

No Timing Variations Observed in Third Transit of Snow-Line Exoplanet Kepler-421b

Authors:

Dalba et al

Abstract:

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler Spacecraft only observed two transits of Kepler-421b leaving the planet's transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3-meter Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion (BIC) and find that a transit model with no TTVs is favored to 3.6-sigma confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ 3470b

Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b

Authors:

Awiphan et al

Abstract:

GJ3470b is a hot Neptune exoplanet orbiting an M dwarf and the first sub-Jovian planet to exhibit Rayleigh scattering. We present transit timing variation (TTV) and transmission spectroscopy analyses of multi-wavelength optical photometry from 2.4-m and 0.5-m telescopes at the Thai National Observatory, and the 0.6-m PROMPT-8 telescope in Chile. Our TTV analysis allows us to place an upper mass limit for a second planet in the system. The presence of a hot Jupiter with a period of less than 10 days or a planet with an orbital period between 2.5 and 4.0 days are excluded. Combined optical and near-infrared transmission spectroscopy favour a H/He dominated haze (mean molecular weight 1.18±0.22) with high particle abundance at high altitude. We also argue that previous near-infrared data favour the presence of methane in the atmosphere of GJ3470b.

A Cloudiness Index for Transiting hot Jupiters Based on the Sodium and Potassium Lines

A Cloudiness Index for Transiting Exoplanets Based on the Sodium and Potassium Lines: Tentative Evidence for Hotter Atmospheres Being Less Cloudy at Visible Wavelengths

Authors:

Heng et al

Abstract:

We present a dimensionless index that quantifies the degree of cloudiness of the atmosphere of a transiting exoplanet. Our cloudiness index is based on measuring the transit radii associated with the line center and wing of the sodium or potassium line. In deriving this index, we revisited the algebraic formulae for inferring the isothermal pressure scale height from transit measurements. We demonstrate that the formulae of Lecavelier et al. and Benneke & Seager are identical: the former is inferring the temperature while assuming a value for the mean molecular mass and the latter is inferring the mean molecular mass while assuming a value for the temperature. More importantly, these formulae cannot be used to distinguish between cloudy and cloudfree atmospheres. We derive values of our cloudiness index for a small sample of 7 hot Saturns/Jupiters taken from Sing et al. We show that WASP-17b, WASP-31b and HAT-P-1b are nearly cloudfree at visible wavelengths. We find the tentative trend that more irradiated atmospheres tend to have less clouds consisting of sub-micron-sized particles. We also derive absolute sodium and/or potassium abundances ∼102 cm−3 for WASP-17b, WASP-31b and HAT-P-1b (and upper limits for the other objects). Higher-resolution measurements of both the sodium and potassium lines, for a larger sample of exoplanetary atmospheres, are needed to confirm or refute this trend.

Kepler-539b & Kepler-539c are Wide Orbit Gas Giants

Kepler-539: A young extrasolar system with two giant planets on wide orbits and in gravitational interaction

Authors:

Mancini et al

Abstract:

We confirm the planetary nature of Kepler-539 b (aka Kepler object of interest K00372.01), a giant transiting exoplanet orbiting a solar-analogue G2 V star. The mass of Kepler-539 b was accurately derived thanks to a series of precise radial velocity measurements obtained with the CAFE spectrograph mounted on the CAHA 2.2-m telescope. A simultaneous fit of the radial-velocity data and Kepler photometry revealed that Kepler-539 b is a dense Jupiter-like planet with a mass of Mp = 0.97 ± 0.29 MJup and a radius of Rp = 0.747 ± 0.018 RJup, making a complete circular revolution around its parent star in 125.6 days. The semi-major axis of the orbit is roughly 0.5 au, implying that the planet is at ≈0.45 au from the habitable zone. By analysing the mid-transit times of the 12 transit events of Kepler-539 b recorded by the Kepler spacecraft, we found a clear modulated transit time variation (TTV), which is attributable to the presence of a planet c in a wider orbit. The few timings available do not allow us to precisely estimate the properties of Kepler-539 c and our analysis suggests that it has a mass between 1.2 and 3.6 MJup, revolving on a very eccentric orbit (0.4

DYNAMICS AND TRANSIT VARIATIONS OF RESONANT EXOPLANETS

DYNAMICS AND TRANSIT VARIATIONS OF RESONANT EXOPLANETS

Authors:

Nesvorný et al

Abstract:

Transit timing variations (TTVs) are deviations of the measured midtransit times from the exact periodicity. One of the most interesting causes of TTVs is the gravitational interaction between planets. Here we consider a case of two planets in a mean motion resonance (orbital periods in a ratio of small integers). This case is important because the resonant interaction can amplify the TTV effect and allow planets to be detected more easily. We develop an analytic model of the resonant dynamics valid for small orbital eccentricities and use it to derive the principal TTV terms. We find that a resonant system should show TTV terms with two basic periods (and their harmonics). The resonant TTV period is proportional (m/M *)−2/3, where m and M * are the planetary and stellar masses. For m = 10−4 M *, for example, the TTV period exceeds the orbital period by about two orders of magnitude. The amplitude of the resonant TTV terms scales linearly with the libration amplitude. The ratio of the TTV amplitudes of two resonant planets is inversely proportional to the ratio of their masses. These and other relationships discussed in the main text can be used to aid the interpretation of TTV observations.

No asymmetries in the transit of hot Jupiter CoRoT-29b

The GTC exoplanet transit spectroscopy survey III. No asymmetries in the transit of CoRoT-29b

Authors:

Pallé et al

Abstract:

Context.

The launch of the exoplanet space missions obtaining exquisite photometry from space has resulted in the discovery of thousands of planetary systems with very different physical properties and architectures. Among them, the exoplanet CoRoT-29b was identified in the light curves the mission obtained in summer 2011, and presented an asymmetric transit light curve, which was tentatively explained via the effects of gravity darkening.

Aims.

Transits of CoRoT-29b are measured with precision photometry, to characterize the reported asymmetry in their transit shape.

Methods.

Using the OSIRIS spectrograph at the 10-m GTC telescope, we perform spectro-photometric differential observations, which allow us to both calculate a high-accuracy photometric light curve, and a study of the color-dependence of the transit.

Results.

After careful data analysis, we find that the previously reported asymmetry is not present in either of two transits, observed in July 2014 and July 2015 with high photometric precisions of 300 ppm over 5 min. Due to the relative faintness of the star, we do not reach the precision necessary to perform transmission spectroscopy of its atmosphere, but we see no signs of color-dependency of the transit depth or duration.

Conclusions.

We conclude that the previously reported asymmetry may have been a time-dependent phenomenon, which did not occur in more recent epochs. Alternatively, instrumental effects in the discovery data may need to be reconsidered.

Dynamics and Transit Variations of Resonant Exoplanets

Dynamics and Transit Variations of Resonant Exoplanets

Authors:

Nesvorny et al

Abstract:

The Transit Timing Variations (TTVs) are deviations of the measured mid-transit times from the exact periodicity. One of the most interesting causes of TTVs is the gravitational interaction between planets. Here we consider a case of two planets in a mean motion resonance (orbital periods in a ratio of small integers). This case is important because the resonant interaction can amplify the TTV effect and allow planets to be detected more easily. We develop an analytic model of the resonant dynamics valid for small orbital eccentricities and use it to derive the principal TTV terms. We find that a resonant system should show TTV terms with two basic periods (and their harmonics). The resonant TTV period is proportional (m/M_*)^(-2/3), where m and M_* are the planetary and stellar masses. For m=10^(-4) M_*, for example, the TTV period exceeds the orbital period by ~2 orders of magnitude. The amplitude of the resonant TTV terms scales linearly with the libration amplitude. The ratio of the TTV amplitudes of two resonant planets is inversely proportional to the ratio of their masses. These and other relationships discussed in the main text can be used to aid the interpretation of TTV observations.

Predictable patterns in planetary transit timing variations and transit duration variations due to exomoons

Predictable patterns in planetary transit timing variations and transit duration variations due to exomoons

Authors:

Heller et al

Abstract:

We present new ways to identify single and multiple moons around extrasolar planets using planetary transit timing variations (TTVs) and transit duration variations (TDVs). For planets with one moon, measurements from successive transits exhibit a hitherto undescribed pattern in the TTV-TDV diagram, originating from the stroboscopic sampling of the planet's orbit around the planet-moon barycenter. This pattern is fully determined and analytically predictable after three consecutive transits. The more measurements become available, the more the TTV-TDV diagram approaches an ellipse. For planets with multiple moons in orbital mean motion resonance (MMR), like the Galilean moons, the pattern is much more complex and addressed numerically in this report. Exomoons in MMR can also form closed, predictable TTV-TDV figures if the drift of the moons' pericenters is sufficiently slow. We find that MMR exomoons produce loops in the TTV-TDV diagram and that the number of these loops is equal to the order of the MMR, or the largest integer in the MMR ratio. We use a Bayesian model and Monte Carlo simulations to test the discoverability of exomoons using TTV-TDV diagrams with current and near-future technology. In a blind test, two of us (BP, DA) successfully retrieved a large moon from simulated TTV-TDV by co-authors MH and RH, which resembled data from a known Kepler planet candidate. Single exomoons with a 10% moon-to-planet mass ratio, like to Pluto-Charon binary, can be detectable in the archival data of the Kepler primary mission. Multi-exomoon systems, however, require either larger telescopes or brighter target stars. Complementary detection methods invoking a moon's own photometric transit or its orbital sampling effect can be used for validation or falsification. A combination of TESS, CHEOPS, and PLATO data would offer a compelling opportunity for exomoon discoveries around bright stars.

Transiting planets as a precision clock to constrain the time variation of the gravitational constant

Transiting planets as a precision clock to constrain the time variation of the gravitational constant

Authors:

Masuda et al

Abstract:

Analysis of transit times in exoplanetary systems accurately provides an instantaneous orbital period, P(t), of their member planets. A long-term monitoring of those transiting planetary systems puts limits on the variability of P(t), which are translated into the constraints on the time variation of the gravitational constant G. We apply this analysis to 10 transiting systems observed by the Kepler spacecraft, and find that ΔG/G≲5×10−6 for 2009-2013, or G˙/G≲10−6yr−1 if G˙ is constant. While the derived limit is weaker than those from other analyses, it is complementary to them and can be improved by analyzing numerous transiting systems that are continuously monitored.

New Observations of hot Jupiter HAT-P-24b

Solution of newly observed transit of the exoplanet HAT-P-24b: no TTV and TDV signals

Authors:

Kjurkchieva et al

Abstract:

We present photometric observations of transit of the exoplanet HAT-P-24b using the Rozhen 2 m telescope. Its solution gives relative stellar radius r_{s}=0.1304 (a/R_{s}=7.669), relative planet radius r_{p}=0.01304 and orbital inclination of 90 degree. The calculated planet radius is R_{p}=1.316 R_{J} and corresponds to planet density of rho_{p}=0.37 g cm^{-3}. Our parameter values are between those of the previous two solutions. We did not find evidences of TTV and TDV signals of HAT-P-24b.

WASP-12b and Qatar-1b do NOT Appear to be in Multi Exoplanetary Systems

Transit Timing Variation Measurements of WASP-12b and Qatar-1b: No Evidence for Additional Planets

Authors:

Collins et al

Abstract:

WASP-12b and Qatar-1b are transiting Hot Jupiters for which previous works have suggested the presence of transit timing variations (TTVs) indicative of additional bodies in these systems---an Earth-mass planet in WASP-12 and a brown-dwarf mass object in Qatar-1. Here, we present 23 new WASP-12b and 18 new Qatar-1b complete (or nearly complete) transit observations. We perform global system fits to all of our lights curves for each system, plus RV and stellar spectroscopic parameters from the literature. The global fits provide refined system parameters and uncertainties for each system, including precise transit center times for each transit. The transit model residuals of the combined and five minute binned light curves have a RMS of 183 and 255 parts per million (ppm) for WASP-12b and Qatar-1b, respectively. Most WASP-12b system parameter values from this work are consistent with values from previous studies, but have ~40-50% smaller uncertainties. Most of the Qatar-1b system parameter values and uncertainties from this work are consistent with values recently reported in the literature. We find no convincing evidence for sinusoidal TTVs with a semi-amplitude of more than ~ 35 s and ~ 25 s in the WASP-12b and Qatar-1b systems, respectively. On the other hand, the data are sparsely sampled and it may be possible that short period, low level, or non-sinusoidal TTV signals are lurking in the data.

Revising the Kepler-10 System for Exoplanet Characteristics & Adding Kepler-10d (KOI-72.X)

Revised Masses and Densities of the Planets around Kepler-10

Authors:

Weiss et al

Abstract:

Determining which small exoplanets have stony-iron compositions is necessary for quantifying the occurrence of such planets and for understanding the physics of planet formation. Kepler-10 hosts the stony-iron world Kepler-10b (K10b), and also contains what has been reported to be the largest solid silicate-ice planet, Kepler-10c (K10c). Using 220 radial velocities (RVs), including 72 precise RVs from Keck-HIRES of which 20 are new from 2014-2015, and 17 quarters of Kepler photometry, we obtain the most complete picture of the Kepler-10 system to date. We find that K10b (Rp=1.47 Re) has mass 3.72±0.42 Me and density 6.46±0.73 g/cc. Modeling the interior of K10b as an iron core overlaid with a silicate mantle, we find that the iron core constitutes 0.17±0.11 of the planet mass. For K10c (Rp=2.35 Re) we measure Mp=13.98±1.79 Me and ρ=5.94±0.76 g/cc, significantly lower than the mass computed in Dumusque et al. (2014, 17.2±1.9 Me). Internal compositional modeling reveals that at least 10% of the radius of Kepler-10c is a volatile envelope composed of hydrogen-helium (0.2% of the mass, 16% of the radius) or super-ionic water (28% of the mass, 29% of the radius). Analysis of only HIRES data yields a higher mass for K10b and a lower mass for K10c than does analysis of the HARPS-N data alone, with the mass estimates for K10c formally inconsistent by 3σ. Splitting the RVs from each instrument leads to inconsistent measurements for the mass of planet c in each data set. This suggests that time-correlated noise is present and that the uncertainties in the planet masses (especially K10c) exceed our formal estimates. Transit timing variations (TTVs) of K10c indicate the likely presence of a third planet in the system, KOI-72.X. The TTVs and RVs are consistent with KOI-72.X having an orbital period of 24, 71, or 101 days, and a mass from 1-7 Me.

Sensitivity bias in the mass-radius distribution from Transit Timing Variations and Radial Velocity measurements

Sensitivity bias in the mass-radius distribution from Transit Timing Variations and Radial Velocity measurements

Authors:

Steffen et al

Abstract:

Motivated by recent discussions, both in private and in the literature, we use a Monte Carlo simulation of planetary systems to investigate sources of bias in determining the mass-radius distribution of exoplanets for the two primary techniques used to measure planetary masses---Radial Velocities (RVs) and Transit Timing Variations (TTVs). We assert that mass measurements derived from these two methods are comparably reliable---as the physics underlying their respective signals is well understood. Nevertheless, their sensitivity to planet mass varies with the properties of the planets themselves. We find that for a given planet size, the RV method tends to find planets with higher mass while the sensitivity of TTVs is more uniform. This ``sensitivity bias'' implies that a complete census of TTV systems is likely to yield a more robust estimate of the mass-radius distribution provided there are not important physical differences between planets near and far from mean-motion resonance. We discuss differences in the sensitivity of the two methods with orbital period and system architecture, which may compound the discrepancies between them (e.g., short period planets detectable by RVs may be more dense due to atmospheric loss). We advocate for continued mass measurements using both approaches as a means both to measure the masses of more planets and to identify potential differences in planet structure that may result from their dynamical and environmental histories.