An Excess of Jupiter Analogs in Super-Earth Systems

We use radial velocity observations to search for long-period gas giant companions in systems hosting inner super-Earth (1-4 R_Earth, 1-10 M_Earth) planets to constrain formation and migration scenarios for this population. We consistently re-fit published RV datasets for 65 stars and find 9 systems with statistically significant trends indicating the presence of an outer companion. We combine these RV data with AO images to constrain the masses and semi-major axes of these companions. We quantify our sensitivity to the presence of long-period companions by fitting the sample with a power law distribution and find an occurrence rate of 39+/-7% for companions 0.5-20 M_Jup and 1-20 AU. Half of our systems were discovered by the transit method and half were discovered by the RV method. While differences in RV baselines and number of data points between the two samples lead to different sensitivities to distant companions, we find that occurrence rates of gas giant companions in each sample are consistent at the 0.5$\sigma$ level. We compare the frequency of Jupiter analogs in these systems to the equivalent rate from field star surveys and find that Jupiter analogs are more common around stars hosting super-Earths. We conclude that the presence of outer gas giants does not suppress the formation of inner super-Earths, and that these two populations of planets instead appear to be correlated. We also find that the stellar metallicities of systems with gas giant companions are higher than those without companions, in agreement with the well-established metallicity correlation from RV surveys of field stars.Comment: published in A

Formation and Migration Histories of Giant Exoplanets in Multi-stellar Systems

The first planets discovered outside of our solar system were very different from the solar system planets. These discoveries raised new challenges to planet formation models, which were designed to explain the origin of the solar system planets. One particularly intriguing population, the "hot Jupiters" were some of the first planets discovered. These gas giant planets have masses similar to Jupiter and Saturn, however, they were found on orbits 100 times closer to their star than Jupiter is to the sun. Proposed formation scenarios involve models that argue for formation at presently observed locations, but these are challenged by the lack of planet-building materials so close to the host star. Other models assume these planets form at more moderate locations, perhaps in a manner similar to Jupiter and Saturn, followed by inward migration via some other mechanism. These models are challenged by the lack of a known migration mechanism. This dissertation compiles three studies conducted over the past five years to investigate the formation and migration histories of gas giant exoplanets. After the discovery of the first hot Jupiter, additional discoveries revealed some population characteristics that could provide evidence for certain formation or migration scenarios. A large fraction of hot Jupiters were found to have eccentric orbits and/or misaligned orbits relative to the star's spin axis. These properties suggest that a gravitational interaction with an additional massive object may have played a role in the dynamical history of these hot Jupiters. Studies of stellar multiplicity for nearby, sun-like stars have also revealed that multi-stellar systems are common. The studies presented in this dissertation investigate whether stellar companions to giant planet systems influence the planets. In the first and second study, we conduct a survey for stellar companions around stars that host hot Jupiters detected by the transiting method. The first study examines whether stars hosting misaligned planets are more likely to host a companion star. We found no such correlation, suggesting that stellar companions do not play a dominant role in causing planetary misalignment. In the second study, we look at the population of stellar companions as a whole to quantify the fraction of hot Jupiters that might have migrated due to stellar interactions. We find that less than 20% of hot Jupiters might have experienced this migration scenario. However, we do find that hot Jupiters are three times more likely to be in a wide multi-stellar system compared to nearby stars that do not host hot Jupiters, suggesting some other connection between the companion star and the giant planet. In the third study, we search for stellar companions around stars that host giant planets over a wide range of separations, from the close-in hot Jupiters to giant planets as far away as Jupiter is to our sun. These planets were found via the radial velocity method. We compare the giant planets' orbital properties for single- and multi-stellar systems to determine whether planets in multi-stellar systems show some evidence for star-planet interactions. With the current dataset, we find no evidence to support the hypothesis that planets in multi-stellar systems have a different set of orbital properties. Finally, we present preliminary results of an ongoing survey to understand giant planet formation on the other extreme end. Instead of hot Jupiters on close-in orbits, this survey seeks to explain the origin of the very distant giant planetary mass objects found by direct imaging surveys. These objects are often found on separations that are ten to one hundred times farther away than Neptune is to our sun. Due to their distance and size, it's not certain if these objects are some of the biggest planets in existence or if they are the smallest stars. This new survey will search for planets to serve as the link between known giant exoplanets and these unknown directly imaged objects.</p

Passive Tracking System and Method

System and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes antenna array with three antenna elements, which preferably are patch antenna elements placed apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol

KELT-16b: A Highly Irradiated, Ultra-short Period Hot Jupiter Nearing Tidal Disruption

We announce the discovery of KELT-16b, a highly irradiated, ultra-short period hot Jupiter transiting the relatively bright (V = 11.7) star TYC 2688-1839-1/KELT-16. A global analysis of the system shows KELT-16 to be an F7V star with T_(eff) = 6236 ± 54 K, log g⋆ = 4.253^(+0.031)_(-0.036), [Fe/H] = -0.002^(+0.086)_(-0.085), M⋆ = 1.211^(+0.043)_(-0.046) M⊙, and R⋆ = 1.360^(+0.064)_(-0.15)R⊙. The planet is a relatively high-mass inflated gas giant with M_P = 2.75^(+0.16)_(-0.15)M_J, R_P = 1.415^(+0.084)_(-0.067)R_J, density Ρ_p = 1.20 ± 0.18 g cm^(−3), surface gravity Log g_P = 3.530^(+0.042)_(-0.049), and T_(eq) = 2453^(+55)_(-47)K. The best-fitting linear ephemeris is T_C = 2457247.24791 ± 0.00019 BJD_(TBD) and P = 0.9689951 ± 0.0000024 day. KELT-16b joins WASP-18b, −19b, −43b, −103b, and HATS-18b as the only giant transiting planets with P < 1 day. Its ultra-short period and high irradiation make it a benchmark target for atmospheric studies by the Hubble Space Telescope, Spitzer, and eventually the James Webb Space Telescope. For example, as a hotter, higher-mass analog of WASP-43b, KELT-16b may feature an atmospheric temperature–pressure inversion and day-to-night temperature swing extreme enough for TiO to rain out at the terminator. KELT-16b could also join WASP-43b in extending tests of the observed mass–metallicity relation of the solar system gas giants to higher masses. KELT-16b currently orbits at a mere ~1.7 Roche radii from its host star, and could be tidally disrupted in as little as a few ×105 years (for a stellar tidal quality factor of Q’* = 10^5). Finally, the likely existence of a widely separated bound stellar companion in the KELT-16 system makes it possible that Kozai–Lidov (KL) oscillations played a role in driving KELT-16b inward to its current precarious orbit

Obliquity Constraints on an Extrasolar Planetary-Mass Companion

We place the first constraints on the obliquity of a planetary-mass companion outside of the solar system. Our target is the directly imaged system 2MASS J01225093–2439505 (2M0122), which consists of a 120 Myr 0.4 M⊙ star hosting a 12–27 M_J companion at 50 au. We constrain all three of the system's angular-momentum vectors: how the companion spin axis, the stellar spin axis, and the orbit normal are inclined relative to our line of sight. To accomplish this, we measure projected rotation rates (v sin i) for both the star and the companion using new near-infrared high-resolution spectra with NIRSPEC at Keck Observatory. We combine these with a new stellar photometric rotation period from TESS and a published companion rotation period from Hubble Space Telescope to obtain spin-axis inclinations for both objects. We also fitted multiple epochs of astrometry, including a new observation with NIRC2/Keck, to measure 2M0122b's orbital inclination. The three line-of-sight inclinations place limits on the true de-projected companion obliquity and stellar obliquity. We find that while the stellar obliquity marginally prefers alignment, the companion obliquity tentatively favors misalignment. We evaluate possible origin scenarios. While collisions, secular spin–orbit resonances, and Kozai–Lidov oscillations are unlikely, formation by gravitational instability in a gravito-turbulent disk—the scenario favored for brown dwarf companions to stars—appears promising

Friends of Hot Jupiters II: No Correspondence Between Hot-Jupiter Spin-Orbit Misalignment and the Incidence of Directly Imaged Stellar Companions

Multi-star systems are common, yet little is known about a stellar companion's influence on the formation and evolution of planetary systems. For instance, stellar companions may have facilitated the inward migration of hot Jupiters towards to their present day positions. Many observed short period gas giant planets also have orbits that are misaligned with respect to their star's spin axis, which has also been attributed to the presence of a massive outer companion on a non-coplanar orbit. We present the results of a multi-band direct imaging survey using Keck NIRC2 to measure the fraction of short period gas giant planets found in multi-star systems. Over three years, we completed a survey of 50 targets ("Friends of Hot Jupiters") with 27 targets showing some signature of multi-body interaction (misaligned or eccentric orbits) and 23 targets in a control sample (well-aligned and circular orbits). We report the masses, projected separations, and confirmed common proper motion for the 19 stellar companions found around 17 stars. Correcting for survey incompleteness, we report companion fractions of $48\%\pm9\%$, $47\%\pm12\%$, and $51\%\pm13\%$ in our total, misaligned/eccentric, and control samples, respectively. This total stellar companion fraction is $2.8\,\sigma$ larger than the fraction of field stars with companions approximately $50-2000\,$AU. We observe no correlation between misaligned/eccentric hot Jupiter systems and the incidence of stellar companions. Combining this result with our previous radial velocity survey, we determine that $72\% \pm 16\%$ of hot Jupiters are part of multi-planet and/or multi-star systems.Comment: typos and references updated; 25 pages, 7 figures and 10 tables, accepted for publication in Ap

No difference in orbital parameters of RV-detected giant planets between 0.1 and 5 au in single vs multi-stellar systems

Our Keck/NIRC2 imaging survey searches for stellar companions around 144 systems with radial velocity (RV) detected giant planets to determine whether stellar binaries influence the planets' orbital parameters. This survey, the largest of its kind to date, finds eight confirmed binary systems and three confirmed triple systems. These include three new multi-stellar systems (HD 30856, HD 86081, and HD 207832) and three multi-stellar systems with newly confirmed common proper motion (HD 43691, HD 116029, and HD 164509). We combine these systems with seven RV planet-hosting multi-stellar systems from the literature in order to test for differences in the properties of planets with semimajor axes ranging between 0.1-5 au in single vs multi-stellar systems. We find no evidence that the presence or absence of stellar companions alters the distribution of planet properties in these systems. Although the observed stellar companions might influence the orbits of more distant planetary companions in these systems, our RV observations currently provide only weak constraints on the masses and orbital properties of planets beyond 5 au. In order to aid future efforts to characterize long period RV companions in these systems, we publish our contrast curves for all 144 targets. Using four years of astrometry for six hierarchical triple star systems hosting giant planets, we fit the orbits of the stellar companions in order to characterize the orbital architecture in these systems. We find that the orbital plane of the secondary and tertiary companions are inconsistent with an edge-on orbit in four out of six cases.Comment: 34 pages, 10 figures, 16 tables, including 4 tables in machine readable format and 7 tables with online supplemental dat

KIC 7177553: a quadruple system of two close binaries

KIC 7177553 was observed by the Kepler satellite to be an eclipsing eccentric binary star system with an 18-day orbital period. Recently, an eclipse timing study of the Kepler binaries has revealed eclipse timing variations (ETVs) in this object with an amplitude of ~100 s and an outer period of 529 days. The implied mass of the third body is that of a super-Jupiter, but below the mass of a brown dwarf. We therefore embarked on a radial velocity (RV) study of this binary to determine its system configuration and to check the hypothesis that it hosts a giant planet. From the RV measurements, it became immediately obvious that the same Kepler target contains another eccentric binary, this one with a 16.5-day orbital period. Direct imaging using adaptive optics reveals that the two binaries are separated by 0”.4 (~167 AU) and have nearly the same magnitude (to within 2%). The close angular proximity of the two binaries and very similar γ velocities strongly suggest that KIC 7177553 is one of the rare SB4 systems consisting of two eccentric binaries where at least one system is eclipsing. Both systems consist of slowly rotating, nonevolved, solar-like stars of comparable masses. From the orbital separation and the small difference in γ velocity, we infer that the period of the outer orbit most likely lies in the range of 1000–3000 yr. New images taken over the next few years, as well as the high-precision astrometry of the Gaia satellite mission, will allow us to set much narrower constraints on the system geometry. Finally, we note that the observed ETVs in the Kepler data cannot be produced by the second binary. Further spectroscopic observations on a longer timescale will be required to prove the existence of the massive planet