452 research outputs found

    Passive turbulent flamelet propagation

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    We analyze results of a premixed constant density flame propagating in three-dimensional turbulence, where a flame model developed by Kerstein, et al. (1988) has been used. Simulations with constant and evolving velocity fields are used, where peculiar results were obtained from the constant velocity field runs. Data from the evolving flow runs with various flame speeds are used to determine two-point correlations of the fluctuating scalar field and implications for flamelet modeling are discussed

    General Aviation Trends in the European Market Memorandum Report

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    In 1969, as western Europe was becoming a common market, significant economic growth was projected. His Highness, The Aga Kahn requested that Economics Research Associates (ERA) perform a memorandum report and forecast the trends for private aviation potentials in Europe over the decade of the 1970s. The resulting report by ERA reviews the history of European aviation, current and future economic trends in the common European market area as these pertain to the growth of private aviation, advantages and disadvantages involved in noncommercial flying, and future trends in private aviation. Data was gathered from such sources as aviation publications, interviews with persons connected with private aviation, and market studies and projections of commercial organizations. The report includes the following sections: 1) introduction, 2) summary and conclusions, 3) the western European economy, 4) general aviation, 5) general aviation and future trends in aviation design, 6) impact of general aviation on tourism. The report includes four tables

    KOI-3890: A high mass-ratio asteroseismic red-giant++M-dwarf eclipsing binary undergoing heartbeat tidal interactions

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    KOI-3890 is a highly eccentric, 153-day period eclipsing, single-lined spectroscopic binary system containing a red-giant star showing solar-like oscillations alongside tidal interactions. The combination of transit photometry, radial velocity observations, and asteroseismology have enabled the detailed characterisation of both the red-giant primary and the M-dwarf companion, along with the tidal interaction and the geometry of the system. The stellar parameters of the red-giant primary are determined through the use of asteroseismology and grid-based modelling to give a mass and radius of M=1.04±0.06  MM_{\star}=1.04\pm0.06\;\textrm{M}_{\odot} and R=5.8±0.2  RR_{\star}=5.8\pm0.2\;\textrm{R}_{\odot} respectively. When combined with transit photometry the M-dwarf companion is found to have a mass and radius of Mc=0.23±0.01  MM_{\mathrm{c}}=0.23\pm0.01\;\textrm{M}_{\odot} and Rc=0.256±0.007  RR_{\mathrm{c}}=0.256\pm0.007\;\textrm{R}_{\odot}. Moreover, through asteroseismology we constrain the age of the system through the red-giant primary to be 9.11.7+2.4  Gyr9.1^{+2.4}_{-1.7}\;\mathrm{Gyr}. This provides a constraint on the age of the M-dwarf secondary, which is difficult to do for other M-dwarf binary systems. In addition, the asteroseismic analysis yields an estimate of the inclination angle of the rotation axis of the red-giant star of i=87.61.2+2.4i=87.6^{+2.4}_{-1.2} degrees. The obliquity of the system\textemdash the angle between the stellar rotation axis and the angle normal to the orbital plane\textemdash is also derived to give ψ=4.24.2+2.1\psi=4.2^{+2.1}_{-4.2} degrees showing that the system is consistent with alignment. We observe no radius inflation in the M-dwarf companion when compared to current low-mass stellar models.Comment: 11 pages, 5 figures, accepted for publication in MNRA

    Asteroseismology of the Hyades with K2: first detection of main-sequence solar-like oscillations in an open cluster

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    The Hyades open cluster was targeted during Campaign 4 (C4) of the NASA K2 mission, and short-cadence data were collected on a number of cool main-sequence stars. Here, we report results on two F-type stars that show detectable oscillations of a quality that allows asteroseismic analyses to be performed. These are the first ever detections of solar-like oscillations in main-sequence stars in an open cluster.Comment: 12 pages, 8 figures, 2 tables; accepted for publication in MNRA

    Synchronous deficits in cumulative muscle protein synthesis and ribosomal biogenesis underlie age-related anabolic resistance to exercise in humans

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    Ageing is associated with impaired hypertrophic responses to resistance exercise training (RET). Here we investigated the aetiology of ‘anabolic resistance’ in older humans. Twenty healthy male individuals, 10 younger (Y; 23 ± 1 years) and 10 older (O; 69 ± 3 years), performed 6 weeks unilateral RET (6 × 8 repetitions, 75% of one repetition maximum (1-RM), 3 times per week). After baseline bilateral vastus lateralis (VL) muscle biopsies, subjects consumed 150 ml D2O (70 atom%; thereafter 50 ml week−1), further bilateral VL muscle biopsies were taken at 3 and 6 weeks to quantify muscle protein synthesis (MPS) via gas chromatography–pyrolysis–isotope ratio mass spectrometry. After RET, 1-RM increased in Y (+35 ± 4%) and O (+25 ± 3%; P < 0.01), while MVC increased in Y (+21 ± 5%; P < 0.01) but not O (+6 ± 3%; not significant (NS)). In comparison to Y, O displayed blunted RET-induced increases in muscle thickness (at 3 and 6 weeks, respectively, Y: +8 ± 1% and +11 ± 2%, P < 0.01; O: +2.6 ± 1% and +3.5 ± 2%, NS). While ‘basal’ longer term MPS was identical between Y and O (∼1.35 ± 0.1% day−1), MPS increased in response to RET only in Y (3 weeks, Y: 1.61 ± 0.1% day−1; O: 1.49 ± 0.1% day−1). Consistent with this, O exhibited inferior ribosomal biogenesis (RNA:DNA ratio and c-MYC induction: Y: +4 ± 2 fold change; O: +1.9 ± 1 fold change), translational efficiency (S6K1 phosphorylation, Y: +10 ± 4 fold change; O: +4 ± 2 fold change) and anabolic hormone milieu (testosterone, Y: 367 ± 19; O: 274 ± 19 ng dl−1 (all P < 0.05). Anabolic resistance is thus multifactorial

    Kepler-93b: A Terrestrial World Measured to within 120 km, and a Test Case for a New Spitzer Observing Mode

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    We present the characterization of the Kepler-93 exoplanetary system, based on three years of photometry gathered by the Kepler spacecraft. The duration and cadence of the Kepler observations, in tandem with the brightness of the star, enable unusually precise constraints on both the planet and its host. We conduct an asteroseismic analysis of the Kepler photometry and conclude that the star has an average density of 1.652+/-0.006 g/cm^3. Its mass of 0.911+/-0.033 M_Sun renders it one of the lowest-mass subjects of asteroseismic study. An analysis of the transit signature produced by the planet Kepler-93b, which appears with a period of 4.72673978+/-9.7x10^-7 days, returns a consistent but less precise measurement of the stellar density, 1.72+0.02-0.28 g/cm^3. The agreement of these two values lends credence to the planetary interpretation of the transit signal. The achromatic transit depth, as compared between Kepler and the Spitzer Space Telescope, supports the same conclusion. We observed seven transits of Kepler-93b with Spitzer, three of which we conducted in a new observing mode. The pointing strategy we employed to gather this subset of observations halved our uncertainty on the transit radius ratio R_p/R_star. We find, after folding together the stellar radius measurement of 0.919+/-0.011 R_Sun with the transit depth, a best-fit value for the planetary radius of 1.481+/-0.019 R_Earth. The uncertainty of 120 km on our measurement of the planet's size currently renders it one of the most precisely measured planetary radii outside of the Solar System. Together with the radius, the planetary mass of 3.8+/-1.5 M_Earth corresponds to a rocky density of 6.3+/-2.6 g/cm^3. After applying a prior on the plausible maximum densities of similarly-sized worlds between 1--1.5 R_Earth, we find that Kepler-93b possesses an average density within this group.Comment: 20 pages, 9 figures, accepted for publication in Ap

    Kepler-68: Three Planets, One With a Density Between That of Earth and Ice Giants

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    NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68. Follow-up Doppler measurements have established the mass of the innermost planet and revealed a third jovian-mass planet orbiting beyond the two transiting planets. Kepler-68b, in a 5.4 day orbit has mass 8.3 +/- 2.3 Earth, radius 2.31 +/- 0.07 Earth radii, and a density of 3.32 +/- 0.92 (cgs), giving Kepler-68b a density intermediate between that of the ice giants and Earth. Kepler-68c is Earth-sized with a radius of 0.953 Earth and transits on a 9.6 day orbit; validation of Kepler-68c posed unique challenges. Kepler-68d has an orbital period of 580 +/- 15 days and minimum mass of Msin(i) = 0.947 Jupiter. Power spectra of the Kepler photometry at 1-minute cadence exhibit a rich and strong set of asteroseismic pulsation modes enabling detailed analysis of the stellar interior. Spectroscopy of the star coupled with asteroseismic modeling of the multiple pulsation modes yield precise measurements of stellar properties, notably Teff = 5793 +/- 74 K, M = 1.079 +/- 0.051 Msun, R = 1.243 +/- 0.019 Rsun, and density 0.7903 +/- 0.0054 (cgs), all measured with fractional uncertainties of only a few percent. Models of Kepler-68b suggest it is likely composed of rock and water, or has a H and He envelope to yield its density of about 3 (cgs).Comment: 32 pages, 13 figures, Accepted to Ap

    Kepler-432: a red giant interacting with one of its two long period giant planets

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    We report the discovery of Kepler-432b, a giant planet (Mb=5.410.18+0.32MJup,Rb=1.1450.039+0.036RJupM_b = 5.41^{+0.32}_{-0.18} M_{\rm Jup}, R_b = 1.145^{+0.036}_{-0.039} R_{\rm Jup}) transiting an evolved star (M=1.320.07+0.10M,R=4.060.08+0.12R)(M_\star = 1.32^{+0.10}_{-0.07} M_\odot, R_\star = 4.06^{+0.12}_{-0.08} R_\odot) with an orbital period of Pb=52.5011290.000053+0.000067P_b = 52.501129^{+0.000067}_{-0.000053} days. Radial velocities (RVs) reveal that Kepler-432b orbits its parent star with an eccentricity of e=0.51340.0089+0.0098e = 0.5134^{+0.0098}_{-0.0089}, which we also measure independently with asterodensity profiling (AP; e=0.5070.114+0.039e=0.507^{+0.039}_{-0.114}), thereby confirming the validity of AP on this particular evolved star. The well-determined planetary properties and unusually large mass also make this planet an important benchmark for theoretical models of super-Jupiter formation. Long-term RV monitoring detected the presence of a non-transiting outer planet (Kepler-432c; Mcsinic=2.430.24+0.22MJup,Pc=406.22.5+3.9M_c \sin{i_c} = 2.43^{+0.22}_{-0.24} M_{\rm Jup}, P_c = 406.2^{+3.9}_{-2.5} days), and adaptive optics imaging revealed a nearby (0\farcs87), faint companion (Kepler-432B) that is a physically bound M dwarf. The host star exhibits high signal-to-noise asteroseismic oscillations, which enable precise measurements of the stellar mass, radius and age. Analysis of the rotational splitting of the oscillation modes additionally reveals the stellar spin axis to be nearly edge-on, which suggests that the stellar spin is likely well-aligned with the orbit of the transiting planet. Despite its long period, the obliquity of the 52.5-day orbit may have been shaped by star-planet interaction in a manner similar to hot Jupiter systems, and we present observational and theoretical evidence to support this scenario. Finally, as a short-period outlier among giant planets orbiting giant stars, study of Kepler-432b may help explain the distribution of massive planets orbiting giant stars interior to 1 AU.Comment: 22 pages, 19 figures, 5 tables. Accepted to ApJ on Jan 24, 2015 (submitted Nov 11, 2014). Updated with minor changes to match published versio

    Stellar Spin-Orbit Misalignment in a Multiplanet System

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    Stars hosting hot Jupiters are often observed to have high obliquities, whereas stars with multiple co-planar planets have been seen to have low obliquities. This has been interpreted as evidence that hot-Jupiter formation is linked to dynamical disruption, as opposed to planet migration through a protoplanetary disk. We used asteroseismology to measure a large obliquity for Kepler-56, a red giant star hosting two transiting co-planar planets. These observations show that spin-orbit misalignments are not confined to hot-Jupiter systems. Misalignments in a broader class of systems had been predicted as a consequence of torques from wide-orbiting companions, and indeed radial-velocity measurements revealed a third companion in a wide orbit in the Kepler-56 system.Comment: Accepted for publication in Science, published online on October 17 2013; PDF includes main article and supplementary materials (65 pages, 27 figures, 7 tables); v2: small correction to author lis

    Fundamental Properties of Kepler Planet-Candidate Host Stars using Asteroseismology

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    We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius and mass, respectively. The results include new asteroseismic solutions for four host stars with confirmed planets (Kepler-4, Kepler-14, Kepler-23 and Kepler-25) and increase the total number of Kepler host stars with asteroseismic solutions to 77. A comparison with stellar properties in the planet-candidate catalog by Batalha et al. shows that radii for subgiants and giants obtained from spectroscopic follow-up are systematically too low by up to a factor of 1.5, while the properties for unevolved stars are in good agreement. We furthermore apply asteroseismology to confirm that a large majority of cool main-sequence hosts are indeed dwarfs and not misclassified giants. Using the revised stellar properties, we recalculate the radii for 107 planet candidates in our sample, and comment on candidates for which the radii change from a previously giant-planet/brown-dwarf/stellar regime to a sub-Jupiter size, or vice versa. A comparison of stellar densities from asteroseismology with densities derived from transit models in Batalha et al. assuming circular orbits shows significant disagreement for more than half of the sample due to systematics in the modeled impact parameters, or due to planet candidates which may be in eccentric orbits. Finally, we investigate tentative correlations between host-star masses and planet candidate radii, orbital periods, and multiplicity, but caution that these results may be influenced by the small sample size and detection biases.Comment: 19 pages, 10 figures, 4 tables; accepted for publication in ApJ; machine-readable versions of tables 1-3 are available as ancillary files or in the source code; v2: minor changes to match published versio
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