226 research outputs found

    Fast Radio Burst Tomography of the Unseen Universe

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    The discovery of Fast Radio Bursts (FRBs) at cosmological distances has opened a powerful window on otherwise unseen matter in the Universe. In the 2020s, observations of >104>10^{4} FRBs will assess the baryon contents and physical conditions in the hot/diffuse circumgalactic, intracluster, and intergalactic medium, and test extant compact-object dark matter models.Comment: Science white paper submitted to the Astro2020 Decadal Survey. 15 pages, 3 color figure

    Fast Radio Burst Tomography of the Unseen Universe

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    The discovery of Fast Radio Bursts (FRBs) at cosmological distances has opened a powerful window on otherwise unseen matter in the Universe. Observations of >104 FRBs will assess the baryon contents and physical conditions in the hot/diffuse circumgalactic, intracluster, and intergalactic medium, and test extant compact-object dark matter models

    KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra

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    We announce the discovery of a highly inflated transiting hot Jupiter discovered by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with Teff=5754−55+54T_{\rm eff} = 5754_{-55}^{+54} K, log⁥g=4.078−0.054+0.049\log{g} = 4.078_{-0.054}^{+0.049}, [Fe/H]=0.272±0.038[Fe/H] = 0.272\pm0.038, an inferred mass M∗=1.211−0.066+0.078M_{*}=1.211_{-0.066}^{+0.078} M⊙_{\odot}, and radius R∗=1.67−0.12+0.14R_{*}=1.67_{-0.12}^{+0.14} R⊙_{\odot}. The planetary companion has mass MP=0.867−0.061+0.065M_P = 0.867_{-0.061}^{+0.065} MJM_{J}, radius RP=1.86−0.16+0.18R_P = 1.86_{-0.16}^{+0.18} RJR_{J}, surface gravity log⁥gP=2.793−0.075+0.072\log{g_{P}} = 2.793_{-0.075}^{+0.072}, and density ρP=0.167−0.038+0.047\rho_P = 0.167_{-0.038}^{+0.047} g cm−3^{-3}. The planet is on a roughly circular orbit with semimajor axis a=0.04571−0.00084+0.00096a = 0.04571_{-0.00084}^{+0.00096} AU and eccentricity e=0.035−0.025+0.050e = 0.035_{-0.025}^{+0.050}. The best-fit linear ephemeris is T0=2456883.4803±0.0007T_0 = 2456883.4803 \pm 0.0007 BJDTDB_{\rm TDB} and P=3.24406±0.00016P = 3.24406 \pm 0.00016 days. This planet is one of the most inflated of all known transiting exoplanets, making it one of the few members of a class of extremely low density, highly-irradiated gas giants. The low stellar log⁥g\log{g} and large implied radius are supported by stellar density constraints from follow-up light curves, plus an evolutionary and space motion analysis. We also develop a new technique to extract high precision radial velocities from noisy spectra that reduces the observing time needed to confirm transiting planet candidates. This planet boasts deep transits of a bright star, a large inferred atmospheric scale height, and a high equilibrium temperature of Teq=1675−55+61T_{eq}=1675^{+61}_{-55} K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies.Comment: Submitted to ApJ, feedback is welcom
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