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TN, United States

Spot Observatory

TN, United States
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Oberst T.E.,Westminster College, Pennsylvania | Rodriguez J.E.,Vanderbilt University | Colon K.D.,NASA | Colon K.D.,Bay Area Environmental Research Institute | And 54 more authors.
Astronomical Journal | Year: 2017

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 K and . The planet is a relatively high-mass inflated gas giant with density g cm-3, surface gravity , and K. The best-fitting linear ephemeris is and 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 ). 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. © 2017. The American Astronomical Society. All rights reserved..


Collins K.A.,University of Louisville | Eastman J.D.,Las Cumbres Observatory Global Telescope Network | Eastman J.D.,University of California at Santa Barbara | Beatty T.G.,Ohio State University | And 44 more authors.
Astronomical Journal | Year: 2014

We report the discovery of KELT-6b, a mildly inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V = 10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T eff = 6102 ± 43 K, log g* = 4.07 +0.04 -0.07, and [Fe/H] = -0.28 ± 0.04, with an inferred mass M· = 1.09 ± 0.04M· and radius R· = 1.58+0.16 -0.09 R ·. The planetary companion has mass MP = 0.43 ± 0.05MJup, radius RP = 1.19+0.13 -0.08 RJup, surface gravity log gP = 2.86+0.06 -0.08, and density .P = 0.31+0.07 -0.08 g cm-3. The planet is on an orbit with semimajor axis a = 0.079 ± 0.001 AU and eccentricity e = 0.22+0.12 -0.10, which is roughly consistent with circular, and has ephemeris of Tc(BJDTDB) = 2456347.79679 ± 0.00036 and P = 7.845631 ± 0.000046 days. Equally plausible fits that employ empirical constraints on the host-star parameters rather than isochrones yield a larger planet mass and radius by ∼4}-7}. KELT-6b has surface gravity and incident flux similar to HD 209458b, but orbits a host that is more metal poor than HD 209458 by ∼0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a comparative measurement of two similar planets in similar environments around stars of very different metallicities. The precise radial velocity data also reveal an acceleration indicative of a longer-period third body in the system, although the companion is not detected in Keck adaptive optics images. © 2014. The American Astronomical Society. All rights reserved.


Pepper J.,Lehigh University | Pepper J.,Vanderbilt University | Siverd R.J.,Vanderbilt University | Beatty T.G.,Ohio State University | And 35 more authors.
Astrophysical Journal | Year: 2013

We report the discovery of KELT-3b, a moderately inflated transiting hot Jupiter with a mass of 1.477?0.067+0.066 MJ, radius of 1.345 ± 0.072RJ, and an orbital period of 2.7033904 ± 0.000010 days. The host star, KELT-3, is a V = 9.8 late F star with M* = 1.278+0.063?0.061M⊙, R* = 1.472+0.065?0.067 R *, Teff = 6306+50?49 K, log(g) = 4.209+0.033?0.031, and [Fe/H] = 0.044 +0.080?0.082, and has a likely proper motion companion. KELT-3b is the third transiting exoplanet discovered by the KELT survey, and is orbiting one of the 20 brightest known transiting planet host stars, making it a promising candidate for detailed characterization studies. Although we infer that KELT-3 is significantly evolved, a preliminary analysis of the stellar and orbital evolution of the system suggests that the planet has likely always received a level of incident flux above the empirically identified threshold for radius inflation suggested by Demory and Seager. © 2013. The American Astronomical Society. All rights reserved. Printed in the U.S.A.


Eastman J.D.,Harvard - Smithsonian Center for Astrophysics | Beatty T.G.,Pennsylvania State University | Siverd R.J.,Las Cumbres Observatory Global Telescope Network | Antognini J.M.O.,Ohio State University | And 44 more authors.
Astronomical Journal | Year: 2016

We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of ahierarchical triple stellar system. The host star is an F star with Teff =6206 ± 75 K, log g =4.108 ± 0.014, [Fe/H]= -0.116+0.069 +0.065, M∗ = 1.201-0.061 +0.067 M⊙, and R∗ = 1.603-0.038 +0.039 R⊙. The best-fit linear ephemeris is BJDTDB =2456193.29157±0.00021 + E(2.9895936±0.0000048). With a magnitude of V∼10, a planetary radius of 1.699-0.045 +0.046 RJ, and a mass of 0.902-0.059 +0.060 MJ, it is the brightest host among the population of inflated Hot Jupiters (RP > 1.5RJ), making it a valuable discovery for probing the nature of inflated planets. In addition, its existence within a hierarchical triple and its proximity to Earth (210 pc) provide a unique opportunity for dynamical studies with continued monitoring with high resolution imaging and precision radial velocities. The projected separation between KELT-4A and KELT-4BC is 328±16 AU and the projected separation between KELT-4B and KELT-4C is 10.30±0.74 AU. Assuming face-on, circular orbits, their respective periods would be 3780±290 and 29.4±3.6 years and the astrometric motions relative to the epoch in this work of both the binary stars around each other and of the binary around the primary star would be detectable now and may provide meaningful constraints on the dynamics of the system. © 2016. The American Astronomical Society. All rights reserved.


Beatty T.G.,Ohio State University | Pepper J.,Vanderbilt University | Siverd R.J.,Vanderbilt University | Eastman J.D.,Las Cumbres Observatory Global Telescope Network | And 31 more authors.
Astrophysical Journal Letters | Year: 2012

We report the discovery of KELT-2Ab, a hot Jupiter transiting the bright (V = 8.77) primary star of the HD42176 binary system. The host is a slightly evolved late F-star likely in the very short-lived "blue-hook" stage of evolution, with T eff = 6148 ± 48 K, log g = 4.030 +0.015 - 0.026 and [Fe/H] = 0.034 ± 0.78. The inferred stellar mass is M * = 1.314+0.063 - 0.060 M ⊙ and the star has a relatively large radius of R * = 1.836+0.066 - 0.046 R ⊙. The planet is a typical hot Jupiter with period 4.1137913 ± 0.00001 days and a mass of MP = 1.524 ± 0.088 M J and radius of RP = 1.290+0.064 - 0.050 R J. This is mildly inflated as compared to models of irradiated giant planets at the 4Gyr age of the system. KELT-2A is the third brightest star with a transiting planet identified by ground-based transit surveys, and the ninth brightest star overall with a transiting planet. KELT-2Ab's mass and radius are unique among the subset of planets with V < 9 host stars, and therefore increases the diversity of bright benchmark systems. We also measure the relative motion of KELT-2A and -2B over a baseline of 38years, robustly demonstrating for the first time that the stars are bound. This allows us to infer that KELT-2B is an early K dwarf. We hypothesize that through the eccentric Kozai mechanism KELT-2B may have emplaced KELT-2Ab in its current orbit. This scenario is potentially testable with Rossiter-McLaughlin measurements, which should have an amplitude of 44m s-1. © 2012 The American Astronomical Society. All rights reserved.


Fulton B.J.,University of Hawaii at Manoa | Collins K.A.,University of Louisville | Collins K.A.,Vanderbilt University | Gaudi B.S.,Ohio State University | And 31 more authors.
Astrophysical Journal | Year: 2015

We announce the discovery of a highly inflated transiting hot Jupiter 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+54 K, log g = 4.078-0.054+0.049, [Fe/H] = 0.272 ± 0.038, an inferred mass M = 1.211 -0.066+0.078 M, and radius R = 1.67-0.12+0.14 R. The planetary companion has a mass MP = 0.867-0.061+0.065 MJ, radius RP = 1.86-0.16+0.18 RJ, surface gravity log gP = 2.793-0.075+0.072, and density ρP = 0.167-0.038+0.047 g cm-3. The planet is on a roughly circular orbit with semimajor axis a = 0.04571-0.00084+0.00096 AU and eccentricity e = 0.035-0.025+0.050. The best-fit linear ephemeris is T0 = 2456883.4803 ± 0.0007 BJDTDB and P = 3.24406 ± 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 and large implied radius are supported by stellar density constraints from follow-up light curves, as well as 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+61 K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies. © 2015. The American Astronomical Society. All rights reserved.

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