Sonoita, AZ, United States
Sonoita, AZ, 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.

Siverd R.J.,Vanderbilt University | Beatty T.G.,Ohio State University | Pepper J.,Vanderbilt University | Eastman J.D.,Las Cumbres Observatory Global Telescope Network | And 34 more authors.
Astrophysical Journal | Year: 2012

We present the discovery of KELT-1b, the first transiting low-mass companion from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North) transit survey. A joint analysis of the spectroscopic, radial velocity, and photometric data indicates that the V = 10.7 primary is a mildly evolved mid-F star with T eff= 6516 ± 49 K, log g = 4.228 +0.014 -0.021, and [Fe/H] = 0.052 ± 0.079, with an inferred mass M⊙* = 1.335 ± 0.063 M ⊙and radius R* = 1.471+0.045 -0.035 R. The companion is a low-mass brown dwarf or a super-massive planet with mass MP= 27.38 ± 0.93 M⊙Jup and radius RP= 1.116+0.038 -0.029RJup. The companion is on a very short (∼29 hr) period circular orbit, with an ephemeris Tc(BJDTDB) = 2455909.29280 ± 0.00023 and P = 1.217501 ± 0.000018 days. KELT-1b receives a large amount of stellar insolation, resulting in an estimated equilibrium temperature assuming zero albedo and perfect redistribution of T eq= 2423+34 -27 K. Comparison with standard evolutionary models suggests that the radius of KELT-1b is likely to be significantly inflated. Adaptive optics imaging reveals a candidate stellar companion to KELT-1 with a separation of 588 ± 1 mas, which is consistent with an M dwarf if it is at the same distance as the primary. Rossiter-McLaughlin measurements during transit imply a projected spin-orbit alignment angle λ = 2 ± 16 deg, consistent with a zero obliquity for KELT-1. Finally, the vsin I* = 56 ± 2 km s-1 of the primary is consistent at ∼2σ with tidal synchronization. Given the extreme parameters of the KELT-1 system, we expect it to provide an important testbed for theories of the emplacement and evolution of short-period companions, as well as theories of tidal dissipation and irradiated brown dwarf atmospheres. © 2012. The American Astronomical Society. All rights reserved..

Mighell K.J.,National Optical Astronomy Observatory | Rehnberg M.,Beloit College | Rehnberg M.,University of Colorado at Boulder | Crawford R.,Rincon Ranch Observatory | And 2 more authors.
Publications of the Astronomical Society of the Pacific | Year: 2012

We present PHAST, a new IDL astronomical image viewer, based on the existing ATV application, which has been optimized for astrometry of Near Earth Objects (NEOs). After describing the features of PHAST, we describe how PHAST enabled the recovery of the Virtual Impactor (VI) 2011AX22 and the Potentially Hazardous Asteroid (PHA) 2008OX1. The recovery of 2011AX22 led to a large improvement in the time of perihelion passage and in the semimajor axis and eccentricity of its orbit. The distance of closest approach in May 2055 was moved away from Earth to >1 lunar distance. As a result of the orbital improvement made possible by the successful recovery, NEODyS downgraded 2011AX22 from a VI to a PHA, having ruled out the chance of an Earth impact this century. The recovery of 2008OX1 extended its observational arc to 1303 days-more than 2.5 orbital revolutions. It was confirmed to be a PHA and its orbit was improved sufficiently to permit prediction of its sky position to within 1″ over an interval of 10 years into the future. We discuss the astrometric and photometric performance of PHAST and then conclude by briefly describing future enhancements to the application. © 2012 The Astronomical Society of the Pacific.

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.

PubMed | Light Technology, Sotto le Stelle, McMaster University, and 20 more.
Type: | Journal: Scientific reports | Year: 2015

Despite constituting a widespread and significant environmental change, understanding of artificial nighttime skyglow is extremely limited. Until now, published monitoring studies have been local or regional in scope, and typically of short duration. In this first major international compilation of monitoring data we answer several key questions about skyglow properties. Skyglow is observed to vary over four orders of magnitude, a range hundreds of times larger than was the case before artificial light. Nearly all of the study sites were polluted by artificial light. A non-linear relationship is observed between the sky brightness on clear and overcast nights, with a change in behavior near the rural to urban landuse transition. Overcast skies ranged from a third darker to almost 18 times brighter than clear. Clear sky radiances estimated by the World Atlas of Artificial Night Sky Brightness were found to be overestimated by ~25%; our dataset will play an important role in the calibration and ground truthing of future skyglow models. Most of the brightly lit sites darkened as the night progressed, typically by ~5% per hour. The great variation in skyglow radiance observed from site-to-site and with changing meteorological conditions underlines the need for a long-term international monitoring program.

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.

Bieryla A.,Harvard - Smithsonian Center for Astrophysics | Collins K.,University of Louisville | Beatty T.G.,Pennsylvania State University | Eastman J.,Harvard - Smithsonian Center for Astrophysics | And 34 more authors.
Astronomical Journal | Year: 2015

We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of 1.28 ± 0.18MJ, radius of 1.533 0.047 0.046RJ, and an orbital period of 2.7347749 ± 0.0000039 days. The bright host star (HD 33643; KELT-7) is an F-star with V = 8.54, Teff= 6789 49 50 K, [Fe/H] 0.139 0.081 = -0.075, and log g = 4.149 ± 0.019. It has a mass of 1.535 0.054 0.066 Me, a radius of 1.732 0.045 0.043 Re, and is the fifth most massive, fifth hottest, and the ninth brightest star known to host a transiting planet. It is also the brightest star around which Kilodegree Extremely Little Telescope (KELT) has discovered a transiting planet. Thus, KELT-7b is an ideal target for detailed characterization given its relatively low surface gravity, high equilibrium temperature, and bright host star. The rapid rotation of the star (73 ± 0.5 km s-1) results in a RossiterMcLaughlin effect with an unusually large amplitude of several hundred m s-1. We find that the orbit normal of the planet is likely to be well-aligned with the stellar spin axis, with a projected spin orbit alignment of = 9.7 ± 5. 2. This is currently the second most rapidly rotating star to have a reflex signal (and thus mass determination) due to a planetary companion measured. © 2015. The American Astronomical Society. All rights reserved.

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