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 sub(eff) = 6516+ or -49 K, log g = 4.228 super(+0.014) sub(-0.021) , and Fe/H = 0.052+ or -0.079, with an inferred mass M sub(*) = 1.335 + or - 0.063 M sub(middot in circle) and radius R sub(*) = 1.471 super(+0.045) sub(0.035) R sub(middot in circle). The companion is a low-mass brown dwarf or a super-massive planet with mass M sub(p) = 27.38 + or - 0.93 M sub(Jup) and radius R sub(p) = 1.116 super(+0.038) sub(-0.029) R sub(Jup). 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 + or - 1 mas, which is consistent with an M dwarf if it is at the same distance as the primary.
We report on the design and first year of operations of the DEdicated MONitor of EXotransits and Transients (DEMONEXT). DEMONEXT is a 20-inch (0.5-m) robotic telescope using a PlaneWave CDK20 ...telescope on a Mathis instruments MI-750/1000 fork mount. DEMONEXT is equipped with a 2048 × 2048 pixel Finger Lakes Instruments (FLI) detector; a 10-position filter wheel with an electronic focuser and B, V, R, and I, g ′ , r ′ , i ′ , z ′ ; and clear filters. DEMONEXT operates in a continuous observing mode and achieves 2-4 mmag raw, unbinned, precision on bright V < 13 targets with 20-120 second exposures, and 1 mmag precision achieved by binning on 5-6 minute timescales. DEMONEXT maintains sub-pixel ( < 0.5 pixels) target position stability on the CCD over 8 hours in good observing conditions, with degraded performance in poor weather ( < 1 pixel). DEMONEXT achieves 1%-10% photometry on single-epoch targets with V < 17 in 5 minute exposures, with detection thresholds of V 21 . The DEMONEXT automated software has produced 143 planetary candidate transit light curves for the KELT collaboration and 48 supernovae and transient light curves for the ASAS-SN supernovae group in the first year of operation. DEMONEXT has also observed for a number of ancillary science projects including Galactic microlensing, active galactic nuclei, stellar variability, and stellar rotation.
The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extrasolar planets now known, only six have been ...found that transit hot, A-type stars (with temperatures of 7,300-10,000 kelvin), and no planets are known to transit the even hotter B-type stars. For example, WASP-33 is an A-type star with a temperature of about 7,430 kelvin, which hosts the hottest known transiting planet, WASP-33b (ref. 1); the planet is itself as hot as a red dwarf star of type M (ref. 2). WASP-33b displays a large heat differential between its dayside and nightside, and is highly inflated-traits that have been linked to high insolation. However, even at the temperature of its dayside, its atmosphere probably resembles the molecule-dominated atmospheres of other planets and, given the level of ultraviolet irradiation it experiences, its atmosphere is unlikely to be substantially ablated over the lifetime of its star. Here we report observations of the bright star HD 195689 (also known as KELT-9), which reveal a close-in (orbital period of about 1.48 days) transiting giant planet, KELT-9b. At approximately 10,170 kelvin, the host star is at the dividing line between stars of type A and B, and we measure the dayside temperature of KELT-9b to be about 4,600 kelvin. This is as hot as stars of stellar type K4 (ref. 5). The molecules in K stars are entirely dissociated, and so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. Furthermore, KELT-9b receives 700 times more extreme-ultraviolet radiation (that is, with wavelengths shorter than 91.2 nanometres) than WASP-33b, leading to a predicted range of mass-loss rates that could leave the planet largely stripped of its envelope during the main-sequence lifetime of the host star.
The Kilodegree Extremely Little Telescope (KELT) project is a survey for planetary transits of bright stars. It consists of a small‐aperture, wide‐field automated telescope located at Winer ...Observatory near Sonoita, Arizona. The telescope surveys a set of 26° × 26° fields that together cover about 25% of the northern sky, and targets stars in the range of
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mag, searching for transits by close‐in Jupiters. This paper describes the system hardware and software and discusses the quality of the observations. We show that KELT is able to achieve the necessary photometric precision to detect planetary transits around solar‐type main‐sequence stars.
ABSTRACT We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of MJ, radius of RJ, and an orbital period of days. The bright host star (HD 33643; KELT-7) is an F-star with V = ...8.54, Teff = 6789 K, Fe/H , and . It has a mass of M , a radius of R , 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 ( km s−1) results in a Rossiter-McLaughlin 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 λ = 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.
Baseline values and ranges for 10 hematologic and 32 plasma chemistry parameters were analyzed for 36 free-ranging Sonoran desert tortoises (Gopherus agassizzi) collected in Yavapai and La Paz ...Counties (Arizona, USA) from 1990 to 1995. Tortoises were radio-tagged from 1990 to 1994, and attempts were made to recapture them three times a year. Tortoises were weighed, measured, and chemically immobilized to collect blood for hematology and blood chemistry assessments. Tortoise biochemistry differed (P < 0.01) between sites and sexes and among seasons and years. Normal reference ranges for hematologic and plasma biochemistry parameters were determined. Seasonal and annual differences in hematology and blood chemistry were related to rainfall patterns, forage availability, and physiological condition.
We report the discovery of KELT-20b, a hot Jupiter transiting a early A star, HD 185603, with an orbital period of days. Archival and follow-up photometry, Gaia parallax, radial velocities, Doppler ...tomography, and AO imaging were used to confirm the planetary nature of KELT-20b and characterize the system. From global modeling we infer that KELT-20 is a rapidly rotating ( ) A2V star with an effective temperature of K, mass of , radius of , surface gravity of , and age of . The planetary companion has a radius of , a semimajor axis of au, and a linear ephemeris of . We place a upper limit of on the mass of the planet. Doppler tomographic measurements indicate that the planetary orbit normal is well aligned with the projected spin axis of the star ( ). The inclination of the star is constrained to , implying a three-dimensional spin-orbit alignment of . KELT-20b receives an insolation flux of , implying an equilibrium temperature of of ∼2250 K, assuming zero albedo and complete heat redistribution. Due to the high stellar , KELT-20b also receives an ultraviolet (wavelength nm) insolation flux of , possibly indicating significant atmospheric ablation. Together with WASP-33, Kepler-13 A, HAT-P-57, KELT-17, and KELT-9, KELT-20 is the sixth A star host of a transiting giant planet, and the third-brightest host (in V) of a transiting planet.
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.
Worldwide variations in artificial skyglow Kyba, Christopher C M; Tong, Kai Pong; Bennie, Jonathan ...
Scientific reports,
02/2015, Letnik:
5, Številka:
1
Journal Article
Recenzirano
Odprti dostop
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.
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